If you have ever wondered how to live more sustainably, you have probably come across solar panels. More and more homeowners are looking to reduce their electricity costs and use more green energy by adding solar power to their homes. One of their most frequently asked questions is, “Can solar panels power a whole house?” The simple answer is, yes.
However, the question of powering an entire house gets a lot more complicated when looking at what it will take for a particular house and whether it makes sense to do it. The size and type of solar equipment that will be required to get rid of your energy bills are going to require a deep dive into a wide variety of considerations including how you use electricity.
How Does Solar Energy Work?
Let’s start with the question of how solar energy is even produced. According to the U.S. Department of Energy, “When the sun shines onto a solar panel, energy from the sunlight is absorbed by the PV cells in the panel. This energy creates electrical charges that move in response to an internal electrical field in the cell, causing electricity to flow.”
Beyond the science speak on solar power generation, there are two key concepts here that should be obvious but that people sometimes neglect when considering solar energy systems.
- The sun has to be shining
- The sun has to be shining on the solar panels
How Much Solar Energy Can a House Produce?
When considering the sunscore or solar potential of any house there are a few different considerations:
- The amount of sunshine in the general area of the house
- Temperatures – solar panels are less efficient in extreme heat
- The amount of shade the house has
- The roof orientation configuration or angle of the house’s roof to the sun
It is also important to recognize that shorter days and a lower sun angle result in less solar electricity being produced during the winter.
Here are a couple of different ways to get an actual estimate of your home’s sunscore.
Google Project Sunroof
To get a reasonable sunscore estimate for your home, check out Google Project Sunroof. All you have to do is enter the address of the home and your monthly electricity costs.
Google Project Sunroof will estimate your home’s sunscore based on peak sunlight hours and then recommends a solar system size. This is based on an estimate of the kilowatt hours or KWh of electricity usage of your home.
One other element of Google Project Sunroof is an estimate of the impact of solar installations on your carbon footprint. Solar is arguably the best small-scale renewable energy option so it’s a great way to do our part!
To get a more accurate estimate of your home’s sunscore you should find reputable solar companies in your area. There will generally be many to choose from so here is some good information to help you prepare before you start searching for solar power companies near me.
How Much Solar Power do I Need?
After determining how much power your house can produce, you’ll need to figure out the energy usage you need to cover if using solar electricity for your entire house.
The easiest place to start is your home’s average monthly energy consumption rate. You can usually get this information by simply looking at your most recent power bill. To get a more accurate estimate, you can contact a solar installation company for a power audit.
However, your average current monthly energy consumption rate is only the beginning.
Upcoming Change in Electrical Needs
With more people looking for an alternative energy source, it makes sense to look ahead to things that might significantly change your energy requirements. One, in particular, is if you are planning to acquire an electric vehicle. With the clean energy vehicle federal tax credit, a lot of people are looking at electrical planning to looking to get an electric vehicle.
Electric cars are not the only changes that people are considering that may increase electricity consumption. Many people are looking to utilize eclectic space heating as opposed to gas-fired central heat. Also, electric and battery-powered options are replacing small engine equipment. Factor in any of these changes you are thinking of making in estimating how many watts of electricity you need.
Another factor to consider is that in most places, power usage varies considerably during the year. A primary cause for this is your air conditioner. During periods of higher power consumption, utility companies often increase the average cost of electricity because of the increased electricity demand.
Higher electricity costs make it tempting to install enough solar panels for energy capacity to meet the daily energy usage of the summer months. But solar systems sized for the peak electrical demand during summer months will produce excess power during periods of lower demand. Without a means of storing or sharing, this extra energy capacity is wasted during periods of lower needs.
Average Home Energy Consumption
Since each home is different, let’s take a look at average energy consumption and what that means for the number of solar panels.
According to the U.S. Department of Energy, “the average annual electricity consumption for a U.S. residential utility customer [in 2020] was 10,715 kilowatt hours (kWh), an average of about 893 kWh per month.” This is the power consumption estimate we use in looking at solar panel systems.
How Many Solar Panels Do I Need?
So, how many solar panels would the average house need to replace all its energy consumption? As you probably already guessed, the answer is that it depends. The math of calculating the power generation potential of solar panels based on cell efficiency and size is straightforward. But that math reflects theoretical potential, not necessarily practical potential.
Of course, all of the factors that impact the power generation potential of a home impact the amount of electricity that solar panels can produce. Also impacting the number of solar panels needed are what the plans are for backup for power at night and times when extra power is needed.
We’ll discuss those considerations more below, but let’s just look at just average solar panel performance and average locational conditions. According to this article from Forbes, the average home needs a solar power generation system rated between 6kW and 8kW, or about 20 to 25 solar panels, to offset all its power consumption. This range is consistent with all the other information you will see online.
How Much Will the Solar Panel System Cost?
So, now that you know how many panels you’ll need for successful eco home improvements, the next question most homeowners ask is, “How much do solar panels cost?” Again, there is a lot that goes into answering that question so we’ll just stick with national averages.
