Solar question

cheesesarnie

Hi
We've got a decent sized south facing detached house which was extended some years ago. The extension gave the south facing roof multiple odd shaped elevations which, according to a recent attempted quote, meant solar on the roof is unviable due to only 1 or 2 of their panels would fit on each of the 4 part south facing elevations and apparently splitting the banks multiple ways is not cost effective?. A neighbour with the same house layout pre extension has got a bank of 12+ panels easily on.

We also have a double detached garage with a south facing pitched roof. Same supplier measured the garage and determined it could only fit 4 of their panels on (annoyingly didnt record the measurements). The panels mentioned sounded massive to me hence are less flexible in their use of space.

I wondered if different suppliers fit smaller panels which might handle a more limiting available space better. Couldnt see much online about it. Thought I'd ask the pro's!!

Thanks
Tony

ABrass

Traditionally solar panels connect to the inverter that converts their DC power to AC on a 'string'. That's just all the panels in series. However when you do that then any shading or loss of light for one panel drops the power for all of them. Similar to how old fairy lights used to go if one bulb was out.

That means that if you've got some panels facing E and some facing W then you're going to lose out on a lot of power when the sun isn't perfectly overhead.

If you've got different elevations then you need to go for something with optimisers. Those allow each panel to work at its most effective, in effect they work in parallel. Solar Edge are the most famous examples but there are plenty of others.

Optimisers cost a bit more, but not a huge amount.

The size of panels has been creeping up over the last decade. It is generally more efficient that way but can limit flexibility.

cheesesarnie

Annoying thing is the different bits of roof facing different directions will now only each fit 1 or 2 of the IMO big panels due to the angles so actually the use of space is super inefficient. 

I've found a sun power panel online that is smaller and according to my calculations would fit 9-12 on the garage just by shaving 20 cm on the length of each panel.

I just need to fit a company that fits them now (oh and supply too)

Cheers

Teaspoonsaurous

On a similar note. I am considering putting solar panels on to an external building. This is a fully wired out house that then connects back into the main fuse board.

I was going to add the panels and not a battery. My question is when the panels are generating power and feeding it back into the main house, how does the system now to prioritise our domestic produced energy over the energy of our electricity provider...? 

I am clearly not an electrical engineer.

ABrass

Your meter detects the flow of power through it.

If there is power being generated on your side of the meter and consumed on your side of the meter then no/less power will be drawn from the grid and there will be none/less to detect.

ispookie666

What size system are you looking at? It is possible DNO might limit your export to 3.68 in certain places or might let you export as much as you need. Your neighbour having panels can result in consideration. 

Alternate is to look into Enphase microinverters. Similar but different to optimers, making each panel fully independent. It is an expensive system and is suitable for roofs with multiple orientation

cheesesarnie

I was hoping for 4kw but I cant see me getting up to that.

Thanks..I'll have a look at Enphase.

Seems to me the logical solution is the double garage roof option but that would definitely need way smaller panels that the 2mx1m I've talked to 1 fitter about to efficiently use the space.

Of I might need to give up on the idea which seems tragic on actually collectively a load of roof space.