By Betsy Longendorfer • Building Electrification Committee
There are numerous articles about choosing solar panels, but not many about your experiences with them after they are installed.
Billing
Let’s assume that the electric utility and the contractor have sized your solar array such that it reasonably covers your needs, according to your past records and your planned future electric use.
You will be billed monthly for maintaining a connection to the grid (in our case, that is $5.75). Excess power that you produce but do not simultaneously consume is sent to the grid. If you have batteries installed, you will be able to store solar energy for when the sun isn’t shining or a grid outage. Most residential solar systems are designed to stop operating during a grid outage to avoid feeding power into the grid, which could be dangerous for workers. We chose not to install batteries because they were as expensive as the entire solar array, and we did not expect to have many power outages.
You will, of course, draw power from the grid during the night, as well as on cloudy days, and whenever you are using more electricity than you produce.
At the end of the billing period, the total electricity that you produced is subtracted from what you used. Short-term excess production will offset future bills. If you do not have enough production credits saved up, you will be billed for the difference.
At the end of each year’s solar panel installation anniversary, you will be paid (wholesale price) for any remaining production credits, your credit balance will be reduced to zero, and the credit accrual process begins again. Your unused production credits will be auctioned as solar renewable energy credits (SRECs) in a special marketplace, and you will be paid for those (approximately $90 currently), too.
SRECs were a rebate strategy to get people to install solar panels, and the incentive programs are being replaced and reduced as the price of solar installations comes down and fewer rebates are needed. An SREC is awarded every time your solar panels generate 1 MWh (or 1,000 kWh) of energy, even if you then consume it yourself or are paid for it in credits from your utility.
We have had our solar panels for two years, receiving a credit balance at the end of both years, and we paid out of pocket only one month out of the 24 (January 2024), because it was cloudy most of the month and our energy consumption was relatively high.
If your energy consumption pattern is like ours, you will produce more than you consume in the spring and fall, and you will break even or run a deficit in the summer and the winter.
Reports
Our solar panel manufacturer, Enphase, has an app for our smartphones that lets us monitor our panels in a very detailed way. It shows power production and consumption in 15-minute increments, as well as daily, monthly, and yearly. It also shows the functionality of each of the individual solar panels, so we can tell if they’re working properly or are being shaded by an overgrown branch.
We’ve been able to use the 15-minute incremental report (Graphic) to see our real-time import or export of energy. For you energy nerds out there, this shows exactly what happens to your energy usage when you turn on one appliance at a time (toaster oven, microwave, window A/C, lights, etc.). One of the interesting things we discovered was that our mini split heat pump was cycling on and off when it should have been running steadily at a higher efficiency.
There are also electricity usage reports from our electric utility. These include weekly usage, with any changes highlighted, and comparisons of electricity usage over the days of the week.
This level of detailed reporting causes you to think more carefully about changes you can make to reduce your usage.
Maintenance Considerations
One of the lessons we learned was the importance of making sure that your roof will last a long time prior to installing panels. We were assured by the installer that we had 10 years of life left, and it turned out to be just one. To avoid voiding the panel warranty, the original solar installer usually must remove and reinstall the panels, even if a different roofing contractor is used. The quote for the removal and reinstallation was quite high, although it added just a few hours to the whole job.
Squirrels or birds sometimes nest under the panels. Protective guards can be added to prevent access.
Future Plans
We did not plan for a heat pump or EV charging when we added the solar panels. While we do have extra production capacity at this time, we may not have enough for these devices.
While we did not install batteries initially, there are several developments that may compensate. EVs are being built with batteries that can power a home for short periods of time and even supply power to the grid. There are also standalone portable solar-powered generators/batteries that can power a home for short periods of time. These might be a better investment than dedicated batteries.
