Performance of panels on east/west facing roof?

[F357]

I have two large industrial buildings which I need to upgrade the available power from the utility. It might work out better to install a solar system that would reduce our load. We use several thousand kilowatt hours every month in both buildings.

Unfortunately, both roofs have about a 10:12 pitch pointing east and west, not south. If I covered the whole roof, I could get up to 80kw of panels on each building I think. It would be a substantial investment, but, may also produce quite a lot of electricity every month.

Can anybody help me determine the average monthly power produced by an 80KW system on an east/west facing steep roof?

I did the math based on what this web site says:

http://www.solarpowerrocks.com/square-feet-solar-roof/

I too am near Portland, Oregon. It says I will produce about 87,360 KWH per year or 7,280 KWH per month. Does that sound about right or will it be less without a south facing roof?

I would install more panels on the south facing wall (building is very tall), but I want to calculate that separately.

[J.P.M.]

I have two large industrial buildings which I need to upgrade the available power from the utility. It might work out better to install a solar system that would reduce our load. We use several thousand kilowatt hours every month in both buildings. Unfortunately, both roofs have about a 10:12 pitch pointing east and west, not south. If I covered the whole roof, I could get up to 80kw of panels on each building I think. It would be a substantial investment, but, may also produce quite a lot of electricity every month. Can anybody help me determine the average monthly power produced by an 80KW system on an east/west facing steep roof? I did the math based on what this web site says: http://www.solarpowerrocks.com/square-feet-solar-roof/ I too am near Portland, Oregon. It says I will produce about 87,360 KWH per year or 7,280 KWH per month. Does that sound about right or will it be less without a south facing roof? I would install more panels on the south facing wall (building is very tall), but I want to calculate that separately.

I'd run PVWatts. Free, about 10-20 min. reading intro material. Suggest using 8-10% rerate instead of the default rate of 14%. You will need to run it 2X, one for each orientation and sum the results. Gives long term estimate. Between the weather and the model limitations, actual annual output will vary year/year w/weather by something like +/- 10% or so. Most of this ain't rocket science and, like weather forecasting, not that precise. Then compare that PVWatts output with what you have.

[J.P.M.]

I have two large industrial buildings which I need to upgrade the available power from the utility. It might work out better to install a solar system that would reduce our load. We use several thousand kilowatt hours every month in both buildings. Unfortunately, both roofs have about a 10:12 pitch pointing east and west, not south. If I covered the whole roof, I could get up to 80kw of panels on each building I think. It would be a substantial investment, but, may also produce quite a lot of electricity every month. Can anybody help me determine the average monthly power produced by an 80KW system on an east/west facing steep roof? I did the math based on what this web site says: http://www.solarpowerrocks.com/square-feet-solar-roof/ I too am near Portland, Oregon. It says I will produce about 87,360 KWH per year or 7,280 KWH per month. Does that sound about right or will it be less without a south facing roof? I would install more panels on the south facing wall (building is very tall), but I want to calculate that separately.

I'd run PVWatts. Free, about 10-20 min. reading intro material. Suggest using 8-10% derate instead of the default rate of 14%. You will need to run it 2X, one for each orientation and sum the results. Gives long term estimate. Between the weather and the model limitations, actual annual output will vary year/year w/weather by something like +/- 10% or so. Most of this ain't rocket science and, like weather forecasting, not that precise. Then compare that PVWatts output with what you have.

[acamato]

Another tool in addition to PVWatts is https://psegli.powerclerk.com/Incent...alculator.aspx

I don't know if it will work with a zip code outside NY.