As concern over our environment grows, sources of clean energy become more and more valuable. Solar power has been touted as a solution to our energy needs. Using the sun for electricity, with minimal pollution and no carbon emissions, appeals to anyone concerned about the global environment.
Solar Power has some significant advantages, but it also involves some costs and risks. Solar panels are well-proven technology, and they provide inexpensive power as long as the sun is shining, but they depend on daylight and are vulnerable to bad weather.
How Solar Power Works
At the core of solar power are thin pieces of silicon called solar cells. Solar cells will have two layers. The top will have an excess of electrons, while the bottom layer will have fewer electrons. When light strikes the top layer, it jars electrons from the top to the bottom layer, creating an electrical current. A solar panel will have dozens of cells in them, protected from the elements by a clear, durable screen.
A single solar cell might generate enough power to run a calculator. Tie several cells into panels, and dozens of panels in a solar array, and you can generate enough power to run a house or even a city.
But to run household appliances on solar power, it must be converted from the direct current that solar cells produce into alternating current that utilities provide, and it must be stepped up to the correct voltage. Power inverters convert electricity from solar panels into a form that can power your home.
Advantages of Solar Power
1. Solar Power is Good for the environment
There is little doubt that solar power can do a lot of good for the environment, locally and globally. Solar power requires no fuel. There is no need to drill for oil or gas or mine for coal, and it does not give off any ash or fumes. Unlike nuclear power, there is no radioactive waste to dispose of. Unlike hydropower, it does not even affect local waterways.
Solar power does not create any greenhouse gases once it is installed, so a solar power installation will do nothing to make global climate change any worse the whole time it is operating.
Solar power is not totally harmless. The process of making solar cells itself requires the mining and refining of specialized materials. Solar panels contain toxic materials that will need to be disposed of carefully when the time comes to retire them. But most power generation technologies involve similar problems when they are built and torn down.
Watt for watt, solar power is probably the greenest electrical power source we have.
2. Solar Power is Scalable
Solar power is extremely flexible in terms of size. An individual solar cell is small and doesn’t generate all that much power by itself. But stringing cells together and combining them to make more power isn’t complicated.
As a result, solar power can function on tiny scales and huge ones, or anything in-between. You can hide a solar cell behind the face of a wristwatch and have an extremely reliable timepiece. Or you can install a couple of solar panels and have them power a bike rental station. Or you can build an array of solar panels that covers several square miles and provides most of the power for a decent-sized city.
This scalability means that solar power generation has many applications. You can fit solar power in and generate electricity wherever there is space and sufficient sunlight.
3. Solar Power is Mechanically Reliable and Easy to Maintain
Unlike nearly every other method we have for generating power, solar energy has no moving parts. No windmill blades are turning, and no generator is spinning.
The only place where there might be moving parts is the inverter. Inverters themselves are solid-state, but they do generate heat, so you might use a fan motor to keep it cool. But with a high enough capacity inverter the fan won’t be needed most of the time.
Individual solar cells might be fragile, but solar panels are built to be extremely durable, with aluminum frames and tough transparent shielding that lets light in but can hold up to golf-ball-sized hail. There’s very little that can be broken or is likely to wear out prematurely.
That makes the day-to-day management of a solar array an easy task, something that won’t burden a homeowner with a set of solar panels. For larger utilities a small staff can handle even the largest solar facility. With little upkeep and no need to reload fuel, a solar power facility almost runs itself.
Disadvantages of Solar Power
1. Solar Power is Inconsistent
Solar power might be extremely friendly to the environment and easy to operate, but it won’t always be there for us. Solar power depends on sunlight, which means any solar array will quit generating power when the sun goes down. And output will drop on cloudy or rainy days.
In theory, one should be able to store up power generated during sunny days and then draw from that overnight. But batteries don’t scale up as easily as solar cells do: batteries used for utility-scale power storage can hold a charge for up to six hours, but no longer than that. Solar batteries won’t get a utility through a long night, and don’t come close to being able to cover a long spell of overcast weather.
For storage longer than six hours, we are left with “pumped hydro,” –basically using electric pumps to push water up into a tank, then releasing the water to turn generators later on. This is extremely inefficient, and all the pumps, turbines, and generators add moving parts to the system, negating solar power’s ease of maintenance advantage.
Evenings and bad weather will inevitably create solar outages. Solar power may be an extremely valuable addition to our electrical grid, but current technology will not allow for it to become the only power source we use.
2. Solar Power Takes Up a Lot of Space
A solar power facility will take up anywhere from 50 to 100 times as much land as a generating plant powered by coal, gas, or nuclear power. That’s a lot of land. And it won’t come cheap.
One megawatt of electricity will be enough to power a small town of about 200 homes. Generate a megawatt of power with solar panels requires a grid covering 2.5 acres, about the area of a baseball diamond.
A rooftop solar grid can power one home, but utility companies need much bigger power plants. Utilities need to serve hundreds of thousands — maybe millions — of customers. While it is possible to send power over long distances through high-power-lines, it’s generally better to keep power stations reasonably close to customers to cut down on power loss.
A solar power facility will take up much more real estate than a coal or gas-powered plant that generates the same amount of electricity, and utilities won’t always be able to put them on the cheapest land — or stick them in the desert where the sun is most reliable. This adds to the expense of solar power and cuts off one path around the reliability issue.
3. Financing Solar Power Can Be Tricky
A solar power plant may not need any fuel and only a little maintenance, so day-to-day operations will be cheap. But there’s a tradeoff: finding a large enough site and installing a solar array can be expensive. The savings come down the road. The expenses are all upfront.
This makes solar power a bit of a gamble for utility companies. That ballpark-sized solar farm generating a megawatt of electricity will cost around $3 million to build. A natural gas plant taking up a lot less room but cranking out the same amount of power will only cost around $800,000.
Again, the solar plant won’t need as much maintenance and won’t need any fuel. But the high initial price tag will affect how utilities use solar power. Utilities need to plan years ahead based on estimates of where power will be needed in the future, not just where their customers are now. If their estimates are off, a large solar plant that they don’t need will be an expensive mistake.
To be safe, electricity providers will probably wait until they are sure the demand is there before building any solar power plants.
Solar power by itself won’t be the answer to all our power needs. Between nighttime and bad weather, there will be too many times when solar electrical power won’t be available, and batteries for power storage are not advanced enough to cover the gaps.
When the sun is shining, however, solar power is a real asset. It requires no fuel, and it requires little in the way of maintenance. Solar power is extremely flexible in terms of size and layout. The startup costs may be a little steep, but as long as the financing is available both homeowners and utilities should be able to find ways to make solar fit in.
Solar power might not be the solution by itself, but it will become a more and more important source of power throughout the world.