Solar battery

• The power of your solar panel system – there's no point buying a higher capacity battery if your system will never generate enough electricity to charge it
• How often you think you will need to charge your battery
• Your budget
• Whether you care about having the latest technology and a recognisable brand name

Tesla’s top-of-the-range battery storage system is still one of the most expensive on the market. It has a huge 13.5kWh usable capacity and can even keep you up and running during a power cut. But how long does a Tesla Powerwall battery last? And does this mean it’s worth investing in one?

The Tesla Powerwall 2.0 comes with a 10-year warranty. But Tesla says that it should last way beyond this – at least 5 years longer. The standard warranty says that it should work at 70% capacity for the full 10 years – so if it loses more than 30% of its storage capacity within that time, it should still be covered.

While the Tesla Powerwall does last a long time, it has a large capacity that most average households won’t require, and it’s a costly option. After installation, the Powerwall 2.0 will set you back between £6,500 and £9,000, so ideally you want it to last past its 10-year warranty.

Before you splash out, consider the size of the solar panel system you want to install or you already have. Will it generate enough electricity to make it worth storing in the Powerwall? If not, are you expecting to upgrade your solar panels to a larger system in the future? If you are, then it might be worth investing in a Powerwall. It might also be better to wait until you come to upgrade your solar panels – the solar battery price trend is going the same way as solar panels, so they will probably continue to decrease in price as more people adopt the technology.

There are a few factors that will determine whether it’s worth getting a solar battery. They involve how much electricity you use, how often you’re at home and whether you receive any export payments.

To work out whether it’s worth getting a solar battery, you need to work out how much of the electricity you generate you’re using already. If you’re able to run all your appliances during the day while your solar panels generate electricity, then it sounds like you’re already using your electricity well. It might not be worth you getting a solar battery in this case.

However, if you’re not at home for a lot of the day, then you’ll be missing out on the electricity your panels are generating while the sun’s shining. If you install a solar battery system, you can store the electricity that your panels generate in the battery and use it when you get home. This will help you cut your electricity bills even further.

You’ll also need to consider whether you’re getting paid to export your electricity. If you’re on the Feed-in Tariff scheme (FITs) or receive payments from the Smart Export Guarantee (SEG), you’ll get paid for every unit of electricity you export to the National Grid. Before you decide whether it’s worth getting a solar battery, you’ll need to weigh up whether you’d be better off carrying on exporting your unused electricity rather than storing it to use yourself. If you’re unsure, visit the Energy Saving Trust’s website or speak to an MCS-registered installer who will be able to help you work out which is more cost-effective.

Most people want to connect solar panels to a battery when they’re not at home all day to use the electricity they generate, or generate more than they consume over a day. Solar batteries are a great way to maximise the savings on your energy bills since you can use every unit of electricity you generate.

If you want to connect your solar panels to a battery, the best – and safest – way is to ask an MCS-registered company to do it for you. They’ve had lots of training and hold qualifications in handling electricity and installing solar batteries, so they will be able to recommend the best battery for your solar panels and for the among of electricity you use. Some of the brands they might recommend include Tesla, SolarEdge and SolaX, but there are many more to choose from. If you want to send electricity to the grid from your battery to receive Smart Export Guarantee (SEG) payments, it’s also worth leaving installation up to a registered installer. This is because you might not be eligible for payments if your battery wasn’t installed by an MCS-registered company.

However, if you do want to have a go at connecting your solar panels to a battery, it’s worth finding out whether your system is ‘storage ready’. Most relatively new systems will be, since batteries are becoming more commonplace. If your solar panels are storage ready, they will have an inverter that can easily have a battery added to it. If this is the case, then you should be able to buy the solar battery you want and follow the manufacturer's instructions to install it.

But it’s worth remembering that electricity is extremely dangerous when handled improperly. If you don’t get the solar battery connected properly and something goes wrong, it could cause a fire or you could electrocute yourself. If a fire breaks out due to your battery, it’s unlikely that your home insurance company would pay out since you connected the battery yourself. That’s why it’s always worth speaking to a registered installer to install a solar battery storage system for you.