Solar Panel Batteries: Do You Need Them?

Our solar panel battery guide covers the benefits, types, and integration of battery systems with solar panels.

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 sunny days, many home solar panel systems generate more electricity than the household actually uses. This creates a surplus of energy that, if not utilised or stored, gets sent back to the grid, often resulting in only small returns for homeowners. To make the most of their solar energy, many people choose to store this excess power in a battery. This way, they can tap into that stored energy later, whether it’s during the evening or on cloudy days, ensuring that none of their hard-earned solar energy goes to waste.

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What is solar panel battery storage?

On sunny days, many home solar panel systems generate more electricity than the household actually uses. This creates a surplus of energy that, if not utilised or stored, gets sent back to the grid, often resulting in only small returns for homeowners. To make the most of their solar energy, many people choose to store this excess power in a battery. This way, they can tap into that stored energy later, whether it’s during the evening or on cloudy days, ensuring that none of their hard-earned solar energy goes to waste.

What are solar batteries made from?

Batteries come in a variety of materials, with traditional options like lead-acid and nickel-cadmium being common in the past. Nowadays, though, most modern solar batteries we use are made from lithium-ion technology. This is the same kind of battery found in laptops and electric vehicles. Lithium-ion batteries are great because they can store a lot of energy in a compact size, making them a popular choice for solar systems. They’re efficient, lightweight, and perfect for maximising your solar power investment.

What size are solar batteries?

Batteries come in different sizes, but the solar panel batteries we typically install are roughly the size of a small briefcase and weigh around 25 kg. This makes them easy to fit into most spaces without taking up too much room.

What Size Battery Do I Need for My Solar Panel System?

Selecting the right battery size is crucial for getting the most out of your solar panel system. It’s all about finding that sweet spot! The size you need depends on how much energy your household uses and how much extra energy your solar panels produce. By understanding these factors, you can ensure your system runs efficiently and meets your energy needs effectively.

Factors to Consider

1. Energy Consumption: Start by evaluating your average daily energy usage. Look at your electricity bills to determine how many kilowatt-hours (kWh) you consume on a typical day. This figure will help guide you in selecting a battery with adequate capacity to meet your needs.
2. Solar Production: Assess how much energy your solar panels produce during the day. Factors like the number of panels, their efficiency, and local sunlight conditions will influence this. Understanding your solar production will give you a clearer picture of how much excess energy you might store.
3. Battery Capacity: Battery capacity is measured in kWh and indicates how much energy the battery can store. For example, if your household consumes around 30 kWh per day and your solar system produces about 20 kWh on a sunny day, you’ll need a battery that can handle at least a portion of that deficit, potentially in the range of 5-10 kWh, depending on your energy usage patterns.
4. Days of Autonomy: Consider how many days you want your battery to provide power without solar input. If you’d like to have backup energy for a few cloudy days, you might need a larger capacity battery. For instance, if you want to cover three days of usage, multiply your daily consumption by three to find the appropriate battery size.
5. Future Needs: Think about potential changes in your energy consumption in the future, such as adding electric vehicles or home appliances. Selecting a scalable battery option that can expand with your energy needs can be a smart long-term investment.

Consultation and Tools

To make an informed decision, consider scheduling a free consultation with one of our Green Homes Gurus. They can help analyse your specific energy needs and recommend the ideal battery size. Additionally, you can use the MakeMyHouseGreen solar panel calculator to get a preliminary estimate of the battery capacity that would best suit your home. This tool takes into account your unique energy requirements and provides tailored recommendations to make the most of your solar investment.

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 plays a crucial role in your solar energy system by converting the electricity generated by your solar panels into usable power for your home. If you're thinking about starting with just solar panels now and adding a battery later, it’s a smart move to select an inverter that’s already compatible with battery storage. This way, you won’t have to worry about the added cost of replacing your inverter down the line, ensuring your system is ready for battery integration from the get-go.

While the prices of solar panels have stabilised recently, the technology surrounding batteries is expected to evolve significantly in the next five years. By preparing for these advancements now, you’ll be in a great position to fully benefit from the latest innovations in solar battery technology when you're ready to expand your system.

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:

Let’s take a look at a typical usage profile from MakeMyHouseGreen. Imagine a household that uses energy fairly consistently throughout the day, with a few small spikes in the morning and evening when people are most active. This home, equipped with 10 south-facing solar panels, generates about 4,025 kWh of electricity each year. 

Without a battery, the family only utilises around 40% of the energy produced by their solar panels, sending the rest back to the grid. However, by adding a 7.2 kWh battery, they can dramatically increase their usage - tapping into 74% of the energy they generate. This means more savings and less reliance on external energy sources. It's a great example of how battery storage can make a real difference in maximising solar energy benefits!

To understand how a battery could impact your energy usage, simply check the box on the right side under the System tab while using our platform. You can easily toggle it on and off to see how the changes affect your energy consumption. It’s a straightforward way to visualise the benefits a battery could bring to your home!

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. Just like solar panels, solar batteries have very few moving parts, which means that any issues are likely to surface well within the warranty period. It’s a good idea to look up the average lifespan of the battery you’re considering - simply type the battery’s name along with “average lifespan” into a search engine, and you’ll get a clearer picture of whether it might need replacing before the warranty expires, whether that’s the standard or extended warranty.

Many customers who choose extended warranties find comfort in knowing they have that extra layer of protection, just in case something doesn’t go as planned with their system. It’s always better to be prepared!

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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