e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Solar Photovoltaic Theory 1-2. Potential assessment

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Potential assessment 1-2. Potential assessment Basic principle of assessment Insolation measurement Estimation of annual power generation Case practice Contents

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Basic principle of assessment Insolation Solar radiation (Insolation ) is “light energy” from sun. Global Radiation (Insolation) 1m1m 1m1m Horizontal plane Sun light from any direction Energy: kWh/m 2 Power: kW/ m 2 Energy: kWh/m 2 Power: kW/ m 2 REFLECTE D PV Solar radiation (insolation) reaches the ground as: direct radiation diffused radiation Energy received within a unit time

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Out of atmosphere ( 1.35 kW/m 2 = kW/feet 2 ) Ground surface on the equator ( 1.00 kW/m 2 = kW/feet 2 ) Absorbed by H 2 O, O 2, O 3, CO 2 Visible Green Basic principle of assessment Insolation spectrum on the surface of ground 1.35 kW/m2 (0.125 kW/f 2 ) 1.00 kW/m2 ( kW/f 2 )

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Basic principle of assessment Various effects for insolation Local latitude effect “Air mass” effect ( Atmospheric path length effect) Seasonal effect Weather effect Face rotation effect Surrounding obstacles effect ( Shading effect )

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Basic principle of assessment Effect of Local Latitude : Local latitude Actually, you can measure this value +90 deg (N pole) -90 deg (S pole) 0 deg (Equator) I0I0 I0I0 I0I0 I0I0 Earth Local Horizontal Insolation mathematical Cosine curve about 1.0 kW/m 2 (0.093 kW/feet 2 ) 1.0 kW/m 2 (0.093 kW/feet 2 )

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Basic principle of assessment Effect of Local Latitude Tilted plane (yellow plane) Horizontal plane (blue plane) Meaning of convert equation I 0 (kW/m 2 ) 1 m m (kW/m 2 ) Insolation energy of the tilted plane(yellow) and the horizontal plane(blue) is same. Rectangle plane towed sun light Horizontal plane

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Appendix A-2 Triangle Function ( Cosine Function ) A C B c a b Example Please calculate by your handy computer

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Basic principle of assessment Best tilt angle Your horizontal plane I0I0 I0I0 Earth You are here Ideal tilt angle = local latitude Ideal PV plane Local latitude is Best tilt angle is almost same as “local latitude”

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Basic principle of assessment I0I0 I0I0 I0I0 Earth Air “Atmospheric path length” depend on its latitude. Air mass effect +90 deg (N pole) -90 deg (S pole) 0 deg (Equator) I0I0 mathematical Cosine curve With Air mass effect Effect of “Air mass” ( Atmospheric path length ) about 1.0 kW/m 2 ( kW/f 2 ) about 1.37 kW/m 2 ( kW/f 2 ) Lp At Air Mass = At (thickness of air) Lp (Light pass length)

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Basic principle of assessment Effect of Season LatitudeMax.Min. Japan+35degJun.Dec. Singapore 0degMar.Sep.Jun.Dec. Australia- 35degDec.Jun.

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Basic principle of assessment Effect of Season Month kWh/m 2 day -13 Samoa -17 Vanuatu +1 Kiribath -21 Cook Is. -8 Tuvalu. +34 Japan Seasonal effect is more strong in high latitude

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Basic principle of assessment Effect of Weather Daily output curve of various weather condition Fine day Cloudy day Rainy day Actual output / Rated capacity Time Data in JAPAN

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Basic principle of assessment Effect of Weather Fiji Insoration6822 (MJ/m 2 year) Utilization15.8% Fine day77.5% Cloudy day17.9% Insoration6131 (MJ/m 2 year) Utilization14.2% Fine day68.4% Cloudy day21.2% Nandi Suva  Key factor of solar resource Latitude Atmospheric path length Length of daytime Opportunity of fine day. Almost same in PPA countries Depend on the geographical aspect.

