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Solar Energy Basics: Answering the 5 Hows of Solar Power

Solar energy is fast becoming a go-to source of energy for many across the globe. In the United States alone, solar is one of the fastest-growing energy sectors; it witnessed a 33% growth in the last decade.

Given the ubiquity of solar panels on rooftops everywhere, it is important to understand some of the basics of solar energy. It is especially necessary if you have installed a solar PV system or are about to install one.

Read through our article to find out:

  • How do solar panels produce energy?
  • How does a home solar system work?
  • How much energy does one solar panel produce?
  • How much solar energy is needed to power your home?
  • Do solar panels store energy?

1. How do solar panels produce power?

Solar panels produce solar energy through a phenomenon discovered accidentally by Edmond Becquerel in 1839, known as the photovoltaic effect. It states that an electric current is produced when a semiconductor is exposed to sunlight (or any other source of light in visible spectrum that contains photons).

Given that other kinds of light are not that strong, and since the sun is the richest source of photons, we rely upon the sun to produce solar energy.

So, when the sunlight falls on solar panels, the photons knock electrons free and set them in motion, producing an electric current in the panel. This current is transmitted by the wires connected to the solar array (a group of solar panels is called a solar array).  

2. How does a home solar power system work?

A home solar system has the following components:

  • Solar panels
  • Solar Inverters
  • Wiring
  • Racking and mounting
  • Charge controllers (if batteries are attached to the system)
  • Solar Batteries (optional)

As discussed in the first section, solar panels produce solar energy. But this energy is in the form of direct current (DC), which does not have much utility for our households, as our appliances are run on alternating current (AC). To convert the DC to AC, we would need an inverter or a few of them.

When converted to AC, it is sent to the distribution box, ready for use at home. Most homes in the United States install grid-tied systems. These systems are connected to the grid and do not have batteries. When the electricity generated by your solar panels is more than you need, it is sent to the grid—you get energy credits for the exported electricity.

Some solar systems, such as off-grid systems, only have batteries. In that case, solar panels also have to provide energy to batteries to keep them charged for later use.

3. How much energy does one solar panel produce?

The amount of energy produced by one solar panel depends upon the solar panel’s wattage and the number of peak sun hours your roof receives per day. Solar panels come in various sizes, having a range of outputs, for instance, 260 watts, 300 watts, 400 watts, etc. We will take a 400-watt panel as the standard.

As for as the peak sun hours is concerned, we will take the average peak sun hours as 5. States in the southwest receive the most sunlight; as you move up north, the number of peak sun hours decreases. Check out peak hours in your state here.

So, a 400-watt solar panel receives sunlight for about 5 hours and will generate 2000-watt electricity—that is, 2 kWh per day. Simply multiply the solar panel’s output by the peak sun hours, and you will get how much solar energy one solar panel can produce.

If the output of the panel is 300 watts, and the peak sun hours are 4.5, the energy produced by one solar panel in a day will be 1.35 kWh.

Did you know?

173,000 terawatts of solar energy strikes the earth per hour. That’s more than 10,000 times the world’s total energy use.

Source: explainingscience.org

4. How much solar energy is needed to power your home?

It’s a tricky question. No two homes are alike, and since solar is a unique product whose output depends upon circumstances peculiar to each household, how much energy is needed to power your home varies from home to home.

But generally, a household that consumes around 900 kWh of electricity per month would need a 6 kW grid-tied solar system to match their needs. Check your annual consumption on your bill; divide that by 12, and you will have your average monthly consumption.

If you live in northern states, where peak sun hours are below 5, you might need a 7 kW solar system. This means you would need 17 solar panels for a 6 kW system in regions with six peak sun hours or 20 panels for the same system if the sun shines at peak for 5 hours. (We have assumed that the output of solar panels is 300 watts.)

5. Do solar panels store energy?

If you are referring to solar modules installed on your rooftop, then no, they cannot store energy. Solar panels only can generate as much instant electricity during the daytime as you want or need. When the sun goes away, your solar modules will no longer supply power.

But to store energy for later use, you will need an energy storage system (batteries). Most solar systems installed in the US are grid-tied, with no battery bank attached. However, some systems, such as off-grid and hybrid solar systems, need batteries.

6. Is my roof suitable for solar panels?

Ideally, south-facing roofs with a 30-degree angle are best for solar panels, provided there is little to no shade over the roof. But this never means that you cannot install solar panels on flat roofs facing a different direction. Solar panels can be installed on any roof with a little workaround and additional racking and mounting hardware.

Just make sure that there is no shade on the roof, as the shade affects the performance of your solar panels. Also, if your roof is old and requires replacement in the next ten years or some major structural changes, we recommend replacing the roof before installing solar panels. Solar panels last up to 30 years, and you will have to dismantle the whole system before adjusting the roof and reinstalling it. That will increase the overall cost of your solar project, and in the process, some solar modules may get damaged.

These were some of the basic hows of solar power. Head to our blog section for further reading on all things solar in the United States.

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