How Much Power Will Your DIY Solar Array Produce? Posted on 30 Sep 09:00

Solar Energy Production

Will your DIY solar array produce enough electricity to meet your household’s needs and wipe out your monthly utility bills? Or will you still need to rely on conventional grid power for some of your energy?

The answer depends on how much power you need and how much your DIY solar panels produce.

So how can you determine the amount of power a DIY solar energy system will produce? And how can you make sure that your photovoltaic array is the right size to get rid of your monthly bill?

DIY Solar Array Output Under Direct Sunlight

A photovoltaic array’s electricity output depends upon the size of the system and the amount of direct sunlight, or solar radiation, it receives.

Let’s say you have 15 photovoltaic panels in your DIY solar array, each rated at 300 watts. Because system size is calculated in kilowatts (kW) rather than watts, you must divide that 300 by 1,000 to determine your system output. Each module, therefore, can produce 0.3 kW of electricity. Multiply that by 15 — the number of solar panels in our example — and you now know that you have a 4.5 kW photovoltaic system.

In theory, that means your photovoltaic array will produce 4.5 kW of power for each hour of solar radiation it receives. So if you get five hours of direct sunlight each day, the total energy output for the day will be 22.5 kW. A solar radiation map can tell you how many hours your area gets on an average day.

Calculating the Actual Power Output of a DIY Solar Array

As simple as calculating the power sounds, determining the actual amount of electricity a DIY photovoltaic system will produce isn’t quite that easy. Many factors, such as shading issues or wiring and inverter losses, can affect the energy output of a photovoltaic array. These issues are known as DC to AC derating factors.

The default derating factor used here at Solar GOODs is 83 percent. You may be able to improve this percentage, however, if you reduce your system losses. Taking care of shading problems and choosing micro-inverters, for example, can help increase your solar array’s efficiency.

Sizing a DIY Solar System to Meet Your Energy Needs

Let’s use the example from above and assume that you leave the derating factor at 83 percent. That means that each of your 300-watt solar panels is likely to produce 249 watts. So, your 4.5 kW DIY photovoltaic system will really only have a daily output of 18.675 kW of energy, assuming five hours of direct sunlight.

That’s a difference of nearly 4 kW per day. If you were counting on that 22.5 kW of output, you’re likely to come up short. Do the math and you can see that to generate at least that much power, you’ll need to install 19 photovoltaic panels instead of 15.

Take the DC-to-AC derating factor into account when planning your photovoltaic system to ensure that you design an array large enough to meet your power needs. Visit the Solar GOODs online DIY solar superstore today for help designing your DIY solar array.