Faster than any other electricity source, solar energy production is growing in popularity across the U.S. with installations on homes, businesses, farms, and everywhere else the sun shines and people need power.
If you’re interested in energy independence with rooftop solar, it’s crucial to understand how much electricity your system will produce in designing the optimal installation for your home.
Whether you’re most interested in reducing your utility bills or your carbon footprint, this guide answers the question, “How much energy is produced by a solar energy system?” in full detail to help you maximize your solar savings.
Solar energy production basics
Photovoltaic (PV) solar power systems harness energy from sunlight and convert it into electricity. When sunlight hits the surface of PV panels, it excites electrons and generates electricity in the form of direct current (DC). A solar inverter system then modifies this energy into alternating current (AC), which is the form of electricity most commonly used in homes and across grid power lines.
What influences solar energy generation?
Solar energy generation is influenced by many factors specific to geography, environment, and installation. The amount of energy produced by your solar system will be determined by the exact specifications of your PV installation as well as the unique characteristics of your property and region.
1. Solar irradiance or sun exposure
As solar energy installations rely on the sun to produce electricity, the amount of sunlight your panels receive is the primary factor that will influence your system’s total generation potential. While the southern and western regions receive the most annual sunlight, home solar systems can still be cost-effective across all U.S. states, territories, and Washington, D.C.
Image source: https://www.nrel.gov/docs/libraries/gis/high-res-images/solar-annual-ghi-2018-usa-scale-01.jpg?sfvrsn=135d48b6_1
2. Total panel wattage and system efficiency
Among other factors, your PV installation’s solar energy generation potential depends on your panels’ total wattage and the efficiency of your system’s components.
Most solar panels for homes utilize monocrystalline technology with high-efficiency ratings, above 20%, to reduce the total amount of installation space required. Most of today’s high quality home solar panels are rated between 350 watts and 425 watts (W), with your system’s total capacity equal to the sum of your panels’ wattages.
For example, if you install 15 x 400 W panels, your system’s total wattage would be 6,000 W or 6 kilowatts (kW). As solar installations are measured in DC wattage, high efficiency microinverters will also help enable maximum solar AC production for use in your home or grid-sharing.
3. Panel orientation, installation angle, and shade
To maximize solar energy production, panels should be installed where they can capture the most direct sunlight each day. In the U.S., solar panels can be placed on roofs that face east, west, or, ideally, south—though home systems perform most efficiently on sloped faces between 10 degrees and 40 degrees.
If part of your installation area is shaded during the day by neighboring buildings, trees, chimneys, vents, or other obstructions, this can greatly reduce the solar energy production of your panels. In addition to installing your system on the sunniest parts of your property, the effects of shade on solar panels can be greatly reduced with the use of microinverters or other module-level power electronics (MLPEs).
4. Inverter efficiency and system design
Beyond your solar panels, the power and efficiency of your solar inverters and other system components will ultimately impact the amount of usable electricity your installation can produce. When you go solar, it’s important to talk to your installer about your inverter choices, as this decision can greatly impact your system’s expected lifespan and solar energy production potential.
5. Operating conditions
While operating in the real world, your solar system’s energy production efficiency can be affected by many external influences including weather, temperature, and the condition of your hardware.
Although solar panels can produce significant amounts of electricity at a wide range of temperatures, extreme heat and cold can limit your system’s efficiency. In the same sense, limited sunlight on cloudy days can lower your system’s electricity production potential.
Accumulated dust, dirt, and debris on panel surfaces can also obstruct the amount of sunlight able to reach your solar cells. To keep your system running at maximum efficiency, regular solar panel cleaning is recommended—especially in dry, windy, or heavily polluted areas.
6. Solar energy system age
Lastly, solar panels slowly lose efficiency over time, so your system’s age will influence its daily energy production. Today’s high quality solar panels have annual degradation rates of around 0.5%, meaning that they lose about half of a percent of their total energy generation capacity each year. After 25 years, solar panels with a 0.5% degradation rate could be expected to generate approximately 85% of their initial energy production capacity.
