What is solar power?
The sun doesn’t just provide warmth and light – it’s also a source of energy.
Solar energy (or solar power) is the energy we generate from sunlight. Through a process known as the photovoltaic effect, we can convert energy from the sun’s rays into electricity that can power our TVs, refrigerators, lights and other appliances.
To generate solar energy for your home or office, you need a solar power system. We’ll go over the parts of that system later in this guide, but first let’s talk about the most recognizable part of the system: solar panels.
What are solar panels made of and how do they work?
Solar cells are made primarily from silicon, a chemical element with conductive properties. Exposure to light changes silicon’s electrical characteristics, which generates an electric current.
A cell is a small square of silicon (about 6” x 6”) with electrical contact plates on the face. Solar panels are made by laying out a grid of these cells on a protective back sheet and covering them with glass on the front.
Panels come in 60 and 72-cell configurations (plus a few others which are much less common). If you want to know when you might choose one over the other, read our breakdown of 60 vs 72 cell solar panels.
It takes multiple panels to provide power to a typical home or office. A collection of panels in your system is called an array. Panels wired into the same inverter are known collectively as a string of panels. (Inverters have a maximum string size – an upper limit to the number of panels they can support.)
For example, you may have a system with two inverters supporting two strings of 10 panels each, which comes together to make a 20-panel array.
What are the parts of a solar energy system?
There are other key components to a solar system aside from the panels themselves.
To generate your own energy, you need a complete solar power system. The essential components:
- Solar panels, to capture energy from the sun
- An inverter, to convert that energy to a format that can power our appliances
- Racking, the foundation on which you mount your system
You also need a method to store the energy generated by the panels. If you have access to power lines, this doesn’t require additional equipment. It can simply be fed into the utility grid and used later.
- Batteries, to store the energy you generate
- Charge controller, to control the rate at which batteries charge from solar
These are connected by smaller components like wiring, fuses, and disconnects.
You can also add equipment to monitor your system’s output online, which helps troubleshoot any issues with shading or defective equipment.
What are the pros and cons of solar power?
Here are some reasons why you might choose solar over another source of power:
- Renewable: Sunlight is an infinite resource. It’s not like oil, which we remove from the Earth and spend when we use it. The sun’s rays can be harvested for energy over and over again without depleting the source.
- Lower Electric Bills: As a replacement for grid-tied properties (anywhere with access to power lines), solar power costs just a fraction of what you pay the utility company each month. A properly sized system can drop your electric bill to $0.
- Remote power: If you live in a remote location, it may be too expensive or impossible to run power lines to your house. Solar power systems generate energy when you can’t hook into the power grid.
- Improve Property Value: Homes equipped with solar systems sell for 3.74% more than equivalent homes without solar. Solar homes sell for $14,329 more on average. Read more about how solar impacts property values. Off-grid solar also enables you to buy affordable undeveloped property in rural areas.
Here are some drawbacks to consider before going solar:
- High up-front cost: Even small systems cost a few thousand dollars, and full-scale systems for a family home can reach a 5-figure price tag. Though it pays for itself in the long run, it can be prohibitively expensive to get started.
- Weather Dependent: Shade, snow and other obstacles reduce the output of your solar panels. If your panels don’t get a lot of sun, they won’t work as efficiently as advertised. You can buy equipment designed to mitigate this, but it costs more.
- Takes up space: Solar panels are over 3 feet wide and 6-7 feet tall depending on the configuration. An average residential system might contain a few dozen panels. They take up a lot of space on your property, so you need to make sure you have somewhere to put them.
- Storage is expensive: Batteries are by far the most expensive part of a solar system. If you need them to store power (either off the grid or as a backup for your grid-tied system), that will eat into your return on investment. They should be used out of necessity, or to provide peace of mind in areas with unreliable power.
What’s the difference between grid-tie vs. off-grid solar?
The first thing to decide when you go solar is whether you need a grid-tied or off-grid system.
Each has a distinct benefit:
Grid-tie systems save money on your electric bill. It’s less expensive than buying electricity from the utility company. We recommend this to everyone by default if they can connect to the utility grid. Always build a grid-tied system if you have access to power lines!
Off-grid solar is for delivering power to remote properties without easy access to power lines. They cost more (due to the addition of batteries), and the main value is delivering power to a remote location.
There’s a third system type as well, which is a hybrid of the first two: it connects to the grid, but also includes batteries. Solar companies refer to these as either battery backup or energy storage systems. There are two main benefits:
- Store backup power in case of outages (useful if you live in an area with an unreliable power grid or severe weather)
- Store energy so you can use it or sell it later (useful if you live in an area with the time of use rates, high demand charges, or no net metering)
Energy storage systems provide extra peace of mind and get the most from the electricity you generate. It’s up to you to decide if it’s worth it to spend more on your system for the added flexibility.
How long do solar panels last?
Most manufacturers guarantee under warranty that their panels will be at least 80% efficient for 25 years.
When the warranty is up, the panels don’t break down. They simply keep working at a reduced output. A panel that is rated at 300 watts, for example, would still produce 240 watts of output at the 25-year mark.
Panels tend to be extremely reliable. A study by NREL (National Renewable Energy Laboratory) showed that over 75% of panels outperformed their warranty.
However, other parts like inverters and batteries have a shorter lifespan. You should expect to replace these parts at least once over the life of ownership, and those replacements should factor into total costs over the life of the system.
Inverters are warrantied for 10-20 years. Expect to replace your inverter once or twice in your system’s lifespan.
If you include batteries with your system, those will also need to be replaced. Lead-acid batteries typically last 3-7 years depending on how well you maintain them. Lithium batteries are warrantied for 10-15 years.
Learn more in our article: How Long Do Solar Panels Last?
Is solar energy a sound investment?
In most cases, solar energy happens to cost a lot less than what you pay the public utility for electricity. Let’s do the math.
The utility company bills you for electricity. The national average is about 12 cents per kilowatt hour (kWh) of electricity used.
A kWh is simply a measurement of how much electricity you use. You can check your energy bill to find out how much you use each month in your household.
(Rather have someone do the math for you? Visit our solar cost calculator to run the numbers.)
If you use 1,000 kWh / month billed at 12 cents / kWh, the power bill comes to $120 every month. That’s $1440 per year.
Now let’s look at how to get that done with solar. We’d recommend something like this 7.8 kW system, currently listed for $9,791 at the time of publication. It would cover 100% of the energy usage outlined above.
The federal tax credit shaves 30% off the purchase price, so you pay $6,853.70 for the equipment. (To claim the credit, you must owe taxes. Read about the details here.)
By generating your own power, you get to pocket $1440 every year that you are paying to the utility every year. After 4.76 years, you break even on savings. This is known as the “payback period” – how long it takes for your system to pay for itself.
Lastly, panels are warrantied for 25 years. Over the life of the warranty, the system pays back your investment 4 or 5 times.
Not only is solar energy good for the environment, but it also makes financial sense.