Solar technology had evolved remarkably since 1839 when Edmond Becquerel, a French physicist, discovered how photovoltaic substances generate electricity when exposed to sunlight.1
However, it has pros and cons that need to be understood when considering it for residential use.
The Advantages of Solar Power
It's beneficial for homeowners to have their own energy resources when the public electric grid is compromised, as noted in the following examples:
The Disadvantages of Solar Power
You still need to draw power from the electric grid at night or on cloudy days when your solar panels are not functioning. Alternatively, you can store excess solar power in batteries, but they provide a limited reserve energy supply.4
When your solar panels provide more power than you need, they feed it into the grid, and your meter runs backward. Some utilities will provide a “Net Meter” which keeps track of the amount of electricity you’re using and the amount your solar panels feed back to the grid. The latter earns you energy credits.5
Then when you need more power, you get it from the grid. However, the power utility doesn’t actually store it for you. Instead, they supply it to your neighbors, who pay for the excess power you generate.
Electric power utilities prefer that because it saves them the cost of generating more power. The infrastructure maintenance cost is an important consideration that motivates power companies to offer credits for solar installations and excess usage.
The energy credits accumulate on your electric bill. These credits go toward future use of the utility's power when you need it.
You can’t ever have a negative electric bill, and the power company will not send you a check for the power you feed them. Instead, most states require the electric company to credit you on your bill.
That credit remains on your bill until your solar panels are not generating enough power due to clouds or leaves covering the panels. That is when you draw from the utility, and the credit goes toward your bill, possibly eliminating any charges.
Suppose you are not in the best location for efficient solar power generation. In that case, you still will be able to take advantage of the sunniest days and draw on the reserve you accumulated on those dreary, cloudy days. And, of course, at night as well.
The Inflation Reduction Act passed in 2022 increases the tax credit from 26% to 30% for purchasing solar panels and solar water heaters for your home. This credit is in effect until December 31, 2032.
The scientific name for a solar panel is photovoltaic material, or PV. They can be made from single-crystalline silicon, polycrystalline silicon, or thin film copper indium diselenide.
Copper indium diselenide has an efficiency rating of 12 to 14%, according to the Office of Energy Efficiency & Renewable Energy.6
An alternative to solar panels is the thin-film photovoltaic (PV) laminate, invented by Stan Ovshinsky.
Ovshinsky was the same inventor who was involved with designing flat screen liquid crystal displays (LCD), which is commonly used for television, laptop, and computer monitors, in addition to displays on smartphones and tablets.
The PV laminate can be bonded directly to any surface. The following video shows how it is attached to metal roofing.
One solar panel creates 6 to 24 volts DC, depending on the angle of the Sun and interference such as clouds or shade from trees and buildings. It is best to avoid the possibility of these disturbances. A competent installer will indicate if you will benefit enough by using solar panels on your roof.
In order to get 120 volts, solar panels are wired in series. Voltage adds up serially. This arrangement has an inherent problem, but there is no other solution. If one panel is blocked by shade, it will considerably reduce the total output, just like a flashlight with one dead battery.
Even if the others are good, the current doesn’t flow as well. Another analogy is with Christmas tree lights wired in series. If one bulb is dead, the whole string of lights goes out.
Batteries in a series add up their voltage. That's how four 1.2-volt batteries in a flashlight will power a 6-volt bulb. Solar panels add up the same way. But then the Direct Current needs to be converted to AC. We use 60 cycles AC in the US. The unit that does that is called an inverter.
The final component that you need for a complete system is a battery. The battery holds the charge to provide consistent voltage to the inverter. The inverter changes it to AC and increases the voltage to 120 volts. Two inverters in series are used to produce 240 volts. Alternatively, a transformer can be used to step up 120 volts to 240 volts.
The inverters usually have a 10-year warranty, and the solar panels have a 25-year warranty. You need to check with your supplier for the exact terms they may give you.
Solar panels today are only 16–22% efficient, but don’t let that number confuse you. That means roughly 20% of the energy from the Sun is converted into electricity.7
This rating is taken into account when planning a total installation on your house that will provide 100% of your electric needs.
Solar panels have less efficiency for homes as you go farther north in the northern hemisphere or farther south in the southern hemisphere. That is because the angle of the Sun’s rays increases with the distance you are from the equator.
In the northern hemisphere, the Sun’s rays come from the south during winter since the Earth’s axis is at a 23.5º angle. For this reason, the panels should be placed on roofs that face south. The reverse is true for homes in the southern hemisphere.
It's easy to learn everything you need to know before buying. Go to your nearby home improvement store and ask if they have any seminars hosted by local solar electric providers. I attended a few of them at Home Depot.
This opportunity allows you to meet local installers face-to-face without making any commitments. You’ll come out of it with a wealth of knowledge.
In a neighborhood with high electric utility costs, having solar panels on your roof can make a big difference in value when selling your house.
In addition, when you have solar panels on your roof, you’ll have a secure feeling that your lights will stay on whenever the power grid fails due to vandalism or severe storms.
