Solar Panel Batteries: Do You Need Them?

Elon Musk has made a Gigafactory, but what exactly is it churning out? Everything you need to know about solar panel battery storage in 5 minutes or less!

Do I need batteries for my solar panels?

On a sunny day, most home solar panel systems produce more electricity than the household consumes, leading to an excess of energy. If this surplus energy isn’t used or stored, it’s sent back to the grid, typically resulting in only modest returns. For this reason, many homeowners prefer to store their excess electricity in a battery, allowing them to use it later when needed.

What is solar panel battery storage?

Battery storage is especially beneficial for solar energy since electricity isn’t produced at night, which is often when household energy consumption is higher. Thankfully, any surplus electricity generated by your solar panels during the day can be converted into chemical energy and stored in a battery. Later, this stored energy can be converted back into electricity when you need it, ensuring that none of the energy your solar panels produce goes to waste.

What are solar batteries made from?

Batteries can be made from a number of different materials - traditionally they would have been Lead acid or Nickel-cadmium. However the kind of modern solar batteries we install tend to be made from Lithium-ion, the same technology as laptop batteries and electric vehicle batteries, which can hold significant power in a small space.

What size are solar batteries?

Batteries can vary in size, but the solar panel batteries we install are about the size of a small briefcase and weigh around 25kg.

How many batteries do I need for solar power?

It’s not just about the number of batteries you have, but the capacity they offer. The amount of battery storage you need depends on how much excess electricity your system produces and how much of it you’ll use later. When you book a free consultation with us, we’ll help you determine the ideal battery capacity for your specific needs. You can also explore this yourself using our free platform to get a preliminary idea of what your battery storage requirements might be.

How much will solar panel battery storage cost?

When calculating the cost of solar panels, you’ll have to consider whether you want to include a solar battery. The cost will depend on the energy storage that you require, but adding a battery to your system can increase the cost by around £1,000 to £5,000. Most of the additional cost will come from the solar battery itself, but some come from needing an improved inverter. You see, solar panel systems under 3.6kW (around 10-12 panel systems) will typically have a solar panel inverter cost ranging from £500 - £1500, with the inverters on the more expensive side of the spectrum being what you need if you have a battery. Systems larger than this can require a somewhat more expensive inverter, but your Guru will be happy to discuss this in greater detail.

What does an inverter do?

The inverter is the component that converts the energy generated by your solar panels into usable electricity for your home. If you’re considering starting with just solar panels and possibly adding a battery later, it’s wise to choose an inverter that is already compatible with battery storage. This way, you can avoid the additional expense of replacing the inverter in the future, making your system “battery-ready” from the start. While the cost of solar panels has stabilised, battery technology is expected to advance significantly over the next five years, so being prepared for future developments allows you to take full advantage of these innovations.

Are solar panel batteries worth it?

Whilst there is an additional cost, there are plenty of benefits. If you use most of your energy in the evening, i.e. when the sun isn't shining and you aren't producing solar energy, a battery can help store the excess energy from daylight hours for you to use in the evening. This helps to reduce your reliance on the grid and stops you from having to buy as much energy. If, however, you use most of your electricity during the day, when the panels are producing electricity, it may not be worth it.

How do I know if a solar battery is the right fit for me?

When using our free and impartial tool, you’ll be asked to select a “usage profile” which describes how you use energy. We then map this against what would be produced by your solar panel system, which will look something like this:

This is a MakeMyHouseGreen usage profile featuring a house with fairly constant usage throughout the day, with small peaks in the morning and evening. The household generates 4025kWh per year with its 10 solar panels facing south. Without the battery, the household uses only 40% of the generated electricity, with the rest being sold to the grid. Adding a 7.2kWh battery means the household is able to use 74% of what it generates.

To see the effect a battery would have on your usage, tick the box on the right-hand side, under the System tab when using our platform. Toggle this on and off to see the change.

If you are considering a system that will produce excess energy during the day, a battery may be a good way to capture that value. However, if you have an electric vehicle that is parked at home during the day and/or can heat your water with your solar panels, then the need for a battery may be less strong. Discuss these options with your Green Homes Guru to see what might be most useful for you and your house. Don’t yet have a Guru to ask? Book a free call by going through the MakeMyHouseGreen platform here.

Will my solar battery system power me in a power cut?

No, unfortunately your solar battery system can't power you in a power cut.

Should I get an extended warranty for my solar power battery?

Like solar panels, batteries come with warranties which are usually between 5-15 years. As with solar panels, the low number of moving parts means that any faults will likely come to light well within the warranty period. Check the average lifespan of the battery you are considering - a quick google search for the name of it and "average lifespan" should help you work out if it's likely to need replacing within either the normal or extended warranty (if offered).

We hear that people who opt for extended warranties enjoy great peace of mind in the eventually that something goes wrong with the kit.

Now that you've completed our battery storage masterclass, you should be in a much better position to choose the right solar panel system for your needs. We cover more about other system aspects in other articles, but if you have any questions in the meantime, check out our Guru FAQS or drop us an email via team@makemyhousegreen.com.

Recommended Guides:

- Are solar panels worth it in the uk?

- Do solar panels work without sunlight?

- How efficient are solar panels?

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