Ci a ion: Redeka , A.; Deb, D.;
Ozana, S. Func ionali y Analysis o
Elec ic Ac ua o s in Renewable
Ene gy Sys ems—A Re iew. Senso s
2022,22, 4273. h ps://doi.o g/
10.3390/s22114273
Academic Edi o : Mingliang Zhang
Recei ed: 11 Ap il 2022
Accep ed: 30 May 2022
Published: 3 June 2022
Publishe ’s No e: MDPI s ays neu al
wi h ega d o ju isdic ional claims in
published maps and ins i u ional a il-
ia ions.
Copy igh : © 2022 by he au ho s.
Licensee MDPI, Basel, Swi ze land.
This a icle is an open access a icle
dis ibu ed unde he e ms and
condi ions o he C ea i e Commons
A ibu ion (CC BY) license (h ps://
c ea i ecommons.o g/licenses/by/
4.0/).
senso s
Re iew
Func ionali y Analysis o Elec ic Ac ua o s in Renewable
Ene gy Sys ems—A Re iew
Abhijee Redeka 1, Dipanka Deb 1,∗and S epan Ozana 2
1Depa men o Elec ical Enginee ing, Ins i u e o In as uc u e Technology Resea ch and Managemen
(IITRAM), Ahmedabad 380026, India; abhijee . edeka [email p o ec ed]
2Depa men o Cybe ne ics and Biomedical Enginee ing, Facul y o Elec ical Enginee ing and Compu e
Science, VSB-Technical Uni e si y o Os a a, 17. lis opadu 2172/15, 708 00 Os a a, Czech Republic;
[email p o ec ed]
*Co espondence: dipanka [email p o ec ed]
Abs ac :
Va ious mechanical, hyd aulic, pneuma ic, elec ical, and hyb id ac ua o s can al e mo ion
pe he equi emen s o pa icula applica ions. Howe e , excep o elec ical ones, all ac ua o s
a e es ic ed due o hei size, complex auxilia y equipmen , equen need o main enance, and
sluggish en i onmen in enewable applica ions. This b ie e iew pape highligh s some unique
and signi ican esea ch wo ks on applying elec ical ac ua o s o enewable applica ions. Fou
enewable ene gy esou ces, i.e., sola , wind, bio-ene gy, and geo he mal ene gy, a e conside ed o
e iew elec ic ac ua o s applicable o enewable ene gy sys ems. This e iew analyses he ypes
o ac ua o s associa ed wi h he men ioned enewable applica ion, hei unc ioning, hei mo ion
ype, p esen use, ad an ages, disad an ages, and ope a ional p oblems. The in o ma ion ga he ed in
his pape may open up new ways o op imiza ion oppo uni ies and con ol challenges in elec ical
ac ua o s, he eby making mo e e icien sys ems. Fu he mo e, some ene gy-e icien and cos -
e ec i e eplacemen s o con ec ional ac ua o s wi h new inno a i e ones a e sugges ed. This wo k
aims o bene i scien is s and new en an s wo king on ac ua o s in enewable ene gy sys ems.
Keywo ds:
elec ic ac ua o s; linea ac ua o s; o a y ac ua o s; powe consump ion; sphe ical
ac ua o s; enewable sys em
1. In oduc ion
An ac ua o is a i al componen o any physical sys em enabling mo emen s by
con e ing an ene gy sou ce in o ano he , p ima ily elec ical, ai , o hyd aulic ene gy,
in o mechanical o ce [
1
,
2
] o modi y he cu en sys em’s s a e. Some majo applica ions
include he au omo i e indus y, u ni u e-e gonomics, au oma ion, indus ial machine y,
ma i ime applica ions, he medical indus y, and enewable ene gy sys ems. Va ious ypes
o ac ua o s a e in use (as pe he powe sou ces used) such as elec ical ac ua o s [
3
],
hyd aulic ac ua o s [
4
], pneuma ic ac ua o s [
5
], mechanical ac ua o s, and a combina ion
o hese such as elec o-hyd aulic [
6
], elec o-pneuma ic [
7
], elec o-mechanical [
8
], sel
d i en he mo-mechanical [
9
], e c. An elec ic ac ua o c ea es a load mo emen o an
ac ion equi ing a o ce such as clamping, using an elec ic mo o o c ea e he desi ed
o ce, con e ing elec ici y in o kine ic ene gy o au oma e al es, o dampe ac ions using
p ecise low con ol [
10
]. Elec ic mo o s may wo k on AC o DC supplies depending on
he equi emen s o he applica ion, limi swi ches, b ake mechanisms, esol e s, empe -
a u e senso s, e c. The desi ed o ce is gene a ed om he mo o ’s o que capabili y and
au oma es indus ial al es, p ocess plan s, low con ol, he mal powe plan s, i iga ion
sys ems, e c. [11].
Renewable ene gy plays a pi o al ole in ackling clima e change by educing g een-
house gas emissions and ossil uel use. Ene gy con e sion sys ems d i en by ac ua o s
help ensu e op imal con e sion while ans o ming enewable sou ces in o aluable o ms.
Senso s 2022,22, 4273. h ps://doi.o g/10.3390/s22114273 h ps://www.mdpi.com/jou nal/senso s
Senso s 2022,22, 4273 2 o 26
Ro a y o linea mo ion is achie able using a mechanical ansmission uni , called linea
mo ion ac ua o s, which a e be e in accu acy han o a y ac ua o s, compac in size,
and easy o use in many applica ions such as sola acking sys ems [
12
], whe e sola
panels can ack he sun’s appa en mo ion; sola u nace sys ems [
13
], whe e he mo ion
equi ed o con ol he sun- ays by mo ing shu e s; sola hea e sys ems [
14
], whe e sun
ays a e concen a ed on oil pipes (called ac i e a ea) placed o e he pa abolic sola panels;
sola cleaning sys ems [
15
,
16
], whe e wo mo ions a e pe o med ( iz., x-axis and y-axis
mo ion) o clean he whole sola panel; small-scale wind sys ems [
17
], whe e ac ua o s
a e used as p o ec ion de ices in high wind speeds; wa e sys ems [
1
,
2
,
18
,
19
], whe e ac u-
a o s a e used in he con e sion o wa e mo ion o linea and o a y mo ion o ene gy
gene a ion; and bio-ene gy sys ems [
20
–
23
], whe e ac ua o s au oma e he ope a ion o
geologically dis ibu ed sys ems.
Ene gy op imiza ion is achie able by inc easing ene gy gene a ion o educing ene gy
consump ion. In sola panel cleaning, Williams e al. [
15
] use piezoce amic ac ua o s o
sel -cleaning ope a ion. The esul s show ha dus mo es away om high o low ib a ion
eloci y. The con ec ional sola panel’s mechanical cleaning s uc u e is called a gan y
s uc u e [
24
] and is ope a ed by wo o a y ac ua o s. Using elescopic ac ua o s o e s he
possibili y o educing he use o one o a y ac ua o o educed o e all cos and ene gy
consump ion. In sola u nace sys ems [25], ins ead o o a y ac ua o s by applying linea
ac ua o s, one may neglec he mechanical dead zone o dec eased ope a ion ime due o
he quick esponse inc eased es ing quali y. Fo sola ee applica ions, a 2DOF sphe ical
ac ua o [
26
] is mo e bene icial han a linea ac ua o . The e a e wo ad an ages: less space
equi ed and a mechanical la ch a angemen which uses educed powe while mo ing.
Such an app op ia e selec ion o ac ua o ensu es an op imal sys em ope a ion.
Ac ua o s a e mainly classi iable in o ac i e and passi e ac ua o s. The ac i e ac ua o s
need an elec ic ene gy sou ce o unc ioning. In con as , passi e ac ua o s do no
equi e a sou ce and unc ion based on na u al ene gy, such as he mal expansion ma e ial,
and ene gy s o ed in he sp ing [
27
]. Va ious equi ed mo ions a e ci cula , o a ional,
oscilla o y (seismic), and ec ilinea . The e o e, elec ic ac ua o s a e classi ied acco ding
o hei mo ion, deg ee o eedom (DOF), and exci a ion sou ces o pa icula unc ional
mo ion. As pe mo ion, ac ua o s a e o a y ac ua o s, linea ac ua o s, and a new one called
a sphe ical ac ua o wi h mul iple deg ees o eedom [
26
]. Linea mo ion ac ua o s a e
spli in o wo ca ego ies: o a y- o-linea (hyb id mo ion) ac ua o s in ol ing mechanical
ansmission uni s (also called elec omagne ically linea ac ua o s as shown in Figu e 1)
and di ec linea mo ion ones no equi ing mechanical ansmissions uni s.
Figu e 1. Ac i e elec ic ac ua o s acco ding o hei mo ion used in he enewable applica ions.
Senso s 2022,22, 4273 3 o 26
Ac ua o s a e used in enewable ene gy sou ces such as sola acking applica ions
o d i e sola panels, sola dishes, helios a s, and sola cooke s mo ing owa ds he sun
h oughou he day [
28
]. Sola wa e pumping applica ions use linea ac ua o s in a wa e
pump sys em [
29
], and sola acking, o cooke , applica ions use ac ua o s (mo o s o
shape memo y alloys) o d i e he o a ion o panels owa ds he sun h oughou he day
a a a e o 15
◦
/h [
27
,
30
]. Depending on he empe a u e, ce ain ma e ials in a he mo-
mechanical ac ua o help con ol he collec o ’s angle o inclina ion o ace he sun and
p o ide inc eased p oduc ion o abou 39% compa ed o a ixed sys em. In addi ion, he e
a e some bioene gy applica ions, whe e o a y ac ua o s a e used o ag icul u al machine y
and he au oma ion o geog aphically dis ibu ed biogas sys ems; po able wind ene gy
applica ions [
31
] wi h ac ua o -con olled o e -speeding; wa e ene gy applica ions, whe e
ac ua o s a e used in powe -gene a ion pu poses [
32
]; sma g id o mic og id en i on-
men [
33
], whe e ac ua o s con ol powe gene a ion and consump ion; and geo he mal
powe plan s wi h elec ic al e ac ua o s.
Ro a y (also called elec omechanical o a y) ac ua o s help mo e la ge loads in angu-
la inc emen s. They include elec ical mo o s wi h gea boxes used o change he di ec ion
o o a ion o achie e he desi ed o que and speed wi h he desi ed adjus able o a ion
angle. Examples o he o a y ac ua o s a e induc ion mo o s, DC mo o s (b ushed and
b ushless), synch onous mo o s, and special mo o s such as s eppe and se o mo o s.
