Hello,
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.
P
Piotr19816 Aug 2020 11:25It depends somewhat on the total price, right?! I could get the battery storage for about 3,500 (currency). Minus any subsidies.
Piotr1981 schrieb:
It depends somewhat on the total price, right?! I would get the storage system for about 3,500 (around $3,500). After deducting subsidies.Which subsidy? The one from Brandenburg? Do you receive the full amount? Or the KfW 40 / KfW 40 Plus grant of 6,000 € (about $6,000)? The second one is worth it. The first only if you actually get it. I think those funds are almost depleted.
K
knalltüte6 Aug 2020 16:47Hi,
Don’t forget about inverter losses for battery charging: 100% goes in, but only about 80-90% comes out!
The battery is a power consumer .-/
The already mentioned and recommended photovoltaic forum is the right place. Please present your roof areas there accordingly. Include sketches and drawings with exact measurements! Then you can get help planning an optimal system. Maybe 14 kWp can fit if you use all four surfaces? At a 25° roof pitch, this could be worthwhile if you get a reasonable offer.
Just use a good inverter with 4 MPPTs, or if absolutely necessary, SolarEdge.
Then you can also cover outbuildings (garage, bike shelter, etc.) if needed and desired.
Don’t forget about inverter losses for battery charging: 100% goes in, but only about 80-90% comes out!
The battery is a power consumer .-/
The already mentioned and recommended photovoltaic forum is the right place. Please present your roof areas there accordingly. Include sketches and drawings with exact measurements! Then you can get help planning an optimal system. Maybe 14 kWp can fit if you use all four surfaces? At a 25° roof pitch, this could be worthwhile if you get a reasonable offer.
Just use a good inverter with 4 MPPTs, or if absolutely necessary, SolarEdge.
Then you can also cover outbuildings (garage, bike shelter, etc.) if needed and desired.
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