Solar panels - how important is the battery?

[thebellagio]

Not an AIBU but posting for traffic

ive been looking into solar panels for my house as I’m terrified of the rising energy prices. Last week I was quoted £11.5k for 24 panels plus the inverter, battery and bird cage around the panels. This seems high and he confirmed that it would take 10+ years to break even.

im currently undecided what to do - that’s such a frickin huge outlay and would basically take all our savings. But on the other hand, I feel like it would reduce our bill and potentially add value to the house which we will be staying in for at least 10-15 years.

I guess what I want to know, is if you have solar panels how essential is it to have the battery as well? I completely get it means in the evening you’re working from the solar power you’ve generated rather than buying from the grid but broken down, the panels are about £6k and the battery is £5k so I’m trying to work out if I could save here…

we use about 6kwh electricity a day according to my smart meter. I’ve been quoted for a 4.2kwh system but a 9.5kwh battery so I’m reluctant to spend that amount of money on a battery if we’re only going to use a minimal amount of the solar power generated. At the moment we don’t have electric cars, so our solar usage is unlikely to change for at least 3-4 years

Has anyone got any advice?

Yes we've been considering this too instead of battery. We have a combi boiler and immersion tank which we rarely switch on, so not sure how much faff it is to make sure we use solar electric when we have it rather than the gas boiler?

i presume those figures are weekly yeah?

Lets up the numbers. say that you use 10 kWh per day average over the year. So that’s 3650 kWh.

Lets day you get stuck on a horrendous tariff, where you pay 60p kWh.

under those circumstances, you’ll be shelling out £2190 per year on electricity.

Now, your usage is low, so the battery + solar combo may well cut that to zero.

So in those circumstances, you’ll be paid back in about 5 years. I would say go for it.

But more realistically, you may average 8 kWh per day round the year. And you’ll probably be able to get a tariff around 35p kWh still.

Under those circs, your maximum saving per year is £1090. 10 years to pay off the capital expense. And in those 10 years the tech is going to come down in price. So i wouldn’t.

The other posters are mainly just showing off with their batteries and totally ignoring your energy usage OP. Just do the maths like I did.

Yeah they are weekly figures. Thanks for that breakdown, that's really helpful.

I think I may hold off for a few more months and see how things pan out over winter.

A battery only makes sense if you routinely generate enough to charge it off solar and then empty it overnight, otherwise the extra cost doesn't make sense.

If you download the loop app there is a solar power simulator which will look at your actual usage from your smart meter and the weather forecasts and do the sums for you.

A friend has just had panels installed but is still waiting for the batteries to be installed. She said that in the day all electric was coming from the panels until they put the kettle on - at which point it drew from the grid. Obviously once they get their batteries this will resolve itself.

If you are in all day and can use your solar then leave the battery off for now. It can be added later if you decide to go for an electric car and can also charge your battery up cheaply at night (if such tariffs are still available then).

Like @DilemmaDelilah said it may be better to go for some more energy efficient appliances - we’ve also gone for the same combo of washer dryer and on a regular day (doesn’t even have to be that sunny) they are effectively free to run via panels. Ditto the posters that mentioned using excess to heat water via an immersion heater although not everyone has a tank and combi.

You can run off grid with batteries though. The energy already flows both ways and in the event of a power cut your house will automatically draw from the battery as is. With Tesla you can set up to draw from the grid at certain times (depending on tariff) or not. Octopus asked for a sketch of the system but no more ‘permission’ needed than that. There are also tariffs that utilise the batteries in electric cars although it’s not something that would work well for us so I’ve not investigated further.

It doesn’t sound like they have been set up correctly. They need to go back to the installers now - just giving away free electricity as it is.

I think this is my thought process. I don't think that we'll be using enough power to justify the cost of the battery because I don't think we would use an entire battery every night.

I work from home, so I tend to put the washing machine/dishwasher on during the day, and my hoover is cordless so I can charge that during the day - same as phones and anything else that needs charging. So it's only the TV really that we have on in the evening.

Thank you to everyone for your feedback - it's interesting to get an unbiased view because I've been asking the solar panel people these questions and obviously its in their interests to be pushing the battery

We recently got solar panels and for us the battery was the main selling point. Feed in tariffs are barely worth it these days so given our main usage is in evenings the battery means we can maximise what we are producing from the panels. For the two or so months we’ve had solar we’ve only paid the daily standing charge for electricity and that wouldn’t have happened without the battery. We also installed an iboost to heat the water tank so have paid very little for gas over this time too.
Theoretically as well if you sign up for an agile tariff that tracks the wholesale rates you have the option to charge your battery overnight when prices are low on the days where you’re not producing enough from the panels.

We have a battery, which we find very useful. Selling it back to the grid isn't worth it these days. Having said that, we use more electricity than the OP (on average 10 kWh per day).

On a good day, our battery is over 45% full by around 6pm. Then it drains as I cook in the evening and it has usually emptied by about 10pm.

