New PV - questions to ask

Hi - we’re looking at a PV installation on our east/west roof spaces.

We’ve been in touch with our DNO and they have indicated that we could have 5kW without being limited. This means that we can over-spec to squeeze out a bit more production each end of the day.


Based on this a local PV installer has suggested the below. We haven’t had a site visit yet so expect that this may change. If anyone has any ‘must ask’ questions that we can put to the installer I’m all ears. Thank you!

Note: We’re on Octopus Go Faster, we’re all electric and don’t plan on adding any battery storage at this time. Excess generation will be sold to Octopus at the fixed 5.5p/kWh.

If you have bird feeders in your garden or nearby ask them about the cost of installing pigeon proofing at the same time (see a related thread on this) - it shouldn’t add much more to the cost and it’d be a heck of a lot cheaper than getting the scaffolding back to do it later. It’s by no means always an issue - depends on how hospitable your neighbourhood is to them! Some friends of mine just had to do it because their neighbour was complaining about the noise in his loft conversion.

Other questions: make sure they provide a guarantee for the roof work (they usually do if they’re at all reputable), and make sure they have a clear plan for where they’re going to put the inverter. When I got mine done someone came for the site visit, looked in the loft & said it wouldn’t be a problem but then when it came to fitting they clearly hadn’t got enough space and improvised wildly, made a hell of a mess. More tricky in my case because I got a battery - and ended up with two inverters for the price of one… it was chaos!

I’m sure others will have suggestions too.

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Hi Richard , re pigeon poo and other debris which might land on the panels - we have a tree which sheds a lot of blossom, pollen, seeds etc. It is right by the roof we have on our lean to kitchen where we were considering as a site for some solar panels. Would you advise against having panels here and perhaps opt for the main roof instead - which would hardly be affected at all by said tree!

From what you describe, it sounds like that roof would be significantly shaded by the tree? If so, that would be a strong argument for not putting solar panels there! In Manchester your panels will be washed by rain pretty frequently so I wouldn’t expect this sort of fouling to be too much of a problem otherwise - hard to say without knowing more about the situation.

Looks like shading could be taken care of by the Solar Edge inverter and optimisers on each panel.

Although shade still means less production, so take any estimates with a pinch of salt.
If you want to double check the production figures you could create a free account on Solcast and put in the two roof.

Finally, more is better. Get the most you can on the roof. No one who installs solar ever says later down the line “I wish I hadn’t put all this solar up”. :slight_smile:

If there is scope for even more panels on the roof, could you go upto the SE6000 inverter (which takes upto 9kWh of panels) and export limit to 5kWh with the SolarEdge export limiter. (keeping the DNO happy)

I know from painful personal experience having regrets about not putting more on the roof at original install. :frowning: