validation of HOMER's results
I've just joined this forum and wanted your kind opinion on a query which I had whilst using HOMER pro.
Q. How to validate HOMER's calculation?
Given: residential load = 11.26 kwh/day, peak = 2.09 kw, Lowest Irradiation = 5.3 kwh/m2/day
HOMER's result: (All calculation done using 'HOMER optimizer' option)
PV array: capacity = 5.37, mean output = .999 kw, array efficiency = 18.6%, energy out = 23.9 kwh/day
Battery: capacity = 2585.4 AH, energy out =6.10 kwh/day, energy in = 7.60 kwh/day, round trip efficiency = 80%
Converter capacity: capacity = 2.74 kw, energy out = 11.24 kwh/day, energy in = 11.84 kwh/day, efficiency = 95%
PV array capacity = user needs / (min. av. Irradiation x system efficiency)
Assuming system efficiency = 60%, array capacity = 11.26 / (5.3 x 0.6) = 3.5409 kw
Battery capacity = 11.26 kwh / 12 v = 938.3 AH
Assuming 70% losses, 80% Depth of Discharge (given) and 1.65 days of autonomy (given) Battery capacity = 938.3 x 1.65 / (.70x.80) = 2,764.6339 AH
Ideal PV array to Inverter ratio is 1.2-1.3.
Therefore, inverter capacity = 3.54 / 1.25 = 2.832 KW
1. Why is the PV array capacity oversized?
2. How is the Battery size determined? (formula)
3. How is the Converter size determined? (formula)
4. Below is the Single Line Diagram of the system components with their input and output energy.
- Where does the input of 11.84 kwh/day to Inverter come from?
- where does the input of 7.6 kwh/day to Battery come from?
- Where does the output of 23.9 kwh/day from PV go to?
HOMER FILE and Single Line Diagram of System Components available here
Your comments are welcome.