ron
Senior Member
- Location
- New York, 40.7514,-73.9925
690.7 doesn't seem to permit any voltage drop fudging of the numbers.
I have a situation where 12 panels would make the physical installation easier, but when calculating open circuit voltage, using the manufacturers oc voltage rating and temperature coefficient, puts me slightly above 600V with 12 panels. I can't find a reference that shows higher "lowest expected ambient temperature" but I know in real life, voltage drop will make these panels exhibit an installed condition below the theoretical calculated voltage. I checked ASHRAE tables and Weather.com
I don't want to battle with an inspector later on. Is there anyway to include a fudge factor, or in your experience has inspectors not challenged the 690.7 calculation.
I have a situation where 12 panels would make the physical installation easier, but when calculating open circuit voltage, using the manufacturers oc voltage rating and temperature coefficient, puts me slightly above 600V with 12 panels. I can't find a reference that shows higher "lowest expected ambient temperature" but I know in real life, voltage drop will make these panels exhibit an installed condition below the theoretical calculated voltage. I checked ASHRAE tables and Weather.com
I don't want to battle with an inspector later on. Is there anyway to include a fudge factor, or in your experience has inspectors not challenged the 690.7 calculation.