Can I Add a Battery to My Existing Solar Panels?

How Does Retrofitting a Battery Work?

Retrofitting a battery involves adding a battery storage unit and, if needed, a compatible inverter to your existing solar PV system so surplus electricity is stored instead of exported.

When you already have solar panels installed, retrofitting a battery means adding a battery storage unit to your existing system. The battery connects to your solar PV system through a compatible inverter — sometimes your existing inverter can be used, and sometimes a new hybrid inverter is needed. The battery stores the surplus electricity your panels generate during the day so you can use it in the evening and at night, rather than drawing from the grid. Our surveyor assesses your current setup — including your inverter, panels, wiring and available space — to determine what is needed for the retrofit. You can learn about the full process on our how it works page.

Is My Existing Solar System Compatible with a Battery?

In many cases, yes. Our survey checks your inverter, panels and wiring to confirm compatibility and advise on what is needed.

Most existing solar PV systems can have a battery added, but compatibility depends on your current equipment. The key component is the inverter — the device that converts the direct current (DC) electricity from your panels into alternating current (AC) for your home. If your existing inverter is not battery-compatible, a new hybrid inverter may be needed. The age and type of your panels, the capacity of your existing system, and the wiring between your panels and your consumer unit also factor in. Our surveyor checks all of this during your survey and advises on what is required. Because every installation is different, we provide tailored quotes after the survey rather than giving a one-size-fits-all answer.

What Are the Benefits of Adding a Battery?

A battery lets you store surplus daytime electricity for evening and night use, reducing your reliance on grid electricity during peak hours.

Without a battery, the surplus electricity your panels generate during the day is typically exported to the grid. With a battery, that surplus is stored and available for you to use in the evening and at night. This means you make better use of the power your panels produce, rather than buying electricity from the grid during peak hours. A battery is particularly valuable in Scotland, where long summer days can generate significant surplus energy that can be stored for use during darker winter months. For more on whether solar is worth it in Scotland, read our guide to solar worth in Scotland.

What Should I Consider Before Adding a Battery?

Consider your current system's compatibility, your daily electricity usage, where the battery will be installed, and the cost including 0% VAT.

Before adding a battery, it helps to understand a few key points: whether your existing inverter is battery-compatible or needs replacing, how much surplus electricity your panels typically generate, how much you use in the evening, where a battery could be installed (typically in a garage, utility room or loft), and the total cost including the 0% VAT that applies until 31 March 2027. Our survey covers all of these and provides clear, comparable quotes. Interest-free credit up to £30,000, subject to status, is also available if you want to spread the cost. See our costs page for more on what influences the price.

How Long Does a Battery Retrofit Take?

A battery retrofit is typically completed within one day, depending on the complexity of the installation and whether a new inverter is needed.

If you decide to go ahead, the battery installation is carried out through our MCS-certified partners. For a straightforward retrofit — where the battery is installed alongside your existing system with minimal changes — the work is usually completed within one day. If a new hybrid inverter is needed or the wiring requires significant changes, it may take longer. Your installer gives you a clear timeframe before work begins. Once complete, the system is tested and you are shown how to monitor your battery charge and usage.

How Do I Get Started?

Arrange a no-obligation survey and we will assess your existing solar setup and advise on compatible battery options.

The first step is to arrange a survey. Fill in our quote form and select 'Battery storage only' as what you are interested in, or call us on 0141 230 0198. Our surveyor visits your home, assesses your existing solar PV system, and advises on compatible battery options. We provide clear, comparable quotes with no obligation to proceed. You can also read our FAQs for more information.

For more information, visit More answers from Scottish Energy Efficiency.