2kw PV - worthwhile?

barnitto

Hi all,
Just after some thoughts and feedback on a 2kw solar installation. I already have solar thermal on the house, but have a double garage with a roof facing 138 degrees from north (sww) and a 30 degree pitch with no shading and I’m in Yorkshire. The latest Quote is less than £2500, which I think sounds great.

I’m done an energy audit and we use on average 14kwh per day. About 9kwh is what I refer to as base load (fridge,things on standby etc). The other 5kwh is from things like working from home, dishwasher, dryer, washing. It feels like with some small changes we could end up using most of not all of the output from the panels. If we did use most of the output I’m looking at 10 year payback - which seems good to me. It’s not all about the money, it feels like something worthwhile. Hardly see anyone installing such a small array.

Petriix

I would aim to go bigger if you can. You should be able to get 4kWp for under £4k. Your 'base load' of 9kWh per day seems very high; that's a constant draw of 375W so you should be able to cut that down significantly. Using the big appliances on sunny days will save you a fair bit, but ideally your peak generation would more than cover the heating elements so that you can do your load of washing without having to import anything at all.

barnitto

I would go bigger if I could. I can only fit 6 panels on the roof. I was hoping to get 6 x 415w panels but supply is very limited at the moment. That would give me 2.5kw and would come in around a few hundred more expensive. The only panels available at the moment though that supplier are 335w. I could wait, but the money is sat there doing nothing at the moment. So I could have 2kw installed now or wait 6 months + for 2.5kw?

you are spot on, my constant draw is around 375w and I know why (I won’t bore you with the reasons) The plan is we would run washer, dishwasher etc at peak generation. The cost of generation per kWh (over 10 years) is about the same as what I pay for electric on 100% green tariff (15p) but obviously a lot less than export (5p)

barnitto

I should add that peak load with either the washer or dryer during the day is just over 2kw

Martyn1981

I'd definitely say go for it, but given that panels in the high 300's seem pretty standard now, I think it might be worth waiting  a bit, especially if 415's are possible. Obviously the World is a mess, and so are supply chains, so you could end up in a trap waiting and waiting, but there are a couple of positives:
1. The power of the panels is only going to go up, and
2. October is the last decent(ish) month of generation, so it's not like you will be losing much if you don't get an install till Mch (or so).
Frustrating for 6 months or so, yes, but not as frustrating as the next 30+yrs wishing you'd gone bigger?

barnitto

Thanks, they emailed this afternoon to say they could get 415 panels! So I think I may well go for it.

Hexane

barnitto said:

It’s not all about the money, it feels like something worthwhile. Hardly see anyone installing such a small array.

If (or when) you can get the 415W panels, I would say go for it. Things may have changed now, but relatively recently (within the last five years when most people were already installing 3.6kWp or bigger solar PV systems), a lot of EPC reports would recommend a 2.5kWp solar PV installation as one of the top possible energy saving measures for a specific property. Presumably on the grounds that utilising 2.5kW is relatively easy, compared with 4kW or 6kW involving much more juggling of power-hungry devices and potentially seeing much more going back to the grid rather than actually saving energy within the property. So there's definitely nothing wrong with an approximately 2.5kW system if it can be had for reasonable price.

EricMears

Hexane said:

barnitto said:

It’s not all about the money, it feels like something worthwhile. Hardly see anyone installing such a small array.

If (or when) you can get the 415W panels, I would say go for it. Things may have changed now, but relatively recently (within the last five years when most people were already installing 3.6kWp or bigger solar PV systems), a lot of EPC reports would recommend a 2.5kWp solar PV installation as one of the top possible energy saving measures for a specific property. Presumably on the grounds that utilising 2.5kW is relatively easy, compared with 4kW or 6kW involving much more juggling of power-hungry devices and potentially seeing much more going back to the grid rather than actually saving energy within the property. So there's definitely nothing wrong with an approximately 2.5kW system if it can be had for reasonable price.

There's no 'problem' with exporting surplus power to grid !   For those of us on the original FIT scheme,  it makes no difference to the amount of cash received and  on a modern SEG scheme you'd be earning when exporting.  By going for the biggest possible system,  you might feel you're 'wasting' power in Summer but you'd probably still not have enough in Winter.

Hexane

EricMears said:

Hexane said:

barnitto said:

It’s not all about the money, it feels like something worthwhile. Hardly see anyone installing such a small array.

If (or when) you can get the 415W panels, I would say go for it. Things may have changed now, but relatively recently (within the last five years when most people were already installing 3.6kWp or bigger solar PV systems), a lot of EPC reports would recommend a 2.5kWp solar PV installation as one of the top possible energy saving measures for a specific property. Presumably on the grounds that utilising 2.5kW is relatively easy, compared with 4kW or 6kW involving much more juggling of power-hungry devices and potentially seeing much more going back to the grid rather than actually saving energy within the property. So there's definitely nothing wrong with an approximately 2.5kW system if it can be had for reasonable price.

There's no 'problem' with exporting surplus power to grid !   For those of us on the original FIT scheme,  it makes no difference to the amount of cash received and  on a modern SEG scheme you'd be earning when exporting.  By going for the biggest possible system,  you might feel you're 'wasting' power in Summer but you'd probably still not have enough in Winter.

The OP is going for the biggest possible system - in their circumstances.

It's well established that the biggest money savings are gained from avoiding paying for electricity imports by generating locally, not by the much smaller payments for exporting.

EricMears

Hexane said:

The OP is going for the biggest possible system - in their circumstances.

It's well established that the biggest money savings are gained from avoiding paying for electricity imports by generating locally, not by the much smaller payments for exporting.

Quite so - but the quote posted implied that needing to export would be wasteful though it really isn't.  The 'wasted' energy in  Summer hasn't cost any more to produce so even a small export payment can be seen as a bonus.  Having as much as possible (but very likely still not enough) in Winter justifies the biggest possible system.

Hexane

EricMears said:

Hexane said:

The OP is going for the biggest possible system - in their circumstances.

It's well established that the biggest money savings are gained from avoiding paying for electricity imports by generating locally, not by the much smaller payments for exporting.

Quite so - but the quote posted implied that needing to export would be wasteful though it really isn't.  The 'wasted' energy in  Summer hasn't cost any more to produce so even a small export payment can be seen as a bonus.  Having as much as possible (but very likely still not enough) in Winter justifies the biggest possible system.

Hi,
Seems to be a misunderstanding here. I've not used the words "wasted", "wasteful" or "problem". On the contrary, the point I'm making is that the OP's relatively limited available roofspace is not an undue problem if an installation can be had at a sensible price (which apparently it can).

Again, the OP is going for the biggest possible system.