Quietly and without fanfare, my local utility, PG&E, has gone live with fabulous new functionality for its customers with smart meters who now have nine months or more of smart meter data — about 80% of PG&E customers.

These customers can now compare rates, and see the savings they could expect from switching rates.

I just checked my mother-in-law’s energy usage. (I handle Mom’s business affairs.) I found that she can save 7% on her annual electric bill by switching from her current rate to PG&E’s E-6 Smart rate plan. This estimate is not based on algorithms or forecasts; it’s based on her actual energy usage data, measured every 15 minutes by her smart meter.

Her current plan does not vary by time of day. The E-6 Smart option is a time-of-use rate, with critical peak events. PG&E also offers E-6 (time-of-use without critical peak events). On the E-6 Smart rate, the price of electricity changes by time of day. Also, overall prices are lower on most summer days, but will be higher on up to 15 especially hot afternoons.

The key points:

• Prices are lowest:Overnight, weekends, and holidays in summer and winter.
• Prices are low:Weekday mornings and evenings in summer and winter
• Prices are high:Summer weekday afternoons, 1-7 pm.
• Prices are highest during critical peak events: Summer afternoons 2-7pm on up to 15 hot summer afternoons. PG&E calls these “SmartDays.”

On top of the 7% savings, Mom could save even more money by shifting some of her usage from peak hours to other times.

As if that wasn’t enough, PG&E offers bill protection — so she can try this rate risk free. If in her first year her bills end up being higher, PG&E will refund the difference.

If you have the good fortune to be a PG&E customer, you can see how you’d fare yourself. Log in to your account at PGE.com, click on the “My Usage” tab, then “My Rates.”

Mom’s reaction? “Of course I want to try it!”

Here’s the result of Mom’s online analysis from PG&E:

PG&E customer rate comparison. (Click to enlarge.)