Mo o s’ selec ion ac o s o ac ua ion a e speed, ou pu o que, ype o supply equi ed,
and mo o du y cycle. Howe e , induc ion mo o s, which gi e almos synch onous speed,
a e e ec i e wi h high powe equi emen s. Due o he low ine ia, se o mo o o o s
wo king on AC o DC supply and con olled h ough pulse wid h modula ion can quickly
s a and s op and a e used o posi ion mechanical pa s p ecisely. Such p ecise mo ion
con ol is needed in CNC machines and p oduc ion assembly lines. In addi ion, DC se o,
DC b ushed, and BLDC mo o s a e economical and less complex ac ua ion de ices. Unlike
se os, a s eppe mo o ha di ides he o a y mo ion in o equal small s eps can p o ide
360-deg ee con inuous o a ion and is help ul o high o que ou pu and high accu acy
a low-cos [
34
]. Howe e , due o elec ical (cogging) and mechanical (dead zone) non-
linea i ies [
35
], hese o a y ac ua o s a e ela i ely less e icien and ha e lowe accu acy.
Whene e we may ace mo o concussion p oblem [
36
], accu acy is imp o ed by using
special mo o s such as s eppe mo o s and se o mo o s, which s ill ace mechanical non-
linea i ies and, hus, low pe o mance. In mecha onic sys ems, elec ic o a y ac ua o s
ind ex ensi e use.
A o a y solenoid is mo e sui able o small o a ions and low o que applica ions
han a cos ly and complex con ol ci cui y s eppe mo o . I comp ises an elec omagne ic
coil ope a ed on a DC supply, o o , and o sion sp ing. The change in supply pola i y is
easily handled in he di ec ion o o a ion, p o iding a meage angle o a ional mo emen
a ound a ixed axis (usually
⩽±
360
◦
). Typical o a y solenoids ha e bi-s able posi ions ha
do no equi e powe o hold ei he end posi ion, minimizing ene gy consump ion. I can
d i e came a shu e s and mi o de lec ions, luid/gas al es, he ac ua ion o indica ing
ins umen s, applica ion a eas such as he packaging indus y, medical de ices, appa a us
cons uc ion, and ood echnology o in e locking pu poses. Ro a y- o-linea ac ua o s
(also called elec o-mechanical linea ac ua o s) comp ises elec ic mo o s and mechanical
ansmission elemen s. The o a ional mo ion con e s in o linea mo ion using mechanical
ansmission elemen s, such as he ball and sc ew mechanism, he lead sc ew mechanism,
he ack and pinion mechanism, he bel and pulley mechanism, and igid chains. Such
elemen s slow down elec ic o a ions, he eby inc easing o que such ha he load on he
ansmission pa mo es smoo hly. The ball and sc ew a e made ou o a cylinde o allow
he e-ci cula ion o he balls, causing linea mo emen , bu a e used o dis inc pu poses
and a e no in e changeable [37].
Unlike o a y o linea ones, di ec linea mo ion ac ua o s ha e no ansmission
elemen s and p o ide high accu acy, esolu ion, and speed. The e a e a ious ypes, iz.,
i on co e linea mo o s, U-channel linea mo o s, linea sha mo o s, oice coil mo o s,
Senso s 2022,22, 4273 4 o 26
linea mo ion solenoids, sc ew- ype linea piezoelec ic ac ua o s [
38
], and elec omagne ic
clu ches. The s a o and o ce (called o o ), wi h a pe manen magne and elec omagne ic
coils, espec i ely, c ea e linea o ce. Howe e , he i on co e b ings cogging and eddy
cu en s, hea , magne ic sa u a ion, and la e al o ces. U-channel di ec linea mo o
elimina es such disad an ages, p o iding inc eased o ce h ough an addi ional pe manen
magne on he opposi e side o a double-sided con igu a ion, wi h elec omagne ic coils
in an epoxy-moun ed non- e ous o ce aluminum pla e. The absence o a magne ic
co e elimina es cogging, bu educes hea dissipa ion, and a double-sided con igu a ion
inc eases cos . Al hough hey do no gene a e he same o ces as an i on co e mo o and
U-channel linea mo o s, hey do no ha e o deal wi h he addi ional issues wi h ha
design. Voice coil ac ua o s, wo king on he p inciple o Lo en z o ce, a e a di ec d i e
mechanism ha allows o excellen ine-posi ioning o e small mo emen s.
An elec omagne ic de ice called a “Linea Solenoid” u ns elec ical ene gy in o
a mechanical pushing o pulling o ce o mo ion o apid ON and OFF ope a ion and
mainly comp ises an elec omagne ic coil, a plunge (a ma u e), and a sp ing. When
he coil ene gizes, he sp ing is comp essed o he al e o open, and when he coil
de-ene gizes, he sp ing mo es downwa d o close he al e and con ol luid/ai low
as a solenoid al e. Howe e , he disad an ages a e ha he e a e only wo a ailable
posi ions, i.e., ully open o closed, gene a ing a limi ed linea o ce o elec ically opening
doo s and la ches. Elec ic (also called elec omagne ic) clu ches ha e an elec ic ac ua ion
be ween wo o a ional gea s (d i e/inpu and d i en/ou pu ) o mechanical ansmission
o o que h ough linea mo ion, i.e., ope a e elec ically and ansmi o que mechanically.
The passage o a cu en h ough he clu ch coil makes i an elec omagne p oducing
magne ic lines o lux [
39
]. Al hough mainly used in biogas au oma ion [
20
], clu ches
a e also used in con eyo d i es, packaging machine y, and ac o y au oma ion. Apa
om linea and o a y mo ion, he new sphe ical mo ion ac ua o s [
26
] a e mul i-deg ee-o -
eedom oice coil de ices wi h a sphe ical-shaped s a o , wo coils, a ball-shaped o o ,
and mul iple pe manen magne s (a plu ali y o magne s) [
40
] applied o obo eyes, join s,
and sola ees.
This comp ehensi e li e a u e su ey ocuses exclusi ely on enewable applica ions
wi h elec ical ac ua o s. Pa icula ac ua o s ind a place in mul iple enewable ene gy
sys ems, while o he s ha e only speci ic o limi ed usage. Fu he mo e, he e a e ce -
ain ad an ages and disad an ages (p o ided subsequen ly in each Sec ion) conce ning
ac ua o mo ion. We also sugges some al e na i e solu ions o con en ional ac ua o s.
Howe e , he o e all ad an ages o elec ic ac ua o s agains non-elec ical ac ua o s (such
as hyd aulic and pneuma ic) a e gi en as ollows:
(i)
Lowe esponse ime: Elec ical ac ua o s a e di ec ly d i en wi hou auxilia y acces-
so ies, unlike hyd aulic ac ua o s, which comp ise mo o s, hyd aulic anks, con olling
al e pipes, and cylinde s, and hence a e as ope a ing.
(ii)
Ligh weigh : Compa ed o non-elec ical ac ua o s, elec ic ac ua o s a e ligh weigh
and easy o ins all, wi h no ad e se e ec on sys em pe o mance. The cos o o e all
ins alla ion and ma e ial is educed [15,41].
(iii)
P ecision con ol: The low ole ances compa ed o non-elec ical ac ua o s such as gea
backlash, slack, and inhe en lex p o ide highly p ecise posi ioning [42].
(i )
Compac in size: Elec ic ac ua o s a e compac due o hei di ec elec omagne ic
ene gy con e sion sys em, and hey a e designed o any space and physical size [
26
].
( )
Clean: Elec ical ac ua o s a e a clean sou ce o ene gy wi h no chance o leaking o
di y wo k a eas [43].
( i)
IoT compa ible: Mo ion and posi ion a e easily measu able due o inbuil o a ion
senso s, and encode s and easily ans e o an IoT en i onmen [44,45].
The pape ’s s uc u e is as ollows. Sec ion 2 e iews a ious ypes o elec ic ac ua o s
in di e en sola sys em applica ions such as sola acking, u nace, hea e , and sola panel
cleaning. Sec ion 3p esen s a b ie e iew o elec ic ac ua o s used in wind applica ions,
especially minia u e oo op wind u bines and wa e ene gy applica ions. Then, Sec ion 4
Senso s 2022,22, 4273 5 o 26
e iews ac ua o s used in bioene gy applica ions, including ag icul u e and i iga ion.
Sec ion 5p esen s impo an pe o mance pa ame e s o ac ua o s and e olu ion. Finally,
Sec ion 6p esen s he conclusions and u u e di ec ion.
2. Ac ua o s o Sola Sys em Applica ions
Sola ene gy is a ee and abundan sou ce a ailable on his plane ha is ex ac ed
in a ious ways, such as elec ic powe gene a ion using sola pho o ol aic cells o
sola -dis ibu ed collec o s o hea ing applica ions, such as a sola wa e hea e , u -
nace, hea e , e c. Nex , we p esen a su ey o elec ical ac ua o s used in di e en sola
ene gy applica ions.
2.1. Ac ua o s o Sola T acking Applica ions
Sola panels need o ollow he sun’s mo emen o ex ac he maximum easible
ene gy. As he sun ises om he eas and se s in he wes , he acke sys em aims o ollow
he sun’s mo emen o , du ing he day, keep he sola panel pe pendicula o he sun,
i.e., o ollow he sun’s day o day and seasonal mo emen o maximum powe ex ac ion.
The acking sys em inds use in sola PV panels, in mo ing helios a mi o s, pa abolic
concen a o s, and sola collec o s. We explo e a ious ac ua o s p esen ly in use o sola
acking. Figu e 2shows indi idual sola panel acking and simul aneous- acking (i.e.,
g oup acking) sola panels. The linea mo ion o he linea ac ua o is achie ed om he
mo o ’s o a y mo ion. In e nally some mechanical mo ion change a angemen s con e
he mo ion, such as ball–sc ew, lead–sc ew, e c. This mechanical de ice also manipula es
he o que and speed as equi ed wi h an app op ia e pi ch o he sc ew.
Figu e 2. Elec ic ac ua o s unc ioning in sola acking applica ions.

Senso s 2022,22, 4273 6 o 26
Linea ac ua o s and o a y ac ua o s achie e sola acking. Single-axis acking,
whe e a sola panel acks he day- o-day mo emen o he sun (i.e., only eas o wes
mo emen ), is achie able only using one linea ac ua o [
27
]. The linea mo emen o
he ac ua o is also shown h ough single-axis acking wi h linea ac ua o s in Figu e 2.
In he mo ning, he sola panel aces he eas di ec ion, and he ac ua o s a e in he ini ial
posi ion, i.e., ac ua o pis ons a e inside he ac ua o housing. (No e ha he igu e shows
a wes - acing panel and he ac ua o pis on is en i ely ou side he housing.) As he sun’s
mo emen s a s, he ac ua o ecei es signals om he con olle , and he mo o s a s
o a ing piecewise, which con inues un il sunse on he wes e n side. A his ime, he panel
aces he wes di ec ion. A nigh , he sola panel mo es back o he ini ial posi ion h ough
he linea ac ua o as he mo o o a es an i-clockwise and he pis on goes inside he
housing. The sun changes i s azimu h angle posi ion as seasons change, and he panel
canno change he il ed posi ion [
12
]. Hence, he panel canno ecei e pe pendicula sun
ays, he eby dec easing he yield. When he PV panel is in he e ical posi ion, he panel
cap u es only a ew ays and is he e o e ne e used. When he PV panel is ho izon al,
he panel cap u es mo e ays. When mo ing along wi h he sun’s seasonal mo emen (i.e.,
il ), he panel cap u es maximum sun ays, inc easing he yield.
