Batteries allows you to store any unused solar energy for use later on. Batteries are not the obvious choice you would think as there are a lot of factors to consider. We will ask you questions which may seem like we are putting you off, but we are ensuring you have batteries for the right reasons.

Battery storage mis selling is a real problem so we want to ensure they are right for you.

Having batteries does not mean you are off grid, because in most cases you still need AC power from the grid for them to work. Check out the SMART CONTROLS page, to see how you can create a off grid backup system. 

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Solar PV battery storage systems allow you to store surplus energy generated during the day for use at night, significantly increasing your energy self-consumption from roughly 30–40% to 70–80%. 

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Types of Systems

The way a battery connects to your solar array fundamentally changes its efficiency and installation cost. 

• DC-Coupled (Hybrid): The battery connects to the solar panels on the "DC side" before the inverter.

  • Best for: New installations.

  • Efficiency: Higher (95–98%) because it avoids multiple AC/DC conversions.

  • Cost: Generally 10–20% lower capital costs due to shared infrastructure.

• AC-Coupled: The battery connects to your home's "AC side" via its own dedicated inverter.

  • Best for: Retrofitting a battery to an existing solar setup.

  • Efficiency: Lower, as energy is converted three times (DC to AC to DC back to AC), resulting in roughly 3–10% energy loss.

• Battery Chemistries:

  • Lithium Iron Phosphate (LFP/LiFePO4): Now the market standard (estimated 85% share by 2024). They are safer, last longer (up to 15 years), and can be discharged to 100% without damage.

  • Nickel Manganese Cobalt (NMC): Common in older systems or EVs; higher energy density but more sensitive to high temperatures and deeper discharges. 

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Costs & Savings (UK 2025/2026 Estimates)

The UK currently offers 0% VAT on solar battery installations until March 31, 2027. 

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• Payback Period: Typically 7 to 12 years. This is faster if paired with "Smart Tariffs" that let you charge the battery from the grid when prices are very low (e.g., overnight).

• Export Income: Using stored energy is often 5 to 7 times more valuable than selling it back to the grid via the Smart Export Guarantee (SEG), as buying grid power costs ~28p/kWh while export rates often average 5–15p/kWh. 

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Risks & Trade-offs

• Degradation: All batteries lose capacity over time. Most brands warrant 60–80% retention after 10 years. You will likely need to replace the battery at least once during the 25-year life of your solar panels.

• Fire Safety: While modern LFP batteries are very stable, thermal runaway remains a risk if units are poorly installed or damaged. Proper ventilation and using MCS-accredited installers, like Qualis Energy, are critical.

• Diminishing Returns: Sizing a battery too large for your solar array means it may never fully charge in winter, lengthening your payback time without adding much value.

• Emergency Power (EPS): Not all batteries provide power during a grid blackout. This often requires an additional "gateway" or relay, adding complexity and cost to the installation. 

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