Top 10 Mistakes Before Installing Photovoltaics (Cost Thousands of €)
19/04/2026
If you're thinking about installing solar panels, read this first. The mistakes you'll see here are the most common in Greece — and the most expensively avoidable.
❌ Mistake #1: Incorrect system size
A 3kW system for a family consuming 8,000 kWh/year is like trying to bail out water with a spoon. You lose money and don't solve the problem. Solution: A proper energy study based on your 12-month consumption data.
❌ Mistake #2: Only considering the last bill
In winter, you consume 3× more energy than in summer. If you calculate based on June, you'll end up with the wrong size. Solution: Analyze 12 months of consumption.
❌ Mistake #3: Cheap inverter
The inverter is the heart of the system. A cheap inverter without a warranty can cost you €2,000+ in replacement in 3 years. Solution: Victron MultiPlus-II — 10-year warranty.
❌ Mistake #4: Cheap installation company
The cheapest offer is not always the best. Incorrect installation can void the manufacturer's warranty. Solution: Check licenses, warranties, and the number of installations.
❌ Mistake #5: Incorrect orientation or shading
Shade from a tree or a tile can reduce efficiency by up to 30%. Some discover this after installation. Solution: A shading study before installation.
❌ Mistake #6: Ignoring subsidies
In 2026, there are subsidies up to 40% through Exοikonomo. If you sign a contract without checking them, you lose thousands of euros. Solution: Get informed before signing anything.
❌ Mistake #7: Cheap, unknown brand panels
Cheap panels underperform quickly — in 5 years, you might have a 15-20% efficiency loss. Solution: Longi solar panels — 25-year performance warranty.
❌ Mistake #8: Ignoring maintenance
Dust and dirt reduce efficiency by up to 15%. Cleaning 2-3 times/year is enough. Solution: Set a reminder on your phone and don't forget it.
❌ Mistake #9: Ignoring LiFePO4 batteries
Many buy cheap AGM batteries that last 3-4 years. Pytes LiFePO4 last 10+ years with 6,000 cycles. They are more economical in the long run.
❌ Mistake #10: Decision without a study
Many decide based solely on price. Without a study, you don't know if the system you're buying suits your needs. Solution: Request a free study now with no obligation.
FAQ
How much does a mistake in size calculation cost?
Depending on consumption, it can mean €1,000-€3,000 in lost performance or additional replacement costs.
How do I know if the installation company is reliable?
Ask for their installation license, the number of completed projects, and equipment warranties.
Can I avoid all these mistakes?
Yes — with proper study and reliable equipment. Hellenic Energy offers free study and installation with Victron and Longi equipment.