Mo eo e , single-axis acking is achie able h ough o a y ac ua o s, as shown in
Figu e 2which p o ide oll mo emen achie ed by elec ic mo o gea a angemen .
The o a y ac ua o has a speed educ ion gea box, which dec eases speed and inc eases
o que. Al hough o a y ac ua o s a e no hing bu mo o s wi h a mechanical gea o a
ack and pinion, hey change he di ec ion o mo ion wi h he desi ed o que. In e ac ion
be ween he panel and ac ua o happens h ough a qua e -shaped gea disc a ached
o he sola panel base o achie e oll mo emen o he panel smoo hly. This me hod is
qui e uneconomical o indi idual acking due o he ample o que o o a y ac ua o s.
In con as , such o a y ac ua o s a e sui able o simul aneous acking whe e ample o que
is equi ed [
46
]. Fo ecei ing maximum sun ays, he sola panel should achie e bo h
day- o-day and seasonal mo emen s. So, we need dual-axis acking achie able using wo
linea ac ua o s named dual-axis acking wi h linea ac ua o s.
Th ee posi ions o he sola panel is shown in he dual-axis acking o Figu e 2, which
pe ain o he ime o he day be ween 9:00 A.M. and 15:00 P.M. [
27
]. A 9:00 A.M., Ac ua o
1’s ini ial pis on posi ion is inside he housing, as shown in Pa (a) in dual-axis acking,
wi h he panel o ien ed owa ds he mo ning sun. A noon, as shown in Pa (b), Ac ua o
1’s pis on posi ion is pa ially ou side o he cylind ical block panel o ien ed owa ds he
a e noon sun. A 3.00 P.M., as shown in Pa (c), Ac ua o 1’s pis on posi ion is ou side he
housing such ha he panel is o ien ed di ec ly unde he mid-a e noon sun.
Ac ua o 2 helps accoun o seasonal changes. In a sola a m, indi idual panel ack-
ing is non-economical. All sola panels in a pa icula ow need o mo e simul aneously.
Figu e 2also shows simul aneous acking wi h o a y ac ua o s. Only eas - o-wes acking
is possible wi h simul aneous acking. Two ac ua o s, used in a model by Hammed e al.,
is also called a wo-axis acke , whe e wo independen mo o s (o ac ua o s) ensu e mo-
ion along an axis: one accoun ing o he azimu h angle and ano he o he al i ude [
47
].
Jo ano ic e al. use a linea ac ua o [
48
] o ob ain he eas - o-wes mo ion o he sola panel.
Weigh educ ion and cos -e ec i eness a e he p ima y conside a ions in his case and is
accomplished by choosing a single linea ac ua o ins ead o he usual o a ional ac ua o .
Powe consump ion in he ac ua o depends on he ancho loca ion. Fo example, o a
mo ing panel o +45
◦
, mo e consump ion is no ed han
−
45
◦
o a ion due o wind p essu e
du ing posi i e angle acking. The ‘ il ’ and ‘ oll’ (shown in Pa (b) o dual-axis acking
in Figu e 2) acke employs a linea ac ua o and dampe s [
12
]. Linea mo emen wi h a
ba mechanism in he ‘ oll’ axis inds use in he concen a ion o pho o ol aic echnologies,
and wo di e en helios a -based acking me hods a e discussed [49].
The acking ac ua o ope a es in s eps in in e mi en sun- acking sys ems, so he
ac ua o powe consump ion is mo e. Fe daus e al. desc ibe an ene gy-e icien sola
acking sys em using a hyb id (con inuous as well as s a ic) dual-axis using wo ully
Senso s 2022,22, 4273 7 o 26
gea ed s eppe mo o s o wo di e en axes: 0.6 Wa powe consump ion in an ac ua o
and a 25.62% ene gy gain eco ded as compa ed o a s a ic sola panel sys em [
50
]. In
addi ion, Ba ayneh e al. [
51
] apply h ee-s ep in e mi en acking, wi h 0.4 Wa powe
consump ion in ac ua o and an a ound 91–94% ene gy inc emen compa ed o con inuous
acking. As we inc ease he in e mi en s ep by op imiza ion me hod, he e is a sa ing in
ac ua o powe consump ion, and almos he same gain is ob ained compa ed o con inuous
acking. S ill, as pe [
52
], he simula ion esul s a one s age s ep by s ep acking consume
conside able powe in he ac ua o because o he o e shoo ing occu ing when he mo o is
u ned on/o . The ene gy consump ion o achie ing s ep-by-s ep mo ion laws is sligh ly
highe han ha o con inuous mo ion. Table 1shows esul s ha a e he ou h s ep,
he ac ua o consump ion is mo e han he con inuous sys em, and he ene gy gain is
also less.
Table 1. Ene gy consump ion in con inuous and s ep-by-s ep acking [52].
Numbe o S eps One-Day Ene gy
P oduc ion (Wh)
One-Day Ene gy
Consump ion in
Ac ua o (Wh)
One-Day Ene gy
Gain (%)
0 (i.e., con inuous) 898.46 12.82 39.42
8 893.27 13.32 38.21
6 891.73 12.99 38.02
4 887.32 12.92 37.34
2 868.63 12.88 34.41
Bes pe o mance h ough sola acking is achie able when he acke ’s il angle
synch onizes wi h he annual changes o he sun’s al i ude (i.e., he sun’s seasonal mo-
ion). Howe e , a single-axis acke wi h an elec ic linea ac ua o sees highe ene gy
consump ion on sunny days and lowe a smoggy imes, ha is, depending on he local
wea he condi ions [
53
]. Elsewhe e, Ponni an e al. e alua e a single-axis sola - acking
sys em’s pe o mance o h ee di e en o a y ac ua o mo o s used indi idually (AC
induc ion mo o , DC mo o , and s eppe mo o ) [
46
] in compa ison wi h linea ac ua o s.
Finally, in e ms o economic conside a ions, A geseanu e al. e alua e he cos ac o in
acking sys ems by designing a low-cos dual-axis sola acking s uc u e wi h mo o [
54
].
Senso -based acking is mo e accu a e han azimu h-based acking [55].
The e is a signi ican bene i o dual-axis acking [
56
]. Wi hou acking, he yield
g aph looks like a hal -sine wa e wi h he peak a noon. Wi h dual-axis acking, he yield
is a apezoidal shape o a la ge a ea, bu he e is a need o wo ac ua o s, bo h in he
case o linea and o a y ac ua o s. Such ac ua o s wi h dual-axis acking a e e ec i e in
sola a ms wi h se e al ows o panels placed. The numbe o ac ua o s equi ed is less in
such cases due o simul aneous acking, causing a signi ican up ick in powe gene a ion.
Howe e , such ac ua o s a e no sui ed in he sola ee concep whe e space is an issue.
Two ac ua o s o each panel in dual-axis acking a e needed, g oup acking is no easible,
and he numbe o ac ua o s equi ed is mo e like a sola s ee ligh sys em.
The ad an age o a sola acking sys em wi h one ac ua o is ini ial cos educ ion,
bu i dec eases yield. In con as , sola acking wi h wo ac ua o s inc eases yield bu also
he ini ial cos o he sys em. To only seek he ad an ages o bo h, a new ype o ac ua o
called a sphe ical ac ua o [
26
] may be an ideal eplacemen o he linea ac ua o s in
applica ions such as a sola ee, such ha i accomplishes he ask o he exis ing dual-axis
acking wi h a single sphe ical ac ua o . Fu he mo e, wo deg ees o eedom (DOF)
sphe ical ac ua o s shown in Figu e 3d wi h mechanical la ch can pe o m acking on bo h
axes o inc eased ene gy ex ac ion and educed cos . In addi ion, due o he la ching
a angemen , he ene gy is equi ed o he ac ua o only when mo ion is equi ed; hence,
i can be mo e ene gy-e icien han wo-axis acking. The mos signi ican ad an age o
he sphe ical ac ua o is i s compac ness; i can be used in sola ee applica ion as shown
in Figu e 3e and s ee ligh applica ions as shown in Figu e 3c.
Senso s 2022,22, 4273 8 o 26
Figu e 3.
P oposed al e na i e ac ua o s iew: (
a
) sola u nace wi h linea ac ua o , (
b
) sola panel
wi h elescopic linea ac ua o , (
c
) s ee ligh applica ion wi h sphe ical ac ua o , (
d
) 2 DOF sphe ical
ac ua o , (e) sola ee applica ion wi h sphe ical ac ua o .
2.2. Ac ua o s o Sola Fu nace Applica ions
A sola u nace is a enewable (g een) sou ce o ene gy. I is a he modynamic
s uc u e [
13
] ha p o ides concen a ed sola adia ion, as shown in Figu e 4a, using
concen a ed sola powe o p oduce e y clean and high- empe a u e hea , a ound
3500 °C (6330 ◦F) [25].
Figu e 4.
Ro a y ac ua o s unc ioning in sola u nace applica ion (
a
) Schema ic Diag am, (
b
) U.S.
A my’s whi e sands sola u nace commissioned in 1972 [57,58].
Senso s 2022,22, 4273 9 o 26
A sola he mal powe gene a ion plan commonly employs a sola u nace sys em
di e en om a sola ene gy sys em because i is an indi ec use o sunligh e lec ed and
hen concen a ed on one poin o in e es . The gene a ed hea is mainly aluable o
indus ial applica ions, he hea ing p ocess o a subs ance, ma e ial es ing, cha ging expe -
imen s, mel ing s eel, hyd ogen uel, and ound y applica ions. The p ima y sola u nace
s uc u e wi h componen s such as helios a mi o s (No isible in Figu e 4b, bu shown
in Figu e 4a), a pa abolic concen a o (Numbe 2, shown in Figu e 4b), and mechanical
shu e s (Numbe 1, shown in Figu e 4b) ope a ed h ough an elec ic ac ua o is s anda d
o all applica ions. A la helios a e lec s he sola adia ion coming om he sun owa ds
pa abolic concen a o mi o s. Ro a y ac ua o s o linea ac ua o s placed a he helios a
mi o s ack he sun’s mo emen o e lec maximum sunligh , passing h ough ows o
ho izon al moun ed mechanical shu e s whose o a y mo ion con ols and egula es he
e lec ed sun ays as pe he hea equi emen [
59
]. The gene al opening and closing ange
o shu e s a e 0–90
◦
, whe e 0
◦
means shu e s a e ully open o allow passage o maximum
sun ays coming om la helios a , and a 90
◦
, he shu e s ully close o p e en means
sun ays om passing o he concen a o . Ro a y and linea ac ua o s achie e such ype o
mo ion, bu p ima ily, o a y ac ua o s ind p e e ence due o la ge o que equi emen s.
