Questions about a "free" JuiceBox EVSE on Oahu

For Oahu electric vehicle owners: have you bought a “free” EVSE?
https://evcharging.enelx.com/eex-store

We’ve been charging our Nissan Leafs just fine so far with the OEM 110v L1 cord. Now we’ve ordered a JuiceBox Pro 40 240v L2 EVSE as part of a HECO research project.
https://evcharging.enelx.com/eex-store/juicebox-pro-40-heco

The program has been around for a couple months-- if you’re already participating then I’d love to read what you’ve learned so far:
https://www.hawaiianelectric.com/smart-charge-hawaii-program-to-make-free-ev-charging-stations-available-to-residents-and-businesses

I’ve read a few of this forum’s JuiceBox threads and I understand the basics. Does anyone else here have EVSE experience to share about a newer JuiceBox Pro 40? HECO wants us to have it on our WiFi router for their data collection, and our signal in the garage is weak but usable. If our signal is too weak then I’d rather plug in an Ethernet cable than boost the router.

We'd mount the EVSE on the inside garage wall near our circuit-breaker panel. Our 30-year-old 240v circuit breaker for our electric dryer receptacle is only 30 amps, which might slow down the L2 charge. If we want to put a dedicated 240v EVSE breaker in our garage box then we’re probably going to have to move around another circuit breaker to make room, although I’m not sure how large we could go by our local electrical code. The 240v circuit breaker for our kitchen range is already 50 amps, so ideally we’d be able to add a second 50-amp breaker for the EVSE... or whatever capacity is appropriate.

Please let me know if you can recommend an Oahu electrician. (I understand home electrical systems but I’m inexperienced with the NEC.) We’ll hire an electrician to mess around in our circuit-breaker panel and hopefully do it right the first time.

Whether we use the dryer receptacle or a dedicated circuit, our home’s electrical load is very low. We have a solar water heater and no heating or air conditioning (only ceiling fans). Our biggest starting surge is probably our refrigerator or a vacuum cleaner.

We also have a 4KW photovoltaic array and one of Oahu’s original net-metering agreements from 2005, so our power is essentially free at all hours. HECO won’t use time-of-day metering on us and our only utility expense is the $18/month connection fee. I’ve run the array’s numbers through PVWatts and it looks like we’ll have more than enough annual production to supply our Leafs (one at a time) and our house.

Nords said:

If our signal is too weak then I’d rather plug in an Ethernet cable than boost the router.

Click to expand...

My version of the JuiceBox doesn't have an Ethernet jack, although it's possible this has changed. (They change specs without changing the model name.)

Our 30-year-old 240v circuit breaker for our electric dryer receptacle is only 30 amps, which might slow down the L2 charge.

Click to expand...

Not much -- the Leaf can only draw ~27.5 A in any case. (That sounds like less than 30, but on a 30 A circuit, continuous draws should be limited to 24 A. I think there are some settings to restrict this in the JuiceBox app, although I didn't have to limit mine.)

We're up and running.

wmcbrine said:

Nords said:

If our signal is too weak then I’d rather plug in an Ethernet cable than boost the router.

Click to expand...

My version of the JuiceBox doesn't have an Ethernet jack, although it's possible this has changed. (They change specs without changing the model name.)

Click to expand...

Thanks, ours doesn't have one either... on the outside anyway. It's a sealed box with no other external connections, and I'm not going to open up the case before the HECO program ends in 2022.

Our WiFi signal is very weak in the garage (intentionally), and the JuiceBox struggled for a few minutes to log in. I moved our router (at the other end of the house) a few feet closer to a doorway, and the JuiceBox eventually connected and has stayed on the network.

I really appreciate the app's data showing us how much of our energy consumption goes to our EVs. It looks like a 4KW solar array should generate enough power for both of them and our house. We'll certainly catch up when we're on travel and the cars are just sitting in the garage.

wmcbrine said:

Our 30-year-old 240v circuit breaker for our electric dryer receptacle is only 30 amps, which might slow down the L2 charge.

Click to expand...

Not much -- the Leaf can only draw ~27.5 A in any case. (That sounds like more than 30, but on a 30 A circuit, continuous draws should be limited to 24 A. I think there are some settings to restrict this in the JuiceBox app, although I didn't have to limit mine.)

Click to expand...

We brought in an electrician to install a 50-amp breaker and a new receptacle. (And to inspect & clean the service drop and the rest of the 30-year-old distribution panel.) He moved one breaker over to the left side to make room for the double-pole breaker on the right, and it all works fine.

The EV seems to limit itself to 27 A (from what I see on the JuiceBox app during a charge) but we've only charged a couple of times. I didn't realize our 2015 Leaf would run its cooling fan during a L2 charge.

We only have a 100-amp service drop but we'll never be simultaneously running the electric oven, the electric dryer, and a Leaf charge at the same time.

It'll be interesting to see whether HECO has enough EV-charging load on the evenings and midwatches to cause them to have the JuiceBox reschedule a charge. The L2 charger is much faster and we might end up doing most of our charges during daylight hours anyway. That'd come straight out of our photovoltaic inverter and HECO would never see much of that load on the grid.

Nords said:

It'll be interesting to see whether HECO has enough EV-charging load on the evenings and midwatches to cause them to have the JuiceBox reschedule a charge. The L2 charger is much faster and we might end up doing most of our charges during daylight hours anyway. That'd come straight out of our photovoltaic inverter and HECO would never see much of that load on the grid.

Click to expand...

Fully Charged did a video on a charging station sold in the UK (called zappi) that will work with your photovoltaic (PV) system to charge your car when you have excess PV energy or when grid prices are lowest. It would be nice if something like that was available in North America. The priority for PV energy should be:

1. Supply current demand in your home
2. Charge your EV
3. Charge your batteries
4. Sell to the grid*

* Selling to the grid could be a higher priority if the rate they will pay you is higher than the off peak rate (sell high, buy low).

roger1818 said:

Fully Charged did a video on a charging station sold in the UK (called zappi) that will work with your photovoltaic (PV) system to charge your car when you have excess PV energy or when grid prices are lowest. It would be nice if something like that was available in North America.

Click to expand...

Yeah, JuiceBox doesn't seem to do that.

Our app defaults to starting charges after 11 PM, although we can override that to start right away or at some time before 11 PM. The 11 PM default is supposedly based on HECO's time-of-day rates, but those rates don't apply to our ancient version of HECO's net-metering agreement. Either HECO messed up that detail of the pilot with Enel X or they don't care.

Now that Enel X has our JuiceBox registered in their server, it's never charged our EVs before 11 PM. Usually it starts the charge around 2 AM and finishes around 3-5 AM. If we want to charge on our own schedule then we have to override the app.

Under HECO's 2005 net-metering agreement we're compensated for our PV production at the retail rate (KWhr for Kwhr), and our excess credit can be carried forward on a 12-month rolling total, but we're not able to cash out that excess. It's just truncated from the spreadsheet after 12 months. We pay roughly $18/month to be connected to HECO's grid voltage and we don't have to care what time of day we charge our EVs.

Of course HECO cares about peak loads and generator capacity, but if they were tracking our PV production as part of this pilot then they'd happily charge our EVs while the sun is shining. HECO's current net metering agreement with new PV customers is different because I don't think customers are compensated for excess PV production. They might not even be able to dump power into the grid after they charge their batteries.