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Basic principle of assessment Face-rotation effects on daily insolation curve S WE Time Insolation Face to S Face to SEFace to SW Location = 35N If you rotate PV module face to East, output peak will shift to earlier. If you rotate PV module face to West, output peak will shift to later. Northern hemisphere

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Basic principle of assessment Face-rotation effects on daily insolation curve Insolation Face to S Face to SE Face to SW This effect is more strong in high latitude. Low latitude area (under 15deg), this effect is negligible. Latitude 15N Latitude 35N Latitude 60N Face to S Face to SE Face to SW Insolation Face to S Face to SE Face to SW Insolation

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Basic principle of assessment Various effects on daily insolation curve Time Insolation Summer Winter Latitude effect Seasonal effect (depended on sun height angle) Air mass effect Weather effect Day light time Seasonal effect

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Basic principle of assessment Necessity of on site insolation measuring Key factor of solar resource Latitude dependent Atmospheric path length Length of daytime Seasonal sun height-angle Weather dependent Opportunites of fine day Mist in the air Site situation Shade of mountain, tree, buildings Contamination by dust, salty gusts Easy to estimate Un-known Difficult Un-known On site insolation measuring is necessary before planning. (at least 1 – 3 years. Use meteorological observatory data)

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Basic principle of assessment Basic theory of PV panel adjustment Latitude effect Air Mass effect Seasonal effect Daily effect Weather effect Obstacle shad effect Basic theory of PV panel adjustment You cannot avoid these effect. The best things you can do are to: - Tilt PV plane the same as your latitude. - Face true north or true south. PV same angle as latitude Face to N or S (as possible as you can) Avoidable. Try to find good location

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Basic principle of assessment Basic theory of PV panel adjustment (Note) In high latitude locations, the optimum tilting angle is slightly lower than the local latitude. difference between local latitude and optimum tilt +deg -deg 45 deg local latitude -7deg under At 45N point, Optimum tilt angle is 45 – 7 = 38 deg In low latitude region such as 10 to 20 deg, error is negligible By using computer, you can calculate accurate tilting angle easily.

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Basic principle of assessment Insolation of the world

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Basic principle of assessment Definition of PV’s Rated Capacity “Rated capacity 1kW” means ( Power ) If insolation is 1 kW/m 2, this PV can output 1 kW. ( Energy ) If PV has 1 kW/m 2 insolation in 1 hour, this PV can generate 1 kWh Rated Capacity “1 kW” 1 (kW / m 2 ) Output 1 kW Rated Capacity “1 kW” 1 (kW / m 2 ) Generate 1 kWh for 1 hour Note: This is the definition that, we use metric system here.

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Basic principle of assessment Definition of PV’s Capacity “Rated capacity 1kW” means Rated Capacity “1 kW” 1 (kWh / m 2 day) Generate 1 kWh for a day ( Accumulated Energy ) If PV has 1 kWh/m 2 day, this PV can generate 1 kWh for a day In resource assessment, “Accumulated Insolation (energy)” is used widely. Daily accumulated insolationkWh/m 2 day Monthly accumulated insolationkWh/m 2 month Annual accumulated insolationkWh/m 2 year

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Basic principle of assessment Definition of PV’s Capacity “Efficiency” parameter is already included in “Rated Capacity”. Rated Capacity “1 kW” 1 (kW / m 2 ) Generate 1 kW Rated Capacity “1 kW” 1 (kW / m 2 ) Generate 1 kW High-efficiency PV ( Single crystal PV 15% ) Low-efficiency PV (Amorphous PV 8 %) Module is larger. If you use “rated capacity”, you don’t have to consider about efficiency.

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Insolation measurement How to observe Insolation Pyranometer for Horizontal Global Solar Radiation (Insolation) Pyranometer Horizontal plane

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Insolation measurement How to observe Insolation Pyranometer for Horizontal Global Solar Radiation (Insolation) Place Pyranometer on the horizontal plane. Make sure no shadow is cast all day long. Clean upper window frequently. Insolation data is very common in meteorology. Ask your meteorological observatory for local insolation data. Sun window (receives light from all directions) 20 cm Data logger Instant valueXX.XX (kW/m 2 ) or Accum. valueXX.XX (kWh/m 2 )

