How Do Solar Panels Work (Explaining Solar Energy)
How do solar panels work? Scientists tell us that in one second the sun generates more energy than has been used in all of mankind’s history! That’s an amazing amount of power! But the truth is that only a very, very tiny fraction of this energy actually reaches our Earth.
That’s great news though! Because our planet is exactly the right distance from the sun, life, can exist here in abundance. Were we just a tiny bit closer, the sun’s energy would burn us all to a frazzle!
But how do solar panels work for you? Using solar panel technology, we can now effectively convert the sunlight pouring down, into usable electric power to supply our energy needs.
Is solar energy preferable to the traditional fossil fuels?
As we have seen, an enormous amount of energy pours down daily from our sun. The supply is endless, and we can never deplete it. It emits no carbon dioxide, so it doesn’t contribute to the carbon footprint. Best of all it’s completely free.
The traditional fossil fuels have none of these advantages. The non-renewable fossil fuel supplies are running low and will ultimately become uneconomical to source. This scarcity is largely the reason for the constant increase in prices that we pay for our energy needs. In addition, burning these fuels is contributing to an increase in the carbon footprint and endangering the environment
The search for alternative, renewable energy sources has led to amazing developments over the past few decades. Enormous wind-turbine and solar panel farms have sprung up around the world. The electricity generated by these farms is increasingly helping to supplement the constant world-wide demand for more power.
How do solar panels work to convert sunlight into electricity?
So how can we make use of this endless solar energy resource to power our homes? We are all familiar with the heat generated when our car has been standing out in the midday sun. It’s even possible to fry an egg directly on the hood! It has long been known that when that same sunlight falls on the right materials, energy is produced in the form of an electrical current rather than as heat. This electricity can then be harnessed to supply power wherever we need it.
So why hasn’t solar energy been used more widely up until now?
While the ability to convert the sun’s energy into usable power has been available to us for some time, it has not been economically viable for the average person’s needs. Now, with the amazing technological advances that have been made over the last decade, the cost of converting solar power into usable energy has come down tremendously. The result is a surge in Solar renewable energy usage across the globe.
The International Energy Agency (IEA) reports in an article that Solar energy generated 26% more energy world-wide in 2016 over 2015, with the amount continuously increasing. The report states that “Over the next five years, solar PV is expected to lead renewable electricity capacity growth”
So how do solar panels work to convert sunlight into usable electric current?
Briefly put: solar panels work by harnessing sunlight with photovoltaic (PV) cells. These PV cells then generate direct electric current (DC). We cannot immediately use this DC current directly in our homes. We can however convert it into the suitable alternating current (AC) energy that our homes need. The system automatically does this using an “inverter”. The AC current then enters the home’s electrical system and is available wherever required.
Here’s how it works:
Solar panels consist of lots of photovoltaic cells. Each cell is a two-layer sandwich which is made from the element Silicon. Because Silicon is a semiconductor, one layer is set up with a positive charge while the other layer has a negative charge.
When the energy particles of sunlight, called photons, hit the solar cell, they knock electrons loose from atoms of the cell, These electrons then fly off the atoms. Each cell has two attached conductors, one attached to the positive side, and the other to the negative side. This arrangement forms an electric circuit, so when the freed electrons fly off, they flow through this circuit, generating an electric current.
The multiple cells in a panel are in turn linked to further panels in an array, providing a flow of electric current that increases in power as you increase in the number of panels in the array. Thus, employing more panels in your system generates more current.
How are solar panels made?
The modern solar panels we use in our homes are highly sophisticated and advanced in design and construction. They are extremely strong with a durable glass exterior casing which protects the silicon PV cells. The panels are weatherproof and cope with severe weather conditions such as hail storms. They also have suitable insulation to minimize heat loss, and a protective base.
Can we use this electricity directly to power our homes?
The PV solar panels generate a direct current which flows one way through the circuit. This produces what we call DC or direct current electricity. Like the battery in a flashlight, the electrons flow from the negative side of the battery through the bulb and back to the positive side of the battery. The current therefore always travels in the same direction while completing the circuit.
DC current like this can charge small appliances such as cell phones and mp3 players, but it cannot power the larger household appliances which run on standard AC current from the commercial grid.