Gene ally, AC o DC mo o s and gea boxes help change he posi ion o he shu e s [
13
].
Finally, he sun ays eaching he pa abolic mi o s a e concen a ed on o a es a ea (Num-
be 3, shown in Figu e 4b) o es ing elec ical, mechanical, and me allu gical ma e ials
unde high- empe a u e hea . Speci ically, mol en sal is pumped in o he u nace es a ea
(also called he owe ) in a sola he mal powe plan . The mol en sal empe a u e ises
om a ound 300
◦
C o o e 600
◦
C. Then, high- empe a u e mol en sal is anspo ed o a
s o age ank and is used o s eam gene a ion and e en ually elec ic powe gene a ion.
The disad an age o a o a y ac ua o in mo ing shu e s is ha he e will be no quick
esponse o opening and closing shu e s due o he backlash nonlinea i y o he gea ing
box. In addi ion, he e is he addi ional disad an age o inc eased space equi emen .
Ins ead o a o a y ac ua o , a low-powe linea ac ua o will be ad an ageous, as shown
in Figu e 3a, because he e will no be an ac i e load on he shu e s, and so he linea
ac ua o s pe o m he shu e ’s ask wi h low ene gy consump ion and also occupy less
space. Adjus men o shu e angle wi h a o a y ac ua o enables con ol o sola lux by
con olling he speed o shu e opening, and closing [
60
]. An aluminum shu e blade
ope a ed by a closed-loop se e mechanism helps con ol sun ays passing om sola
mi o o concen a o . Cos a e al. also use a sola u nace [
13
] whe ein b ushless DC
mo o and gea mechanism, i.e., o a y ac ua o , con ols he shu e blade mo emen .
Shu e s con ol sola adia ion, which helps educe he concen a ion so ha o e hea ing
o he sola u nace is p e en ed.
Fo ins ance, a 1 MW la ge sola u nace ha has been ope a ional since 1968 in Fon
Romeu Odeillo [
43
] has seen an upg ade om hyd aulic ac ua o s o elec ic b ushless DC
mo o s o e icien ope a ion. These e olu ions in he applica ion o he ac ua o and hei
powe consump ion a e shown in Table 2.
Table 2. Re olu ion in applica ion o sola u nace ac ua o ins alled a Fon Romeu Odeillo.
Gene a ion Yea Ac ua o
Powe
Consump ion in
Ac ua o
Main enance
F equency
Deg ee o
Cleanliness
Fi s gene a ion 1968–1994 Hyd aulic jacks No a ailable da a High (due o
hyd aulic leaks) Ve y less
Second gene a ion 1992–2014
S eppe mo o s
wi h ball sc ew
jacks
Up o 32 kWe Mode a e Good
Thi d gene a ion 2014 onwa ds BLDC wi h ball
sc ew jacks Up o 6 kWe Low Good
Senso s 2022,22, 4273 16 o 26
con ol ci cui s and one angula momen elemen play an impo an ole. Table 4shows a
compa ison o ac ua o s based on selec ed pa ame e s. Such ac ua o s a e es ic ed o he
sys em wi hin a ed powe .
Table 4. Compa ison o he wind u bine ac ua o s.
Pa ame e s LAT Ac ua o [42] S eppe -Mo o -Based Ac ua o [82]
Powe consump ion high low
Complexi y low medium
Weigh high low
Reliabili y high low
Elec onic con ol complexi y low medium
Ene gy ha es ed a high speed medium high
Wa e powe is a p edic able enewable ene gy sou ce ha can c ea e mo e elec ici y
han wind and sola combined. Wa e ene gy abso p ion om ocean wa es a ying in ime
scales and p oduced by wind ac ion indi ec ly om sola ene gy [
1
] is a hyd odynamic
p ocess esul ing in adia ion wa e phenomena. Howe e , he con e sion o wa e kine ic
ene gy in o smoo h elec ic ene gy is di icul due o he low equency o wa e mo ion
(
~0.1 Hz
), andom wa e, and high- o ce oscilla ions [
84
]. A “sma ” oscilla ing-body de ice,
also called a hea ing buoy, ha a els eely up and down wi h he ise and all o he
wa es con e s wa e mo ion in o linea mo ion o he powe -gene a ion sys em [
18
].
Linea mo ion is c ea ed by eac ing an oscilla ing buoy agains a ixed e e ence ame
called deeply subme ged eac ion mass, as shown in Figu e 10, and i is s a iona y due o
i s hea y mass.
Figu e 10. Cylind ical buoy ac ua o o wa e applica ions.
The eac ion mass connec ed o he seabed h ough he ope ensu es a ixed loa ed
posi ion in he sea. A linea ac ua o placed be ween he loa ed buoy and subme ged
eac ion mass ans e s he ela i e mo ion o hese wo h ough a od connec ed be ween
ansla o and loa ed buoy. A de ice called powe akeo (PTO) helps he od’s linea
mo ion (up and down) o con e in o usable powe [
19
]. A pis on pump de ice (such as a
hyd aulic d i e o mechanical d i e), ai o wa e u bines, o a ing elec ical gene a o ,
o linea elec ical gene a o can se e as a powe akeo de ice (PTO) [
2
]. The pis on
pump supplies high-p essu e wa e o a hyd aulic u bine [
1
], whe e linea mo ion con e s

Senso s 2022,22, 4273 17 o 26
in o o a ing mo ion h ough wa e u bines placed onsho e. When a o a ing elec ical
gene a o is a ailable as a PTO, he ac ua o i s con e s he linea mo ion in o o a ional
mo ion so ha he o a ing gene a o gene a es elec ici y. Fo o sho e sys ems, he o a ing
gene a o is in he PTO i sel . Figu e 10 shows he enla ged iew o he c oss-sec ion o a
linea gene a o ha gene a es elec ical powe h ough linea ac ua ion. I has wo dead-
end s op sp ings and s a o elec omagne ic coils placed in he pe iphe al o he cylind ical
body o he ac ua o . A ansla o wi h a solid pe manen magne p o iding magne ic lux
inside he gene a o can eely mo e i e ically placed a he cen e . The ela i e mo ion o
he buoy and he eac ion mass is di ec ly ans e ed h ough he od o he ansla o o
elec ici y gene a ion h ough linea mo ion and he p inciple o elec omagne ic induc ion.
Ac ua o s used in wa e ene gy con e sion (WEC) sys ems a e ca ego ized in o os-
cilla ing wa e columns (OWCs) and oscilla ing body sys ems o wa e-ac i a ed body
sys ems. Figu e 10 shows he second ca ego y along wi h a linea PTO mechanism. This
ype o mo ion con e sion sys em (ac ua o ) and PTO de ice is essen ial in he pe spec i e
o wa e powe con e sion e iciency. Ade in o e al. [
85
] explained de ailed PTO ypes,
scales, and e iciencies, among which we e he e iciencies o i e di e en combina ions o
ac ua o s and PTO de ices, and he esul s o hei nume ical simula ion wi h compu a-
ional luid dynamics (CFD) a e shown in Table 5. The di ec -d i e linea gene a o sys em
wi h an oscilla ing buoy shows 95% e iciency, which is he highes compa ed o o he s.
Excep o linea gene a o s, all o he PTOs ha e losses in hei mo ion con e sion p ocess,
bu in linea gene a o s, no mo ion con e sion is equi ed and, he e o e, comes wi h highe
e iciency.
Table 5. E iciencies o di e en PTO.
Ac ua o and PTO Combina ion Type E iciency (%)
Hyd aulic d i e wi h oscilla ing body 65 [85]
Wa e u bine wi h oscilla ing body 85 [85]
Ai u bine wi h OWCs 55 [85]
Mechanical d i e wi h oscilla ing body 90 [85]
Piezoelec ic de ice wi h oscilla ing body e y low [86]
Linea gene a o wi h oscilla ing buoy 95 [85], 90.03 [86]
Linea gene a o wi h OWCs 83.6 [87]
Rahman e al. [
86
] epo ed ha PTOs, which a e also buil o piezoelec ic ac ua o s,
a e used o p oduce a signi ican quan i y o elec ical powe om he ocean. The e o e,
ene gy con e e s can be used o powe applica ions ha unc ion in he ocean, such as
a ious elec ical sensing elemen s, loa ing ha bo s, obo ics, e c. Wa e ene gy con e e s
(WECs) can imp o e hei ene gy con e sion e iciency by including se e al ypes o
piezoelec ic ma e ials. Expe imen s e eal ha by s aining he ma e ial wi h a p essu e o
1.196 kPa a a equency o 20 Hz, 0.2 W elec ic powe wi h 2.2 V may be ob ained using
his echnology.
Nex , we discuss ac ua o s used in bio ene gy- ela ed sys ems such as ag icul u e,
sola i iga ion, biogas, biomass, e c.
4. Ac ua o s in Bioene gy Applica ions
Huo e al. p esen a dis ibu ed con ol sys em and communica ion opology o sa e
and au oma ic (s a /s op) egula ion o biogas d i en appliances such as a ice cooke ,
s o e, and wa e hea e , e c., con igu ed wi h a ZigBee endpoin o con ol he ele an
ac ua o s and ansmi he da a [
20
]. Fo example, a biogas ice cooke ypically consis s o
cooking and wa ming swi ches o a h ee-s age ope a ion: (1) hea ing wi h bo h swi ches
p essed; (2) wa m s age wi h cook swi ch li ed h ough a s ep-mo o i cooking is o e ;
and (3) he u n-o s age, wi h bo h swi ches li ed. The s ep-mo o o a es a a ixed angle
as commanded o p ess o ele a e he swi ch. A single s anda d biogas s o e wi h swi ches
and gea s con olled by a Knob’s o a ion angle comes wi h a s ep-mo o , an igni ion
ci cui , and an elec omagne ic clu ch o u n he knob on when he o a ional powe o
he s ep-mo o passes h ough he clu ch o he gea and manually when he clu ch is ou
Senso s 2022,22, 4273 18 o 26
o powe . The mechanical s uc u e o he biogas wa e hea e is simila o he ice cooke .
Biomass (g a e) combus ion being a easonable al e na i e o ossil uels, i is expec ed o be
a signi ican playe in a sus ainable u u e [
88
] and can i e a wide ange o uels o a ying
mois u e con en s, equi ing less uel p epa a ion and handling [89].
Ag icul u e was es (mos common a e wood chips and suga cane bagasse) a e he
p ima y uel sou ce o biomass u naces. These biomass g a es equi e ac ua o s o ope a e
an in e mi en ash emo al sys em. Biomass- i ed powe plan s a e cogene a ion acili ies
p oducing hea o p ocess hea ing and elec ici y gene a ion, d i en by elec ic al e
ac ua o s o eedwa e ea men , s eam gene a ion, u bine injec ion, lue gas cleaning,
and p ocess hea ing. In addi ion, elec omagne ic ac ua o sys ems obus ly d i en by an
induc ion se o mo o d i e ( o a y ac ua o ) a e used in ag icul u al applica ions [
21
].
