Looking into Solar Power is it worthwhile for my house?

[Megadethmaniac]

I`m looking into Solar.

I live in the UK ( South East) and have a reasonable sized detached property. The issue is that the orientation of the property isn`t going to be great for Solar pannels. The back of the house is around a 40deg pitch. The size of the roof would easily take 14 panels and might just take 16. So I might just get 6kwh of panels on the roof. Obviously these would work well during the morning and get full sunlight until 1-2 ish. After that the sunlight will fade insofar as the system is concerned.

Obviously I`m limited by the grid ultimately but understand that the system could be throttled to 4 or 5 kwh feed into the grid. I`ve had a couple of people round and they seem keen to sell a 4kwh "package" with 3-5kwh of batteries. I do like the idea of batteries and just wonder if 4 kwh is enough panel wise How badly do modern panels production drop off after losing direct light?

 

[MichaelK]

I don't live in the UK, so I don't know all the details of your local grid-tie systems, but I have to ask, why would you want to throttle back your solar production to only 4-5kWh of power? Why not contribute to the grid as many watts as possible?

In terms of production, your panels likely will NEVER produce their full output. A good rule of thumb is that in direct, perpendicular sun, you are likely to generate around 85% of what your panels are rated for. So with 6kW of panels, you are likely to see at most ~5100W. As the sun gets more and more angled away from your panels, production drops precipitously. At 8am, or on a cloudy day, expect production to equal no more than 10% of rated output.

But, for a UK home, a 40 degree angle doesn't sound too bad, and you may be able to create angled frames that improve on that by a bit.