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Stadtvilla1917 Mar 2020 09:21Hello,
I’m curious if anyone here is really knowledgeable about photovoltaic systems or if anyone knows of a website where you can calculate the performance and orientation.
We have a townhouse measuring 12 x 9 meters (39 x 30 feet) with 60 cm (24 inches) roof overhangs and a 25° pitch. The house offer stated that we would get a 9.9 kW photovoltaic system. However, we were already told that the roof area is not sufficient and that some panels would have to be placed on the extension. We actually don’t want that; we want everything on the hipped roof. According to the technical company, only 9.5 kW would fit there with an east/west orientation.
Since our house’s main roof surfaces are oriented roughly northeast/southwest, I’m a bit concerned whether it makes sense to install half the system on the northeast side. According to a table I found, that would be an azimuth of -110° and only yield about 79% efficiency. Now I’m wondering which would make more sense: the technical company’s suggested layout or utilizing the smaller roof surface nearby, which faces southeast. Of course, fewer panels would fit there, so the system would probably be closer to 7 kW, but could it generate more energy this way? We would also save money because fewer panels are needed. The technical company probably just wants to install whatever they quoted, whether it makes sense or not, as long as they make the sale.
Therefore, I would like to calculate what can be achieved with fewer solar panels but better orientation, compared to more panels with a less optimal orientation.
I’m curious if anyone here is really knowledgeable about photovoltaic systems or if anyone knows of a website where you can calculate the performance and orientation.
We have a townhouse measuring 12 x 9 meters (39 x 30 feet) with 60 cm (24 inches) roof overhangs and a 25° pitch. The house offer stated that we would get a 9.9 kW photovoltaic system. However, we were already told that the roof area is not sufficient and that some panels would have to be placed on the extension. We actually don’t want that; we want everything on the hipped roof. According to the technical company, only 9.5 kW would fit there with an east/west orientation.
Since our house’s main roof surfaces are oriented roughly northeast/southwest, I’m a bit concerned whether it makes sense to install half the system on the northeast side. According to a table I found, that would be an azimuth of -110° and only yield about 79% efficiency. Now I’m wondering which would make more sense: the technical company’s suggested layout or utilizing the smaller roof surface nearby, which faces southeast. Of course, fewer panels would fit there, so the system would probably be closer to 7 kW, but could it generate more energy this way? We would also save money because fewer panels are needed. The technical company probably just wants to install whatever they quoted, whether it makes sense or not, as long as they make the sale.
Therefore, I would like to calculate what can be achieved with fewer solar panels but better orientation, compared to more panels with a less optimal orientation.
Hi,
yes, the site exists: search for Photovoltaic Forum on Google.
There you can introduce your house, roof, and quotes, and you will receive very good support. Having plans ready is useful.
General info: cover the entire roof! Storage systems are less recommended. Note: the subsidy cap is almost reached, please check for updates.
Based on your information, our houses/roofs are quite similar. With our slightly smaller roof area, 9.9 kWp fits with 31 modules.
We have filled three sections (SW = 12 modules, S/SO = 9 modules, NO = 10 modules).
For a hipped roof, it is better to use a SolarEdge inverter.
yes, the site exists: search for Photovoltaic Forum on Google.
There you can introduce your house, roof, and quotes, and you will receive very good support. Having plans ready is useful.
General info: cover the entire roof! Storage systems are less recommended. Note: the subsidy cap is almost reached, please check for updates.
Based on your information, our houses/roofs are quite similar. With our slightly smaller roof area, 9.9 kWp fits with 31 modules.
We have filled three sections (SW = 12 modules, S/SO = 9 modules, NO = 10 modules).
For a hipped roof, it is better to use a SolarEdge inverter.
Yes, PVGIS. Do not cover the north side. Instead, fully utilize the southwest. Especially in summer, this will benefit you. You will still get reasonable yields in the late hours, whereas I only get some double-digit output with my south-facing roof at that time.
I’m not a fan of north-facing roofs unless money is no object.
I’m not a fan of north-facing roofs unless money is no object.
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Stadtvilla1917 Mar 2020 11:08So, we should get 14 modules per roof side; it seems more won't fit.
I just calculated this using the recommended website. The plan is for 28 modules, 14 facing southwest (SW) and 14 facing northeast (NE). According to the website you recommended, the 14 modules facing NE would produce about 3650 kWh. If I calculate the same for the smaller roof section facing southeast (SE), I only need 10 modules to reach almost the same output.
Of course, I don’t know if 10 modules will fit there, but wouldn’t it be better to save the cost of 4 modules while achieving the same yield?
I just calculated this using the recommended website. The plan is for 28 modules, 14 facing southwest (SW) and 14 facing northeast (NE). According to the website you recommended, the 14 modules facing NE would produce about 3650 kWh. If I calculate the same for the smaller roof section facing southeast (SE), I only need 10 modules to reach almost the same output.
Of course, I don’t know if 10 modules will fit there, but wouldn’t it be better to save the cost of 4 modules while achieving the same yield?
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Stadtvilla1917 Mar 2020 11:18This is approximately how our roof and its orientation look.
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