Forums

Sub Meter for my Home

Sub Meter for my Home

I currently have a 2019 Model 3D and find that I spend $60 a month to charge with Dominion in Ashburn, VA on a one rate plan. I need this as I have kids and a nanny at home during the day. I’m finding that if I get a sub meter installed and run that for the Tesla, it would only be $20 a month to charge the same amount. Is it worth it? Has anyone in Loudoun County done this? If so, for how much? Any recommendations for an electrician?

bosbynyc | 17/06/2019

It's all about playing the long game. You'll probably spend a couple of thousand getting a new meter and panel installed. It will take a few years before you break even and start saving.

nirava | 17/06/2019

Thanks. I have someone coming from Beacon Electric this Wednesday. Will see what they quote. I'm estimating about $40 per month in savings, which would only make sense if I can recoup within 2 years or maybe 3, so no more than $1500

Tronguy | 17/06/2019

For what it's worth: In New Jersey, if one has solar panels on the roof, it came to pass that one wasn't allowed to use the kW-hr generation numbers on the solar inverters in order to get SRECs (which are worth $$); a change was put in that required one to have a utility-grade meter, accurate to a percent (or whatever a utility grade meter is accurate to) on the solar panel outputs.
Since the first couple of estimates for the installation of such a meter came up at a grand or so, I started investigating. Turns out that there's lots of these kinds of meters; if one isn't putting one outdoors, one can get a nice, LCD-based display that's accurate and can't be cheated with for around $80 or so.
Installation wasn't a big deal: Run two wires at 240 VAC and ground to power the thing, then there's a pair of toroids that get installed with the wires that one is attempting to monitor going through each toroid. I read through on-line instructions from the manufacturing company a couple of times, then checked with an electrician I knew to make sure I hadn't lost my mind and it wasn't more complicated then that; went to Home Depot, got the conduit to carry the sense wires from point A to point B, and installed it all.
Further, went to the local town and got an electrical building permit, then had the local electrical inspector come down and give it a gander. He blessed it and sent me on my way.
Total cost was just over a $100 or so, including the permit.
This was about six years or so ago. New York State has, somewhere, a very long list of approved meters. The one I used, while handy for measuring solar power generation, has a primary purpose of allowing a landlord, say, to monitor the power usage of individual tenants.
You don't need the glassed-in traditional power meter unless you like the look.

OCModel3 | 17/06/2019

FWIW, Southern Cal Edison had a similar program for meters exclusively devoted to EV cars. I looked into earlier this year and the rep told me that they were abandoning the program. Those that have them can keep them and their rate plans, but no new ones would be offered.

I guess you can take this with a grain of salt, but the rep said they discovered the program was not very popular for EV owners given the upfront costs and permitting process (which in over-regulated California is no small concern). So they replaced the sub-meters with a Time of Use (TOU) plan that I adopted and have been very pleased with. Charging between 10PM and 8AM is only .12 kwh and we set the M3 charging to start at 11PM so it never charges at any higher rate.

I would not be surprised if VA and other states wind up dropping the sub-meters as well. So you should decide now if it is worth it to get it while they are offered and if they make that big of savings versus other plans.

TexasBob | 17/06/2019

Interested to see how this pans out for you. The meters themselves are only a few hundred dollars. The installation should be inexpensive if you are truly doing a submitter rather than adding capacity to the house. The DIY version would come in under $600. Please let us know what you discover.

nirava | 17/06/2019

Thanks, will do. I first contacted Dominion who said that having the off peak rate from 10pm - 7am, it would come to .02 per KW. Then one of their designers came by to say it was feasible to have a submeter at my home but knew nothing more. On Wednesday, I will find out the cost to do it and let you all know. Paying the current $60 a month to charge on my wall charger is not a big deal, but going down to $20 is tempting...

FISHEV | 17/06/2019

I'd suggest doing the sub-meter to getting the special rate even if install costs are a couple thousand. Don't see why they would be as it is a sub-meter, should be relatively inexpensive.

Reason for doing the sub meter is that utilities change daily on loving and then hating EV's and their policies change as the figure out how to make money from EV.

So you if you get the meter and low rate and then they change policy, they will likely leave you with your sub meter in place but do no new ones so you gain an advantage. One that might also go with the house if you sell in future.

kevin_rf | 17/06/2019

I went that route, installed a second meter, actually third, my utility requires a separate meter for solar panels. In my case, the utility supplies the meter, I just have supply the housing and everything else. $4 a month for the meter.

Fully licensed local contractor who works closely with the local municipal utility did the work. Permit, housing, 60a disconnect, 100' 6awg conduit run,
a little drywall work, wired into a HPWC was $1600.

Something to watch out for, if you currently have a single meter, going with a double meter housing instead of two separate housings. The double housing hookup is higher in the housing than the existing meter. Meaning, if you have a buried service, your existing wires won't reach the new attachment point. They will have to lower the meter, which can be a code violation. A separate housing can be mounted above the existing housing and jumpers into your main meter. That's what we did with my meter.

terminator9 | 17/06/2019

Do you have any links for Dominion EV sub-meter or off-peak rates? Everything I find online seems like is expired. I am also in Loudon and would like to explore this.

nirava | 19/06/2019

So, the Beacon Tech showed up this morning and quoted $2,000. As far as seeing the rates for off peak, what I did was call Dominion and got transferred to the special EV team who had all of the answers.

TexasBob | 19/06/2019

$2,000 is highway robbery! This is just a sub meter on your existing 200A service right? No new line into the house, no new breaker cabinet, just a $300 sub meter wired into one of your existing circuits. (I hate monopoly utilities!)

rxlawdude | 19/06/2019

Wow, the SCE meter pilot actually required nothing other than a device that measured current, and had a WiFi connection. A third party collected the usage data, and then transmitted that to SCE. Then, that consumption would be subtracted from the main meter usage and was billed at the then EV rate.

Accounting (looking at consumption on SCE's website) was a hot mess, and there was the inevitable finger pointing between SCE and the third party. (If SCE did not receive the data, it just billed based on the main meter.)

roger.klurfeld | 20/06/2019

I'm in northern VA too. From what I've seen, Dominion used to have a lower rate for EV charging. It closed for new applicants Sept. 2016. The latest discounted rate was effective March 2019. But it is good for only a maximum of 750 users who were in the program that closed in Sept. 2016. I would not trust what you were told over the phone. If you find otherwise, please let me know.