Calculating rooftop solar energy generation
There are many ways to calculate how much electricity can be produced by a solar energy system on your roof, including a home assessment from a certified professional. To estimate how much electricity a solar system could generate on your property, you can also use a solar power calculator or use the following formula to estimate future electricity production:
In other words, the capacity of your system multiplied by the average number of peak daily sun hours on your property can help you estimate your installation’s approximate solar electricity generation. Peak sun hours vary greatly across the country and even within each state. There are several ways to estimate the number of peak sun hours on your property, including this guide and the National Renewable Energy Laboratory’s PV watts calculator.
While actual solar energy generation will vary based on many other factors, here are a few examples of how much electricity systems of varying capacities could be expected to produce throughout the U.S.
| System wattage | Peak sun hours/day (average) | Daily output (kWh) | Monthly output (kWh) | Yearly output (kWh) |
| 6 kW | 5.00 (Denver, CO) | 30 | 913 | 10,950 |
| 8 kW | 4.25 (Chicago, IL) | 34 | 1,034 | 12,410 |
| 9 kW | 4.75 (Atlanta, GA) | 43 | 1,300 | 15,604 |
| 10 kW | 5.50 (Dallas, TX) | 55 | 1,673 | 20,075 |
For another perspective and greater understanding, the table below demonstrates how much electricity the same solar energy system could be expected to produce in varying locations.
| System wattage | Peak sun hours/day (average) | Daily output (kWh) | Monthly output (kWh) | Yearly output (kWh) |
| 8 kW | 4.25 (Chicago, IL) | 34 | 1,034 | 12,410 |
| 8 kW | 4.75 (Atlanta, GA) | 38 | 1,156 | 13,870 |
| 8 kW | 5.00 (Denver, CO) | 40 | 1,217 | 14,600 |
| 8 kW | 5.50 (Dallas, TX) | 44 | 1,338 | 16,060 |
Discover the ideal solar energy system for your home
As you discover how much solar energy you can produce on your property, determining the right equipment, installer, and contract can help you find the most cost-effective solution for your home’s ongoing electricity expenses.
To maximize your long-term solar savings, we recommend finding a reputable installer near you and investing in high quality solar panels, microinverters, and other system components.
By choosing a high quality Enphase Home Energy system, you can access a nationwide network of certified professionals, industry-leading warranty coverage, and flexible installation options to help you produce as much solar electricity as possible on your property.
Solar energy generation FAQs
What are the best times for maximum solar energy production?
Maximum solar energy production typically occurs during peak sun hours: in the late morning and early afternoon. The exact times for maximum solar energy production vary depending on where you live and the time of year, but they generally occur between 10 a.m. and 4 p.m.
How long do solar panels last?
Modern solar panels typically last for over 25 years. The Department of Energy estimates that the average operational lifespan of a PV module is between 30 and 35 years. Over time, solar panels slowly lose production efficiency, though most products can be installed with a performance warranty for at least two decades of efficient solar energy generation.
How do I calculate potential savings from solar energy?
The best way to calculate your potential savings from solar energy is with the help of a professional in your area who understands local electricity rates, utility billing structures, and PV installation regulations. To quickly see your potential savings, you can also use our home solar calculator.
How does temperature affect solar panel efficiency?
Extremely high and low temperatures can decrease solar panel efficiency, though high quality hardware can minimize this impact. Solar panels usually produce the most electricity at temperatures around 77° F (25° C), and are rated to perform at varying efficiencies from -40° F to 150° F.
Do solar panels work during cloudy or rainy days?
Yes, solar panels still work during cloudy or rainy days. However, overcast and other weather conditions can lower solar energy production efficiency levels when less sunlight is available. Enabling panel-by-panel performance and built with advanced sunlight-capturing technology, IQ Microinverters can help maximize your system’s total solar energy generation potential in low-light conditions.
Can I install solar panels if my roof has shading issues?
Yes, although shade can reduce solar energy generation efficiency, it’s still possible to install panels on partially shaded roof areas and produce significant amounts of electricity each day and year. With independent panel operation, microinverters can also help minimize the impact of shading on your roof and maximize your home’s solar potential.
