Frequently Asked Questions
How much does solar cost?
When discussing solar it is often compared to more conventional forms of energy generation (coal, natural gas, oil). Solar is applied fundamentally different that these forms, rather than paying for your energy over the course of the year you're instead investing in a stable energy cost for the life of the solar system (typically 30-50 years).
Roof-mounted PV systems are usually less expensive than ground-mounted or pole-mounted systems. The installed cost for a roof-mounted system can range from $2-$5 per Watt depending on size. A common residential system such as a 8kW can come in around $22,000 to $30,000. Costs vary considerably, a detailed quote specific to your location is the best way to find out!
What is the difference between a grid-tied system and an off-grid system?
A "grid-tied" solar electric system is where your solar array (and the structure it's connected to) is also connected back to your utility company. This allows you to use power from either your solar array or utility company depending on how much energy you're using and how much energy you're making. In addition if you're generating more energy than you can use that additional energy is sold back to the utility company.
An "off-grid" system is a solar electric system that is connected to a series of batteries that store the excess power for use during periods where you're not generating enough energy. These off-grid system generally cost 50% or more than a standard installation.
A "grid-tied battery back-up" system is the best of both worlds, allowing a grid connection, but provides energy security in the event of a power outage. These systems also can cost about 50% more than a standard grid-tied system.
What is net metering and how can it help me finacially?
Net metering is a billing mechanism that allows solar energy system ownders to be credited for the electricity they utilize and add back to the grid. If a residential customer has a PV system on their roof, it will likely produce more energy than the home is using during the day. With net metering, the electricity meter will run backwards to offset what electricity is consumed at other times of the day and times of heavy usage. Customers are only billed for their "net" energy use.
Utilities in Minnesota are required by law to allow net metering and pay a retail rate (~$0.10/kWh) up to a 40kW AC (50kW DC) solar system size. Generally they treat any excess energy produced as a "rollover credit" on your bill. The excess $ will roll month to month until year's end. Any excess remaining will be a check in your hands. This allows for high energy production in the summer to benefit you financially in the winter months as well.
What is the payback period for my solar system?
For the entire U.S. the average return on investment for a solar array is around 13 year depending on the state; for Minnesota this average drops down to about 10-11 years. This number will vary depending on your usage, system size, utility, possible maintenance and available solar resource at your site.
Commercial systems leveraging federal incentives and depreciation can see paybacks closer to 8 years or less. Again, highly dependent on system variables.
What type of maintenance would a solar installation require?
One of the huge benefits to solar is it's resilience and durabilities. Throughout the lifetime of a solar system very little physical maintenance is required. Depending on the site of the installation it may be necessary to wash or clean the surface of the panels occasionally.
In colder environments, like Minnesota, snow build-up can cause low output during winter months. Fortunately due to design of the panels a day or two of direct sunlight will usually be enough to clear off much of that built-up snow and ice, this can always be removed manually if needed.
How big of a system should I have?
PV (photovoltaics), or solar electricity system size is commonly measured in kilowatts.
A kilowatt is a measurement of power, and 8kW means 8 kilowatts, or 8,000 Watts.
The average MN household uses about 10,000 kWh in a year. An 8kW solar array will generally produce about that much energy in a year. A typical roof in MN can generally support half of that, or 4kW, but many can support more!
How much electricity does a 8kW system produce?
To estimate annual electricity production from a solar electric system, multiply the system size (8kW) by the number of sunshine available on average (4.3 Peak Sun Hours), by 365 days, taking into account some system losses (80%).
8kW * 4.3PSH/day * 365 days * 80% = 10.0448kWh per year
NREL's PVWatts and the University of MN's Solar Map are great tools to help determine this yourself at home!
How large are the PV modules?
PV module size generally is based on cell count. 60 cell modules are generally around 325W and are about 39" by 66". Larger 72 cell modules that we use very commonly come in around 400W and are about 39" by 80".
What happens if the grid fails? Will I have power?
The vast majority of PV installations in the United States are tied into the electric grid. This is convenient, simple, and inexpensive. However, when the grid goes down, losing power due to a storm or other cause, even if you have a solar electric system, you will not have power either. When the grid goes down, you go down.
A battery back-up system will allow residences to maintain power even when the grid goes down and is therefore appealing to many people. However, adding batteries will add expense, generally 50% increase in cost of a grid-tied system.
In Minnesota, electric utilities are required to purchase excess power generated at retail rate, up to 40kW.
Is my home suitable for solar?
Solar panels are built to work in all climates, but in some cases, rooftops may not be suitable for solar systems due to age or tree cover. If there are trees near your home that create excessive shade on your roof, rooftop panels may not be the most ideal option. The size, shape, and slope of your roof are also important factors to consider. Typically, solar panels perform best on south-facing roofs with a slope between 15 and 40 degrees, though other roofs may be suitable too. You should also consider the age of your roof and how long until it will need replacement.
If a solar professional determines that your roof is not suitable for solar, or you don’t own your home, you can still benefit from solar energy. Community solar allows multiple people to benefit from a single, shared solar array that can be installed on- or off-site. Costs associated with purchasing and installing a solar energy system are divided among all of the participants, who are able to buy into the shared system at a level that best fits their budget.
How much is the U.S. Federal Tax Incentive?
A residential federal tax credit is available for solar energy systems. The credit is 26% of total installed project cost WAS EXTENDED UNTIL 2022!! Learn more and find state and local incentives.
The Corporate Federal Tax Credit is separate and doesn't fully expire. It is 26% for 2020-2022, 22% for 2023, 10% for 2024 and beyond. Business entities may apply MACRS Depreciation to their solar asset as well. This can return about 25% of project costs back depending on tax structures. For more information on the Corporate Tax Incentive visit: DSIRE USA