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Insolation measurement There are many units of Insolation data. Pyranometer for Global Solar Radiation Be sure to note which unit your pyranometer is using. Metric(m)Imperial(feet) MJMJ / m 2 yearMJ / feet 2 year kWhkWh / m 2 yearkWh / feet 2 year x 3.60 x 1 / 10.76

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Insolation measurement Example of raw data (monthly data) Average Insolation for a day (kWh/m 2 day) January Date Accumulating Time

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Insolation measurement Example of raw data ( Annual data) Annual total insolation Summarize Daily average Insolation

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Insolation measurement Convert “horizontal insolation” to “tilted insolation” I0I0 I0I0 I0I0 Earth I0I0 I0I0 I0I0 Hj Plane of PV Panel (Tilted same as local latitude) Raw insolation data ( Horizontal insolation ) Hj : Tilted insolation Horizontal to Tilted conversion

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Insolation measurement Convert “horizontal insolation” to “tilted insolation” Hj (kWh / m 2 year) I (kWh / m 2 year) Measured Plane (Horizontal) PV Module Plane (Tilted as local Latitude) (kWh / m 2 year) (Note) This conversion can be used in low latitudes (less than 20deg.)

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Insolation measurement Convert “horizontal insolation” to “tilted insolation” Tilted plane (yellow plane) Horizontal plane (blue plane) Meaning of convert equation Insolation energy of the tilted plane(yellow) and the hori- zontal plane(blue) is same. Hj (kW/m 2 ) 1 m m (kW/m 2 ) I

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Insolation measurement Convert “horizontal insolation” to “tilted insolation” (Example) (kWh / m 2 year) Local Latitude = -10 (deg) Horizontal InsolationI = 2,000 (kWh/m 2 Year) I = 2,000 kWh/m 2 year (Measured raw data) 10 deg. Hj = 2,031 kWh/m 2 year ( Tilted insolation )

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Estimation of annual power generation Actual generation energy of PV Actual generation energy Pu = Rated Capacity of PV Module (=1.0 kW) hg = System efficiency (= 0.7 depending on type of PV cell) H = Tilted Plane Insolation in kWh unit. Hg = 70% (System Efficiency) Converter Loss8% Surface Contamination7% Temperature Rise 15% (Example) Tilted InsolationHj = 2,031 (kWh/m 2 Year) PV rated capacityPu=10 (kW) (kWh/year)

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Estimation of annual power generation Calculate “Load Factor ( Syaytem Utilization parameter)" To estimate various capacities of PV system, calculate Unified Parameter, called " Load Factor (System Utilization Parameter )". This parameter means “Annual average output power” of unit capacity of the PV system. p = Annual Available power for Unit Capacity of PV Module Pu = Unit Capacity of PV Module (=1.0) (Example) Annual power generationp= 14,217 (kWh/Year) PV rated capacityPu=10 (kW) 16.3 (%)

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Estimation of annual power generation Calculate annual power by System Utilization Parameter (Example) System utilization parameterUg= (%) PV rated capacityPu=50 (kW) (kWh/year) If you install a 50kW PV system in this place, how much power can you generate?

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Estimation of annual power generation Exercise Step1 Convert “horizontal insolation” to “tilted insolation” Step2 Calculate annual earned energy (Insolation data) Local Latitude = -15 (deg) Horizontal InsolationI = 1,800 (kWh/m 2 Year) PV CapacityPu = 5kW

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Estimation of annual power generation Exercise (Insolation data) Local Latitude = -15 (deg) Horizontal InsolationI = 1,800 (kWh/m 2 Year) PV CapacityPu = 5kW Step1 Convert “horizontal insolation” to “tilted insolation” Step2 Calculate annual earned energy (kWh / m 2 year) (kWh/year)

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Estimation of annual power generation Exercise Step3 Calculate “Load Factor" Step4 If you install 50kW PV system in this place, how much energy (kWh) can you earn?

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Estimation of annual power generation Exercise Step3 Calculate “Load Factor" Step4 If you install 50kW PV system in this place, how much energy (kWh) can you earn? 14.9 (%) (kWh/year)

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Case practice Case Practice

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Case practice February has 28 days