With electricity rates going up, it makes sense to consider how to be 100 percent solar powered. A solar powered home producing more energy than it consumes can eliminate an electric bill altogether. However, a little bit of solar goes a long way, so while a net zero home might not be possible for everyone, reducing your energy bill with solar can protect you from future rate hikes.
How to be 100 percent solar powered
Can a house run on solar power alone? It’s a common question from homeowners interested in a 100 percent solar powered house, and it’s one of the many benefits of solar energy.
Never having to pay an electricity bill again sounds attractive, but is it actually possible?
Homeowners looking to offset 100 percent of their energy are actually looking to become a net-zero home, generating as much or more energy as their home consumes on an annual basis. For example, if a home’s solar panels generate 8,000 kWh in a year and the home consumes 10,000 kWh a year, then the home would only have an 80% energy offset. But a home with the same system that only consumes 7,500 kWh would be net-zero, with an extra 500 kWh to spare.
Okay great, so how much solar offset do I need to have all my energy demand covered by my solar panels?
Why knowing your consumption is important
In order to accurately determine if a net-zero home is possible, it’s important to know approximately how much energy a home consumes. While each home is different, determining the correct size of a home’s solar energy system comes down to examining energy bills. An electric bill provides the information that tells us exactly how much electricity a home consumed as measured by kilowatt-hours or kWh.
Two identical homes in the same neighborhood can have significantly different utility bills. One might have an electric vehicle. Or a hot tub. Or all-electric heating. While another might heat their home with gas and have a gas water heater.
Changes in energy usage can also play a large role, such as switching from gas to electric appliances, purchasing an EV, having guests stay for an extended period of time, or severe weather that requires more energy than usual to heat or cool a home. This is why energy consumption figures are always estimates – there’s simply no way to predict how usage will change in the future.
After determining approximately how much energy your home uses, it’s a matter of estimating the expected solar production and designing a solar energy system that can meet performance guarantees (make sure to ask your installer if they guarantee production). Unlike estimating energy usage, we can predict with great accuracy how much energy a solar system will produce annually and over its 25+ year lifetime.
Let’s clear up one misconception about net-zero and off-grid. They are different.
While offsetting 100 percent of a home’s energy consumption relates to being a net-zero home, off-grid refers to being completely disconnected from the utility (like a cabin in a remote area). Most homes that offset 100 percent of their energy remain connected to the grid thanks to advancements in energy efficiencies, and net metering policies, which provide homeowners energy credits proportionate to the surplus energy generated by their system. These credits can be used to pay energy bills when there’s not enough sunlight to generate electricity to cover the consumption of the home in a given period, such as in the winter months.
With the help of these policies in many states, including net-metering in Washington and Oregon, homeowners may be able to become a net-zero home. It depends on a home’s energy demand and the size and effectiveness of its solar system.
How to estimate expected solar production
Here are some considerations when estimating expected solar production:
- How much direct sunlight a roof receives (unshaded by trees or nearby buildings)
- The orientation of the roof face (whether it faces east, west, south, or north)
- The pitch (steepness) of the roof
- Total usable roof space free from obstructions (vents, skylights)
- Local geography and climate
With the help of modeling software and other tools, a solar design consultant can accurately measure a home’s potential solar energy production and design a solar energy system such that it can offset as close to 100 percent of the home’s energy demand as possible.
A net-zero home: is it possible? Let’s review
By knowing a home’s approximate electricity consumption, we can model a system that will attempt to provide enough energy to offset home energy demand and possibly become a net zero home.
Solar Production / Home Consumption = Percent Offset
For example, your home consumes approximately 4,000 kWh/yr, and your roof allows for a system that can produce 3,000 kWh/yr:
3000 / 4000 = 75% of your consumption is offset by solar
A Net-zero home is great but it isn’t necessary
If it is not possible to install a system large enough to cover 100% of your electricity usage, moving forward with a solar installation still makes just as much sense. Any effort to reduce a home’s energy consumption is a good step. And the economics of solar energy in Washington and Oregon are such that utility incentives don’t care how much energy you’re offsetting.
That being said, there is an economy of scale with solar. A bigger array is usually cheaper than a smaller array on a per unit basis. That means installing 20 panels will not cost twice as much as installing 10 panels, but there are factors to consider, especially the characteristics of your roof. For instance, costs can increase if solar panels extend across multiple roof faces, requiring more complex conduit and wire runs, which can increase the cost of installing solar.
A solar professional can help
What’s right for one homeowner, may not be the right for another. That’s why it’s important to speak with a solar design consultant to understand the potential that solar can offer in offsetting your electric bill. We’ll work with you to determine your goals and understand your budget. Then we’ll design a system that will be optimized for you.
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