Quick Solar Panel PV question about differing outputs

nwrm

Hi,
Apologies if this question goes over old ground elsewhere in the forum, but it's quite urgent. I am having solar thermal (thanks, green homes grant) installed next week (19 May) with the scaffolding going up tomorrow (14 May). I am also having solar PV installed at the same time.

My supplier has just told me that they can't source the planned 380 watt PV panels they had planned to install, and they don't know when those panels will be available - it could be months. They can, however, source and fit 360 watt PV panels next week. I am having 13 panels installed, so that takes the maximum output from 4.94Kwp to 4.68 Kwp. They want to know tomorrow whether I want to press on with the smaller panels or wait for the bigger panels, so they know how much scaffolding to install tomorrow. The change in panel spec doesn't reduce the overall cost by enough to make that a relevant factor in this decision.

My question is, do you think that the reduction in output is enough to make it worth waiting for the panels to be installed (I'm struggling to understand how much of a difference it will make in practice), or should I just take the bird in the hand?

Many thanks in advance for your help!

QrizB

If there is no cost implication (so your supplier is happy to take down the thermal scaffold, then re-build for PV, without charging extra) then it's a tricky one. If you really do have to wait "months" you'll miss the peak generating season this year; June to September is 45% of my annual output.

Personally I'd take 360s now rather than the promise of 380s manana.

nwrm

Thanks, that’s helpful. There is definitely no cost implication for me in waiting (slightly to my surprise), and the supplier said they he felt I should work on the basis that if I wait I’ll miss a lot of this summer. 

Martyn1981

I know you didn't ask about this, but is it worth getting solar thermal? It's a lot of money and a simple solar diverter will heat your tank up from excess PV generation. You will, presumably be able to add 2 or 3 more panels instead of the ST?
Not knocking ST (well I suppose I am a bit) but it's slowly gone out of favour since it's quite expensive, but only provides a low value product (hot water), whereas PV saves you v's leccy import costs.
Just a thought, sorry for the digression (or diversion  ).

tim_p

Completely agree with Martyn, why on earth bother with solar thermal and the cost implications it brings, from install to ongoing maintenance (there must be some surely?). Replace it with extra PV panels, add a diverter and away you go.  

saveallmymoney

Order the 380's yourself for next day delivery? https://!!!!!!/2QjLjfl

mnbvcxz

For many older houses solar thermal is the only green grant eligible option...

(Or was, I should have said)