Have a look at Solcast or one of many similar apps which will give you forecasts for any location and orientation of panels.

I have 10 panels east and 14 west and got about 7000MWh in total last year.  I'm near Hertford.

@downfield 7000MWh?  From 24 panels ? Do you mean 7MWh?  ( I got 5.8MWh from 29 south facing panels last year)

@carpenterstation oops - yes I do!  7MWh

@carpenterstation, adding panels to your east-facing roof could work, but personally, we’d be more inclined to go for west-facing panels instead. In our case, we find that we use more power later in the day, so we’d prioritise west-facing panels to extend generation into the afternoon and evening when demand is typically higher.

That said, if your household tends to use a lot of electricity in the mornings, an east-facing array could still be useful, especially since you’ve already got an inverter and battery in place.

Let us know what you decide… we’d be interested to hear how it plays out.

Posted by: @editor

↑

@carpenterstation, adding panels to your east-facing roof could work, but personally, we’d be more inclined to go for west-facing panels instead. In our case, we find that we use more power later in the day, so we’d prioritise west-facing panels to extend generation into the afternoon and evening when demand is typically higher.

That said, if your household tends to use a lot of electricity in the mornings, an east-facing array could still be useful, especially since you’ve already got an inverter and battery in place.

Let us know what you decide… we’d be interested to hear how it plays out.

Interesting. We currently find morning solar is most beneficial for us as we can run the heat pump on solar following an overnight switch off (we often don't get up before 10am). The afternoon is financially less beneficial as we are on Octopus Cosy where the afternoon import rate of 12.86p is cheaper than the solar export rate of 15p so we would happily import in the afternoon.

Hopefully adding a battery to the mix soon, which will totally change the dynamic, and just highlights how these choices are very dependant on personal circumstances and intended use.

@carpenterstation  as @downfield  suggested, I use PVGIS to model predicted solar generation and have found it to be pretty accurate, certainly sufficiently so to model and compare your proposed solar addition.

Yes. Thanks all. I have used the guides and have found that our East is actually 120 degrees (so more ESE than East) and that the solar is only slightly down on south (our “south” is 210 degrees). Our usage suggests early mornings when we prep car for work, tends to be more of a drain than evening- and we don’t really have a West roof. 

but it is the clear sun early in the day (rather than later cloudy sun) that I think might be the clincher. Need to check with DNO though as another 5 kw might give them problems. And it is viable with Octopus Cosy while there is still an export market.  But if that goes it’s a very different proposition….

Scuppered by the DNO unfortunately. I have been told that the grid does not currently have enough resilience to cope with an additional 5 or 6 kw - so the economics won’t work for us. Shame - I think it would have been viable.

I remember when ours were installed 18 months ago the limit was 5kW total of panels, but the discussion was never clear if that was total installed on roof, which solar panel insatllers seemed to think it was, or 5kW as the highest power export level.

We have 4.9kW of panels installed, with one third pointing south east and 2/3 pointing south west, so the highest power we get is about 4kW.  I have wondered about putting more panels up but wouldn't want to bump up against export limits and our battery isn't big enough to absorb extra and we don't yet have an electric car.

Posted by: @guthrie

↑

I remember when ours were installed 18 months ago the limit was 5kW total of panels, but the discussion was never clear if that was total installed on roof, which solar panel insatllers seemed to think it was, or 5kW as the highest power export level.

We have 4.9kW of panels installed, with one third pointing south east and 2/3 pointing south west, so the highest power we get is about 4kW.  I have wondered about putting more panels up but wouldn't want to bump up against export limits and our battery isn't big enough to absorb extra and we don't yet have an electric car.

 

General wisdom is to oversize the array slightly, so if your export limit is 5kW (and you have or can add a 5kW inverter), then being able to generate around 6kW peak with 1kW of clipping is not unreasonable. You would benefit for the majority of the year when you are not clipping, and from your figures it sounds like a 6kWp array would never generate more than 5kW on your roof anyway.

You may have a smaller inverter (e.g, 3.68kW) which cannot handle any more than 5kW of installed panels, which is where the '5kW' limit may have come from, or the DNO may have set a 5kW export limit on you. You would need to establish which is the case.

Posted by: @carpenterstation

↑

Scuppered by the DNO unfortunately. I have been told that the grid does not currently have enough resilience to cope with an additional 5 or 6 kw - so the economics won’t work for us. Shame - I think it would have been viable.

Gutted for you. We are waiting to hear on our application to increase our solar array to 7.2kWp and add a Tesla PW3 battery (max 11.04kW export), but are not expecting an enthusiastic yes. If they will give us 5-6kW export, we can work with that but if they say nothing above the current 3.68kW then it's not looking great.