If you are looking at a home with solar panels, it is easy to feel a mix of excitement and confusion. On one hand, the idea of a lower electricity bill is incredibly appealing. On the other hand, you might wonder: How do these things actually save me money? And what kind of maintenance am I on the hook for?
As home inspectors, our goal is to cut through the marketing hype and give you the practical facts. Here is what you need to know about buying a home with an existing solar photovoltaic (PV) system.
1. How the Savings Actually Work
Solar panels don’t just power your electronic devices directly from the sun; they integrate with the local power grid. Here is how the financial benefits break down:
Net Metering: Most residential solar setups utilize a system called net metering. During the middle of the day, your panels will often produce more electricity than your home is actively using. This excess power is sent back into the utility grid, and your electric company gives you a credit for it.
The "Banked" Credits: At night or during cloudy winter days when your panels aren't producing enough power, you draw electricity back from the grid, using up those accumulated credits.
The Bottom Line: Solar panels rarely eliminate an electric bill entirely because most utilities charge a flat monthly connection fee. However, a properly sized system can drastically offset your actual energy usage costs, saving typical homeowners hundreds to thousands of dollars a year.
2. Setting Realistic Expectations (No Over-Promising)
While solar panels are an excellent asset, it is important to understand their boundaries:
Power Outages: A common misconception is that solar panels will keep your lights on during a blackout. Unless the home has a dedicated, expensive backup battery storage system (like a Tesla Powerwall), your solar system will automatically shut off during a power outage. This is a mandatory safety feature designed to prevent your panels from sending electricity down the lines and injuring utility workers who are trying to fix the grid.
Natural Degradation: Solar panels naturally lose a tiny amount of efficiency every year—usually about 0.5\% to 1\%. If you are looking at a system that is 10 or 15 years old, it will produce slightly less power than it did on day one, which is completely normal.
3. Maintenance: What’s Worth Your Money (and What Isn’t)
Solar systems are incredibly resilient because they have no moving parts. However, managing them wisely will save you from unnecessary expenses.
❌ Skip the Professional Cleaning
You will see plenty of companies offering professional solar panel cleaning services, claiming it boosts efficiency. However, university engineering studies show that normal dust and pollen only reduce panel efficiency by a minor 3% to 7%.
Hiring a professional crew usually costs between $150 and $300+. The tiny bump in electricity generation from a cleaning will only save you about $20 to $40 a year. Financially speaking, the math doesn't add up. In most climates, regular rainfall is completely sufficient to keep your panels washed off.
⚠️ Budget for the Inverter
While solar panels can easily last 25 to 30 years (this isn’t a warranty), the inverter (the box usually mounted near your electrical panel that converts solar power into usable household electricity) has a shorter lifespan.
Standard string inverters generally last 10 to 15 years.
If you are buying a home with a 10-year-old system, you should anticipate and budget for an inverter replacement in the near future.
🏠 The "Hidden" Roof Cost
If the roof underneath the solar panels is nearing the end of its lifespan, keep in mind that a solar roofing contractor must be hired to detach and temporarily remove the panels before the roofers can work, and then reinstall them afterward. This process can cost anywhere from $2,000 to $5,000+ depending on the size of the array, so it is crucial to know the age of both the roof and the solar system.
Final Takeaway for Buyers
An existing solar system is a fantastic feature that can provide immediate monthly savings on your energy bills. To protect yourself, always ask the seller for:
The original installation records and age of the system.
Historical production logs (usually accessible via an app like SolarEdge or Enphase) to verify the system is operating normally. Unfortunately the seller may not even be aware of this, or it may not always be available.
Warranty transfer documentation to ensure you are covered if an inverter or panel needs replacement.
Henry “Sonny” Toman
1st American Home Inspections
443-388-2410
Serving our neighbors in:
Anne Arundel, Howard, Montgomery, Prince George's, and Baltimore Counties.
