Additional Panels on North Facing Roof

goose06

Just looking for a bit of advice here, we're in the middle of a renovation of a house and due to the shape of the roof we can only fit 7 panels on the South Easterly facing roof so only about 2.9 worth of panels. Company are suggesting installing 10kW of battery to offset this as they had originally hoped to install 5.8 of so of panels. I've asked them about putting 7 panels on the NW side of the roof as well and I'm wondering if it would be worth it or just go with the panels on the optimal side only and the batteries or go with only 5Kw of battery and add another 2.9 to the less optimal roof and add an additional battery down the line?

Thanks

curioustony

Battery alone is very valuable in terms of buying when electricity is cheap. Works all year round.

This table is based on EAB figures, and just one supplier plan. It excludes solar.

Very large batteries can also have spare charge left at the end of the day, drowning in use, which can be exported, for more credit, if you have the right inverter.

North facing sleep during winter, but build up credit in summer.

The above android app will let you play with what-if scenarios, with solar data from PVGIS for your location and orientation.

It is of course easier to add a battery later.

No right answer!

goose06

That's my thinking as well that it'd probably be easier/cheaper to add the battery later than to get someone up on the roof to add additional panels

DC999

https://www.boards.ie/discussion/2058366301/additional-panels-on-north-facing-roof

I have some NW panels and they are great for 6 months.To end of Sept. Then they produce very little each day. Sun won,t hit then directly until late March again.

But...I'm glad I gotthenm. I filled the roof and used the less optimal NW orientation too. Cheapest cost is to fill the roof on install day. Labour is a huge % of the cost and installing a few extra panels is fast.

conor_mc

8x435 on NNE roof vs (7x435 SSW/3x435 WNW with optimisers), all at 35 degree slope.

Best day of the summer, June 23rd:

Random day, yesterday, Aug 26th:

NNE are pure FiT generators for me, but pretty happy with decision to install at marginal cost - I wouldn’t have paid for only this string, nor would I have paid more to add them later.

At worst if FiT drops, in summer I can get an early charge into battery before we start waking up due to the slightly easterly orientation.

Calahonda52

www.suncal.org will show you the suns orientation vis vis your roofs.

Its the low angle in winter that reduces the contribution, especially if you are any trees around.

note the PV drop down

As noted earlier, get all the panels up now as adding them later will be expensive and if its not the same installer you may have some bs about the existing set up as some sparks don't like working on other folks work and might even insist on a full check of the house wiring

curioustony

I tried that again with force discharge to grid for any battery charge left after 11pm stopping at 20% in case of a power cut. Different supplier this time.

Amazing savings, just with a battery and the right plan. Liable for tax, but so what...

The discharge to grid is a new feature in the app, still in alpha test.

What's the going rate for a hybrid inverter and a 20kWh DIY battery? 3 to 4 years payback at current rates?

championc

My North facing 10 x 400w panels generated 2.44MWh in the 12 months to the end of June

That's 2.44MWh more than zero !!!