Upwind Solar Expedition!

theboylard

Here's Upwind's house:



I'll leave this now for Upwind to tell us what he's after...

theboylard

From the off, I'd suggest both roofs?

Upwind

Cheers theboylard. Expedition indeed.........

My trouble is I"m currently visiting in-laws with Head of Domestic Services and I am trying to interact using a hudl with a cracked screen I am evidently struggling...

I only envisaged on side - house in street next to me has 16 panels in a square on just one roof side - never thought about both sides - is there a limit?

theboylard

Generally the only limits really are budget or roof space!

But getting ahead of ourselves here, your first port of call is the PV FAQ, lovingly maintained by Martyn1981.
There is a lot to take in, but it is a really useful resource.

This will either answer many of the common questions that we all had when starting out, or will give rise to more questions based on your circumstances?

Continuing with my reply to your question....
You could go mad but it comes down to what you expect from them? Is anyone home during the day to make use of the generation (until storage becomes viable)?

Have a look here: PVOutput Map for some local installs around you.
These show what sort of generation you could get from similar sized systems - but these folk may have had limits on what they could install, again typically either roof space or budget?

Martyn1981

theboylard wrote: »

From the off, I'd suggest both roofs?

Upwind wrote: »

I only envisaged on side - house in street next to me has 16 panels in a square on just one roof side - never thought about both sides - is there a limit?

My penny's worth. Hmmmm!

Ok, will try for more detail. Looks like that orientation is SE (perhaps just short, but better than ESE). That's pretty good. If the roof can take 16 panels (or if necessary 14 285Wp) then that's a simple and cheap solution.

But, I like bigger systems, might as well do as much as you can whilst you're up there. And that house to the south looks like it may cause some shading from the late afternoon onwards (depending on the time of year?)

Can you go bigger, well yes ..... but:-

Firstly, if you install more than 4kWp (even 4,001Wp) then the whole install will get the 4-10kWp FiT rate which is 10% less. That's not actually too bad, but you'd logically probably want to aim for 4 or 5+kWp, not anything inbetween.

Secondly, the NW roof will generate less, try PVGIS (see section 5 of the PV FAQs). I did a quick check and got a rough ratio of NW 590kWh/kWp v's SE 875kWh/kWp. I used an azimuth (panel orientation to the sun (south)) of SE -50 and NW +130, as a guess from the photo.

Thirdly, you can install a system with a capped output of 3.68kW, and simply notify the DNO (district network operator) afterwards. A 3.68kW capped inverter on a 4kWp system would work fine. To go with a larger inverter output needs prior permission from the DNO, and you may not get it. However, if for space reasons you placed 3kWp on the SE and 2kWp on the NW, then they wouldn't peak at the same time, and there'd probably wouldn't be that much capping over a year.

Fourthly (back to photo) if shading is an issue, then you may want to install less panels and avoid the SW part of the roof, [Edit: what I mean is install panels on the SE roof, but avoid using the space nearest your neighbour. M.] hence shifting panels to the NW roof. Or add some shade mitigation, such as a SolarEdge system, or place less panels, but use higher efficiency ones that are smaller but cost more. If you went for the simplest solution of less panels, then that's another reason for considering the NW roof too.

If you are willing to consider going bigger, then it's probably not a bad idea to ask for quotes from installers for a split system, as it's always nice to generate later in the day from a westish roof, though clearly NW isn't great. Perhaps ask about a 3SE + 2NW install, or 4SE + 2NW, or 3SE + 3NW depending on roof space limitations. However, for the 6kWp options you probably want to consider asking the DNO for permission to go a bit bigger with the inverter, perhaps 4.5kW (or so).

None of this is as complicated as it sounds, just one step at a time, get prices, work out incomes, compare relative returns, then add on a little value for having a wider spread of generation, especially teatime generation. Loads of us can number crunch and ponder this stuff with you.

Mart.

Upwind

Thanks Mart. Appreciate you taking the time to explain all the options in such detail

Going to get some quotes next week and see what is advised by the 'experts'. Will update when I get these.

tunnel

Upwind wrote: »

Going to get some quotes next week and see what is advised by the 'experts'. Will update when I get these.

Just make sure they know you may need some sort of shade management after looking at your aerial view and try to aim for £5k or less, it is doable.