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HomeMy WebLinkAboutB14-0266 calcs.pdf
Page 4 of 6 7/7/2014
Calculations
13.5kW System Size (STC)
50 SolarWorld Plus SW270 mono solar modules @ 270watts
50 Enphase M-250 240v micro-inverters (4 string of 7/13/14/16)
Array tilt angle: 26.57°/41.51°
Array azimuth: 105º/195°/285° (where 180º is south)
Estimated annual power production: 16,164kWh
Maximum PV System Voltage: 690.7
Voc= 39.2V/module
39.2V x 1 module = 39.2V
Temperature correction factor 690.7(A)
STC = 25°C, Temperature Coefficient (Voc) = -.3%/°K
(-65°C (-.003) = .195%
((.195% x 39.2V) x 1 panel) + 39.2V = 46.8V
Temperature correction factor Table 690.7
For -40ºF use 1.25
39.2V x 1.25 = 49V
Maximum PV Source Circuit (String) Current: 690.8 (A)(1)
Isc =9.44A
9.44A x 1.25 = 11.8A
Maximum PV Output Circuit (Array) Current: 690.8 (A)(2)
11.8A x 1 strings = 11.8A
Inverter Output Circuit Current: 690.8 (A)(3)
1A @ 240V
John Wiles, “Photovoltaic Power Systems and the National Electrical Code: Suggested
Practices”, 2005, pp. E1-E25.
pdf version online at: http://www.nmsu.edu/%7Etdi/Photovoltaics/Codes-
Stds/PVnecSugPract.html