What is solar power?
Solar power is the ability to convert energy from the sun into usable electricity. Sunlight is either harnessed as thermal energy (heat) or through the use of photovoltaic cells in solar panels.
Solar-electric or photovoltaics (PV) technology converts sunlight directly into electricity. PV can provide electricity for residential and commercial buildings.
Parts of the Solar Energy System
A complete energy system is made of four parts: solar panels, an inverter, racking and a performance monitoring system.
Solar panels consist of a series of silicon solar cells covered by a sheet of glass. These are held together by a metal frame, with circuitry in and behind the cells to collect the flow of electrical current.
Most solar panels are about 4 feet x 6 feet and weigh about 30 pounds.
When sunlight hits the silicon solar cells, it activates electrons, which flow through the cell. Wires in the cells capture this flow of electrons, which is then combined with the output of other cells in a solar panel.
The encapsulant provides a layer of protection for the solar cells from the environment. It also provides electrical insulation.
The frame is usually made of aluminum and provides structural stability.
The solar cells are connected in series by cross-connectors.
There are two types of solar panels: monocrystalline and polycrystalline.
Monocrystalline panels are made with silicon wafers cut from a single crystal. In general, monocrystalline panels are capable of a higher efficiency than polycrystalline because they use a higher grade of silicon.
Polycrystalline panels are made by melting many fragments of silicon together. They are typically less efficient and less expensive than monocrystalline.
Solar panels last anywhere from 25-30 years or longer. The energy production of the panels will decrease by what their manufacturers consider optimal to meet the average family’s needs.
Solar panels work on both sunny and cloudy days. Though they are most efficient on sunny days, they also generate power during cloudy days because the panels operate from light, not heat.
Panels undergo rigorous testing to be UL certified. This includes:
Damp heat tests–inducing stress from high humidity and high temperatures. This tests for corrosion, discoloration and connection issues
Thermal cycling–induces stress with high and low temperatures. This tests for cell cracks and mechanical instability.
Humidity freeze–combines thermal cycling and high humidity to test for cell cracks, mechanical instability and delamination
Panels should be cleaned once or twice a year. Using 1-part vinegar and 2-parts water, this solution will clean off any debris and lingering dust.
The solar panels collect the energy from the sun and turn it into direct current (DC) electricity. Most homes and businesses, however, use alternating current (AC). Inverters are necessary to change the DC electricity to AC electricity. There are two basic types of solar inverters: string (or centralized) inverters and microinverters.
String inverters are actually a single inverter that connects your entire array to the electrical panel. They are usually less expensive and very durable. A drawback of this system is if one were to have a panel drop in production, then it could temporarily reduce the performance of the whole string.
Microinverters are usually installed at each solar panel, allowing them to maximize production. These also minimize performance issues, as each panel has its own inverter. These are usually a bit more expensive than sting.
Racking is the piece of hardware that affixes your panels to your roof or on the ground.
Performance Monitoring System
This can provide you with detailed information about the performance of your solar panel system. With a proper system, you can monitor your electricity produced on an hourly basis.
Advantages of Solar Power
Energy from the sun is renewable and sustainable. Coal and natural gas pollute our air–60% of power in the US comes from these two sources, producing 3,078 pounds of CO2 per megawatt hour.
Going solar saves the average household $1,500 annually on energy bills. Over the lifetime of a system, this can add up with $40,000 or more.
Solar panels provide great value to your home. Homes with solar systems sell for 3.74% more than homes without, averaging an increase of $14,329.
Potential Freedom from the Grid
Equipped with a proper battery, there is potential for a homeowner to obtain freedom from the grid completely.
Net Energy Metering
Net energy metering (NEM) is a billing structure that allows a homeowner to “store” energy in the electric grid. When panels produce more energy than needed, that energy is sent to the electric grid in exchange for a credit against future consumption. A customer on this plan is only charged for their net usage. On average, only 20%-40% of a system goes to the grid, and this will serve nearby customers’ loads.
How the System Works
Photovoltaic cells absorb energy from the sun and convert it into DC electricity.
Solar inverters convert DC energy into AC electricity.
Electricity used in the building.
Bi-directional meter measures the energy used.
Excess electricity is fed back to the grid.
Available Credits and Deductions
Consumers who install a PV system are eligible for a 30% federal tax credit for the total cost of the system.
A business with a solar PV system placed in service between January 1, 2018, and December 31, 2022, can elect to claim a 100% bonus depreciation tax deduction. Starting in 2023, the percentage of capital equipment that can be expensed immediately drops 20% per year (e.g., 80% in 2023 and 60% in 2024) until the provision drops to 0% in 2027.