Should I Add Battery Storage to My Existing Solar PV System?

Why add battery storage to existing solar?

Adding battery storage to an existing solar PV system is one of the most effective upgrades for rural Scottish homes. Without a battery, surplus daytime solar generation is exported to the grid for a modest payment (approximately 12p per kWh with Octopus Energy as at March 2026). With a battery, you store that surplus and use it yourself in the evening, which is worth more per unit because it offsets purchased electricity at your full retail rate.

For rural and island properties with weaker grid connections, battery storage provides an additional critical benefit: power during outages. Many Highland, island, and Borders communities experience more frequent power interruptions than urban areas. A battery system with backup capability keeps essential loads running during these outages.

Which battery systems do you install?

We install three battery systems suited to rural Scottish properties: Tesla Powerwall 3, Duracell Dura5, and Pylontech. Each has different capacity and feature profiles. Tesla Powerwall 3 offers integrated backup capability and smart energy management. Duracell Dura5 provides reliable storage at a competitive price point. Pylontech systems are modular and scalable for larger properties or higher consumption. We install through MCS-certified partners.

How much does adding battery storage cost?

Battery storage costs depend on capacity, system type, and whether backup capability is required. Interest-free credit up to £30,000 is available, subject to status, which can cover both the battery and installation. 0% VAT applies to qualifying battery storage installations until 31 March 2027. Contact us for a tailored quote based on your existing solar system and consumption profile.

Will the battery work during a power cut?

Yes, if the system includes backup capability. Tesla Powerwall 3 and some Pylontech configurations can automatically switch to backup mode during a power outage, keeping essential loads running. This is particularly valuable for rural and island properties where grid interruptions are more common. The specific loads covered depend on the wiring configuration, which your installer will discuss during the survey.

How long does a battery last?

Modern home battery systems are designed for 10 to 15 years of daily cycling, with warranties typically covering 10 years or a specified number of cycles. Battery capacity may degrade gradually over time, but modern lithium-ion systems maintain high performance for many years. Your installer will discuss warranty terms and expected performance for your specific system.

See our battery storage page, our solar PV guide, or more answers from Scottish Energy Efficiency.