What ‘time of use’ means
At the beginning of this month, San Diego Gas & Electric instituted new TOU rates.
Approved by the California Public Utilities Commission, TOU pricing fluctuates to encourage customers to run appliances and devices that consume a lot of energy — such as air conditioners and washer/dryers — when demands on the power grid are not as high.
For example, SDG&E offers residential solar customers a couple of TOU options, dividing the hours of the day into peak, off-peak and “super” off-peak time frames
Here’s the breakdown on weekdays:
- On-peak: 4 p.m. to 9 p.m.
- Off-peak: 6 a.m. to 4 p.m. and 9 p.m. to midnight
- Super Off-peak: Midnight to 6 a.m.
And here’s the pricing that SDG&E offers households with a solar energy system during the summer months (June through October) when the grid often gets stressed from things like higher air conditioning usage:
- On-peak: 54.2 cents per kilowatt hour
- Off-peak: 27.9 cents per kilowatt hour
- Super Off-peak: 21.9 cents per kilowatt hour
The price differential during winter months (November through May) is much less dramatic — just two cents per kilowatt hour separating On-peak and Super Off-peak.
But clearly, during the summer months, there’s a big financial incentive for customers to use power during off-peak and super off-peak hours.
What it means for solar customers
And that has an effect on the approximately 120,000 SDG&E customers with rooftop solar systems that produce electricity during the course of the day.
“In this new world order, when you use energy is as important as how much energy you use,” said Daniel Sullivan, CEO of Sullivan Solar Power.
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