If you’re considering solar panels for your home in Essex, Kent or the wider South East, you’ve likely come across terms like product warranty, performance warranty and inverter warranty. But what do they actually mean – an more importantly, what really matters when choosing a solar system?
At SolarTherm UK, we regularly speak with homeowners who are unsure how to compare warranties between installers and manufacturers. This guide breaks it down clearly, so you can make an informed, confident investment.
Why Solar Warranties Matter
Solar panels are a long term investment – typically designed to last 25-30 years or more. A strong warranty package protects that investment and gives you confidence that your system will perform reliably over time.
However, not all warranties are created equal. The length, coverage and provider reliability are what truly count.
The Three Key Types of Solar Warranties
1. Product Warranty (Equipment Protection)
This covers defects in materials or manufacturing. If a panel fails due to a fault, the manufacturer will repair or replace it. Typical length is 10-25 years depending on brand, with premium panels often offering 25 years or more.
However, longer isn’t always better, always check the manufacturer’s reputation, ensuring the warranty is backed by a financially stable company. You also need to confirm who handles any claims – the installer or the manufacturer.
2. Performance Warranty (Power Output Guarantee)
This guarantees how much electricity your panels will produce over time. Typically they guarantee ~90-95% output in year 10 and ~80-85% output by year 25. Low degradation rates of ~0.25-0.5% per year mean your solar panels will generate more electricity for longer. A linear performance warranty is more transparent than stepped guarantees.
Real world installation quality can impact performance, just as much as the panel itself.
3. Inverter Warranty
The inverter is the hardest working component in your system – and the most likely to need replacement during its lifetime. Depending on brand, most inverters have a warranty lasting 5-12 years with extensions often available up to 15-20 years. When choosing your inverter, choose a reliable brand with UK support and consider a hybrid inverter if you are planning on battery storage. Budgeting for a potential replacement inverter is usually needed and at SolarTherm UK, we take these additional costs into account when calculating your performance and returns estimates.
What About Battery Storage Warranties?
With more homeowners than ever adding battery storage, understanding battery warranties is essential. Battery warranties usually cover:
- Throughput (total energy cycled)
- Capacity retention (70-90% after 10 years)
- Time period (typically 10-15 years)
What matters:
- High cycle life (more usable energy over time)
- Clear degradation terms
- Compatibility with your solar system
The Hidden Factor: Workmanship Warranty
Many homeowners focus only on manufacturer warranties, but your installer plays a critical role.
A workmanship warranty covers installation quality, roof mounting integrity and electrical connections. At SolarTherm UK, we provide a robust workmanship guarantee alongside premium equipment warranties – ensuring your system is protected end to end.
Real World Insight: What Actually Matters
From years of installing solar systems across Essex, Kent and the wider South East, here’s what we’ve found truly matters:
Installer Quality > Warranty Length
A poorly installed system can underperform regardless of warranty coverage.
Manufacturer Stability
A 25 year warranty is only valuable if the company still exists to honour it.
System Design
Correct sizing, orientation and integration with battery storage have a bigger impact than minor warranty differences.
Aftercare and Support
Fast, local support is crucial if issues arise – something national providers often lack.
Why Choose SolarTherm UK?
As a trusted solar installer in the South East, SolarTherm UK combines technical expertise with transparent advice – no hard sell, just honest guidance.
Our Commitment:
- Experience: over 15 years of residential and commercial solar and battery installations across Essex, Kent and the wider South East
- Expertise: fully qualified, MCS accredited engineers
- Authoritativeness: trusted local installer with proven project portfolio
- Trustworthiness: clear quotes, no pressure and ongoing, long term customer support
We carefully select Tier 1 manufacturers and proven battery systems to ensure long term reliability – because your system should perform for decades, not just the first few years.
Key Takeaways
- Focus on overall system quality, not just warranty length
- Ensure both product and performance warranties are strong
- Don’t overlook inverter and battery warranties
- Choose a reputable local installer with solid workmanship guarantees
Speak to a Solar Expert
If you’re at the start of your solar journey and want clear, honest advice on warranties, system design or battery storage contact SolarTherm UK. We are here to help with any questions you may have.
Contact us today for a free, no obligation quote and design, tailored to your property, usage and future energy needs. No hard sell, just honest, expert advice – and the time you need to make an informed decision.
Your home. Your energy. Your future.
FAQs
How long do solar panel warranties typically last?
Most solar panels come with a product warranty of 10–25 years and a performance warranty of 25 years.
Are longer warranties always better?
Not necessarily. The manufacturer’s reliability and installer quality are more important than headline numbers.
What happens if my solar panel underperforms?
If it falls below the guaranteed output in the performance warranty, the manufacturer may compensate or replace the panel—depending on terms.
Do I need to extend my inverter warranty?
In many cases, yes. Since inverters often need replacing within 10–15 years, an extension can provide peace of mind.
Are battery warranties different from solar panels?
Yes. Battery warranties focus on cycles, capacity retention, and usage, rather than just time.
