Can I Add a Battery to My Existing Solar System?
Yes. Battery storage can be retrofitted to most existing solar PV systems. A battery stores daytime solar surplus for evening use, reducing grid import. In areas with frequent power outages, a battery provides backup power. 0% VAT applies until March 2027. A no-obligation survey assesses compatibility and recommends the right capacity.
Last updated October 2026
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Key facts
- ✓Battery storage can be retrofitted to most existing solar PV systems
- ✓Stores daytime solar surplus for evening use instead of exporting to grid
- ✓Provides backup power during outages common in remote Highland areas
- ✓0% VAT on battery installations until 31 March 2027
- ✓A 5kWh battery is typically sufficient for a 4 to 5kW solar system
- ✓Interest-free credit up to £30,000, subject to status
- ✓Compatibility and capacity assessed during a no-obligation survey
Last updated: 30 October 2026
How Battery Add-Ons Work
A battery stores surplus electricity generated by your solar panels during the day. Instead of exporting that surplus to the grid for a small SEG payment, you keep it on-site and use it in the evening when your panels are not generating. This reduces the amount of electricity you import from the grid, increasing your self-consumption and savings.
For Highland homes in areas with frequent power outages, a battery also provides backup power. Depending on your system configuration, a battery can keep essential circuits running during a grid failure — particularly valuable for remote properties.
Compatibility with Existing Systems
In most cases, a battery can be added to an existing solar PV system. Some systems need an additional battery inverter, while others may require upgrading to a hybrid inverter. Our installer partners assess your existing inverter, panel array and electrical setup during the survey and advise on exactly what is needed. There is no obligation to proceed.
Choosing the Right Battery Size
A 5kWh battery is typically sufficient for a 4 to 5kW solar system. Larger batteries store more surplus but cost more. The right size depends on your evening electricity consumption and how much surplus your solar system generates. Our installer partners recommend capacity during the survey — see our costs page for cost factors and our finance page for payment options.
0% VAT applies to battery installations until March 2027, whether installed alongside new solar or added to an existing system. For a deeper look at home battery options across Scotland, our sister site Battery Storage Scotland covers the subject in detail.
For more questions, see our FAQ page or the questions resource at Scottish Energy Efficiency. Ready to start? Book a no-obligation survey.
Battery Add-On — FAQ
Can I add a battery to my existing solar PV system?
Yes. Battery storage can be retrofitted to most existing solar PV systems. A battery lets you store daytime solar surplus for evening use instead of exporting it to the grid. Our installer partners assess compatibility during a no-obligation survey.
What size battery do I need?
A 5kWh battery is typically sufficient for a 4–5kW solar system. Larger batteries store more surplus but cost more. The right size depends on your evening consumption and how much surplus your system generates. Our partners recommend capacity during the survey.
How much does a battery add-on cost?
Cost depends on battery capacity, brand, and installation complexity. 0% VAT applies to battery installations until 31 March 2027, reducing the overall cost. Interest-free credit up to £30,000 is available, subject to status. A survey gives you an accurate price.
Will a battery work with my existing inverter?
In most cases yes. Some systems need an additional battery inverter or a hybrid inverter upgrade. Our installer partners assess your existing inverter and solar setup during the survey and advise on compatibility and any hardware changes needed.
Can a battery provide backup power during outages?
Yes. In areas with frequent power outages — common in remote Highland locations — a battery can provide backup power to keep essential circuits running. The level of backup depends on battery capacity and whether your system is configured for islanding.
Is 0% VAT available on battery add-ons?
Yes. 0% VAT on battery storage installations applies until 31 March 2027. This applies whether you install a battery alongside new solar panels or add one to an existing system. It is automatic — no application needed.
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