thit k mt h solar, chng ta ln lt thc hin cc bc sau:

thit k mt h solar, chng ta ln lt thc hin cc bc sau:

1. Tnh tng lng tiu th in ca tt c cc thit b m h thng solar phi cung cp.

Tnh tng s Watt-hour s dng mi ngy ca tng thit b. Cng tt c li chng ta c tng s Watt-hour ton ti s dng mi ngy.

2. Tnh s Watt-hour cc tm pin mt tri phi cung cp cho ton ti mi ngy.Do tn hao trong h thng, s Watt-hour ca tm pin tri cung cp phi cao hn tng s Watt-hour ca ton ti.

S Watt-hour cc tm pin mt tri (PV modules) = 1.3 x tng s Watt-hour ton ti s dng

3. Tnh ton kch c tm pin mt tri cn s dng tnh ton kch c cc tm pin mt tri cn s dng, ta phi tnh Watt-peak (Wp) cn c ca tm pin mt tri. Lng Wp m pin mt tri to ra li ty thuc vo kh hu ca tng vng trn th gii. Cng 1 tm pin mt tri nhng t ni ny th mc hp thu nng lng s khc vi khi t n ni khc. thit k chnh xc, ngi ta phi kho st tng vng v a ra mt h s gi l "panel generation factor", tm dch l h s pht in ca pin mt tri. H s "panel generation factor" ny l tch s ca hiu sut hp thu (collection efficiency) v bc x nng lng mt tri (solar radiation) trong cc thng t nng ca vng, n v tnh ca n l (kWh/m2/ngy).

Mc hp thu nng lng mt tri ti Vit Nam l khong 4.58 kWh/m2/ngy cho nn ly tng s Watt-hour cc tm pin mt tri chia cho 4.58 ta s c tng s Wp ca tm pin mt tri.

Mi PV m ta s dng u c thng s Wp ca n, ly tng s Wp cn c ca tm pin mt tri chia cho thng s Wp ca n ta s c c s lng tm pin mt tri cn dng.

Kt qu trn ch cho ta bit s lng ti thiu s lng tm pin mt tri cn dng. Cng c nhiu pin mt tri, h thng s lm vic tt hn, tui th ca battery s cao hn. Nu c t pin mt tri, h thng s thiu in trong nhng ngy rm mt, rt cn kit battery v nh vy s lm battery gim tui th. Nu thit k nhiu pin mt tri th lm gi thnh h thng cao, vt qu ngn sch cho php, i khi khng cn thit. Thit k bao nhiu pin mt tri li cn ty thuc vo d phng ca h thng. Th d mt h solar c d phng 4 ngy, ( gi l autonomy day, l nhng ngy khng c nng cho pin mt tri sn sinh in), th bt buc lng battery phi tng hn v ko theo phi tng s lng pin mt tri. Ri vn s dng pin loi no l ti u, l thch hp v mi vng a l u c thi tit khc nhau. Tt c i hi thit k phi do cc chuyn gia c kinh nghim thit k nhiu nm cho cc h solar trong vng.

4. Tnh ton b inverter i vi h solar stand-alone, b inverter phi ln c th p ng c khi tt c ti u bt ln, nh vy n phi c cng sut bng 125% cng sut ti. Nu ti l motor th phi tnh ton thm cng sut p ng thi gian khi ng ca motor.

Chn inverter c in p vo danh nh ph hp vi in p danh nh ca battery. i vi h solar kt ni vo li in, ta khng cn battery, in p vo danh nh ca inverter phi ph hp vi in p danh ca h pin mt tri.

5. Tnh ton battery Battery dng cho h solar l loi deep-cycle. Loi ny cho php x n mc bnh rt thp v cho php np y nhanh. Loi ny c kh nng np x rt nhiu ln ( c nhiu cycle) m khng b hng bn trong, do vy kh bn, tui th cao.

S lng battery cn dng cho h solar l s lng battery cung cp in cho nhng ngy d phng (autonomy day) khi cc tm pin mt tri khng sn sinh ra in c. Ta tnh dung lng battery nh sau:

-Hiu sut ca battery ch khong 85% cho nn chia s Wh ca ti tiu th vi 0.85 ta c Wh ca battery

-Vi mc deep of discharge DOD (mc x su) l 0.6, ta chia s Wh ca battery cho 0.6 s c dung lng battery

Kt qu trn cho ta bit dung lng battery ti thiu cho h solar khng c d phng. Khi h solar c s ngy d phng (autonomy day) ta phi nhn dung lng battery cho s autonomy-day c s lng battery cn cho h thng.

6. Thit k solar charge controller Solar charge controller c in th vo ph hp vi in th ca pin mt tri v in th ra tng ng vi in th ca battery. V solar charge controller c nhiu loi cho nn bn cn chn loi solar charge controller no ph hp vi h solar ca bn. i vi cc h pin mt tri ln, n c thit k thnh nhiu dy song song v mi dy s do mt solar charge controller ph trch. Cng sut ca solar charge controller phi ln nhn in nng t PV v cng sut np battery.

Thng thng ta chn Solar charge controller c dng Imax = 1.3 x dng ngn mch ca PV

V d c th: Tnh h solar cho 1 h dn vng su c yu cu s dng nh sau:- 1 bng n 18 Watt s dng t 6-10 gi ti. - 1 qut my 60 Watt mi ngy s dng khong 2 gi. - 1 t lnh 75 Watt chy lin tc

1. Xc nh tng lng in tiu th mi ngy = (18 W x 4 gi) + (60 W x 2 gi) + (75 W x 12 gi) = 1,092 Wh/day

(t lnh t ng ngt khi lnh nn xem nh chy 12 gi ngh 12 gi)

2. Tnh pin mt tri (PV panel)PV panel = 1,092 x 1.3 = 1,419.6 Wh/day. Tng Wp ca PV panel = 1,419.6 / 4.58 = 310WpChn loi PV c 110Wp th s PV cn dng l 310 / 110 # 3 tm

3. Tnh inverterTng cng sut s dng = 18 + 60 + 75 = 153 WCng sut inverter = 153 x 125% # 190W Chn inverter 200W tr ln

4. Tnh ton Battery

Vi 3 ngy d phng, dung lng bnh = 178 x 3 = 534 AhNh vy chn battery deep-cycle 12V/600Ah cho 3 ngy d phng.

5. Tnh solar charge controller Thng s ca mi PV module: Pm = 110 Wp, Vm = 16.7 Vdc, Im = 6.6 A, Voc = 20.7 A, Isc = 7.5 ANh vy solar charge controller = (3 tm PV x 7.5 A) x 1.3 = 29.25 AChn solar charge controller c dng 30A/12 V hay ln hn.