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If you want to connect solar panels to a battery, it’s likely that it’s because you want to make sure that you don’t waste any electricity when your solar panels are generating energy but you’re not around to use it. Batteries are particularly useful for homeowners that have solar panels but are out during daylight hours; with a solar battery system, your solar panels will feed the electricity they generate into the battery for you to use when you get home.

If you want to connect your solar panels to a battery, the best thing to do is to get in touch with an MCS-registered company who can talk you through your options. There are different size batteries and the size that’s suitable for you will depend on how much electricity you plan to store and how large your solar panel system is. Some of the top brands of battery storage system include Tesla, SunPower and SolarEdge. If you want to be able to take advantage of selling electricity back to the grid through the Smart Export Guarantee (SEG), it’s worth getting an MCS-registered company to install your battery for you, as you may not be eligible for payments if you connect your solar panels to a battery yourself.

You should also consider whether your solar panel system is a ‘storage ready’ solar system. Today, most systems will be, since battery storage is becoming much more common. This means that your solar panel system will have an inverter that can easily integrate a battery. If this is the case, you should be able to purchase the battery you want and follow the manufacturer’s instructions to install it.

However, it’s worth bearing in mind that electricity is extremely dangerous when handled incorrectly. If something goes wrong, you could electrocute yourself or cause a fire. If your solar panels and battery cause a fire, it’s unlikely that your home insurance company would pay out if you connect the battery yourself. That's why it’s best to ask a reputable installer with all the correct qualifications to connect your solar panels to a battery for you.

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.

The more you’re at home during the day, the more you can save on your electricity bill, since solar panels generate electricity during the day. The Feed-in Tariff scheme (FITs) ended in March 2019, but the new Smart Export Guarantee (SEG) pays you, via your energy supplier, for the electricity you export back to the grid. With the savings involved in generating your own electricity and SEG payments, you can expect to save up to £390 per year on your electricity bill.

How much energy a solar panel produces depends on its manufacturer and exposure to the sun. A good-quality solar panel typically has a power output of about 300 watts per hour, but this can vary from about 240 to 360 watts. How much energy your solar panel will produce per day depends on how many hours of unshaded daylight it’s exposed to.

Here’s an idea of how much energy you could expect a large commercial solar panel installation to produce in a year.

Solar panel system size, No. of solar panels, Annual electricity output

11kW, 44, 9,350kW

20kW, 80, 17,000kW

30kW, 120, 25,500kW

40kW, 160, 34,000kW

50kW, 200, 42,500kW

It’s important to get the right size solar panel system for your commercial property. Solar panels are usually installed on pitched roofs, although they can be fitted on stands on the ground if you have some unused outdoor space. The more panels you install, the more power you’ll generate, but there’s no point buying more panels than you have space for.

Solar panel system sizes are measured in kW. 4-10kW solar panel systems are usually too big for domestic properties but are ideal for smaller commercial properties. Here’s an idea of how many panels and space you’ll need for a few different system sizes:

System size, Number of panels, Area required (approximate)

4kW, 16, 23m²

6kW, 24, 35m²

8kW, 32, 46m²

10kw, 40, 58m²

Bear in mind that solar panels can’t be less than 30cm away from a roof edge, so you’ll need more space than the area that the panels take up.