Calculating ideal azimuth for solar panels

I am thinking of adding a combined sunshade/solar array to the WSW side of my house. Normally the ideal azimuth is due true south (not due magnetic south) however due to severe shading this wall receives no direct sunlight until noon (13:00 in summer).

So, how do I calculate the ideal azimuth under these conditions? I’m assuming seasonal variation, in which case I prefer to optimise for winter.

I am planning a frame with front and back rails parallel to the house wall with panels mounted at an angle on it.

Probably not much help directly, but if you can implement something yourself or wait for someone else to, Google has released a new APIs which cover the UK and can do a lot of these sort of optimisations.

Thanks, I’m sure the links would help some people but I’m afraid I wouldn’t know what to do with an API, even if I recognised one.

I don’t know the answer to your specific question. But I think that even if you don’t know the ideal azimuth, it doesn’t much matter within 30 degrees or so. There’s a great EC calculator which tells me that in my location, with PVs tilted at 35 degrees, the reduction in annual generation for an azimuth 30 degrees west of south compared with true south is only 2%.

Photovoltaic Geograhical Information System

I think that the main reason it is so insensitive to direction is that most of the energy arrives diffusely from the sky rather than in the direct beam from the sun

Thanks. I was getting the feeling that an informed guess would be adequate. I’m thinking of orientating to SW(ish) to be half way between south and sunset mid winter. I should be able to look up the orientation of sunset somewhere.

Your point about diffused light is particularly pertinent in winter.