To solar, or not to solar? Cost/benefit is the question!

MSR01

You've all no doubt hear this one before...

I've been reading all the threads, and a couple of books including a very good one by Michael Boxwell, Solar Electricity Handbook 2021 Edition. But I'm still stuck on the question of just how cost effective they will be, and am wondering if now is the right time to get them. So, I will describe my situation and history, below:

I first looked into this one year ago this month and fairly quickly found a good local supplier (an engineering firm who does not pay for a customer services agency) who gave me a very good price (which, compared to the quotes I had from the page one Google search results companies, has given me a fair idea of how expensive customer services agencies are!). I am satisfied these guys are kosha but Real Life happened in a variety of ways and I had to delay. The delay ended up running to 12 months, but they have decided to honour the original quote from a year ago, if I choose to go ahead, now.

The house is ideal for solar. South West facing rear roof could take 11 panels with no shading. The current quote is for 7 panels for an approximately 3kWp array, with an immersion diverter for the hot water tanks. No battery, but I'm work-from-home and a lot of our appliances are run during daylight hours, and I keep them running in breaks from the desk, so I have close to an ideal user profile from that point of view.

I don't have a smart meter so calculating our actual daily use verses the utterly farcical "predictions" that I see on the energy bill is difficult. We're a family of four, two of whom are often working from home. Best guess, we're probably bang in the middle of the bell curve, at somewhere between 5 to 7 kWh/day.

The cost of living isn't going away, and I don't know what to believe about the predictions for energy prices over the next few months. The original quote would still be a stretch to fund right now, but we've discussed a budget option for 5 panels for a 2.1 kWp array which knocks about a grand off. However, my feeling is that this wouldn't be worth the cost: that the same money for 5 panels may as well sit in the account and help fund the cost of living over the coming year. My feeling is that 3 kWp is the minimum that should be considered in order to gain real benefits.

But will it reap real benefits for our electricity costs, this year? Will we notice the difference?

Right now, I've got a good quote that undercuts the opposition by up to two grand, but it won't last another 12 months, so I either get it now or lose it.

But is it better to go into survival mode right now and use the money to get through the price hikes of 2024, and then come back to this idea in the future?

Other factors that occur to me are things like it being an El Nino year. We're highly likely to cook over summer, perhaps more than the last two years. I ran an air conditioner a lot last year, and two of us now have health problems which make us heat intolerant, so I expect to do the same again, this year. Does the solar money just go into funding those running costs, or into an array that powers the air con during the long summer days?

I am vexed  

Wise words and sagacity would be greatly appreciated!

QrizB

You should be paying less than £4k for a 3kWp array, installed and commissioned and with your MCS cert and DNO confirmation. Dont' bother with the diverter; currently electricity is worth more for export than gas/oil/LPG costs to buy.

A 3kWp array in a good location will generate ~3000kWh a tear.

For a typical household, you'll then use 1000kWh instead of grid electricity (at 27p/kWh, saving £270) and export the other 2000kWh (at 15p/kWh, earning £300). That's £570 per year. You'll earn your £4k back in 7 years. For the remainimg life of the system (20+ years) you'll be in profit.

What could go wrong? Well, if electricity prices go back to "normal" that £270 and £300 becomes £160 and £100 and your payback period turns into 15 years.

markin

As scaffolding is around £800 you really want to fill the roof to get your best value out of it, So many people regret not getting more on the roof at the time and then having to pay that extra cost again.

Reed_Richards

MSR01 said:

I don't have a smart meter ...

QrizB said:

...Dont' bother with the diverter; currently electricity is worth more for export than gas/oil/LPG costs to buy...

Electricity is potentially worth more for export than those fuels cost to buy but without a smart meter to measure what you export then you won't get paid at all.  So unless you can rule out ever wanting to have solar panels, you need to get a smart meter fitted.

JSHarris

And for those who don't have gas, a solar diverter VERY quickly pays for itself!  Roughly 70% of my total annual hot water comes for free, thanks to the solar diverter.  Even had two days this week (despite the sub-zero weather, or perhaps partly because of it) where there was enough solar generation spare to heat the hot water system up to its maximum. 

Payback time isn't easy to calculate, though.  I estimated that my 25 panel solar system might take about 8 years to pay back, but I didn't foresee the big hike in electricity prices, nor did I factor in "free" charging for the car during the summer months.  The reality was that I'd recovered the cost of the solar system in under 4 years.

My gut feeling is that solar is worth the risk if you're not borrowing in order to pay for it.  It will most probably give a better return than savings I think.

Petriix

It's not just gas that makes a solar diverter pointless. If you have access to cheap overnight electricity then you're currently far better just exporting during the day and importing at night. 

It's no use saying you've got a 'good price' without specifying what that is. It's almost certainly better to go for as many panels as will fit, as long as you have DNO approval for that level of export. Whatever you do, don't even think about it until you've got a working smart meter. 

cm4ever

Agree, once you have smart meters installed, you'd have a much clearer view of your electricity usage and your usage pattern throughout the day.

badmemory

I don't know anything about solar really but have thought of it especially since they were promising us a lot of power cuts this winter which so far don't seem to have happened.  Sorry for tempting fate there.  But it was those power cuts that really made me consider solar.  If you are working from home & have a battery then surely you would be able to continue to work.  As I said I know nothing about the subject really but it seems to me that without a battery you are depriving yourself of a real benefit.

MultiFuelBurner

badmemory said:

I don't know anything about solar really but have thought of it especially since they were promising us a lot of power cuts this winter which so far don't seem to have happened.  Sorry for tempting fate there.  But it was those power cuts that really made me consider solar.  If you are working from home & have a battery then surely you would be able to continue to work.  As I said I know nothing about the subject really but it seems to me that without a battery you are depriving yourself of a real benefit.

I suspect the media made a mountain out of a sugar grain with regards to potential power cuts. Very unusual for the media to do that hey 😂😂

JSHarris

badmemory said:

I don't know anything about solar really but have thought of it especially since they were promising us a lot of power cuts this winter which so far don't seem to have happened.  Sorry for tempting fate there.  But it was those power cuts that really made me consider solar.  If you are working from home & have a battery then surely you would be able to continue to work.  As I said I know nothing about the subject really but it seems to me that without a battery you are depriving yourself of a real benefit.

FWIW we've had four power cuts since the start of October 2023.  A couple  of the cuts only lasted about half an hour or so but one went on all day (about 8 hours) and another lasted about 4 hours.  So far we've been fortunate and not had a really long duration cut, although I'm expecting to lose power again later today when storm Isha will most likely take more cables down.

We've had a better winter than some, so far, perhaps because we had a major outage last year that resulted in a fairly long run of old overhead cables being replaced.  We still have a lot of pretty dodgy looking overheads around, though, and a couple of poles on the feed to our valley are now leaning badly as a consequence of storm Henk a couple of weeks ago.

Officer_Dibble

Another vote against solar diverters. Even if you don't have gas or can't benefit from cheap overnight prices, a smart spur on your immersion can do the job almost as well and is more likely to work reliably for many years. Just turn it on to heat the water when it's sunny - or set up an automated process if you're feeling flash.

Another vote against @badmemory expecting PV to help out in power cuts too. The cheap way will only get you a double socket somewhere near your inverter to use in a power cut. It'll probably have no proper earth as well, so be careful what you run off it. Any more useful solution involves a major rewire and almost certainly won't be worth it unless you're running a life support machine. Most laptops will have enough battery life to get you through a power cut of a couple of hours, and you can use phone data if the router loses power.