I had a customer ask me about installing a solar panel system for his residence. I have heard different numbers as far as calculating efficiency and what to use as the number of hours per day of sunlight. One person told me that I should use .666 efficiency and 10 hours per day for my location (Northern Iowa/Southern MN). Another persons calculations are almost half of that. I don't want to tell the customer that he's going to produce more than what it will likely produce. There can be some room for error just because of cloudy days and things that can't be predicted. Does anyone have any good information on the best way to calculate this with some degree of accuracy?
Solar calculations
- Thread starter ammklq143
- Start date
- Status
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
Look at the government (NREL) website "PVWatts".
It will do the calculations for you, taking into account panel orientation and typical weather.
You should expect closer to 4 *equivalent* hours of sunlight in summer and half that in winter.
It will do the calculations for you, taking into account panel orientation and typical weather.
You should expect closer to 4 *equivalent* hours of sunlight in summer and half that in winter.
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
This thread should be in the photovoltaics subforum.
PVWatts is a great first pass tool for estimation of solar output. If you are interested in the equivalent hours of 1000W/meter sunlight for a location varying a few parameters, go here: http://rredc.nrel.gov/solar/old_data/nsrdb/1961-1990/redbook/sum2/state.html and look up the nearest station to the location you are interested in. PVWatts uses this data.
PVWatts is a great first pass tool for estimation of solar output. If you are interested in the equivalent hours of 1000W/meter sunlight for a location varying a few parameters, go here: http://rredc.nrel.gov/solar/old_data/nsrdb/1961-1990/redbook/sum2/state.html and look up the nearest station to the location you are interested in. PVWatts uses this data.
- Status