What do we mean by renewable energy? Renewable energy comes from resources that will never run out (National Geographic). Examples of renewable energy sources are the sun, wind and water as well as biomass and geothermal energy. The question is whether solar energy is renewable or non-renewable.
Is solar energy renewable or non-renewable?
Technically the sun can ‘run out’ but that is extremely unlikely and in the event it does, life on earth would no longer exist anyway. Scientists estimate it is about halfway through its existence and has about 5 billion years left to go (NASA). So solar energy is regarded as renewable. But we couldn’t replace it. Once it is gone, it is gone.
Solar power, on the other hand, relies on us being able to harvest solar energy. The materials for solar panels are from finite resources. We can’t replenish them. We can’t make them either. We could replace some materials with alternatives.
Let’s look at:
- how solar panels work,
- what solar panels are made of & whether the materials are renewable,
- how we process these materials during production,
- whether the processes are eco-friendly,
- whether solar panels can be recycled, and lastly
- whether we should use solar power in our homes.
How does solar power work?
Solar panels can be photovoltaic (PV) or thermal. Photovoltaic cells convert the sun into electricity. Thermal cells heat water or fluid directly.
Solar panels can be installed in domestic homes or in larger commercial applications. A group of solar panels is called an array, and they are often installed on the roof of a house for domestic use. Larger numbers of solar panels can be installed on the ground in what is called solar farms, solar parks or solar power plants.
The photovoltaic cells in solar panels are made of silicon. Silicon is a semiconductor that is particularly important in the electronics and technology fields (Britannica).
Photons (light particles) hit a solar panel and knock electrons off the silicon atoms. This generates an electrical direct current which is converted to AC current by an inverter. AC currents are used for domestic electricity.
Are the materials used in solar power panels renewable?
Solar PV panels are made of silicon, either monocrystalline silicon or polycrystalline silicon. They also contain metal and glass (National Grid)
Silicon (Si) is an element. It is a finite natural resource found in sand and rocks like quartz and granite. But it is the second most abundant element in the earth’s crust, after oxygen. So, silicon is not renewable but it is abundant.
That’s as well as the glass covers for solar panels are also made from sand, which contains silicon dioxide. Sand is heated in a furnace with other ingredients, like sodium carbonate and calcium carbonate. Recycled glass may also be part of the mix. The liquid glass is then poured onto flat surfaces to make glass sheets. So the sand used for glass is also finite (non-renewable) but abundant.
Commercial glass is produced in a furnace fired by fossil fuels. Technically, using renewable sources of energy to fire furnaces is possible, but these options are still being developed.
Furnaces for glass need to produce high heats (up to 1600°C for float glass and run for 50 hours. RICS estimated that burning fossil fuels for furnaces generates 75%-80% of the carbon emissions from glass manufacturing.
Silicon can be produced in electric furnaces called arc furnaces created by a Frenchman called Paul Herault. They need to be heated to 2000°C which uses a significant amount of electricity (Hypertextbook). So both processes use a large amount of energy.
You might be surprised to hear that silver is in solar panels. Approximately 7% of the world’s silver goes into solar panels as a paste that helps to conduct the electricity. Silver, of course, is also a finite resource. A study in 2014 estimated that by 2240, silver mines could be all but depleted (Science Direct).
The ribbon in solar panels is copper, with tin and lead coatings used to solder the connections. Solar panels contain lead, despite it being a known toxin in the US and EU, for its low melting point (PV Magazine).
The aluminum used in solar panel frames is an element and as such is not renewable. It is not known how long the world’s aluminum will last, some estimates say 80 years (BBC).
There are alternative semiconductors to silicon, two of which are cadmium telluride (CdTe) and copper indium gallium diselenide (CIGS). Both are not as cost effective or long lasting as silicon. They are also composed of finite resources (elements) . The SC DHEC regard CdTe and CIGS as potential hazardous waste due to the chromium and arsenic they contain. Also, any silver, lead, cadmium or arsenic (found in CIGS).
Manufacturers design solar panels to last a long time (up to 30 years). Once their useful life is complete, recyclers can reuse many solar panel components, including the silicon, glass and aluminum . By becoming more efficient at recycling, we could eke out the remaining resources we have of aluminum and reduce the costs of production for silicon and glass.
Should we install solar energy in our homes?
So far, so negative. So, should we use solar panels for our renewable energy needs?
The answer is yes, we think. Solar power is still much cleaner energy, in terms of lower carbon emissions, than using fossil fuels.
ICC estimates that renewable energy sources like solar, wind, hydropower and geothermals produce very low levels of greenhouse gas (GHG) compared to fossil fuels, between 4g-46g CO2 eq/kWh compared to 469 to 1,001 g CO2 eq/kWh (ICC – pdf).
For the domestic home, solar power panels are long lasting and provide a good clean source of energy. This is a consideration for those of use who are environmentally conscious. They require an initial investment, estimated on average at $16,000 (Forbes). An average family will use $1450 per year on electricity. Over the lifetime, even assuming that the family sell no electricity back to the national grid, and ignoring any price increases, solar panels will save a family $20,250 over a conservative 25 year lifespan.
Solar energy is renewable energy because it is not expected to run out. The materials that go into solar power panels are finite e.g aluminum and some of them are precious, e.g. silver. We need to manage these materials and recycle whenever possible. The production processes for solar power panels use a lot of energy and use non-renewable energy sources like fossil fuels. There is potential to explore new and replacement materials and processes to make the production of solar power panel components more eco-friendly and sustainable.
Finally, solar energy is a low carbon renewable energy source that is currently not tapped to its full potential and could be part of the solution to finding alternative, cleaner energy sources than burning fossil fuels. Solar energy saves money for a family in a typical domestic home. This makes it an attractive prospect if our goal is green living.