Charging EV w/Excess (Export) Solar (Emporia)

[2TrevorJ]

So, Jasonhc73 on here posted on a (different) FB group about Emporia's EV Chargers and their "Excess Solar" function that charges only when exporting and dynamically adjusts current to match export (until pegged).

https://help.emporiaenergy.com/hc/en-us/articles/9227254158103-Excess-Solar-Management

I jumped in based on his recommendation and purchased one of their chargers and a VUE Gen 2 energy monitor to feed it export info and holy crap...it works!. I armed it last night and this morning once my house ESS battery was full (from running the house overnight) and export started the Emporia system watched the export for a bit then fired up automatically; ramping up output over ~9 minutes to the max my car would accept. Later in the cycle the sun went away for 2-3 minutes and the Emporia modulated EV charging current to maintain a slight export through the power reduction. Once the clouds cleared it went back to max automatically until I shut it down when the car hit 82% (where I normally stop).

I'm not sure if I believe it but I found some info that Emporia learns your system's normal export pattern and makes some assumptions about when and how much charging current might be available. Sounds like it won't be so hesitant to watch the export for 3-4 minutes then ramp slowly like it was with my first use. Again...sounds like some advanced stuff so it could be marketing.

Now, one kicker is I run my house off battery whenever solar isn't sufficient and as such I believe there is a possibility that as the sun goes down or a cloud passes overhead and my export nears zero the EV could keep charging because the power just keeps on coming; slowly transitioning the source from solar to my house's ESS for power. To get around this I figured out that I can set the max ESS battery draw during the EV charging window to <240W (1A @ 240V - one "unit" in the charger's adjustment range) so that the effective power will decrease and the EV charger will step down 1A at a time until it shuts down when it sees <1440W available (6A @ 240V - the minimum the charger can run at). With this you might have to pull a bit of grid if there's a spike in home load but it's the best thing I could come up with. ?‍

Sure beats watching production and manually starting/stopping the charger to keep from dumping my ESS's juice into the car (or turning off/on TOU).
?
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[goldserve]

Not doubt this sounds like the way to go if you don’t have a way to set up your own infrastructure to do mqtt and other services to allow you to do the same with openevse and solar divert option.

I run a server with dockers that host a mqtt service and another service to query the Envoy consumption meters to figure out how much I am exporting.

The openevse has a function to set an export threshold before following the pv excess amount to charge. Minimum is 6A @ 240V and if solar goes under this amount, there is a minimum turn on time to prevent the delay from excess activations. I believe this is 600 seconds.

Reach out to me if anyone wants more details.

 

[niktak11]

Will it work in a "limited to home" scenario? Like have it throttle down until I'm only importing 100W.

 

[2TrevorJ]

Will it work in a "limited to home" scenario? Like have it throttle down until I'm only importing 100W.

I don't think so as the "excess solar" function is looking for export to initially activate and then regulate charging current.

 

[goldserve]

For ev charging, the protocol has a minimum of 6A and it can go up in 1A increments. That means the minimum it can 1440w + 240W. If you set as level 1, I guess you can regulate 720w + 120w

 

[hayhayday]

Will it work in a "limited to home" scenario? Like have it throttle down until I'm only importing 100W.

You might be able to set it to 0.1-0.2kw using the peak demand setting instead of excess solar. It uses a 15 min interval so if you are below the level it will start charging and cycle on/off to keep interval under setting even if less than 6A average.

 

[yabert]

Lot of good info here. Thanks to share.

 

[2TrevorJ]

Just got some data from charging as the sun went down. Was regulating pretty well during the initial hit (6.6 kW is my car's max) but after it initially shut down as production waned it reactivated multiple times drawing a bit too much current (8-11A / 1.95-2.68 kW) for what being exported at the time (1.5-1.8 kW). You would think in that situation it would start conservative at 6A / 1440W and "try it on for size" prior to going for more amps.

 

[hayhayday]

I find on mine it tends to overshoot then overcorrects and repeats. I found that changing the circuit breaker size(15-30A depending on time of year for me \ expected max export) in the settings to a lower value reduces the effect somewhat. If the evse or consumption meter looses connectivity it also may go into override and charge at full speed (11.5kw for me) causing significant imports which are also mitigated by lower breaker value. I have also use the TOU setting to shut off about an hour or two before sundown as charging at 1-2kw is pretty inefficient as some cars use 3-500w just to stay awake.

 

[2TrevorJ]

I left the max charge at 40A after install...I might try dropping that to 26A since that's all I'll ever see with this Leaf. Sounds like it might help out a bit.

 

[2TrevorJ]

Check out the attached. Not bad...not bad! ? Low power overcast day today so it was a good test. The low load window was when the wife took the car on a trip.

Temporarily limiting available house battery power to <220W seems to be doing the trick to keep from discharging the house battery to charge the car.

All is not rosy though. Yesterday evening we cranked up the oven (3.3 kW) when export power was medium-low and the Emporia EVSE shut down and restarted 7x in 35 minutes as the oven cycled to maintain target temp. Probably not optimal for the charger & car contactors to keep cycling like that. I'm not surprised or miffed at how it performed but I wouldn't recommend excess solar mode charging when you're (relatively) low on export power and you have 2+ kW intermittent loads. Be curious to see how it does in similar power conditions with my 3 & 4-ton A/C units in the mix (probably not good either).

 

[2TrevorJ]

Temporarily limiting available house battery power to <220W seems to be doing the trick to keep from discharging the house battery to charge the car.

Circling back on this, I had multiple issues in the last couple weeks with my two 15K Sol-Arks intermittently limiting solar production while utilizing Emporia's Excess Solar function and the aforementioned setting. PV Voltage would shoot up to max and current would drop though the floor on all 6 MPPTs (overall dropping from 14-15 kW to 5-6 kW) with:

Limited Power to Load
Max Solar Power - 18000W
Grid Sell - 16000W
Time-of-Use: On
Time-of-Use Max Power: 110W (remember this is per inverter)
Time-of-Use Min Battery: 1%

As production took a nose dive the charger would match what was available. It just knew there wasn't enough export to run full bore 26-27A.

I touched base with Sol-Ark support and they said it looks like the system "curtailed the solar power to stop charging the battery." Battery voltage at the time was higher than normal (52.6V / 3.51V per cell - absorb is listed by the mfg at 52.5V) vs the 51.7V-51.8V it usually hangs at when 100% SOC but that still doesn't jive when unlimited grid sell is active. Keep in mind this is all closed-loop battery comms.

Sol-Ark pushed a new comm update (143F-1726) to my master 15K and recommended I update the batteries (which I did). I haven't rechecked the config as I found just turning off Time-of-Use while utilizing Emporia's Excess Solar to work great. Zero MPPT/production issues since and the charger current tracks great with what is available when solar production is less than stellar.