There is a lot of good information out there on the installation costs of residential systems. HomeGuide provides a good, comprehensive solar installation cost guide. They estimate the average installation cost of a 6kW to 8kW system at between $15,000 and $25,000 before considering the federal solar tax credit and any available state or incentives from your state or local government or utility company. These can significantly lower the net upfront investment.
Of course, the initial cost is only part of the story. Looking down the road, the cost of your annual electricity usage without a solar panel system would be expected to continue to go up. Increasing energy demands and energy costs are why many people see solar as offering a strong return on investment over time as a solar system offers low-cost electricity for decades to come.
The initial investment in a solar panel system results in the reduction or even elimination of electricity bills for years to come. This significantly reduces the effective cost of solar panel installations over time making it a great long-term investment.
Types of Solar Energy Systems
There are basically two different kinds of solar panel systems:
Grid-tied systems are the most popular type of system for homes. It ties your system directly to the utility grid allowing a flow of electricity from your solar panels to the electric grid.
The advantage of a grid-tied system is that it allows excess electricity produced by your panels to be fed back into the electricity grid, usually in exchange for a reduction in your electricity rates or overall utility bills.
Conversely, if you need excess power beyond what your panels can produce, you can purchase that energy back to your local utility company.
This arrangement is often referred to as net-metering. It is the simplest means of balancing the environmental impact and economic advantages of a solar-powered home with the convenience of being tied into your local utility grids.
A net-metering arrangement also allows easier comparison of the upfront cost of the system with the projected reduction of ongoing energy costs by directly accounting for the unused electricity produced by the solar system.
Grid-tied systems can operate with or without battery storage for excess energy.
Off-grid systems are used primarily by people who either have no other available electrical utility or who want to completely get away from the electric company.
Because a home using off-grid systems cannot tap into the electric grid for excess energy, the solar system has to be sized for the peak demand of the home.
Also, a battery storage system or a secondary means of power generation (fossil fuel, wind, or hydro, for instance) becomes essential to preserve power during the night and during days when direct sunlight is limited by cloudy weather.
Given how much most people depend on electronics for their daily lives, an off-grid system that does not require significant lifestyle changes will generally be very expensive both initially and on an ongoing basis.
An off-grid system will also involve many additional elements that will require ongoing repair or replacement and which increase the risk for system failure.
On the other hand, a home that is off-grid would no longer be subject to power failures of the electric grid, including the rolling brownouts that are becoming increasingly more common during the summer months, particularly in parts of California.
Off-grid systems would also completely protect a homeowner from ongoing rate increases for utility companies and reduce any reliance on the fossil fuels on which many power utilities still rely for power generation.
Overall, there certainly are situations where an off-grid system is the only option or where it makes sense based on the circumstances of the homeowner. However, there are a lot of considerations that you need to take into account in determining if an off-grid system is right for you.
Battery Storage Systems
One other increasingly important consideration in designing residential solar panel systems is a battery storage system. Off-grid systems will almost always utilize a backup battery system to store extra energy.
Increasingly, owners of grid-tied systems want some form of battery storage as an emergency backup during times when the electric grid is down and they have no other available source of energy.
While battery backup systems can be a great solution for some people, a whole-home battery and a whole-home battery backup system will be expensive, possibly even approaching the cost of the solar panel system. The cost of the popular Tesla Powerwall is now over $10,000 a piece before considering installation costs. Also, the Tesla Powerwall is now only available in combination with the Tesla solar panel system which may not be the most cost-effective solar panel solution for your home.
One other problem that battery storage systems used to present was the space they required. A battery array from 20 years ago would have been just a series of batteries, often just car batteries, that were wired together. Even in racks, the number of batteries needed for the system required a lot of space.
Newer battery technologies and designs, such as the Tesla Powerwall and the Generac PWRcell, largely eliminate this problem. Nevertheless, these batteries still require an appropriate storage location and wiring extended to that location which may prove challenging for some homes.
The good news on battery storage systems is that battery technology continues to improve. If battery technology gets to a point where it is both economically and environmentally practical, we may get to a point where solar panels become part of every new home built.
Unfortunately, we still have a ways to go until battery technology gets there as current battery technology relies on materials that are expensive to produce and present problematic environmental issues.
So, can solar panels power a whole house? Hopefully, this information has helped you better understand that while the answer is “yes,” there are a lot of follow-up questions you need to ask to see if a whole-home system is right for you.
If you’re ready to find out more, contact local solar companies who can evaluate your home and power consumption and design a system that is right for your circumstances. We strongly recommend getting multiple bids.
Just know that you are going to be talking to a salesperson so be ready to say “no” and to tell them you are getting bids from several companies. Spend some time comparing the prices, products, customer reviews, guarantees, and your comfort level with them.
A solar panel system is a big investment so don’t let a pushy salesperson try to force you to make a decision until you’re ready.
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