Fall is almost here, and with it cooler weather which I personally enjoy much more than the summer heat. It also means fewer hours of daylight as we head into winter. Normally that would mean the solar system that worked well in summer would only produce a fraction of what it produced a few months ago, leaving you with an electric bill.
Thankfully, Colorado's net metering law means the electric company credits you for all the excess you produce (typically in the summer). Then, as your system produces less in the fall and winter, they pull from your built up excess and credit your account accordingly. Note, they aren't literally storing that power. This is only through accounting.
When we design an on-grid rooftop solar system, our software knows to roll over any excess into future months. This picture shows the simulation results from a recent bid. Notice the green bars which show this system's production. Unless there is a shading issue all systems will look like this in Colorado. (Note: This is an east facing roof so produces less than a south facing roof would.)
Without net metering we'd either have to increase the size of the system to meet their electrical needs in winter, which adds expense, or the customer would accept having an electric bill for those months. They'd still be saving money, but not as much. Also, all the excess energy produced in the summer would be wasted as far as the homeowner is concerned.
Thankfully, all those months where production (green) outpaces consumption (grey) compensates for the winter months. That's why this system is able to produce 115% of last year's usage. This will of course change year by year due to weather and other variables.
Colorado law requires that electrical companies pay for the excess energy you produce at the end of their fiscal year. If your electric company does this in December, you will have an electric bill in January at the least, and likely February while your production is catching up. Those bills may not be large, especially if you use gas for heating. Xcel Energy provides an alternative, however. If you select indefinite roll-over they will never cash out your excess energy but allow you to roll it forward each year. While it sounds nice to be paid for your excess electricity, it is done at a very low rate so it's best to roll forward the excess.
IREA ends their fiscal year in May, so if you live in IREA territory you won't be affected by this issue as June is one of the best months for solar production.
Red Flag Alert
If you receive a quote and they did not use a month by month comparison, it's possible they are overestimating your financial benefits. Ask to see a month by month comparison. If they can't produce this data it's a red flag that their simulation software is likely of poor quality, assuming they use software at all.
For more information
If you'd like an accurate assessment of your current solar needs, contact us.As you just learned, we'll want your last 12 months of usage so if you send that with the email we can discuss your options more precisely from the beginning.