Son ake e al. [
90
] p esen a e iew o sola PV powe ed wa e pumping sys em wi h a
linea ac ua o as shown in Figu e 11a. The sys em comp ises a pis on- ype pump, a wo-
phase a iable- eluc ance linea s eppe mo o ha wo ks as a linea ac ua o , a ese oi ,
a pulley, and a coun e weigh . The enla ged iew o he linea ac ua o p o ides he linea
e ical mo ion o he pis on- ype pump. The sola PV a ay p o ides powe supply o
he con ol uni , con e ing i o a wo-phase supply using con e e s and ed o he linea
s eppe mo o . Due o he wo-phase supply, elec omagne ic coils A and B ene gized
al e na ely o c ea e downwa d linea mo ion.
Figu e 11.
Linea wa e pump ac ua o s (
a
) a iable- eluc ance linea s eppe mo o ; (
b
) linea
pump [29].
Fo c ea ing an upwa d mo ion, he con olle changes he sequence o he exci a ion
supply o he elec omagne ic coil. S ill, he e is a need o a mo e signi ican up-s oke o
li wa e , so a coun e weigh is help ul. Aliyu e al. [
29
] p esen an op imized design o a
sola wa e pumping sys em, as shown in Figu e 11b, which shows a c oss-sec ion iew o
he cylind ical ac ua o , comp ising an elec omagne ic coil, a pis on, a pis on chambe , an
inle al e, an ou le al e, and a pis on e u n sp ing, which p o ide es o ing o ce (no
shown). The inle al e is subme ged in he wa e by a wa e ank. The elec omagne ic coil
exci ed by he PV panel supply se s up a solid magne ic a ac i e o ce, causing he pis on
o mo e upwa ds. Wi h he coil exci a ion emo ed, he pis on e u ns due o he es o ing
o ce o a sp ing. The pis on’s e ical linea (up–down) mo emen happens due o he
magne ic ield and he e u n-sp ing. On he upwa d s oke o he pis on, wa e in he inle
and pis on chambe is expelled owa ds he ou le al e in o he ising main. The pis on
d ops downwa d a he end o he up-s oke, closes he ou le al e, and ills wa e in o
he pis on chambe ia he inle al e. Due o he non- e u ning al e a angemen s,
Senso s 2022,22, 4273 19 o 26
wa e low ne e e u ns once i en e s he pis on chambe , p o iding an e icien wa e
pumping a angemen .
Tala e a e al. discussed ag o-indus ial and en i onmen al ields whe e emo e
ac ua o de ices such as al es, pumps, humidi ie s o main ain consis en humidi y, elay,
and ala ms, among o he s, a e in use [
22
] o op imize he usage o wa e by scheduling
i iga ion imings and p opo ions, e ilize s, and pes icides as pe he s a e o he c op, he
g ow h cycle, and based on a ailable in o ma ion om wea he p edic ion sys ems o an
on-si e wi eless ne wo k o senso s and ac ua o s o e an IoT pla o m o con ol he s a e o
he p ocess o i iga ion, e ilize s, pes icides, illumina ion, and access con ol. Elsewhe e,
Yoo e al. desc ibe an au oma ed ag icul u e sys em based on an in e connec ed ac ua o
ne wo k o moni o ing he g ow h o g eenhouses plan s, which depend on ambien ligh ,
empe a u e, and humidi y, h ough con olled illumina ion ia a elay ac ua o [
91
]. I an
ag icul u al in usion is de ec ed, he p oposed sys em-gene a es ala ms in he a me ’s
house [
92
]. Localized (d ip o ickle) i iga ion applies wa e a low p essu e (<2 ba )
o a small a ea o he soil su ace, some imes only pa o he oo zone, and is widely
adop ed in g eenhouse ege ables [
93
], h ough ha dwa e componen s such as pumps,
al e ac ua o s, senso s, pipes, ubing, and emi e s. A scheme o a localized i iga ion
sys em wi h wo-way la ch- ype solenoid al es wi h limi ed s oke leng h, wo po s o
wa e low (inle and ou le ), and wo swi ching s a es (open o closed) o s a /s op he
con olled wa e low, which is usually in open condi ion so ha he al e closes on powe
ailu e [23,94], is shown in Figu e 12.
Figu e 12. Localized i iga ion sys em and la ch- ype Solenoids [93].
Gene ally, la ch- ype ac ua o s ope a e on a di ec cu en (DC) supply. The selec ion
c i e ia o such ac ua o s depend on he pipe connec ion size, ope a ing ol age, seal
ma e ial, p essu e, empe a u e, bo e size, and mo e. When he coil ecei es supply, i
becomes ene gized, and he mo able plunge changes i s s a e (ON o OFF).
The e a e many o he enewable ene gy sou ces no co e ed in his manusc ip ha
also deploy elec ic ac ua o s. Fo example, he di ec u iliza ion o geo he mal hea ene gy
ex ac ed in he o m o liquid o ai using a g ound hea pump sys em and u ilized as
wa m o ho wa e (in he win e season) and ice e sa in he summe season, which
is clean and sa e, is also help ul o elec ici y gene a ion and mine al p oduc ion [
95
].
The wa e ci cula ing loops o he g ound hea pump sys em consis s o cen i ugal pumps
and low con olling ac ua o s [96].
Senso s 2022,22, 4273 20 o 26
5. Impo an Pe o mance Pa ame e s o Ac ua o s and E olu ion
Some majo pe o mance pa ame e s, hei speci ica ions, and applica ions a e shown
in Table 6, which gi es a summa y o he ac ua o s’ majo pa ame e s/speci ica ions.
Some o he pape s do no men ion speci ica ions, so only he pa ame e s a e p o ided.
The ac ua o s’ d i e ange de e mines he size o he easible sola acking egion [
49
] (i.e.,
s oke leng h). In addi ion, he maximum a ed load, maximum speed, con inuous powe ,
and sys em backlash a e all i al pe o mance c i e ia o conside when selec ing linea
ac ua o s [97].
Table 6. Summa y o Majo Pe o mance Pa ame e s, Speci ica ions, and Applica ions.
Types o Ac ua o Majo Pe o mance Pa ame e s/Speci ica ions Applica ions
Elec ic o a y ac ua o (AC mo o ) [13,60] Shu e a el ime: 0.5 s o opening and closing Sola u nace shu e ope a ing sys em
Piezoce amic ac ua o s [15] F equency ange: 400–5000 Hz Sola a ay dus emo al sys em
Elec ic o a y ac ua o (DC Mo o ) [47] Mo o speed and gea a io Sola acke
Piezoelec ic ac ua o [16] DC ol age: 6 , panel inclina ion angle Sola panel cleaning
Relay [20] Max. coil ol age, Max con ac cu en capaci y Con olling g eenhouse pa ame e s
Elec omagne ic clu ch [20] Coil ol age, clu ch o que Bio-gas s o e
Induc ion se o mo o (ISM) [21]Ope a ing ol age, ope a ing speed (in sec/deg),
o que (kg/cm o N/m) Ag icul u al machines
La ch ype solenoids [23]Ope a ing ol age: 12 V DC, Connec ion size
one-eigh h inch, Val e bo e: 2.5 mm, Nominal
powe : 7 VA Localized i iga ion sys em
AC induc ion mo o [46] Gea a io Biomass g a e boile
Linea ac ua o [46,48,49,53]S oke leng h: 1005 mm, ol age: 12 V DC, speed:
4 mm/sec, o ce: 1500 N T acking applica ions
Ro a y al e ac ua o [61]Range o mo ion, Val e S em S oke Leng h,
Ac ua ion Time, Fail-sa e Sola hea ing sys em
Linea piezoelec ic ac ua o [41]Pla es size: 10 mm ×10 mm ×1 mm, piezoelec ic
ma e ial: PZT-8H, ope a ing equency: 18.8 kHz
and ope a ing ol age: 100 Vo−p
Sola panel cleaning, as onau ic and ae onau ic
applica ions
Limi ed-Angle To que (LAT) ac ua o [42] Th eshold coil ol age, o a ing angle 0◦ o 90◦O e -speed p o ec ion o wind mill
Solenoid [94] S oke leng h: 10mm, Ope a ing ol age: 24 V DC Fo limi ed s oke on–o posi ion.
A mo o , gea s, and swi ches make up an elec ic o a y ac ua o . In some applica ions,
he mo o speed is an impo an pa ame e , e.g., he minimum shu e a eling ime is
equi ed o ope a e mechanical shu e s o he sola u nace sys em. The e is no signi ican
ex e nal load on shu e s excep o i s weigh . Some applica ions equi e mo e signi ican
o que han he speed o he ope a ion: in sola acking applica ions, he sola panel weigh
is he e; in a biomass g a e boile sys em, a o a y al e ope a es agains luid p essu e. In
such cases, he ac ua o gea a io plays a signi ican ole. A gea ain is used in elec ic
ac ua o s o inc ease mo o o que and con ol he ac ua o ’s ou pu speed. The e o e,
he ac ua o o que and ange o mo ion should be conside ed while choosing an elec ic
o a y ac ua o . In compu e ized nume ical con ol machines whe e p ecise mo ion con ol
is essen ial, se o mo o s a e sui able due o low ine ia, enabling quick s a and s op
op ions. In addi ion, a se o ampli ie can modi y o que and speed e o lessly. Figu e 5
has al eady shown a schema ic diag am o an elec ic al e ac ua o ha can con ol wa e
ci cula ion a e. Howe e , some ad an ages, disad an ages, and hei limi a ions a e gi en
in Table 7.
O e hea ing p o ec ion is a ailable o p e en majo b eakdowns. Piezoelec ic ac ua-
o s a e a new class o ac ua o s o ac i e mechanical sys em con ol. Piezoelec ic ma e ials
ha e been adap ed o applica ions ha equi e jus small quan i ies o displacemen , such
as sola panel dus cleaning, despi e he magni udes o piezoelec ic ol ages, mo ions,
o o ces being modes and o en equi ing ampli ica ion. The e o e, he displacemen ,
p essu e, esonan equency, and ol age applied o piezoelec ic ac ua o s a e i al cha -
ac e is ics. Limi ed-angle o que ac ua o s a e especially used o p o ec small windmills
Senso s 2022,22, 4273 21 o 26
agains o e -speeding. They wo k on a p ede ined ol age a ing o he coil called he
h eshold ac ua o coil ol age. The e o e, he ol age and o a ion angles a e essen ial.
Table 7. Compa ison o elec ic ac ua o s used in he a ious enewable applica ions.
