Tadol said:
We have had PV on the house for many years, and are grandfathered in on an old PGE rate E6(?) - essentially its tiered with 2 time periods. noon to 6pm, and 6pm to noon.
So I'm looking for advice - do I sign up all our service for the EV-A, which has more tiers, but has an off peak max of under .10, or do I try for some submeter rate for charging the vehicles, or is there some other option - like a secondary solar array with micro inverters.
If anyone has a better grasp of this, and can offer any advice, or even point me to resources to get the information to do the analysis - I'd really appreciate it -
Yeah, sign up for a rate plan that gives you low overnight rates for charging your cars. The overnight rate can be many times less than the normal rates. Take a look at PG&E's pages:
http://www.pge.com/en/myhome/saveenergymoney/pev/rates/index.page?
Or the EV schedule:
http://www.pge.com/tariffs/tm2/pdf/ELEC_SCHEDS_EV.pdf
And similarly the solar-oriented ones. I'm actually still on my solar E6 time-of-use plan which still has decent overnight off-peak rates (.13) for charging that run longer (9 pm to 10 am weekdays) but better peak time period (1-7 pm weekdays in summer @ .32) to maximize credit from solar production. (Partial-peak is the shoulder time between peak and off-peak. And in winter, it's all off-peak except weekday evenings 5-8 pm.)
By comparison, the EV-A plan is peak from 2-9 pm and partial-peak 7 am - 2 pm and 9-11 p.m – so more partial-peak time (.23) but the peak rate is higher at .42 and off-peak is lower at .10.
And can't you see your usage via your SolarCity monitoring? With my SunPower system, I can see production and consumption over the course of the day (and week, month, year).
Also, you can guesstimate how much you're using to charge the car by thinking about roughly what percentage of a full normal charge (about 35 kWh ) you use and then adding it up, rounding up for charging overhead.
Here's the thread on this topic in this forum (PG&E Rates - Solar E-6 vs EV-A):
http://www.myrav4ev.com/forum/viewtopic.php?f=7&t=574