By Gwendolyn Craig
Here are some tips and tricks from two renewable energy developers on planning an off-grid home in the Adirondack Park:
Estimate how much battery storage you need
ADK Solar’s Broc Jennings said he will make a list of all household appliances and the number of hours a day they’re used to estimate electrical load. Jennings said they usually plan a battery storage system to hold two days of autonomy. Some people may want more.
Ray Falk, of Suntric, said a basic rule of thumb is to anticipate at least 1 kilowatt, or 1,000 watts, of energy per individual in a household. An average house could run off of 5 kilowatts of solar and about 18 kilowatts of battery storage.
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“When you’re talking about central air and all the creature comforts of the flat apartment in Any Town, USA, it’s going to take a system twice that size to live comfortably,” Falk said.
Jennings said their average systems tend to run 8 kilowatts with 16 kilowatts of storage.
Create your system
Once the battery storage is sized, a contractor will size an inverter system. It converts power from direct current to alternating current and charges the batteries from alternate sources, like a generator. The final step is sizing the solar, hydro or wind power system.
Based on interviews, people disfavor rooftop solar panels, as they proved difficult and dangerous to clear of snow. Many recommended pole-mounted panels that follow the path of the sun for the most efficient power capture. The pole systems also can tilt at a 64-degree angle, Jennings said, which helps the snow slide off.
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Balance system needs with your budget
Solar panels’ cost has decreased, Falk said; 5 kilowatts of solar cost about $4,500 now compared to about $45,000 20 years ago.
Lead-acid batteries are the least expensive, lithium-ion batteries are the middle ground and lithium-iron-phosphate are the most costly. Depending on the kind used, storage can range from $4,000 to over $10,000. If using lithium-iron-phosphate batteries, costs could be triple that, though they have more longevity.
Falk figured the average off-grid, full-time and turn-key system ranged between $40,000 and $60,000. That includes batteries and inverters.
Jennings estimated a small-scale system on average is $30,000, but he’s worked on systems in the $80,000 to $200,000 range. A $200,000 project ADK Solar is currently working on involves six lithium-ion batteries, six inverters, 48 solar panels on pole mounted trackers to follow the sun and powers an 8-bedroom, 10-bathroom home and a separate guest house.
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The average payback for panels is between eight and 10 years. Jennings estimated bigger systems with heat pumps could see payback in four to five years.
The upfront costs can be a challenge for people, Jennings said. “It’s a start to an end.”
ADK Solar said there are state and federal tax credits residents should be aware of, including a federal 30% tax credit even for off-grid homes. This is applied when you file your taxes, and unused credit can roll over for up to five years.
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This article first appeared in a recent issue of Adirondack Explorer magazine.
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Just because you are off grid doesn’t mean you can ignore electrical safety codes. That picture is rife with them
You can also estimate your needs by looking at your electric bill. Most company websites can provide a graph of your monthly usage over the year. This may be more accurate than trying to calculate usage of appliances that run irregularly such as a refrigerator or hot water heater.
Also look to the future, as some electric appliances such as heat pumps will be able to replace heat you currently get from a fossil fuel or wood.
I would add that the month of October (and other months too) may be cloudy for a week or more at a time, so you may want to store enough electricity for more than two days.
— VOICE OF EXPERIENCE, Adirondack off-grid since 2003.
The average system including batteries and inverters according to one of the suppliers is $40K to $60K and payback in 8 to 10 years? That implies an off grid system that replaces a traditional hybrid grid system that costs $5K to $6K a year? I think my calculator’s broken.
Right on Time!
The numbers in this story don’t make a lot of sense to me. But at the very least, it should be clarified that batteries are rated in KwH (kilowatt-hours) not kilowatts. It is a measure of how much total power is stored, not how much flows on a momentary basis.