Solar install

Missymoo2

We are looking at solar install and battery storage and have received 3 quotes which are all similar but advice seems to differ.

We have an east roof and west roof with no shading so want to maximise the roof area if possible. So this looks around 8-10 panels per side.

The quotes have suggested different panel sizes from 330w to 395w with total between 6kw to 7.92 depending on number of panels.
We have had differing advice over the size of inverter, one company have said max 6.5 solar on a 5kw inverter, another company has said 7.92 is fine on a 5kw inverter which seems to be stretching it a bit.

We are looking at an 8.2 battery, we are fully EV now but until we add further batteries I don’t think it will benefit the EVs much. For us this is more of a green decision as the figures on payback time do not quote stack up currently but we know that.

Can anyone advise regarding inverters please?

Many thanks

gm624

We have 7.93kWp array split across roofs, with about 6.12kW ESE facing and the remainder WNW facing, installed December 2020, with a 6kW SolarEdge inverter. In the 11 months since it was installed, we've only 'maxed out' the inverter on a handful of occasions - in the summer months on a clear day, the top of the curve tends to be somewhere between 5.5kW and 6kW, even with an array that's quite heavily skewed to one side.

Spies

Because of the east west split you will most likely see about 75% max of the potential output power because even when the sun is directly overhead in the middle of summer the panel angle will not be favourable. 

[Deleted User]

I have a 7kWp array and a 5kW inverter. Your installer should have the appropriate software to size the inverter that will give you the optimum annual output based on the location and orientation of your array. An over sized inverter may give to you slightly more output in the summer but at the expense of lower outputs in the winter.

Missymoo2

The quote which has given us different options for panels and inverters has suggested that we will invalidate the 5kw givenergy inverter warranty if over 6.5 array.
Over that they have offered 2x 3.6 inverters which obviously adds to cost. Will this have handy disadvantages having 2 inverters?

I have read the advantages in winter months of more output but obviously concerned about warranties.

thanks everyone

Missymoo2

The one we were edging towards is a 7.6 kw array which they suggest we will need the 2 small inverters.

Spies

You need to plug your numbers in to pvgis and solcast to see how much generation that east roof is actually going to give you to work out if it's even worth it.

I don't really understand why having a bigger inverter will invalidate the givenergy warranty?

There's other battery solutions available that won't be restricted by silly clauses. 

ABrass

Spies said:

You need to plug your numbers in to pvgis and solcast to see how much generation that east roof is actually going to give you to work out if it's even worth it.

I don't really understand why having a bigger inverter will invalidate the givenergy warranty?

There's other battery solutions available that won't be restricted by silly clauses. 

The implication is that 6.5 kWp is the maximum allowed to be connected to that 5kW inverter. Going higher than that would you be outside the warranty terms as it isn't rated to b undersized too much.

The answer would appear to be to go for a larger inverter, 6kW for example.

JKenH

I have a 3.6kw array on my ENE roof coupled to a 3.6 kw inve and the maximum generation I see on a clear summers day is around 2.7 kw. My WSW roof has 4.2 kw of panels also coupled to a 3.6kw inverter. Occasionally the output is clipped by the inverter but 99% off the time the 3.6 kw inverter is fine. Combined output in the middle of a sunny summers day is around 4.3 kw. I have wondered if I would be better with a single 5kw inverter.