is solar worth it for me?

kev1744

hi all,
ive been in touch with a company caller evergreen solar power re having panels and a battery fitted to my house.
a surveyor is coming out next week but i thought i would get some views on if its worth it first.

house is a small semi detached south facing. the roof will take about 6 panels i think.
last year my electric consumption was around 4000kwh .

i dont have an ev but would be open to getting one in the future.

so any idea if its worth me going solar? and if so what kind of costs would i be looking at?

tia

QrizB

As a very rough guide, six 450w panels plus an inverter (no battery) should be less than £3k fitted.

Swapping the inverter for a hybrid version will add £500, and say 5kW of battery should be less than £2k. So well under £6k for the whole shebang.

Is it worth it? If you're currently using 4000kWh at 25p/kWh that's £1000 a year. The setup I've described might generate 2500kWh a year.

Without a battery, you might use 800 of those (saving £200) and export 1700 (worth another £250, if you choose a supplier that pays 15p/kWh) for a total return of £450 a year. The £3k will be paid back after 7 years.

With the battery, you might use 1600kWh (saving £400) and export 900 (earning £130) for a total return of £530. Payback will take 10-11 years.

If you want to get clever, you can switch to an electricity tariff with a cheaper off-peak rate and increase your savings. But that brings a lot more parameters into the equation and it's not entirely straightforward.

This is all off the cuff and once you get your quotes we can refine the maths. Also, others might have other thoughts. Tagging @Screwdriva who has decent industry contacts and may have better cost estimates than I do!

kev1744

thanks for quick reply....slight update...after doing some more research it seems i might only be able to get 4 panels on the roof which per my calcs would only get me around 1800w (panels say 450w per panel)

QrizB

Four panels rather than six isn't going to save very much on the installation costs, sadly. They still need to send the same workers and equipment and complete all the same paperwork.

If we knock £250 off the cost of the system, we'll also be reducing the total generation to perhaps 1600kWh a year. Your return without a battery becomes £320 a year, paying back £2750 in just under nine years.

With the battery you'll use pretty much all of it, still saving £400 a year. Payback is 13-14 years. Probably not worth the extra unless you're going to do clever things with tariffs.

But let's see what the surveyor quotes. Beware that s/he might be more of a salesman than a surveyor, so don't agree to anything on the day. Say you need to think about it, then come here and give us the lowdown.

Newbie_John

Playing devil's advocate here..
£5000 at 5% savings account will make £250 a year - after X years you still have £5000 (minus inflation of course).

badmemory

Are you sure about only 4 panels.  My house is only15ft wide & I have 8 on one side & 10 on the other.  Mine is E/W though not south facing.

Screwdriva

QrizB said:

Tagging @Screwdriva who has decent industry contacts and may have better cost estimates than I do!

QrizB is spot on - your consumption likely isn't high enough to justify the additional spend for a battery. Most installers won't highlight this as they profit from upselling you on a battery. 

kev1744 said:

thanks for quick reply....slight update...after doing some more research it seems i might only be able to get 4 panels on the roof which per my calcs would only get me around 1800w (panels say 450w per panel)

Are you able to share an image of the roof with dimensions? Another option some of the installers I use sometimes attempt are larger 2.3m X 1.1m 590W bifacial panels, when available dimension restrict the number of panels. As an example, here's an image of a roof which achieved a 4+ kW system size (+ bifacial albedo gains) with only 7 panels. As a side note, I love how the panels line up perfectly on portrait & landscape orientation ( I should get out more!)  

badmemory

I think whether a battery is a good idea will depend on how the energy is used.  A power shower would struggle to be fueled by the solar alone, even on a very sunny day it would need to get over half the power from other than the solar.  You may also find that the installers will not instal without a battery.  Also without a battery anything you use after dark, so 4pm in winter, will come from the grid.

Reed_Richards

If you do get an EV then you can also charge the battery at night at the cheap EV rate, which can be useful for winter and will skew the economics more in favour of a battery.  In summer you can potentially charge the battery at night then export the electricity during the day for more than you paid for it.  

Max68

Don't know the in's an outs of Solar panels but had four installed back in the Spring of 2023 and didn't really think I was saving too much until I did a few calculations recently.  Rather than look at bills which obviously have gone up massively since pre Covid I looked at usage.  Between May 18 and May 19 I used 3723 kw.  19-20 3472kw, 20-21 2597kw, 21-22 2915kw, 22-23 2258, 23-24 1703.  So far 24-25 1357.  So it does help.  My neighbour has a battery and sells back what he doesn't use and claims he pays hardly anything but again it was a costly outlay for a battery.  So quite pleased with them although you do need the sun out!!

kev1744

ok...so quick measure of my roof and photo as requested... from what i can tell its about 4m by 4m. the panels the company use are dmegc 450 if that helps.

QrizB said:

Tagging @Screwdriva who has decent industry contacts and may have better cost estimates than I do!

QrizB is spot on - your consumption likely isn't high enough to justify the additional spend for a battery. Most installers won't highlight this as they profit from upselling you on a battery. 

kev1744 said:

thanks for quick reply....slight update...after doing some more research it seems i might only be able to get 4 panels on the roof which per my calcs would only get me around 1800w (panels say 450w per panel)

Are you able to share an image of the roof with dimensions? Another option some of the installers I use sometimes attempt are larger 2.3m X 1.1m 590W bifacial panels, when available dimension restrict the number of panels. As an example, here's an image of a roof which achieved a 4+ kW system size (+ bifacial albedo gains) with only 7 panels. As a side note, I love how the panels line up perfectly on portrait & landscape orientation ( I should get out more!)