Name o he Ac ua o Ad an ages Disad an ages Limi a ions
Sphe ical ac ua o
• Less space equi ed
• Low powe consump ion
• A ailable in desi ed DOF
• Compac
• No coun e balance
• Sensi i e o ib a ion
• Sui able o disc e e acking
• Fo mo ing la ge weigh , la ch
is equi ed o powe sa ing
• Can be used o single panel
acking only
Ro a y ac ua o • Sui able o g oup acking ap-
plica ions
• Backlash nonlinea i y e ec is
mo e
• Quick esponse canno ob ained
due o dead-zone nonlinea i y
• Canno p o ide p ecision mo-
ion accu acy
Linea ac ua o • Backlash nonlinea i y e ec is
less
• Compac han o a y ac ua o
• La ge space equi ed in sola
ee applica ion • Space limi a ion o sola ee ap-
plica ions
Piezo-elec ic ac ua o • Ligh weigh so no ad e se e -
ec on sola panel acking sys-
em.
• Su ace ib a ion a ea is e y
less
• Complex and cos ly con ol ci -
cui y
• Need mo e han one ac ua o o
e ec i e ib a ion e ec
LAT ac ua o
• Au oma ic ope a ion based on
h eshold ol age, no ex a con-
ol equi ed
• Low complex han o a y ac ua-
o
• Powe consump ion is high han
o a y ac ua o
• Applicable only o up o 2.5kW
domes ic wind u bine speed
con ol applica ion
Solenoid linea al e ac ua o
• Ope a e in p essu ized luid
low
• Fas esponse ime
• Economic easibili y
• Supply ol age de ia ions a -
ec s pe o mance • Canno ob ain in e media e
s age
The elec ic ac ua o , ini ially only a mo o wi h a se o gea s and some mechanical
o que limi swi ches enclosed in a box, was la e coupled wi h some auxilia y componen s
such as posi ion eedback swi ches and o e - empe a u e ( he mos a ) and o e -speed
p o ec ion, hea e , and b ea he con ol. A e ha , elec ic ac ua o design imp o ed
in a ious haza dous loca ions such as oil ields, chemical plan s, o gas pipelines, e c.
The de elopmen o non-in usi e se ups combining new and mo e e ec i e elec onic
con ols wi h communica ion p o ocols was he nex s ep in inc easing commissioning ca-
pabili ies [
98
]. Wi eless ac ua o s a e simple o use, implemen , and commission hese days.
They p o ide bo h communica ion and diagnos ics while ob ia ing he need o cos ly
wi ing and ins alla ion [
99
]. Pneuma ic ac ua o s ha e long been used o con ol al es
in powe plan s. The use o elec ic con ol- al e ac ua o echnology allows o ene gy
e iciency [
66
]. The e a e di e en ac ua o s designed o he powe sec o , bu elec ic ac u-
a o s p o ide solu ions o educing ene gy was e in enewable ene gy-p oducing sys ems
e icien ly [
100
]. Nex -gene a ion ac ua o s will de elop wi h new wi eless communica ion
echnologies such as he In e ne o Things (IoT), 5G, and in elligen obo s, which a e also
expec ed o empowe he ou h indus ial e olu ion. Fo ins ance, Blanco e al. [
101
]
discusses a wi eless ac ua o ne wo k used o c ea e an IoT-based in elligen sys em, called
sma ac ua o s, which accomplishes a educ ion in o e all ene gy consump ion a a gi en
ime by op imizing he unc ioning o de ices and equipmen in he IoT [
102
]. In addi ion,
Lla ia e al. [
103
] apply wi eless ac ua o s [
104
] o in elligen managemen echniques in a
mic og id en i onmen . Junio e al. [
105
] desc ibe senso s used o managemen o ene gy
gene a ed by dis ibu ed enewable plan s.
6. Conclusions and Fu u e Di ec ions
This su ey p esen s a unc ionali y s udy o signi ican elec ic ac ua o s in di e en
enewable applica ions and he cu en ends in usage. T adi ional nonelec ical ac ua o s
a e g adually being eplaced wi h elec ic ac ua o s. P ima ily, ou signi ican elec ic
ac ua o s’ mo ion classi ica ions a e ound in he s udied li e a u e: o a y, linea , sphe ical,
and seismic ac ua o s. Howe e , mic o-le el unc ionali y analysis is necessa y o ind

Senso s 2022,22, 4273 22 o 26
u he ene gy op imiza ion in enewable applica ions. Some o he s udied conclusi e
i al poin s a e lis ed below:
•
Use o elec ic ac ua o s a e mo e ad an ageous in enewable applica ions as compa ed
o non elec ic ac ua o s by hei quick esponse, low wigh , p ecision in con ol,
compac , clean, and mo e impo an IoT en i onmen compa ible.
•
Ro a y ac ua o s a e sui able whe e e accu acy demand is lowe bu ample o que is
needed o d i e he load, as p e e ed in sola g oup acking applica ions and sola
u nace helios a acking applica ions. Howe e , elec ical cogging and mechanical
dead zone nonlinea i y inc ease wi h ime.
•
In disc e e (s ep-by-s ep) acking, inc easing s eps a e uneconomical due o cumula-
i e in e media e s a ing cu en being mo e han he con inuous acking cu en .
•
In dese egions, ne sola powe imp o emen is app oxima ely 3 W o 5 W. Fu -
he imp o emen is no achie able wi h a ailable ac ua o s; di e en ac ua o s a e
equi ed o emo e he dus pa icles e icien ly.
•
Powe consump ion in BLDC is low (6 kWe) compa ed o a s eppe mo o (32 kWe) in
he same capaci y acking applica ion.
•
Linea ac ua ed gene a o wi h oscilla ing buoy gi es mo e e iciency han a hyd aulic
d i e, wa e u bine, o ai u bine due o he educ ion in powe con e sion loss in
di ec ac ua ion.
Addi ionally, di ec linea mo ion ac ua o s wi hou mechanical ansmission elemen s
and i on co e ee ac ua o s educe signi ican p oblems associa ed wi h o a y- o-linea
ac ua o s such as cogging, eddy cu en , hea , magne ic sa u a ion, and la e al o ces
and hence play an impo an ole nowadays. The sphe ical ac ua o is well-sui ed o
sola ee applica ions due o less space equi emen and equi es wo deg ees o ee-
dom. O e all, elec ic ac ua o s ha e become mo e sui able and popula han con ec ional
nonelec ical ac ua o s in enewable applica ions due o hei lowe powe consump ion.
Iden i ying di e en ac ua o con ol p oblems and challenges o elec ic ac ua o s such
as nonlinea i ies, sa u a ion p oblems, and oppo uni ies in op imiza ion and hei app o-
p ia e con ol s a egies o o e come ac ua o - ela ed issues o op imal use in enewable
applica ions. The e ec i eness o such con ol me hods is pa o a possible u u e wo k.
Majo pe o mance pa ame e s a e discussed o acili a e ac ua o selec ion, which helps
ind signi ican pa ame e - ela ed ac ua o selec ion. Nex -gene a ion, sma , IoT-based
ac ua o s will play an essen ial ole in he ene gy sec o and he chemical and au omobile
indus ies due o hei wo-way communica ion wi eless echnologies.
Au ho Con ibu ions:
Concep ualiza ion, A.R. and D.D.; me hodology, A.R. and D.D.; so wa e,
A.R.; alida ion, A.R. and D.D.; o mal analysis, A.R. and D.D. and S.O.; w i ing—o iginal d a
p epa a ion, A.R. and D.D.; w i ing— e iew and edi ing, D.D. and S.O.; supe ision, D.D.; unding
acquisi ion, S.O. All au ho s ha e ead and ag eed o he published e sion o he manusc ip .
Funding:
This esea ch was unded by he Eu opean Regional De elopmen Fund in he Resea ch
Cen e o Ad anced Mecha onic Sys ems p ojec , g an numbe CZ.02.1.01/0.0/0.0/16_019/0000867
wi hin he Ope a ional P og amme Resea ch, De elopmen and Educa ion.
Ins i u ional Re iew Boa d S a emen : No applicable.
In o med Consen S a emen : No applicable.
Da a A ailabili y S a emen : No applicable.
Con lic s o In e es :
The au ho s decla ed no po en ial con lic o in e es wi h espec o he esea ch,
au ho ship, and/o publica ion o his a icle.
Senso s 2022,22, 4273 23 o 26
Re e ences
1.
De Falcão, O.A.F. Wa e ene gy u iliza ion: A e iew o he echnologies. Renew. Sus ain. Ene gy Re .
2010
,14, 899–918. [C ossRe ]
2.
Wa e s, R.; S ålbe g, M.; Danielsson, O.; S ensson, O.; Gus a sson, S.; S öms ed , E.; E iksson, M.; Sundbe g, J.; Leijon, M.
Expe imen al esul s om sea ials o an o sho e wa e ene gy sys em. Appl. Phys. Le . 2007,90, 034105. [C ossRe ]
3.
Buch, A.; Klöckne , S.; Be na ding, E.; Eid, T. Elec ical ac ua o s o mode n in e nal combus ion engines. MTZ Wo ldw.
2010
,
71, 26–30. [C ossRe ]
4.
Hisseine, D. Robus acking con ol o a hyd aulic ac ua ion sys em. In P oceedings o he 2005 IEEE Con e ence on Con ol
Applica ions, 2005, CCA 2005, To on o, ON, Canada, 28–31 Augus 2005; pp. 422–427. [C ossRe ]
5.
P ase ya, S.; Adhi ya, M.; Budiono, H.; Suma sono, D. A in es iga ion o b aking sys em ac ua o s o elec ic shu le bus. E3S
Web Con . 2018,67, 01023. [C ossRe ]
6.
Quan, Z.; Quan, L.; Zhang, J. Re iew o ene gy e icien di ec pump con olled cylinde elec o-hyd aulic echnology. Renew.
Sus ain. Ene gy Re . 2014,35, 336–346. [C ossRe ]
7.
Koumboulis, F.N.; Ska pe is, M.G.; Tzam zi, M.P. Robus PI Con olle s o Command Following wi h Applica ion o an
Elec opneuma ic Ac ua o . In P oceedings o he 2006 14 h Medi e anean Con e ence on Con ol and Au oma ion, Ancona,
I aly, 28–30 June 2006; pp. 1–6. [C ossRe ]
8.
Behbahani, A.R.; Semega, K.J. Con ol S a egy o Elec o-Mechanical Ac ua o s Ve sus Hyd aulic Ac ua ion Sys ems o
Ae ospace Applica ions. In P oceedings o he Powe Sys ems Con e ence, SAE Technical Pape Se ies, Sea le, DC, USA, 11–13
No embe 2010; p. 15. [C ossRe ]
9.
Osman, I.S.; Ha i i, N.G. The mal In es iga ion and Op imized Design o a No el Sola Sel -D i en The momechanical Ac ua o .
Sus ainabili y 2022,14, 5078. [C ossRe ]
10.
Tisse and, O. How Does an Elec ic Ac ua o Wo k. A ailable online: h ps://www.indelac.com/blog/how-does-elec ic-
ac ua o -wo k (accessed on 14 No embe 2021).
