New info for SDG&E installations: Second meter

I had a chance to talk to SDG&E about the EVSE installations that are part of EV Project, and learned some important things.

First, a second utility meter is still required, as they have said before.

The same EV Project (subcontracted) electrician that installs the EVSE will also install a breaker/lock-out box, and a socket to accept a new meter. These will be "surface mount" and near our existing rate meter.

The electrician will bill EV Project for the EVSE installation, and also bill SDG&E for the portion of the labor & materials required for the new meter. SDG&E is picking up the tab for these (not from EV/ARRA funds).

Once the socket, breaker, and EVSE are installed, the City will inspect it first, and then SDG&E will inspect it next. SDG&E will energize the socket, install the new secondary meter, and seal it. For EV Project participants, there is no installation or monthly charge for the additional rate meter.

The new meter will be on the randomly-assigned experimental EV-TOU rate plan, and billed separately from the primary residential meter.

The EVSE meter is "downstream" of the main meter, connected in series, so the billing for the residence involves subtractive math. (They are not in parallel, and the total service amps remains the same.)

There is no way to net out the EVSE usage by PV generation on the primary meter, since they are billed separately.


As an aside, the rate plan that will replace the available-to-anyone EV-TOU-3 will be published in Q1 2011. This is unrelated to the EV Project folks, except that it's the likely plan we will end using after the experimental rates.

GroundLoop said:

As an aside, the rate plan that will replace the available-to-anyone EV-TOU-3 will be published in Q1 2011. This is unrelated to the EV Project folks, except that it's the likely plan we will end using after the experimental rates.

Click to expand...

I hope the monthly charge for the second meter will NOT be coming back after the end of the EV project!

Is the second meter they install a "smart meter" that communicates usage data to SDG&E remotely, or are they going to have to come out to read it every month?

After the end of the EV project, are we going to keep this dual-billing setup, with DR rates on the house and EV-TOU rates on the EVSE circuit, or will they put the whole residence on the TOU billing rate plan? I still don't quite understand what will happen after the end of the EVP.

TT

Being in SDG&E but not in the EVProject:
this new Q1 plan might be an option for me.

For now, I guess (with my curently over-producing PV) I will just
stay with my tiered Net metering, and then I can charge anytime,
until they give me an incentive to do otherwise.

Except for the hot A/C months, I should be able to drive
a fair amount at no cost for about 5 months, and in
tier 1 another 4 or 5 months.

So, it is lkely that the cost of the extra work to install a 2nd meter,
amd its possibly extra monthly fee, would make it a poor choice, with my PV.

It's good to see that there is now some information about how SDG&E will install its meter to support the EV Project participants. Do you happen to know the answers to these questions:

1. How large is the surface mount meter socket/breaker? I have a lot of hardware next to my existing meter and electrical panel to support my PV system.

2. You mentioned that the new meter box will have a breaker? So that means that a separate breaker in the electrical panel is not necessary because the second meter will be wired directly to Blink?

3. I understand that because the second meter is in series with the first meter, that the billing will need to adjust for that. But I'm a little confused about how this works with PV. The PV system feeds into breakers in the electrical panel and when the PV system is producing excess kWs, the energy flows back through the first meter, thus producing credits. But won't this also produce credits on the second meter because it is wired in series (e.g. won't it spin backwards too)?

4 My first meter is a time-of-use meter but which uses different time of use periods than the second EV meter because it is on a different SDG&E rate shedule. Will this be a problem?

1: I have no idea, but I imagine it will be a standard size meter and socket. I raised the same concern, that there's not much exterior space left on that stucco wall, and he seemed confident they would find a place for it.

2: I could be wrong, but it sounded like more than a breaker. It is probably a lockable interrupt, like the one required for PV installations -- a box with a removable link or switch, and a hasp for a padlock. This would be separate from the breaker. From the sound of it, if the downstream meter attaches to the existing service panel, it might not need a new breaker in your existing service panel. I confess I didn't follow this precisely, but it might be worth asking again.

3: Your primary meter (with the PV attached) will spin forward and back, just as it does now. The PV will not impact the second meter reading, since the only thing plugged into the second meter is your EVSE. It will stand still while your PV generates. (Your house stays on the primary meter.) So really, it's like having a utility meter right in front of your Blink EVSE.

4: I wonder about this too. The TOU times might not be in sync with the experimental EV TOU times. That seems like it would make it impossible to accurately subtract out each EVSE reading. They would have to line up the timeslots, or have none that overlap. Hmm.


I'm not sure charging on DR is a good idea for me, since I'm already close to baseline (with PV). If each kW is good for four miles, then the distance between Baseline (300kWh/mo) and 130% Baseline (400kWh/mo) is only 400 miles a month. Getting over 130% gets expensive, so I'm actually happy to keep my EVSE accumulation on a separate meter.

Thanks for the explanation GroundLoop. I haven't yet found an SDG&E representative that could answer questions like these. Hopefully we will get some additional information before the installation occurs.