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

Reed_Richards

By and large solar panels won't work during a power cut.  That is because the inverter controlling them needs an AC power supply.  With a battery it is possible to set up a backup system that keeps your solar panels running in the event of a power cut but you need an automatic isolation switch and this isn't a standard feature of a solar + battery installation. 

Even then, your solar panels and battery may well not provide enough power to run your house in the middle of winter when power cuts are most likely.  I have such a system, added when my house was being rewired.  It runs the lighting circuits and sockets for my fridge, freezer, router and three spares.    

MSR01

Petriix said:

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. 

I'm quoted £5k for a 3kWp array and inverter.

The number of panels is down to budget.

QrizB

MSR01 said:

Petriix said:

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. 

I'm quoted £5k for a 3kWp array and inverter.

That seems a bit steep.

In April 2021 I had a 3.2kWp system installed for £3500. Admittedly the installer's admin was terrible (see thread linked below) but I'd hope you wouldn't need to pay much more than that today, considering that panels are much cheaper now than then.

https://forums.moneysavingexpert.com/discussion/6259990/april-2021-solar-pv-install-3-33kwp-west-berkshire

Netexporter

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.

If power cut security is your main priority the you need something like a Givenergy All-in-One battery with gateway. It will isolate you from the grid in the event of a outage in a few milliseconds, so you won't even see the lights flicker. It will output at 6kW, so you could run most things in the house, as normal. Solar would be a nice adjunct to that but won't contribute a lot in winter, when most power cuts occur. The battery, in conjunction with a smart meter, will allow you to time-shift very cheap off-peak electricity to use at peak times.

wrf12345

Octopus energy made an announcement about accepting solar input from non-certified but electrician signed off systems a while back (with a smart meter), 400W solar panels are down to around a hundred quid and you will not benefit if there is a power cut with grid-tied systems (as the solar closes down) unless you have a battery system. 

mmmmikey

I have an exisiting 4kWp solar system on a combination of East and South facing roof sections. I've been toying with the idea of adding a completely separate 3kWp solar system on a West facing section and based on my location and existing panels I reckon they would generate about 2250kWh per annum. Assuming they cost £4k (haven't researched this yet but seems like a reasonable first guess for a straightforward installation) and lasted 15 years that would work out at a cost of about 12p/kWh over the life of the panels. I'm currently importing/exporting at a cost/income of 15p/kWh so on that basis it seems to make financial sense. I've recently retired and have savings that could pay for this. Part of my thinking is that if prices go up I'll be quids in, but if prices go down I'll save money on energy costs elsewhere, so overall don't stand to lose a lot. So it seems like quite a good way of protecting myself against the risk of future energy price inflation which is a killer if your pension income doesn't keep up.

Any thoughts on this? Is £4k a reasonable target price for a 3kWp system? Does this makes sense or are you rolling around laughing because I've missed something obvious?

( @MSR01 - hope I'm not hijacking your thread, I guess this is all relevant to the discussion and it seemed to make sense to put it here rather than start another thread )

Edit - just re-read this and see that you've been quoted £5k so making me think I'm being optimistic on the price....

MSR01

mmmmikey said:

Any thoughts on this? Is £4k a reasonable target price for a 3kWp system? Does this makes sense or are you rolling around laughing because I've missed something obvious?

( @MSR01 - hope I'm not hijacking your thread, I guess this is all relevant to the discussion and it seemed to make sense to put it here rather than start another thread )

Edit - just re-read this and see that you've been quoted £5k so making me think I'm being optimistic on the price....

When I started, I specified a 2.5 kWp system with an Immersion controller, and had various quotes up to £7,500, which is why I decided to regard the local installer (who works primarily in the commercial market) as a good deal when he offered 3kWp for £5,000 (I've since deleted the immersion controller based on the fact that we're staying on gas, rather than going heat pump). The quote includes scaffolding and any necessary remedial work to the roof prior to installation.

But it's always worth double checking, and I may get a few fresh quotes at today's prices to reassure myself before giving the go-ahead.

I think there's been some significant price inflation in the past few years, driven in part by the Ukraine war and sanctions, the cost of living crisis fuelled by supply-side inflation internationally, the legacy financial and logistical effects of Covid, and more. It doesn't help that China, where we get most of the raw materials for panels and batteries from, has significantly ramped up their domestic use of solar, but the quality of components has also increased. A year ago my quote was for 350w panels. Today, the supplier is offering 435w panels as a free upgrade, simply because that's what he's buying in as his stock. I see a lot of houses with 150w panels fitted by their energy supplier, and I wouldn't touch those with a stick. They fill your roof and you still only get peanuts for kWp. My proposed supplier is a business-to-business operator who fits in domestic installs. I quizzed his survey engineer extensively after doing my reading and the guy never batted an eyelid, and he was in no way a salesman, just a technician doing his job. The supplier has a waiting list, so I wouldn't see him for at least three months, which is often a useful indicator when dealing with smaller, non-public facing concerns: if he's available tomorrow, wonder why? He would fit me in as a one day install between doing warehouse roofs.

I'm only proposing 7 panels out of a possible 11 (although I have a ground floor extension that could take another 5, without the need for a scaffolding to install). However, I'm sanguine about this: a year or two from now, money permitting, I could expand to the full 11 and probably do so with something like 450w or 500w panels for the same unit price, and by then I would hope the options for modular batteries are wider and more affordable. Right now, a 2.5kWh battery would almost double the cost of the total installation.

A note on inverters. I originally went for 5 panels because I was including the cost of a hybrid inverter that would permit the installation of a battery in the future without replacing the inverter. However, I can't foresee getting a battery any time soon, so decided to downgrade the inverter and put the money this saved on the roof, in the form of two more panels. I'm accepting the cost of upgrading the inverter in the future, but as already noted, I would hope to see better prices generally, by that stage. And if the prices remain high, c'est la vie. I've got 7 panels now, rather than 5, giving out 3kWp rather than 2 to 2.5. So, if your money is tight, just get as many panels as you can and don't worry too much about future-proofing.

markin

Its normal to get 20 bad quotes until you find the cheapest, over on the Green forum board.

Just be careful they are MCS and dont vanish ever 6 months

https://mcscertified.com/

JSHarris

My experience of trying to find a reputable supplier/installer for my solar system is still lodged very firmly in my memory a decade later.  To say that the majority of the companies I approached gave cause for concern is an understatement.  At least half of them I approached openly lied about things that were very easy to disprove.  The whole process was pretty disheartening and reminded me very much of the sort of tactics that got the double glazing industry a bad name a couple of decades ago. 

I got lucky in the end and found a company by word of mouth, who turned out to be honest and they did a very good job.  They weren't quite the cheapest but their standard of workmanship more than made up for that.  Ten years later and the system is still slightly outperforming their estimates.

Netexporter

Ten years later and the system is still slightly outperforming their estimates.

They nearly all outperformed the estimates, in those days, because the model used was pessimistic (and based on Sheffield), so any array in the south of the country generally exceeded expectations.