We went solar and here are the real numbers

Solar power produced on our first full day of production, a sunny summer day except for some clouds in the afternoon that you can see in the chart as a bite in our solar energy production.
Energy produced over the first year aligned with our monthly electricity billing periods

The Benefits

Renewable energy

First, the obvious: The energy we consume from solar panels is energy we don’t get from a “non-renewable” source. (I’m putting “non-renewable” in scare quotes because solar panel production is not renewable, and some portion of grid energy is renewable. But let’s leave that aside for now.)

Solar panel array diagram from our Enphase monitoring system dashboard. The front of the house is at the top left.
The two days are centered around solar noon rather than clock time.

Lower energy bills

Any electricity we produce ourselves is electricity we’re not going to billed for by our local power utility. Our local utility has complex tiered pricing depending on how much power is consumed, with rates that change from month to month, so it’s impossible to know for sure what we would have paid for energy we weren’t billed for. The marginal electricity rate shown on our bills varies from about 10 to 12 cents per kWh.

Net metering

Although overall we produce less energy than we consume, there are many moments at the brightest parts of the day when we produce more than we consume at that moment. We don’t have a battery to hold onto that energy for another time (like at night when there is no solar energy), so that excess energy flows back into the power grid for someone else to use. With “net metering,” any energy that flows back into the power grid is credited to our utility bill.

Utility bill showing what we took from and sent back to the grid
Solar panel data for the same time period

The SREC market

On top of everything I’ve mentioned so far, there is another completely separate monetary benefit: SRECs. Keep in mind that this is double-dipping. It’s a benefit completely separate from the electricity we produce.

The Costs

Installation

The cost of the panels & installation was about $28,000. This will be offset by the generous 26% federal solar energy tax credit in next year’s taxes (but if you’re planning on going solar, this credit may have expired by the time you’re reading this).

Our solar panels are mounted on ballasts to avoid potential structural issues with the roof, which is commonly done for rowhouses. Photo courtesy of our installation crew.

Maintenance

We don’t yet have any numbers for maintenance costs. Or, rather, so far maintenance has been $0, but that will likely change due to:

  • Maintenance for the panels themselves and its monitoring components.
  • Higher maintenance costs for the roof, if the panels (or possibly worse, the ballasts holding the panels) have to be temporarily removed for better access to the roof. Our installer said that temporarily removing all of the panels would cost in the ballpark of $1,500 (they gave a real number but I forgot what it was and haven’t needed to know yet).

Environmental

Manufacturing, shipping, and installation of the panels are not without a cost to the environment. And when the panels reach their end of life in 30 or so years, the toxic components in the panels will become hazardous waste.

Will it pay for itself?

Our solar installer projected that through the lower utility bill, SREC credits, and federal tax credit we would recoup the installation cost in around 6 years. But because of panel output decline, unpredictable future electricity prices, unpredictable value of future SRECs, unknown maintenance costs, and even climate change or developments in the buildings or foliage around us that might impact the amount of sunlight on the panels, it’s impossible to know.

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Joshua Tauberer

Joshua Tauberer

Civic hacker/entrepreneur. Changing democracy. Changing myself. f/stop. https://razor.occams.info