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If you live in Fresno, Clovis, Visalia, Madera, Tulare, Sanger, Selma, Hanford or the surrounding Central California area you may have noticed that a lot of homeowner are switching to solar. But how do you know what solar panel system size is right for you?
Determining how many solar panels you’ll need for your home means first knowing what your goals are. Do you want to minimize your carbon footprint? Maximize your return on your investment? Save as much money as possible? Most people want to save money while maximizing their energy production.
To calculate how many solar panels you need, you need to know the following: how much energy your household uses; your roof’s usable surface area; the climate and peak sunlight in your area; the wattage and relative efficiency of the solar panels you’re considering; and whether net metering is available.
One simple way of answering the “How many solar panels do I need” question is to consult a professional solar installer, who can give you a free home solar evaluation.
1. How much solar power will you need?
It depends. The answer is a combination of your current and future state energy use along with factors involving your roof line and shading. When you receive a quote for a home solar panel installation, it will indicate a measurement in size of your system listed in kilowatts (kW). The size of your system mis determined by multiplying total number of panels by how many watts (1,000 watts = 1 kilowatt) each panel is rated. What this means it that two systems with the same number of panels can produce a completely different amount of energy to power a home or business.
If you work with Air Sun Solar, our solar experts will handle all these calculations for you. But to give you some idea of how many solar panels are needed for the average home (or for your home in particular), here is a sample set of questions that a solar professional might use to figure it out: Click here for a free solar guide copy
2. How many watts do you currently use?
Look at your electricity bill for average usage. Look for “Kilowatt Hours (or kWh) Used” or something similar, and then note the time period represented (usually 30 days). If your bill doesn’t show kilowatt hours used, look for beginning and ending meter readings and subtract the previous reading from the most recent one.
You want daily and hourly usage for our calculations, though, so if your bill doesn’t show a daily average, just divide the monthly or annual average by 30 or 365 days, respectively, and then divide again by 24 to determine your hourly average electricity usage. Your answer will be in kilowatt-hours (kWh). (And just in case you are wondering, a kilowatt-hour is how much power you are using at any given time multiplied by the total time the power is being used.)
A small home in a in Fresno, California might use something like 300 kwh per month, and a larger home where air conditioners account for the largest portion of home energy usage might use 2,000 kWh or more. The average U.S. home uses about 900 kWh per month. So that’s 30 kWh per day or 1.25 kWh per hour.
Your average daily energy usage is your target daily average for to calculate your solar needs. That’s the number of kilowatt-hours you need your solar system to produce if you want to cover 100 percent of your energy needs.
It’s important to note that solar panels don’t operate at maximum efficiency at all times. (See Our Solar Guide). Weather conditions, for example, can temporarily reduce your system’s efficiency. Therefore, experts recommend adding a 25 percent “cushion” to your target daily average to ensure you can generate all the clean energy you need.
3. How many hours of sunlight can you expect in your area?
The peak sunlight hours for your particular location will have a direct impact on the energy you can expect your home solar system to produce. For example, if you live in Fresno, California you can expect to have a greater number of peak sunlight hours. The Renewable Resource Data Center provides sunlight information by state and for major cities.
4. What affects solar panel output efficiency?
Here’s where which solar panel manufacturer you choose makes a difference. Not all solar panels are alike. Photovoltaic (PV) solar panels (most commonly used in residential installations) come in wattages ranging from about 150 watts to 370 watts per panel, depending on the panel size and efficiency (how well a panel is able to convert sunlight into energy), and on the cell technology.
For example, solar cells with no grid lines on the front (like SunPower ® Maxeon cells) absorb more sunlight than conventional cells and do not suffer from issues such as delamination (peeling). The construction of these cells make them stronger and more resistant to cracking or corrosion. And a microinverter on each panel can optimize power conversion at the source, in contrast to one large inverter mounted on the side of the house.
Because of these wide variations in quality and efficiency, it’s difficult to make generalizations about which solar panels are right for you or how many you’ll need for your home. The main takeaway is that, the more efficient the panels are, the more wattage they can produce, and the fewer you will need on your roof to get the same energy output. Conventional solar panels usually produce about 250 watts per panel, with varying levels of efficiency. In contrast, Air Sun Solar provides SunPower solar panels that are known to be the most efficient solar panels on the market.
5. What is the effect of solar panel size?
Typical residential solar panel dimensions today are about 65 inches by 39 inches, or 5.4 feet by 3.25 feet, with some variation among manufacturers. Air Sun Solar is an Elite SunPower Dealer and offers SunPower solar panels that are 61.3 inches by 41.2 inches.
These dimensions have remained more or less unchanged for decades, but the efficiency and output from that same footprint have changed dramatically for the better. In addition, Air Sun Solar designs entire systems to have virtually no gaps between panels and SunPower Solar manufactures panels that uses invisible framing and mounting hardware to keep the rooftop footprint as tight, efficient and attractive as possible.
Knowing the answers to the above questions will give you an idea of the ideal number of panels for your electricity generation needs — or at least a realistic range. Next, a professional installer needs to assess your roof architecture, angle to the sun and other factors to see if and how you’d be able to physically arrange the right number of panels on your roof to achieve your daily energy production goals. You should also consider net metering as you’re considering figuring out your ROI for your solar system. Net metering is how your utility company credits you for producing excess solar energy when the sun is shining and then lets you draw from those credits when you’re using conventional power grid at night, if you don’t have a solar battery storage system.
Power to the people,
Air Sun Solar
If you have more questions or are interested in receiving a free solar panel quote, or home battery storage quote we are more than happy to help. Click here to learn more