How much energy does a solar panel produce?

Solar panel power output can get confusing fast. Is 400 watts good? 420 watts? Should you opt for the 450-watt panel? Is it worth the extra cost?

About 97% of home solar panels installed in 2025 produce between 400 and 460 watts, based on thousands of quotes from the EnergySage Marketplace. But wattage alone doesn't tell the whole story. In fact, efficiency matters more than wattage when comparing solar panels—a higher wattage can simply mean that a panel is larger.

The panels you choose help determine how much you'll save on electric bills. Install panels that don't produce enough power, and you'll wait years longer to break even. Choose panels with an output that's too high for your roof space or energy needs, and you'll waste money on capacity you'll never use.

We'll break down everything that influences solar panel output—from efficiency ratings and cell technology to real-world factors like weather and roof angle. That way, you'll know how to evaluate panels based on their actual performance, not just their spec sheets.

Solar panel system size and electricity offset by state

Of all the metrics to look at when you're shopping for solar panels, cell efficiency is one of the most important. The higher a panel's efficiency, the more power it can produce. 

Most solar panels have cells that can convert 17-23% of the sunlight that hits them into usable solar energy. The efficiency depends on the type of cell in the panel. Monocrystalline cells are more efficient and generate more electricity, while polycrystalline cells tend to be more affordable—they are no longer typically used in home solar panels. 

Researchers are constantly working to improve solar cell technology. In 2025, LONGi achieved a 33% solar cell efficiency record, though these advanced cells are still too expensive to be incorporated into most commercially available solar panels. For now, the most efficient residential solar panels available top out around 23%, but ongoing innovation means efficiency continues to improve.

About 97% of home solar panels included in EnergySage quotes today have power output ratings between 400 and 460 watts. The most frequently quoted panels are around 450 watts, so we'll use this as an example. If you live in a sunny state like California, your panel's production ratio is probably around 1.5, meaning a 10 kilowatt (kW) system produces 15,000 kilowatt-hours (kWh) of electricity in a year.

You can calculate your estimated annual solar energy production by multiplying your solar panel's wattage by your production ratio. For example, a 450-watt panel in California will produce about 675 kWh in a year, or about 1.8 kWh daily. That's enough energy to power some small appliances without too much issue.

We looked through thousands of quotes on the EnergySage Marketplace and found that VSUN offers the solar panel with the highest output for homes: 490 watts and 22.65% efficiency.

Highest output home solar panels on EnergySage in 2025

*This table only includes residential solar panel models with over 21% efficiency from brands that are quoted in the EnergySage Marketplace.

We often compare solar quotes based on dollars per watt ($/W) to make it easy to evaluate them based on price and power output. A system with higher wattage panels usually costs more than one with lower wattage panels, but it’s worth it  if you need that extra energy to fully cover your electric bills

Let's assume you spend $150 each month on electricity and need a 10 kW system to fully cover your usage. A 10 kW solar installation costs $2.53/W on average, for a total of $25,400 before any available incentives. A smaller 7 kW system is about $2.59/W, costing $18,060.

Without solar, you'd spend $63,847 on electricity over 25 years, assuming an annual inflation rate of 2.8%. With the 10 kW system, your electricity is essentially free, so your only expense is the system cost of $25,400, excluding any electricity you may need to draw from the grid when your panels aren’t producing. With the 7 kW system, only about 70% of your electric bill is offset, so you still end up paying $19,154 on electricity over 25 years. The 7 kW system may be cheaper upfront, but you will lose $11,814 in overall savings.

When it comes to solar panel size, bigger isn't always better. The highest output panels in our list all share one thing in common: exceptional efficiency. They convert over 22% of the sun's energy into electricity, which is why they generate so much power.

But efficiency matters even more when you're working with limited roof space. A compact, high-efficiency panel can produce just as much electricity as a larger panel with lower efficiency—meaning you can generate the power you need without covering every inch of your roof.

Solar panel wattage isn't just a spec sheet number—it's the foundation of your entire solar investment. Choose panels with output that matches your electricity needs and roof constraints, and you'll watch your utility bills shrink month after month. Miss that mark, and you'll either overpay for capacity you'll never use or you'll undershoot your energy goals.