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27 Mar 2024
How do solar panel batteries work?
Anna Dearden
Home Sector Specialist
Capturing daylight, powering nights. Solar panel batteries give the potential for sustainable living.

Have you ever thought about how nice it would be to keep the sun's energy working for you even after sunset? That's where solar panel battery storage steps in. It's like having your energy locked away in a box, ready to heat and light up your home whenever you need it. 

In a nutshell, these batteries store the energy your solar panels generate during the day for use at night or during power outages. Solar panels and their batteries often function as separate components within a solar energy system, so it’s important to make sure you invest in a battery too, if your solar panel doesn’t come with one already. 

What does a solar panel battery do?

At the heart of it, solar panel systems convert sunlight into electricity using photovoltaic (PV) cells. This electricity can either be used right away by your home appliances or sent to your solar panel battery storage for later use. The batteries store this electricity as direct current (DC) power. However, most homes run on alternating current (AC) power, so an inverter is used to change DC into usable AC electricity.

This setup ensures you're not left in the dark (quite literally) when the sun goes down or when there's a blackout. It's like making a sunny day last 24 hours, energy-wise!

The science behind solar panel batteries unpacked

The process starts with solar panels converting sunlight into electrical energy. But the journey doesn't stop there. The electricity generated is in the form of direct current (DC), which, while perfect for charging batteries, isn't compatible with most home appliances that operate on alternating current (AC). This is where the inverter comes into play, transforming DC into AC, making the stored energy ready for everyday use.

This seamless conversion process ensures that the energy from the sun is efficiently utilised, powering your home with clean, green energy. In addition to this, modern solar battery systems are smarter than ever. They come equipped with software to manage energy flow, optimising both energy consumption and battery life. This smart technology can even predict your energy usage patterns and adjust accordingly, ensuring maximum efficiency.

What happens when the solar panel batteries are full?

The question of what happens when solar panel batteries reach their full capacity is essential. Here's a bit more detail on the two key outcomes:

Excess energy and the grid connection

For homes connected to the grid, sending excess energy back is a common practice. This not only contributes to the community’s energy needs but also offers financial benefits through net metering. Essentially, you become a mini power plant, supplying the grid with renewable energy. 

Smart systems for efficient energy management

The intelligence of modern solar systems cannot be overstated. They are designed to prevent overcharging, which protects the battery’s lifespan.


These smart systems can divert surplus energy to where it's needed most in your home. For instance, if your batteries are full, the system might direct extra energy to power-intensive appliances or even to heat water, ensuring not a single watt of solar power goes to waste.

How many solar panel batteries do you need to power a house? 

When it comes to powering your home with solar panel batteries, the "one size fits all" approach doesn't apply. Determining the number of batteries needed involves a closer look at your home's energy consumption, the capacity of your solar panel system, and the specifications of the batteries themselves. Let's explore these factors in more detail.

Understanding your energy consumption

The first step is to get a grip on how much electricity your household consumes. This can vary widely. For instance, a small, energy-efficient home might sip electricity, whereas a larger home, with all the modern conveniences, could gulp it. Your energy bills over the past year can offer valuable insights into your consumption patterns. On average, the UK household consumes about 242 kWh of electricity per month, but this figure can vary significantly from one household to another.

It's also essential to consider when you use electricity. If you consume most of your power in the evening when solar panels aren't generating electricity, you'll rely more heavily on stored energy. This means you might need more batteries to ensure a seamless supply throughout the night.

Want to learn more about solar panels and energy consumption? Check out our behind-the-scenes look at solar panel installation to see how solar panel companies can use your average energy usage to work out how much your solar panels could save you.


Sizing your solar panel system

The capacity of your solar panel system is another critical factor. A larger system can generate more electricity, potentially requiring more storage capacity to capture excess energy. Conversely, a smaller system will generate less electricity, possibly reducing the need for extensive battery storage.

The ideal scenario is to have a balanced system where your solar panel capacity closely matches your storage capacity, ensuring that you maximise the use of your solar energy and reduce reliance on the grid.

Delving into battery capacity

Battery technology has evolved rapidly, with lithium-ion batteries becoming a popular choice for residential solar systems due to their efficiency and longevity. The capacity of a battery is measured in kilowatt-hours (kWh). A single battery might range from 2 kWh to over 10 kWh in storage capacity.

The decision on how many and what type of batteries to install should be based on your energy consumption patterns and the amount of energy your solar system generates. For example, if your home uses 30 kWh of electricity per day, and you want the ability to run entirely off your batteries for a day, you'd need a storage system that can cover that demand.

Making the calculation

Let's say an average home uses 30 kWh of electricity per day, and the homeowner wants enough battery storage to cover this consumption for one evening and night. If the homeowner opts for batteries with a capacity of 10 kWh each, they would need at least 3 batteries to meet this requirement, not accounting for efficiency losses and assuming that the solar panels can fully recharge these batteries during the day.

However, it's important to note that not all energy needs to be stored. If you're connected to the grid, you can still draw power when your batteries are depleted, and if your system is set up for net metering, you might receive credit for the excess energy your solar panels produce and send back to the grid during the day.

Tailoring the solution to your needs

Ultimately, the best approach is to tailor your solar panel and battery system to your specific needs. Consider factors like your energy consumption patterns, the potential for future changes (like adding an electric vehicle to your household), and your budget. A professional solar consultant can help design a system that balances these factors, ensuring that you have a reliable, efficient, and cost-effective solution.

Remember, investing in solar panel battery storage is not just about meeting your current energy needs. It's also about building a sustainable, resilient energy system that can adapt to future demands and contribute to a greener planet.

Compare solar panel installers with SpotDif 

Finding the right solar panel installer is key to powering up your home efficiently. With SpotDif, you can compare solar panel installers easily to find the best fit for your needs.

Our team at SpotDif is here to help you sift through the options, ensuring you get top-notch solar installations at great prices.

Start your journey to a greener home with SpotDif. Just fill out our quick solar panel installer comparison form, and we'll help tailor your energy solutions to match your lifestyle.

Anna Dearden
Home Sector Specialist
Combining in-depth research with an interest in all things home improvement, I aim to keep SpotDif readers up to date with interior design trends, renewable energy options, and more.
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