Tuesday, July 10, 2018

Suburban 5-4-and-a-Door Solar: Which Rate Plan is the Best?

With a years worth of data to analyze, one of the questions we asked is whether or not we are on the right rate plan. Georgia Power offers three plans that are relevant to us. The one we are on now is a flat plan. It costs the same amount to use power at any time of the day. The cost per kWh rises as we use more power during a billing period, but there is no dependence on when we use that power.

The two other options are the Nights and Weekends plan and the PEV (Plug-in Electic Vehicle) plan. Each of those has a rate that changes depending on when you use power. The Nights and Weekends plan has a lower rate outside of the hours of 2pm and 7pm, Monday through Friday. The PEV plan has high rates from 2pm to 7pm Monday through Friday and very low rates from 11pm to 7am every day.

Since our smart meter give us access to our power usage every 15 minutes, we can make a good estimate of what our bills would be under the other rates. (Although one can never be entirely sure - read here for how we estimate some of the fees and charges.)

Based on our calculations and current usage schedule, we wouldn't see a whole lot of savings under the other plans. Our estimate is that we'd save about $41 over the year with the Nights and Weekends rate and about $48 with the PEV rate. It's not nothing, but it's not enough to make us change our plan immediately.

Since Georgia Power only allows changes in residential rate plans once a year, we wanted to wait a year to see exactly what our usage would be before making a change. And since the flat rate was actually lower cost in June, we'll probably wait a month or so to make the change this year.

We suspect that once we change to a different rate, our usage may change as well. We'll be more careful about using power during those low cost times and set the dishwasher and other appliances to run after 11pm. However, since there are two of us working at home right now, there's not a lot we can do to change our patterns. For people who aren't home during the day or who have batteries that can arbitrage power (buy during low cost periods, use battery during high cost periods), your options will likely be more clear.

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