The real power of a solar panel lies in its energy production capabilities. That's what they're engineered for, after all!
If you're considering the shift to solar energy, it's likely you have a target amount of energy you're looking to generate. Perhaps you aspire to meet your household's entire energy demand or maybe you're content with covering just half. Whatever your goal, it's essential to note that various factors can influence a solar panel's energy production and the number of panels required to meet your target.
Thanks to a substantial 60% drop in solar costs over the past decade, it's now more feasible than ever for homeowners and businesses to outfit their properties with solar panels. Let's dive deeper into how these panels work and how they generate energy.
Unpacking the Basics: How Does a Solar Panel Generate Energy?
Solar panels function by permitting particles of light, also known as photons, to dislodge electrons from their atomic orbits. These freed electrons are captured in the form of an electric current, which is then harnessed and stored. This reaction takes place within a photovoltaic cell or a solar cell.
Each solar panel or module contains hundreds or thousands of these cells. Several panels form a solar array, which is then linked to the existing power grid and/or battery storage. This setup allows the energy generated to be routed appropriately.
Deciphering Solar Panel Lingo: kW, kWh, DC, and AC
To accurately grasp the energy production figures, we must first understand some basic units.
Kilowatt (kW): This denotes electrical power, equivalent to 1,000 watts. The electrical energy generated by a solar panel or system is expressed in terms of watts or kilowatts.
Kilowatt-hour (kWh): This represents electrical energy equivalent to the consumption of 1,000 watts for 1 hour. It's the unit utility companies use to bill individuals for their energy usage. One kilowatt-hour is equivalent to 3.6 megajoules.
Direct Current (DC) power: This is the initial form of power generated by the panel.
Alternating Current (AC) power: Most household appliances run on AC power. The DC electricity produced by solar panels is converted into AC for efficient use throughout your home.
Determining Solar Panel Energy Production
To assess a solar panel's energy output, you'll need two metrics:
- The solar panel's output (measured in Watts)
- The daily peak sun hours in your location
Solar panels vary in output, ranging from about 250 to 450 Watts, which represents their potential energy production per hour under optimal conditions. In 2022, 400W panels became the standard, so we'll use that figure in our example.
Peak sun hours measure the usable sunlight received by your solar panels. This can vary from over 5.75 hours per day in the Southwest to less than 4 hours in the northernmost parts of the US.
Assuming most of the US gets around 4.5 peak sun hours per day, we can calculate a solar panel's daily energy output by multiplying its output by peak sun hours. Therefore, a 400W panel can generate 1,800 Watt-hours per day, or 1.8 kWh when converted to the standard measurement.
Monthly Solar Panel Energy Output
Using the daily energy production of 1.8 kWh from our example, we can calculate the monthly output by multiplying by 30 days, giving us an average of 54 kWh per month for a 400W solar panel receiving 4.5 peak sun hours.
In sun-drenched states like California, Arizona, and Florida, which receive around 5.25 peak sun hours daily,
a 400W panel can yield 63 kWh or more per month.
For comparison, the average US household electricity consumption is 893 kWh per month, with Hawaii at the lower end with 537 kWh, and Louisiana at the higher end with 1,200 kWh per month.
To fully offset the average household electricity usage of 4.5 peak sun hours per day, you would need a 6.7 kW solar system, which translates to 17 solar panels with a 400W output. For sunnier regions with 5.25 peak sun hours, a smaller system of 5.67 kW composed of 14 400W panels would suffice for 100% offset.
Factors That Influence Solar Panel Output
A comprehensive understanding of a solar panel's energy output also involves consideration of the panel type and its environment.
While peak sun hours and the panel's power output are primary factors, the panel's design also plays a part. Solar panels come in a myriad of models with varying wattages, efficiency ratings, and degradation rates. You might want to begin your selection process by deciding between monocrystalline and polycrystalline panels.
Monocrystalline solar panels:
- Offer higher efficiency
- Tend to be pricier
- Perform well in high temperatures and shady conditions
Polycrystalline solar panels:
- Have lower efficiency
- Are less expensive
- Are less efficient at high temperatures
Powering Your Home with Solar Energy
To wrap up, an average 400W solar panel receiving 4.5 peak sun hours per day can produce approximately 1.8 kWh of electricity per day and around 54 kWh per month.
However, the exact output depends on the panel's power output and the available sunlight. Ultimately, the amount of electricity you require from your panels will depend on your energy consumption and your specific goals.
Bear in mind that solar power costs less per kWh than grid electricity in most parts of the US. Thus, the sooner you switch to solar energy, the sooner you'll start reaping the benefits of long-term savings and price stability.