ost of us spend a great deal of our time at home fully equipped with all imaginable appliances, which is why hardly a month goes by without considerable electricity expenses. As the question of how to save on energy is highly relevant, solar is definitely something you should consider. But how helpful are solar panels when you want to cut your bills? Naturally, it largely depends on how much energy solar panels produce.
How solar panel works
A solar panel is composed of photovoltaic cells. When the sun shines onto a solar panel, solar cells absorb energy from the sunlight and convert it into electricity by the photovoltaic effect. Solar panels can be connected to the electric grid, thus allowing you to sell surplus energy to the utility or operate independently by storing the energy produced during the day in a battery bank.
Solar panel wattage explained
First of all, let’s learn how solar power is measured. The solar panel power output is expressed in watts (usually W for short). Solar panels are rated based on how many watts they can produce. The higher the wattage rating of a solar panel, also known as its power rating, the greater the electric energy the panel will generate.
What is the average wattage of a solar panel?
Residential solar panels typically produce between 250 and 400 watts per hour. Some more sophisticated solar panel models can be rated as highly as 520 watts. Keep in mind that your actual solar power output will depend on several factors we will describe later in the article.
How much electricity solar panels can produce
How much energy can solar panels produce? If you know several basic parameters, calculating the amount of electricity produced is a no-brainer.
How much power does a solar panel produce per day, monthly, and annually?
We cannot but mention it: this is a really simplified way of calculating how much electricity a solar panel produces. The actual amount of electric power will fluctuate during the day, even hour by hour.
Solar panel daily performance
To calculate how much energy solar panels produce per day, you can use this formula for one panel’s output calculation:
Solar Panel Power (in watts) x Number of Peak Sun Hours in a Day = Solar Panel Performance
The electricity a solar panel generates is measured in kilowatt-hours (kWh). Kilowatt (kW) is 1.000 watts.
Well, let’s do the math. For example, a solar panel is 250 watts, and your area receives 4 peak sun hours per day. Then, your photovoltaic module will produce 1 kWh of energy daily (250 x 4 = 1.000).
Solar panel monthly performance
How much energy can a solar panel produce per month? When you need to know your monthly total kWh, simply multiply your solar panel daily performance by 30.
If we proceed with the above-stated example, it will be 1 x 30 = 30 kWh of energy monthly
Solar panel annual performance
You already know the answer! Multiply your daily performance by 365: 1 x 365 = 365 kWh yearly
How some factors influence solar energy generation
It is important to note that the process of producing electricity from solar energy is affected by several factors. Here is what you should know when estimating how much electricity your photovoltaic panels can generate.
Number of solar cells in a single solar panel
The number of solar cells in a photovoltaic panel can vary extensively from 36 cells to 144 cells. But the overwhelming majority on the market today are 60-cell and 72-cell panels.
Thanks to the 12 additional solar cells, 72-cell solar panels have 20% more area than a 60-cell panel. Such solar panels produce more electricity simply because they can capture much more sunlight.
Solar panel material
In the previous paragraph, we mentioned that there are two main types of photovoltaic panels according to the number of cells. Likewise, modern solar panels, most of which are made of silicon, are also divided into two big categories – monocrystalline and polycrystalline – based on the purity of the silicon crystals used.
Monocrystalline solar panels produce more power per square foot than polycrystalline panels. Monocrystalline solar cells perform better because they are cut from a single crystal of silicon, whereas polycrystalline cells are fabricated from multiple silicon crystals. Still, if you want higher performance, you need to pay extra because monocrystalline panels are considerably more expensive than polycrystalline counterparts.
Solar equipment location
The areas with the most sunshine and the clearest weather are perfect for solar panels. The amount of energy your solar panels can produce depends hugely on where you live. This can be illustrated with the following example: studies have shown that in Arizona, one of the sunniest U.S. states, a 1 kW solar kit will generate as much as 5 kWh of power daily on average. But if you install the same solar panels in Washington State, which has a good number of cloudy or partly cloudy days, you can expect just 3 kWh of energy daily.
Solar modules positioning
For solar panels to generate the most output, they should ideally be directed toward the Equator and face south if they are located in the Northern Hemisphere. By positioning panels this way, they will receive much more direct sunshine. Photovoltaic installations that face southwest and southeast are also considered efficient, while east or west-facing systems fall behind in efficiency.
In most cases, the perfect angle for a solar panel installation is next to or equal to the latitude of your home. This angle is often between 30 degrees and 45 degrees. Proper angling of your solar panels can help your home get the maximum output from your solar system throughout the year.
Finally, the golden rule for photovoltaic panel positioning is to avoid shading. The place where panels are installed must be free from shadows and obstacles because anything blocking sun rays will make the panels less efficient.
How to determine your solar electricity needs
The U.S. Energy Information Administration (EIA) states that the average U.S. household consumes approximately 10,600 kWh of electricity annually. To meet their energy needs, an average U.S. homeowner should install 17-42 solar panels depending on their wattage (150 W with a low-wattage and 370 W with high-wattage panels).
How can you identify how many solar panels you need? Measure your monthly electricity consumption; you can usually find this information in your last power bill. Calculate the daily amount of peak sunlight hours in your area and multiply it by 30. Estimate how much electricity your solar panels need to generate: for instance, if you have a monthly consumption of 1.500 kWh and 168.6 monthly peak sun hours, you would divide 1.500 by 168.6 to get 8.9 kW. In other words, your solar system should be 8.9 kW (or 9 kW if we round up) to meet your power needs. In case you decide to install a 9 kW system, you would need around 27-28 solar panels to meet your energy needs.
Solar energy can massively cut your bills
When you purchase or install a home PV energy system, the price you pay is usually based on how much power your solar panels can produce. Does your solar panel system need to be efficient? Yes, of course, especially when the space available for solar equipment installation is limited. Getting the highest possible output from each panel is the be-all-and-end-all if you invest in solar.
The most significant advantage of installing solar panels is saving on your power bills. On average, it is about $1,500 in savings each year. If your solar panels are large enough and, what matters much more, efficient enough, they can provide your whole home with energy.