@thebellagio It won't just be the tv that uses electricity in the evenings. You will be using it for your fridge and freezer, you may use it for cooking, and you will be using it for your kettle, unless you never have hot drinks? we are all electric so have to use it for our storage heaters in the winter, but we also use it for top up heating when it is really cold and for fans when it is hot. Don't discount how much you may use in the evening. If you have gas you may not use as much (cooking and heating). In the winter you will have lighting on earlier, you are likely to be cooking when it is dark etc. Unfortunately in the winter you may not generate enough to charge your battery. Lots of things to think about.

Thank you to everyone for your feedback - it's interesting to get an unbiased view because I've been asking the solar panel people these questions and obviously its in their interests to be pushing the battery

no worries 👍 Although I’m one of the few who days ‘probably don’t bother’ that is only because of your usage. If you were using double the energy I’d say go for it - battery included!

We are waiting for our survey for solar. We use a lot more energy than you as we have ASHP , so a battery makes perfect sense for us and our payback time is shorter.
We are part of a bulk buy organised by the County Council and on one of their Q&A sessions , it seems that its about 50/50 people going for battery, but it is possible to add the battery on later if you change your mind- obviously that will be more expensive.
The other issue at the moment is that there appears to be a bit of a shortage of comonents - so who knows if prices will change or there will be long delays.

I was just away to write an almost identical post

Except we are all electric with predicted use of 5,200 kw hours. And on economy 10.

Also in Scotland so can get an interest free loan from government though there is a small admin fee. This makes the battery more appealing as I'd be as well paying this each month as paying an energy company a massive amount.

Does anyone know if a battery makes more sense on an economy 10 type system? Can you charge them at low cost times if the solar is insufficient?
We are half the price per unit off peak though have to pay 78p a unit for the first 30 regardless. Ouch!

That’s a good point re lights in the winter.

we rarely use the kettle - I have one coffee a day in the morning and that’s it. The only other time is if we’re cooking pasta/rice, we’ll use the kettle to boil the water but that’s it.

i think my problem is my husband isn’t bothered either way whether we get panels or not, so I’ve got no one to really chat through the options. He’s happy to go for it if I think it’s right, but he’s also not fussed if we don’t have them haha

That’s a fantastic price for 24 panels, I’m very jealous! We paid similar to you and could only fit on 14. We’ve got a battery, which was £2.5k. It’s not 100% necessary, but I think it was a useful outlay. We can’t believe how much less we’re drawing from the grid! Literally about 90% less, according to the British Gas app. Our payment plan is 5 years but we’ve already made £1100 of overpayments as we had some savings. Aiming to lay off in three. Getting an electric car next year which I think will be great as there will
be no fuel costs either.

Your energy usage is very low, tbh. 6 kWh/per day, even if the tariffs rise to 50p average is still only £1000 per year ish.
If you invest that money you would get about £200 per year.
For you it does not make financial sense.
I would not want that amount of money locked away that I cannot use. There is too much money in the body of the house already.
Prices of panels are pretty low now but batteries are changing. There is a new type that is not yet viable for individual houses, but is being developed for smaller installations.

Get a new quote every 6 months or so. Ask about Vanadium Flow Batteries. They will make a huge difference and are safer than Lithium ones. far safer. So far the bigger ones are not wearing out, life will be much longer.
Enjoy your money don't let others enjoy it.

Completely agree with PP who said not to get the battery in your situation, it's rarely worth it and it's not in yours. Also RE the birdcage - may well be worth it. It's also worth considering lichen which can damage your panels by causing hot spots and therefore include an annual or every 2 years cleaning into your running cost.

After this current energy crisis blip, I'm banking on mass renewables investment and funding shifts means electric comes way down in price over the next few years years, making home generation redundant.

Sorry to hijack the thread for what may be a stupid question, but does anyone know if you can do domestic ground panels in a garden?

We have a thatched house and just couldn't do roof but have a garden with bags of room to spare and which is a south facing heatsink. I'd be so interested if so, if only to power garden buildings!

This is another thing we're considering! We've been advised it's fine (thinking of building a new shed/ outbuilding to put them on) as long as you have appropriate cable size to account for voltage drop if they are at a distance from the inverter.

We just got 14 panels and a battery, and are actually looking at whether we can get an additional battery. The reason for getting the battery was while you pay 21p per unit to buy from the grid, they pay you about 2p per unit to export it back. So, during the summer at least we want to be as off grid as possible. We have a large battery and it only just lasted the night, and that's without running appliances so just the general stuff that is on all the time, Alexas, cooker clock, wifi etc. We have been running appliances during the day to try to use as much of our energy we generate as possible (actually changed habits because previously always ran dishwasher at night).

That'd be cool if that works! We're hoping to get an electric car in a few years so I'll definitely check that out.

Fantastic. TY @Trondereplay