11.
No g en. Wha Is an Elec ic Ac ua o . A ailable online: h ps://www.no g en.com/uk/en/expe ise/indus ial-au oma ion/
wha -is-an-elec ic-ac ua o (accessed on 14 No embe 2021).
12.
Dá ila-Pe al a, C.; Cabanillas-López, R.; Ga cía-Gu ié ez, R.; Rod íguez-Ca ajal, R. Design o a Linea Ac ua o D i en Sola
T acke o High Concen a ion Pho o ol aics Technologies. J. Clean Ene gy Technol. 2015,4, 197–201. [C ossRe ]
13.
Cos a, B.A.; Lemos, J.M.; Rosa, L.G. Tempe a u e con ol o a sola u nace o ma e ial es ing. In . J. Sys . Sci.
2011
,42, 1253–1264.
[C ossRe ]
14.
Sil a, R.N.; Lemos, J.M.; Ra o, L.M. Va iable sampling adap i e con ol o a dis ibu ed collec o sola ield. IEEE T ans. Con ol
Sys . Technol. 2003,11, 765–772. [C ossRe ]
15.
Williams, R.B.; Tanimo o, R.; Simonyan, A.; Fue s enau, S. Vib a ion cha ac e iza ion o sel -cleaning sola panels wi h piezoce-
amic ac ua ion. In P oceedings o he 48 h AIAA/ASME/ASCE/AHS/ASC S uc u es, S uc u al Dynamics, and Ma e ials
Con e ence, Honolulu, HI, USA, 23–26 Ap il 2007; p. 1746. [C ossRe ]
16. Alagoz, S.; Apak, Y. Remo al o spoiling ma e ials om sola panel su aces by applying su ace acous ic wa es. J. Clean. P od.
2020,253, 119992. [C ossRe ]
17.
Eb ahimpou , M.; Sha agha , R.; Alamian, R.; Shadloo, M.S. Nume ical In es iga ion o he Sa onius Ve ical Axis Wind Tu bine
and E alua ion o he E ec o he O e lap Pa ame e in Bo h Ho izon al and Ve ical Di ec ions on I s Pe o mance. Symme y
2019,11, 821. [C ossRe ]
18.
Lemonis, G. Wa e and Tidal Ene gy Con e sion. In Encyclopedia o Ene gy; Cle eland, C.J., Ed.; Else ie : New Yo k, NY, USA,
2004; pp. 385–396. [C ossRe ]
19.
Wilson,D.G.; Robine , R.D., III; Bacelli, G.; Abdelkhalik, O Non Linea Con ol Design o Non Linea Wa e Ene gy Con e e s.
A ailable online: h ps://www.os i.go /se le s/pu l/1648654 (accessed on 11 No embe 2021).
20.
Huo, P.; Yang, F.; Luo, H.; Zhou, M.; Zhang, Y. Dis ibu ed moni o ing sys em o p ecision managemen o household biogas
appliances. Compu . Elec on. Ag ic. 2019,157, 359–370. [C ossRe ]
21.
Chen, D.F.; Chiu, S.P.C.; Cheng, A.B.; Ting, J.C. Elec omagne ic Ac ua o Sys em Using Wi y Con ol Sys em. Ac ua o s
2021
,
10, 65. [C ossRe ]
22.
Tala e a, J.M.; Tobón, L.E.; Gómez, J.A.; Culman, M.A.; A anda, J.M.; Pa a, D.T.; Qui oz, L.A.; Hoyos, A.; Ga e a, L.E. Re iew
o IoT applica ions in ag o-indus ial and en i onmen al ields. Compu . Elec on. Ag ic. 2017,142, 283–297. [C ossRe ]
23.
Laja a, R.; Albe ola, J.; Peleg í-Sebas iá, J. A Sola Ene gy Powe ed Au onomous Wi eless Ac ua o Node o I iga ion Sys ems.
Senso s 2010,11, 329–340. [C ossRe ]
24.
Deb, D.; B ahmbha , N.L. Re iew o yield inc ease o sola panels h ough soiling p e en ion, and a p oposed wa e - ee
au oma ed cleaning solu ion. Renew. Sus ain. Ene gy Re . 2018,82, 3306–3313. [C ossRe ]
25.
Rosa. Sola Hea o Ma e ials P ocessing: A Re iew on Recen Achie emen s and a P ospec on Fu u e T ends. ChemEnginee ing
2019,3, 83. [C ossRe ]
26. Nguyen, K.D. On he adap i e con ol o sphe ical ac ua o s. T ans. Ins . Meas. Con ol 2018,41, 816–827. [C ossRe ]
27.
Ha ez, A.; Youse , A.; Ha ag, N. Sola acking sys ems: Technologies and acke s d i e ypes—A e iew. Renew. Sus ain. Ene gy
Re . 2018,91, 754–782. [C ossRe ]
28.
Riad, A.; Ben Zoh a, M.; Alhamany, A.; Mansou i, M. Bio-sun acke enginee ing sel -d i en by he mo-mechanical ac ua o o
pho o ol aic sola sys ems. Case S ud. The m. Eng. 2020,21, 100709. [C ossRe ]
Senso s 2022,22, 4273 24 o 26
29.
Aliyu, M.; Hassan, G.; Said, S.A.; Siddiqui, M.U.; Alawami, A.T.; Elamin, I.M. A e iew o sola -powe ed wa e pumping sys ems.
Renew. Sus ain. Ene gy Re . 2018,87, 61–76. [C ossRe ]
30.
Almadani, I.K.; Osman, I.S.; Ha i i, N.G. In-Dep h Assessmen and Op imized Ac ua ion Me hod o a No el Sola -D i en
The momechanical Ac ua o ia Shape Memo y Alloy. Ene gies 2022,15, 3807. [C ossRe ]
31.
Kim, T.; Oh, S.; Yee, K. Imp o ed ac ua o su ace me hod o wind u bine applica ion. Renew. Ene gy
2015
,76, 16–26. [C ossRe ]
32. Mé igaud, A.; Ringwood, J.V. Condi ion-based main enance me hods o ma ine enewable ene gy. Renew. Sus ain. Ene gy Re .
2016,66, 53–78. [C ossRe ]
33.
P ase yo, A.; As o i; Sipahu a , H.; Wibowo, B.S.C.; Gunawan; Nu yadin, D. Policy and Economy Analysis on he Applica ion
o he Sma on G id Ac ua o o Public Road Ligh ing in Magelang Ci y. In P oceedings o he 1s Bo obudu In e na ional
Symposium on Humani ies, Economics and Social Sciences (BIS-HESS 2019), Magelang, Indonesia, 16 Oc obe 2019; A lan is
P ess: Ams e dam, The Ne he lands, 2020; pp. 206–210. [C ossRe ]
34.
Popo ic, M.B.; Lamkin-Kenna d, K.A.; Becke le, P.; Bowe s, M.P. 3—Ac ua o s. In Biomecha onics; Popo ic, M.B., Ed.; Academic
P ess: Camb idge, MA, USA, 2019; pp. 45–79. [C ossRe ]
35.
Nippon Pulse Ame ica, I. Linea Mo o Sys ems: I on Co e, U-Channel, and Tubula Linea Mo o s. 2021. A ailable on-
line: h ps://www.nipponpulse.com/lea ning/whi e-pape s/linea -mo o -sys ems-i on-co e-u-channel-and- (accessed on 31
Oc obe 2021).
36.
Wang, Y.; Deng, X.; Sun, P.; Qiao, D. A Kind o Elec ic Ac ua o Con olle Sol ing The P oblem o Mo o Concussion. In
P oceedings o he 2018 IEEE In e na ional Con e ence on Mecha onics and Au oma ion (ICMA), Changchun, China, 5–8 Augus
2018; pp. 1015–1019. [C ossRe ]
37.
Laskey, D.R. Ball Sc ew and Nu Linea Ac ua o Assemblies and Me hods o Cons uc ing and Ope a ing Them. U.S. Pa en No.
6,101,889, 15 Augus 2000.
38.
Han, L.; Yu, L.; Pan, C.; Zhao, H.; Jiang, Y. A no el impac o a y–linea mo o based on decomposed sc ew- ype mo ion o
piezoelec ic ac ua o . Appl. Sci. 2018,8, 2492. [C ossRe ]
39.
Gao, B.; Chen, H.; Liu, Q.; Chu, H. Posi ion Con ol o Elec ic Clu ch Ac ua o Using a T iple-S ep Nonlinea Me hod. Ind.
Elec on. IEEE T ans. 2014,61, 6995–7003. [C ossRe ]
40. Bande a, P. Mul i-Deg ee o F eedom Sphe ical Ac ua o . U.S. Pa en No. 9,893,574, 13 Feb ua y 2018.
41. Lu, X.; Zhang, Q.; Hu, J. A linea piezoelec ic ac ua o based sola panel cleaning sys em. Ene gy 2013,60, 401–406. [C ossRe ]
42.
Chi ca, M.; D anca, M.; Teodosescu, P.D.; B eban, S. Limi ed-Angle Elec omechanical Ac ua o o Mic o Wind Tu bines
O e speed P o ec ion. In P oceedings o he 2019 11 h In e na ional Symposium on Ad anced Topics in Elec ical Enginee ing
(ATEE), Bucha es , Romania, 28–30 Ma ch 2019; pp. 1–6. [C ossRe ]
43.
Guillo , E.; Rod iguez, R.; Boulle , N.; Sans, J.L. Some de ails abou he hi d eju ena ion o he 1000 kW h sola u nace in
Odeillo: Ex eme pe o mance helios a s. AIP Con . P oc. 2018,2033, 040016. [C ossRe ]
44.
Sys em, A. Top IoT Senso s. 2019. A ailable online: h ps://www.a sys em.com/blog/io -senso s-io -ac ua o s/ (accessed on
23 May 2022).
45.
Wójcicki, K.; Biega´nska, M.; Paliwoda, B.; Gó na, J. In e ne o Things in Indus y: Resea ch P o iling, Applica ion, Challenges
and Oppo uni ies—A Re iew. Ene gies 2022,15, 1806. [C ossRe ]
46.
Ponni an, A.; Hashim, A.; Ali Muni , H. A design o single axis sun acking sys em. In P oceedings o he 2011 5 h In e na ional
Powe Enginee ing and Op imiza ion Con e ence, Shah Alam, Malaysia, 6–7 June 2011; pp. 107–110. [C ossRe ]
47.
Hammad, B.K.; Fouad, R.H.; Ashhab, M.S.; Nijmeh, S.D.; Mohsen, M.; Tamimi, A. Adap i e con ol o sola acking sys em. IET
Sci. Meas. Technol. 2014,8, 426–431. [C ossRe ]
48.
Jo ano ic, V.M.; Ayala, O.; Seek, M.; Ma sillac, S. Single axis sola acke ac ua o loca ion analysis. In P oceedings o he
Sou heas Con 2016, No olk, VA, USA, 30 Ma ch–3 Ap il 2016; pp. 1–5. [C ossRe ]
49.
