Are batteries worth it?
To answer this question, I really need to understand why you might want one, or perhaps why you think you should have one.
But before I get into all that, I need a really quick all-covering caveat, (annoying I know but it is the way it is I’m afraid) it really does depend on your circumstances, and I can’t possibly go into all the different ways people consume electricity. So if you’re screaming at me because you think I am wrong. Then well, I probably am. But I’d argue, that’s probably just your specific circumstances. And sure, batteries do work financially for some people.
Many people arrive at the idea of adding a battery to their existing or yet-to-be-installed solar PV system. But how, and why, they arrive at this idea is varied. Here are a few examples of what I hear…
- I’m not at home during the day so solar won’t work without one
- My quotation included one
- I’m worried about power cuts
- It will save me money in the long run
- I have an electric car and want to charge it on solar power overnight
- I want to take advantage of time-of-use tariffs
- I love technology and batteries are cool (they typically mean that the Tesla Powerwall is cool)
I think the first point is probably the most common with the last point coming a close second. But let me tackle each of the points above individually.
1. I’m not at home during the day so solar won’t work without one
A battery will certainly help you consume less energy from the grid and more of your solar-generated electricity. They’re really rather good at that. The technology is absolutely capable and reliable. But depending on which home battery you choose and your individual energy demand, it is reasonably likely that adding a battery to your system won’t help you financially.
Batteries are expensive. They range from around £3,000 for a small battery with small storage capacity, cheap components and limited functionality to around £12,000 for Tesla Powerwall. Prices can be even higher if you happen to have a challenging set of installation circumstances.
Just because you’re not at home all day does not mean the additional cost of adding a battery will help you financially. It is reasonably likely that it would make more sense for you to get paid for exporting your generation to the grid, either through the Smart Export Guarantee scheme, or other export tariffs. Currently (December 2022), the most generous export tariff is Octopus Outgoing at 15p per kWh.
2. My quotation included one
It is extremely common for installers to include the cost of fitting a battery in their quotations. This is partly down to the widespread assumption that adding a battery to a solar PV system is a must. But, you should also know that there is money to be made on batteries. From an installer’s point of view, it is typically a simple installation with good margins on the product. They are not necessarily included in the quote because it is the best thing for you and your circumstances.
3. I’m worried about power cuts
If you are worried about power cuts, you probably shouldn’t be. Power cuts are pretty rare. Most of us experience very few nowadays and whilst there are genuine fears it could get worse, these fears have yet to manifest into reality. There are a lot of people working on a variety of ways to solve the issues that might cause power outages and I have faith that they can be avoided. If you are unlucky enough to live somewhere where the local infrastructure is prone to more cuts than most of us, then I would urge you to take a look at how often they actually occur. Whilst it might feel like it happens all the time because when it does happen it’s bloody annoying, I suspect that in reality, it will be unlikely to happen more than three times a year. And yes, it’s a nuisance, but as I have already said batteries are expensive and you’ll need to buy some extra kit to keep them operating without grid power. A lot of the cheaper ones require a grid connection to charge and discharge. So financially speaking, you’re almost certainly better off contacting your local Distribution Network Operator (DNO) and badgering them to upgrade their equipment that is causing the power cuts.
4. It will save me money in the long run
It probably won’t! I would encourage you to consider the numbers very carefully. Issues include; the expected life of the battery, how much surplus solar power you have, how much power you use overnight, do you intend to charge from the grid overnight. You’ll also need to be highly engaged to get the best from it. Get in touch, and we can help you understand what adding a battery will mean for you.
5. I have an electric car and want to charge it on solar power overnight
Forget it. A home battery will not help you charge an EV. Home batteries range from 3 kWh to 16 kWh per unit. And whilst you can (normally) stack them for more capacity, it almost certainly isn’t worth it. Car batteries, on the other hand, are typically around the 50-60 kWh mark. Some even have over 100 kWh. So it’s simply a capacity issue. The most cost-effective solution for someone who has solar and an EV but is not able to charge their car during the daylight hours (remembering, of course, summer daylight hours are close to 18), would be to get yourself a good export tariff and a good time of use tariff. Get paid for exporting energy during the day and charge your car on cheaper nighttime tariffs when you can’t get enough of a charge from your solar system in the mornings or evenings, assuming you spend some of your time at home.
6. I want to take advantage of time-of-use tariffs
Time-of-use tariffs are great. I always encourage people to see if they can access a smart tariff with cheaper overnight rates. And yes, most batteries will charge at a cheaper rate overnight which you can then discharge during the day. Great. But, if you have access to this type of tariff you can easily load shift your high-consumption items (dishwashers, washing machines, dryers, electric cars) to the cheaper overnight rate without even spending a penny on new hardware. It’s really easy to do. Just set a timer and boom, you’re saving money and carbon. The grid is a lot less carbon-intensive overnight. Once you’ve done this you’ve probably load-shifted 50-80% of electricity consumption so a battery will only help you reduce the cost of what’s left (tea/coffee making and cooking meals). The remaining consumption is all that you should base the financial analysis on. Load shifting is free and easy, so I’d encourage you to do this before investing in a home battery.
7. I love technology and batteries are cool (they typically mean that the Tesla Powerwall is cool)
Yes, they are cool. The Tesla Powerwall especially, and arguably it’s the best. Weighing up which is the best battery should probably be left for another day though. But if you think the tech is cool, and you’re happy to admit that you’re simply showing off to your friends, then well, go for it.
Look out for our upcoming blog on bidirectional charging, now that’s a different kettle of fish!