When your home battery fails, the first thing you do is call the installer. But before you do, ask yourself: did you register the product within the required window? Did you keep the original invoice? Was the installation certified by a licensed electrician? If the answer to any of these is no, your claim may be dead on arrival — regardless of the battery’s condition. In fact, most warranty claims fail on paperwork, not on the cell. This guide walks you through the fine print that quietly caps your claim, so you can protect your investment.
Home battery warranties typically come in two flavours: product warranty and performance warranty. They are not the same, and confusing them can cost you.
Performance warranties are where the fine print gets tricky. They often include a ‘throughput cap’ — a maximum total energy that can pass through the battery over its life, measured in megawatt-hours (MWh). If you hit that cap before the time limit, the warranty ends. For example, a 10-year warranty might also state ‘or 37 MWh, whichever comes first’. If you cycle your battery daily, you could hit the cap in 7 years. Always check both the time and the throughput limits.
Warranties are tied to two different clocks: calendar age and cycle count. Calendar age is straightforward — time from installation. Cycle life is the number of full charge-discharge cycles. Some warranties use both, and the one that expires first wins.
For example, a warranty might say ’10 years or 6,000 cycles, whichever comes first’. If you cycle your battery twice a day, you’ll hit 6,000 cycles in about 8 years. That’s a cap you might not expect. To estimate your own cycle usage, divide your daily throughput (in kWh) by your battery’s usable capacity. If you have a 10 kWh battery and use 8 kWh per day, that’s 0.8 cycles per day. Over 10 years, that’s about 2,920 cycles — well under 6,000. But if you have a small battery and use it heavily, you could exceed the cap.
Most warranties require professional installation by a certified electrician. Some even require the installer to be accredited by the battery manufacturer. If you install it yourself or use an uncertified installer, the warranty is void. Keep all installation documents, including the certificate of compliance and the commissioning report. Also, many warranties require online registration within a specific period (e.g., 30 days after installation). Missing that window can invalidate your claim.
Batteries are sensitive to their environment. Warranties typically exclude damage caused by:
If your battery fails because it was installed in an unheated garage that hits -15°C in winter, the warranty may not cover it. Always check the operating temperature range and ensure your installation site meets it.
When you need to make a claim, follow these steps:
If the claim is denied, ask for a written explanation. Under EU law, you have rights beyond the warranty. Directive 2019/771 gives you a minimum two-year legal guarantee for all goods, including batteries. This guarantee covers defects that existed at the time of delivery and can be enforced against the seller, even if the manufacturer’s warranty has expired. However, the legal guarantee is shorter than most battery warranties, so it’s a fallback, not a replacement.
| Warranty term | Typical duration | What it actually limits | Watch out for |
|---|---|---|---|
| Product warranty | 5–10 years | Defects in materials/workmanship | Excludes environmental damage and misuse |
| Performance warranty | 10 years (often) | Minimum state of health (e.g., 70% after 10 years) | Throughput caps (MWh) can shorten effective life |
| Cycle life | 6,000–10,000 cycles | Number of full cycles | Daily cycling can hit cap before time limit |
| Calendar life | 10 years | Time from installation | Often ‘whichever comes first’ with cycle life |
| Installation requirement | N/A | Certified installer required | Self-installation voids warranty |
| Registration | 30 days (often) | Online registration within window | Missing window voids warranty |
Before signing a purchase agreement, ask the installer for a copy of the full warranty document. Read it carefully and look for:
If anything is unclear, get it in writing. A reputable installer will be happy to explain.
If your claim is denied, don’t give up. First, ask for a detailed reason. If the denial is based on a technicality, you may be able to appeal. If the battery is still within the EU legal guarantee period (two years from delivery), you can pursue a claim against the seller under Directive 2019/771. This applies even if the manufacturer’s warranty is more restrictive. You can also contact your national consumer protection agency or a consumer ombudsman for mediation.
