East/west roofs -single or twin inverters?

Zarch

theboylard wrote: »

That would be useful, I've got one that is plugged in but has not been updated since i got it, right at the end of the oem kickstarter campaign for the emonpi!!!

Not wanting to derail JKenH thread any further, i'd just say that the emonPi forum and their guides are super helpful.

https://community.openenergymonitor.org/
https://guide.openenergymonitor.org/

If you've already got an emonPi then maybe you're only a few steps away from getting import squirted up to PVO.

pensionpawn

I have a very similar system to yours, 4kWs due East and 3.12kWs due West, all off one 6kW Solaredge inverter. My summer instantaneous peak is around 5.75kWs, so scaling up to your size array is 6.3kWs peak (Lincolnshire maybe less?), which would be clipped to 6kWs max output, probably slightly less. So one possible solution is to bin your existing two inverters and adopt the same solution, however that will obviously cost a little. As with anything in life, you have to balance the cost of not doing nothing against the calculated returnss!

JKenH

I spoke to my installer today who has also spoken to Northern Powergrid and he is going to put in a retrospective application. While he is at it I agreed he put in for 10 kWh to give a bit of scope to beef up the morning PV which is the weak link. I have 12 panels on the east roof and I am thinking if I can get them all on one string I can then use the second string for 4 or 6 panels on the garage roof which is south facing but in shade from 1pm onwards now. I should maybe have done that from the outset but none of the salesmen who came out suggested it. (There are velux windows on the roof which also get in the way and the wiring will be a bit more difficult as with our loft conversion you can’t get to the underside of the roof.) It is just that I have seen how much we miss out this time of year compared to a south facing system that it is worth a bit of effort to get a few panels pointing in that direction.

Assuming we can get it past the DNO then I need to notify my FIT provider of the extra panels. Am I correct in assuming they will then make a pro rata adjustment to my declared generation based on the number of panels added? If I am adding South facing will they make an adjustment to reflect that they produce more than east facing ones?

Exiled_Tyke

May be easier to put the additional panels on their own inverter and simply have them unmetered. Then there’s no discussion needed with the FIT provider?

Martyn1981

JKenH wrote: »

Assuming we can get it past the DNO then I need to notify my FIT provider of the extra panels. Am I correct in assuming they will then make a pro rata adjustment to my declared generation based on the number of panels added? If I am adding South facing will they make an adjustment to reflect that they produce more than east facing ones?

You are spot on. They will apportion on the basis of kWp, so adding south to off-south should give you a small lift, whereas of course adding off-south to a south FiT system, would lose a bit.

BTW, you mentioned adding an extra string, did you mean to a different MPPT? Strings have to match as the inverter will run the MPPT to work with the lesser string - find a voltage point that both strings can operate at, so you need the same number of panels, and same orientation/pitch.

JKenH

Martyn1981 wrote: »

BTW, you mentioned adding an extra string, did you mean to a different MPPT? Strings have to match as the inverter will run the MPPT to work with the lesser string - find a voltage point that both strings can operate at, so you need the same number of panels, and same orientation/pitch.

Ah, right. I thought the two strings worked independently and if you had an east/west roof you could use one string for each side. When I talked about adding a second string I meant using one string (instead of two currently) for the existing panels on the east roof and one for the south roof.

pensionpawn

Bear in mind shading / dirt accumulation as unless you are using micro optimisers each string will be limited by the worst performing panel.