The national electricity grid in the U.S. uses only AC rather than DC current. The preference in countries, world-wide is also to use alternating (AC) current rather than DC current. Unlike DC current which moves only in one direction, AC current moves backwards and forwards continuously. The main advantage in choosing AC current is that it is easier to transport over long distances.
As we will see, it is vital that the current the solar panels produce be compatible with the commercial grid as well as private home circuits, so we have to convert it from DC to AC before we can use it in our homes.
How do solar panels work to make the DC current usable?
In order to make use of the electric current, the system employs a device called an inverter, that “inverts” or converts the current produced by the PV solar panels from DC to AC.
In the earlier days of solar energy, inverters were large and bulky units, but the solar industry has largely introduced newer smaller and highly efficient inverters with a multiplicity of advanced features such as SolarEdge’s HD-Wave PV Inverter.
How do solar panels work at night?
During daylight hours, the solar panels continuously generate current. Even during cloudy or rainy periods current will still flow, although at a somewhat reduced level. At night time, however, they do not generate power, and one must fall back on the commercial grid to obtain power for one’s home. This might sound disappointing, as it means that one always remains tied to the expensive commercial grid. Fortunately, there is an excellent solution to this. The answer is net metering.
What is net metering (NEM)?
When providing you with a free quote, your solar company will calculate the amount of power your home needs. Using historical data from your electricity bills they can quickly compute this. Taking your total electricity usage over the past 12 months, they will then arrive at your average daily usage in kWh.
As each type of solar panel delivers a known amount of electricity, they will then know the exact number of panels you need to satisfy your annual kWh requirements.
With a properly designed system of the right size, your panels will regularly produce more electricity than you need. With net metering, this excess electricity which your panels produce is automatically fed back into your electric utility’s grid. Your utility company will regularly credit you in full with this amount! When you need to draw electricity at night, you are actually drawing on these credits. This in fact really frees from the expensive grid rates even when the panels are not producing current.
How does net metering actually work in practice?
The electricity usage in most homes varies quite widely depending on the time of day. In the average household, there are times when usage is low. This is probably going to be between late morning and the mid afternoon, when most people are not home. It is exactly at this time when your Solar energy system is hitting peak electricity production.
Rather than allow this excess electricity production to go to waste, net energy metering (NEM) “exports” this unused current into the commercial utility grid feeding your home. Because your utility company automatically credits you in full for this amount, the result is that your electricity meter is literally running backwards at these times!
Being able to draw on these accrued credits over time, means that you can in fact cover the cost of any electricity which you will be drawing at times when your system is not producing.
How do solar panels work when the grid goes down?
Most people imagine that when the grid goes down, one will still be able to draw electricity from the panels on one’s roof. Unfortunately, this is not so. For safety reasons the system will automatically shut down in the event of a power outage. This is in order to protect the utility line workers working on the grid,
The answer is to add a solar battery backup system. This provides power in the event of an electrical grid outage. With an independent solar system battery backup, you can continue to enjoy electricity. Your lights are on when everyone else around you is in the dark!
The cost of adding backup batteries to your solar electric system will obviously vary based on your power requirement preferences. In general, most people will elect to go for a system designed to back up just your critical loads. These include your fridge, heating system, water pumps, lighting and security system.
The benefits of a solar battery backup system
In addition to the instant power-on advantages of a solar battery backup, the system is noiseless to operate. This is in sharp contrast to a conventional noisy backup generator. These take time to get running and can be very disturbing to your neighbors.
For absolute peace of mind, a solar battery backup is definitely the answer. It will switch on even if you are away from home. You won’t have to return home from vacation to find a freezer full of defrosted and unusable food!
Environmental benefits from home solar systems
The question is often posed: how do solar panels work to benefit the environment?
Firstly, they reduce the carbon footprint which is of tremendous importance. In addition to this they play another important role which benefits all sectors of the community.
As we have seen, rooftop solar panels generally provide maximum electricity output during the hottest times of the day. It is exactly at these time that the overall demand for air conditioning peaks in businesses and stores. The excess power produced by your solar system now becomes extremely valuable in reducing these demands on the grid. Your excess production is now automatically exported back into the grid. The result is that the utility companies will need to produce less current. This saves costs and increases the efficiency of the power supplied by them.