"I'm thinking I can get some extra panels in over the addition on my garage..."

A letter sent by San Diego Gas & Electric to customers with home solar systems has left some subscribers confused and even worried about the future of their ratepayer agreements with the utility.

"Basically, I trust SDG&E as far as I can spit," says Bob Camacho, a 30-year resident of Scripps Ranch and a retired teacher who most recently taught at Hoover High.

"We were getting killed with electrical bills every month, so I did a little research and decided to put some solar panels up," Camacho continues, explaining that he had a system installed in early 2015, before the utility required new solar customers to adhere to a "time of use" plan that varies the cost of electricity based on the time at which it's consumed. He says that under his current plan he receives a modest rebate for excess power generation at the end of the year.

"My payout works out to something less than $250 a year. I don't look at the bill too closely, but I know they nitpick you for a bunch of little fees that add up."

Last month, Camacho received a letter from the utility notifying him that he had an option to switch to a time-of-use plan, but the choice had to be made quickly because "the California Public Utilities Commission (CPUC) approved changes to electric rates for SDG&E customers."

"It's really confusing — they basically gave you 30 days to do your research and decide whether to change over, but they don't really make it clear that changing is totally optional," Camacho said. After spending a few weeks seeking information on what the changes meant, he contacted SDG&E for help.

"They offered to set me up with a solar specialist, but not until after the deadline to make the choice," Camacho continued, an assertion backed up by a copy of a chat transcript from July 28, the deadline SDG&E had imposed for solar customers to make a rate selection.

Those rate changes, as posted on SDG&E's website, are likely to come as a shock to solar owners.

Under the existing time-of-use system, summer "on-peak" hours run from 11 a.m. to 6 p.m., with "semi-peak" times bracketing this from 6 a.m. to 10 p.m. "Off-peak" hours, when electricity costs the least, run from 10 p.m. to 6 a.m.

After the change, the on-peak period will shift to 3 p.m. to 9 p.m., with off-peak running all other times except "super off-peak" hours running from midnight to 2 p.m. on weekends and holidays and from midnight to 6 a.m. weekdays.

The closer to peak demand on the grid, the more a utility can charge users for electricity. By shifting peak hours into the evening when solar systems are less productive, solar customers will end up paying more for the electricity they buy off the grid and less for the excess power they feed back into it. Solar advocates have decried the change, arguing that the CPUC broke its own rules in allowing the new rates.

Still, Camacho says he plans to double down on his solar investment.

"I'm going to approach the people who put in my system and talk about adding some more panels. The system I have now generates about 80 percent of what I need, but I'm thinking I can get some extra panels in over the addition on my garage, or maybe on a patio cover in my backyard....I just don't want to pay anything more to the utility — aren't we already one of the most expensive markets in the country?"