Solar being installed on roofs are rarely installed in an ideal setting. Ipsun Solar installs solar modules on residential and commercial properties and most have roofs with some deviation from the optimal situation. Most roofs have some shading either from a vent, a nearby building, a tree or HVAC. Large commercial roofs have usually ballasted systems facing South, but the inclination is between 5 and 15 degrees.
We install in Virginia, Maryland and Washington DC, where due South azimuth is ideal with a 30 degree inclination. However, even if the the conditions on a roof are ideal, sometimes an HOA will have problems with a homeowner installing solar in the optimal place on the roof. Check out our post on how to apply for solar with your HOA, and our overview of how solar works, and then use the data below to aid in your communication with them.
The table below is graciously offered by a Washington D.C. official. Keith Winston is the solar specialist at DCRA. The first part of the table is showing the AC output in kWh of a 1kW solar panel system. The 2nd table is the same information, but in percentages where the 0 degree (flat) is equal to 0%.
You see in the table that the maximum output of the 1 kWh solar system is 1,362 kWh and is achieved with a system facing South (azimuth of 180 degrees) and with a 30 degrees tilt.
Important note for all the HOAs trying to restrict access to solar and trying to force people to put solar panels on the other side of the home.
If you have a roof of 30 degrees and you move the panels from the south facing roof to the north facing roof, the difference in production goes from 1,362 kWh to 804 kWh . The difference is 1-(804/1362)= 41%. So moving the panels from South to North facing roof reduces the solar power production by 41%.
If your roof is tilted by 20 degrees, then the effect of moving panels from South to the North facing roof is 30%.
If you have further questions about the process for getting HOA approval or about the optimal placement of solar on your roof, give us a call at 703-249-6594 or click below. We’re happy to help!