Solar 101
SOLAR 101
What is solar power:
The sun doesn’t just provide warmth and light – it’s also a source of energy.
Solar energy is the energy we generate from sunlight. We can convert energy from the sun’s rays into electricity that can power our TVs, refrigerators, lights and other appliances.
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What are the parts of a solar energy system:
The essential components:
- Solar panels, to capture energy from the sun
- An inverter, to convert that energy to a format that can power your appliances
- Racking, the foundation on which you mount your system
But if you are off the grid, you’ll need additional parts:
- Batteries, to store the energy you generate
- Charge controller, to control the rate at which batteries charge from solar
What are some of the advantages 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 4% more than equivalent homes without solar.
What is net metering:
Grid-tie solar systems store the power they generate in the public utility grid. In return, the utility company credits your account for the excess power you generate. Those credits can be claimed to draw power from the grid when the sun isn’t out (at night or during poor weather).
Every utility company has their own policy which outlines the rates at which solar customers are credited and billed for power. This agreement is known as a net metering policy.
What does an inverter do?
A solar inverter converts DC (direct current) into AC (alternating current).
Solar panels generate DC power, but most household appliances run on AC power. The inverter simply takes the energy you generate and turns it into a format that can power your electrical loads.
How is solar panel efficiency measured?
The concept of solar panel efficiency is often misunderstood. Most panels have an efficiency rating in the range of 15-25%, which sounds really low without context.
Some people hear this and think, “wow, I only get 20% of the production from my panel? That sounds like a waste.” The assumption is a 100-watt panel would only produce 20 watts of power. But that’s not what we mean when we talk about efficiency.
In reality, the efficiency rating measures how much of the sun’s potential energy is converted to solar power. Using the same example, a 100-watt panel with a 20% efficiency rating will absorb 20% of the potential 500 watts of continuous power coming from the sun.
Don’t sweat too much about panel efficiency. The only real benefit to more efficient panels is that they fit more solar in less space.
High-efficiency panels matter if you’re trying to build in a tight space, but there’s nothing wrong with building a larger array with less efficient panels. The latter option typically reduces the overall cost of the system (because less efficient panels have a lower cost-per-watt, all other things being equal).
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 end of 25-year.
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.
Does my solar energy system need batteries?
Batteries are mandatory for off-grid systems and optional for On-grid systems.
Every solar energy system needs a method to store the power generated by the panels. With On-grid systems, you can feed that energy into the utility grid, essentially using the grid as a giant battery.
Under a net metering agreement, the utility credits you for anything you contribute, and you can use those credits to withdraw power from the grid whenever you need it. With the grid serving as an energy storage system, On-grid systems don’t need batteries to function.
Off-grid systems are different. Without grid access, you need to store your own power, and that means batteries are mandatory. Off-grid systems are quite a bit more expensive due to the inclusion of batteries, but can still be cost-effective as an alternative to running power lines to a remote property.
Ground mount or roof mounts:
So where should you mount your panels:
Our default choice is to put them on your roof if you have room. Rooftop solar is less expensive to install because the support beams act as a foundation for the mounting hardware. You save on materials and labor because you don’t need to build a substructure to hold the weight of the array.
The alternative is a ground mount—a standalone metal or aluminum framework built somewhere on your property to mount the solar array. Ground mounts cost more because you have to buy the pipe for the frame, but they are easier to access for maintenance and repairs (no climbing on your roof).
What are pole mounts are they worth it:
A pole mount is simply a tall pole that lifts your solar array higher off the ground than a traditional ground mount.
Pole mounts are great for snowy climates. The elevated mount gives the array extra clearance, so the array doesn’t get buried in a snow bank during the winter.
Pole mounts can also be tilted at a steeper angle, which helps snow buildup slide off the face of the panels, keeping them free of obstructions and producing closer to their peak output.
How does local climate impact system sizing:
It shouldn’t come as a surprise that solar performs better in sunny climates. Some regions get more sun hours per day, which gives your system a bigger window each day to hit peak production.
Most regions in the US get 3-6 sun hours a day, which is quite a bit of variation. A system built in Seattle, WA needs to be nearly twice as large as a system built in Arizona to produce the same amount of power!
That said, solar is still quite effective in less than ideal climates. Take a look at this case study submitted by our customer Dave, who shares observations and production data 5 years after going solar in the Frozen Tundra of Wisconsin.
What tax credits and incentives are available for going solar:
The major incentive for going solar is the Federal Tax Credit. Under this credit, 26% of your project costs (including installation) go toward a credit to offset your tax burden when you file with the IRS.
For more info, read our primer on how the federal solar tax credit works.
In addition to the federal credit, there are state and local credits in many regions which add even more incentive for going solar. To research local credits in your area, visit our state solar incentives page.
What solar financing options are available:
There are three common approaches to secure financing for your solar system. In order from highest to lowest value, they are:
- Personal Loan
- Solar Lease
- Solar PPAs (Power Purchasing Agreements)
A personal loan will typically have the lowest interest rate. In addition, taking out a loan to buy the system means you own it yourself. Owning the system allows you to claim the Federal Tax Credit for going solar. That 30% kickback when you file your taxes can help you pay back your loan ahead of schedule.
Solar leases and PPAs have lower ROI because the installer owns the system, which means they have the right to claim the Federal Tax Credit for themselves.
Do solar systems require maintenance?
Solar panels require very little maintenance. Most of it is centered around clearing debris off the panels, which would block sunlight from hitting the solar cells and hinder production.
Solar panels are very durable because there are no moving parts, so there’s very little maintenance on the mechanical and electrical systems. If you keep panels clear, your system needs very little oversight.
How does solar impact the value of my home:
A 2019 study suggests that solar homes sell for 4% more than comparable non-solar homes.
Solar is a major selling point, so long as the homeowner owns the solar system. Leased systems are a different story, as the home buyer must agree to take on the contract and lease payments from the solar installer.
How can we help you?
Solutions; designed and installed to fit each customer’s goals.