Step 3 Acceptance Ratio

Concept

AR Acceptance Ratio, in general, the solar panel project must achieve >=95% AR as minimum requirement

PA stc PV array capacity (W)

PSHi (or called fg) Peak sun hour received in-plane of array/PSH measured per annum/ In Plane PSH per day/month (h)

fmm Power de-rate factor due to mismatch (decimal)

ftemp Temperature derating factor during measurement (decimal)

fclean Power de-rate factor due to dirt (decimal)

fdegrad Power degradation factor due to LID and aging (decimal)

fshade Shading factor (decimal)

ηcable Efficiency of the cable (decimal)

ηinv Maximum efficiency of the inverter (decimal)

3.2 Calculate PSHi

PSHi = Gi /Gstc 

Gi (or called Hi) Solar irradiance received on plane of array, poa (Wm-2)

Gstc Solar irradiance at STC ,1000 Wm-2

PSHi = (0.9*1000)/1000 = 0.9

3.4 Calculate ftemp

The formula is similar to ftemp_ave in Step 1 Choose PV Module  >> 1.4 Calculate ftemp_ave 

Tmod Module temperature at specific time (°C)

Tmod Cell temperature at STC, always 25 °C

γPmax Temperature coefficient for Maximum Power/ Rated Power/ Peak Power/ Power at MPP (Pmax) (% °C-1 or % K-1) 

Convert YPmax from <W °C-1> or <W K-1> to <% °C-1 > or <% K-1 > if need.

YPmax (% °C-1) = [ YPmax (W °C-1) / Pmax STC ] * 100 % 

Example

• SOLARMAN 200W

• YPmax = - 0.76 W °C-1

• YPmax = ( - 0.76 / 200 ) * 100 = -0.38 % °C-1

2.  General Formula

Since we only compare 0 to 1 year, so can be simplify to: 

From question, PV modules have 1st year power drops of 2% and linearly drops of 0.8% per annum until 25th year.

fdegrad = 1 - ( 2% / 100 ) = 0.98

3.8 Calculate ηcable

ηcable = (100 % - Cable Loss %) /100

Refer to MS 1837:2018, the highest cable loss is 3%, so assume 100% - 3% = 97% (0.97) if not given

ηcable = 0.98 (Question Provided)