A bes, F.; Wein ebe, G.; Wöh bach, M. Helios a ield cos educ ion by ‘slope d i e’ op imiza ion. AIP Con . P oc.
2016
,
1734, 160002. [C ossRe ]
50.
Fe daus, R.A.; Mohammed, M.A.; Rahman, S.; Salehin, S.; Mannan, M.A. Ene gy E icien Hyb id Dual Axis Sola T acking
Sys em. J. Renew. Ene gy 2014,2014, 1–12. [C ossRe ]
51.
Ba ayneh, W.; Ba aineh, A.; Soliman, I.; Ha ees, S.A. In es iga ion o a single-axis disc e e sola acking sys em o educed
ac ua ions and maximum ene gy collec ion. Au om. Cons . 2019,98, 102–109. [C ossRe ]
52.
Alexand u, C. The design and op imiza ion o a pho o ol aic acking mechanism. In P oceedings o he 2009 In e na ional
Con e ence on Powe Enginee ing, Ene gy and Elec ical D i es, Lisbon, Po ugal, 18–20 Ma ch 2009; pp. 436–441. [C ossRe ]
53.
Ngo, X.C.; Nguyen, T.H.; Do, N.Y.; Nguyen, D.M.; Vo, D.V.N.; Lam, S.S.; Heo, D.; Shokouhimeh , M.; Nguyen, V.H.; Va ma, R.S.;
Kim, S.Y.; Le, Q.V. G id-Connec ed Pho o ol aic Sys ems wi h Single-Axis Sun T acke : Case S udy o Cen al Vie nam. Ene gies
2020,13, 1457. [C ossRe ]
54.
A geseanu, A.; Ri chie, E.; Leban, K. New low cos s uc u e o dual axis moun sola acking sys em using adap i e sola
senso . In P oceedings o he 2010 12 h In e na ional Con e ence on Op imiza ion o Elec ical and Elec onic Equipmen , B aso ,
Romania, 20–22 May 2010; pp. 1109–1114. [C ossRe ]
55.
Ha i i, N.G.; AlMu awa, M.A.; Osman, I.S.; AlMadani, I.K.; Almahdi, A.M.; Ali, S. Expe imen al In es iga ion o Azimu h-and
Senso -Based Con ol S a egies o a PV Sola T acking Applica ion. Appl. Sci. 2022,12, 4758. [C ossRe ]
Senso s 2022,22, 4273 25 o 26
56.
IFC. U ili y-Scale Sola Pho o ol aic Powe Plan s, a P ojec De elope ’s Guide. A ailable online: h ps://www.i c.o g/wps/
wcm/connec / opics_ex _con en /i c_ex e nal_co po a e_si e/sus ainabili y-a -i c/publica ions/publica ions_u ili y-scale+
sola +pho o ol aic+powe +plan s (accessed on 31 Oc obe 2021).
57.
Balles ín, J.; Rod íguez-Alonso, M.; Rod iguez, J.; Canadas, I.; Ba be o, F.; Langley, L.; Ba nes, A. Calib a ion o high-hea - lux
senso s in a sola u nace. Me ologia 2006,43, 495. [C ossRe ]
58.
Egan, D. Gian Magni ie Reaches 5000 Deg ees Using Only Sunligh . A ailable online: h ps://www.disco e magazine.com/
echnology/gian -magni ie - eaches-5-000-deg ees-using-only-sunligh (accessed on 17 May 2022).
59.
Balles ín, J.; Es ada, C.A.; Rod íguez-Alonso, M.; Pé ez-Rábago, C.; Langley, L.W.; Ba nes, A. High-hea - lux senso calib a ion
using calo ime y. Me ologia 2004,41, 314–318. [C ossRe ]
60.
Cos a, B.A.; Lemos, J.M. Singula pe u ba ion s abili y condi ions o adap i e con ol o a sola u nace wi h ac ua o dynamics.
In P oceedings o he 2009 Eu opean Con ol Con e ence (ECC), Budapes , Hunga y, 23–26 Augus 2009; pp. 1626–1631. [C ossRe ]
61.
Camacho, E.F.; Rubio, F.R.; Be enguel, M.; Valenzuela, L. A su ey on con ol schemes o dis ibu ed sola collec o ields. Pa I:
Modeling and basic con ol app oaches. Sol. Ene gy 2007,81, 1240–1251. [C ossRe ]
62.
Schiel, W.; Hun , B.; Keck, T.; Schwei ze , A. Sola The mal Powe Plan s Fo Cen al o Dis ibu ed Elec ici y Gene a ion. In
P oceedings o he POWER-GEN Eu ope, Ba celona, Spain, 25–27 May 2004.
63.
Ci e, C.M.; Be enguel, M.; Valenzuela, L.; Camacho, E.F. Feedback linea iza ion con ol o a dis ibu ed sola collec o ield.
Con ol Eng. P ac . 2007,15, 1533–1544. [C ossRe ]
64. Lemos, J.M. Adap i e con ol o dis ibu ed collec o sola ields. In . J. Sys . Sci. 2006,37, 523–533. [C ossRe ]
65.
F ank, E.; Mau hne , F.; Fische , S. O e hea ing p e en ion and s agna ion handling in sola p ocess hea applica ions. Technical
Repo A.1.2. In . Ene gy-Agency-Sol. Hea . Cool. Task 2015,49.[C ossRe ]
66.
Mo lagh , N.H.; Mohammad ezaei, M.; Hun , J.; Zake i, B. In e ne o Things (IoT) and he Ene gy Sec o . Ene gies
2020
,13, 494.
[C ossRe ]
67.
Canale i, J.L.; No on, G.; Damian, A.; Colda, I.; C is o a i, C. New concep o sola ai hea e in eg a ed in he building.
In P oceedings o he 4 h IASME/WSEAS In e na ional Con e ence on Ene gy, En i onmen , Ecosys ems and Sus ainable
De elopmen , EEESD’08, Alga e, Po ugal, 11–13 June 2008; pp. 52–59.
68.
Pana , S.; Va anasi, K.K. Elec os a ic dus emo al using adso bed mois u e–assis ed cha ge induc ion o sus ainable ope a ion
o sola panels. Sci. Ad . 2022,8, eabm0078. [C ossRe ] [PubMed]
69.
Dawson, S.; Nick, M.B.S.; S e e, W. Sola A ay Panels wi h Dus -Remo al Capabili y. A ailable online: h ps://www. echb ie s.
com/componen /con en /a icle/ b/pub/b ie s/mechanics-and-machine y/1553 (accessed on 12 No embe 2021).
70.
Al-Bad a, M.; Abd-Elhady, M.; Kandil, H. A no el echnique o cleaning PV panels using an is a ic coa ing wi h a mechanical
ib a o . Ene gy Rep. 2020,6, 1633–1637. [C ossRe ]
71.
Sya iq, A.; Pandey, A.; Adzman, N.; Abd Rahim, N. Ad ances in app oaches and me hods o sel -cleaning o sola pho o ol aic
panels. Sol. Ene gy 2018,162, 597–619. [C ossRe ]
72.
Al ın a¸s, M.; A slan, S. Reduc ion o Dus on Sola Panels h ough Unipola Elec os a ic T a eling Wa e. Appl. Sci.
2021
,11, 9121.
[C ossRe ]
73.
King, M.; Li, D.; Doone , M.; Ghosh, S.; Roy, J.N.; Chak abo y, C.; Wang, J. Ma hema ical Modelling o a Sys em o Sola PV
E iciency Imp o emen Using Comp essed Ai o Panel Cleaning and Cooling. Ene gies 2021,14, 4072. [C ossRe ]
74.
Deb, D.; Bu kholde , J.; Tao, G. Adap i e Compensa ion o Nonlinea Ac ua o s o Fligh Con ol Applica ions; Sp inge :
Be lin/Heidelbe g, Ge many, 2021.
75.
Deb, D.; Bu kholde , J.; Tao, G. Syn he ic Je Ac ua o s and A ays: Modeling and Con ol. In Adap i e Compensa ion o Nonlinea
Ac ua o s o Fligh Con ol Applica ions; Sp inge : Be lin/Heidelbe g, Ge many, 2022; pp. 11–41.
76.
Hamlehda , M.; Kasaeian, A.; Sa aei, M.R. Ene gy ha es ing om luid low using piezoelec ics: A c i ical e iew. Renew.
Ene gy 2019,143, 1826–1838. [C ossRe ]
77.
Han, H.; Ko, J. Powe -Gene a ion Op imiza ion Based on Piezoelec ic Ce amic De o ma ion o Ene gy Ha es ing Applica ion
wi h Renewable Ene gy. Ene gies 2021,14, 2171. [C ossRe ]
78.
Nechib u e, A.; Chawanda, A.; Luhanga, P. Piezoelec ic Ene gy Ha es ing De ices: An Al e na i e Ene gy Sou ce o Wi eless
Senso s. Sma Ma e . Res. 2012,2012, 1–13. [C ossRe ]
79.
On i e os, J.J.; Á alos, C.D.; Loza, F.; Galán, N.D.; Rubio, G.J. E alua ion and design o powe con olle o wo-axis sola
acking by PID and FL o a pho o ol aic module. In . J. Pho oene gy 2020,2020, 8813732. [C ossRe ]
80.
Maindad, N.; Gadha e, A.; Sa pu e, S.; Nanda, B. Au oma ic Sola Panel Cleaning Sys em. In P oceedings o he 2nd In e na ional
Con e ence on Communica ion & In o ma ion P ocessing (ICCIP), Singapo e, 26–29 No embe 2016.
81.
Al Qdah, K.S.; Abdulqadi , S.A.; Al Ha bi, N.Y.; Soqyyah, A.Z.; Isa, K.J.; Alha bi, M.Y.; Binsaad, N.M. Design and pe o mance o
PV dus cleaning sys em in medina egion. J. Powe Ene gy Eng. 2019,7, 1–14. [C ossRe ]
82.
Chi ca, M.; D anca, M.; Op ea, C.A.; Teodosescu, P.D.; Pacu a u, A.M.; Neam u, C.; B eban, S. Elec onically Con olled Ac ua o s
o a Mic o Wind Tu bine Fu ling Mechanism. Ene gies 2020,13, 4207. [C ossRe ]
83. Cuches, J.P.; F azie , R.H. Angula Displacemen Solenoid. US Pa en US3221191, 30 No embe 1965.
84.
D ew, B.; Plumme , A.R.; Sahinkaya, M.N. A e iew o wa e ene gy con e e echnology. P oc. Ins . Mech. Eng. Pa A J. Powe
Ene gy 2009,223, 887–902. [C ossRe ]
85.
Ade in o, T.; Li, H. Re iew on powe pe o mance and e iciency o wa e ene gy con e e s. Ene gies
2019
,12, 4329. [C ossRe ]