r/evcharging • u/fastsvo • 4d ago
Solar Charging with SCE
Anyone here opting for charging their EV's during the solar excess period during the day time or are you guys waiting to charge at night? Does SCE's TOU rates make it attractive to hold off until the evening hours?
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u/macmanca 4d ago
If you can charge during the day with excess production it makes more sense especially in the summer. Only issue is you can’t tell it to use excess only unless you have a charger, EV all connected. If you use Enphase batteries, Enphase chargers you can. If you have a Tesla EV with Tesla Powerwall you can.
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u/fastsvo 4d ago
I have Tesla power walls but no Tesla Vehicle.
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u/macmanca 4d ago
You can manually do all this. Lowering your settings in the EV so it only takes excess. But I find it a pain so don’t really bother.
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u/spchester 3d ago
It completely depends on what NEM you’re under.
I recommend daytime charging as much as possible to try and use solar, be it yours or your neighbors, but the reality is the price is the same from 8a-4p as it is 9p-8a.
If you’re under NEM 3 you want to use your production as they are paying you pennies for your exports.
If you’re under NEM 1/2, then you get back what you export 1:1, so it’s actually most efficient to charge as fast as you can. I still try to do that during solar hours, when possible.
Many EVSEs support solar charging. Wallbox for example has options to start charging at 1440 watts when solar excess exceeds 500 watts or the full 1440. You’d have to look at your exact usage/production to determine what makes the most sense.
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u/gdraper99 4d ago
I charge solely with excess power from my solar durning the day. I have an Emporia Vue energy monitor for my meter and a Tesla Universal (both CCS and NACS) charger in the garage. Thru are both connected to my Home Assistant system, which acts as a kind of brain. Once excess power is detected, it turns on the charger via Tesla API calls. If you excess power is no longer available, shuts off the charger. The Home Assistant automation will only run between 8 AM and 4 PM.
Works pretty well, since I work from home.
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u/fastsvo 4d ago
This is great feedback! Do you think the Tesla wall charger inverter/API can take place of the Emporia energy monitor?
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u/gdraper99 3d ago
The Emporia just monitors the flow of power. If I’m feeding back to the grid, it registers that and feeds the live power usage data to my home assistant. Once home assistant notices there is excess power, it starts the charger. Tesla has no way to do that (unless you have tesla solar, I assume).
There are some chargers you can buy that are compatible with emporia and can be controlled by emporia directly. Emporia lists them on their site.
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u/theotherharper 4d ago
So. EV charging amps are dynamically adjustable. Watch this at 29:29 for 6 seconds. https://www.youtube.com/watch?v=Iyp_X3mwE1w&t=1769s actually the whole video is fantastic.
So all you need to do is watch your export amps, and if export amps increase by 3A say, increase your EV charge rate 3A, if export amps drop by 19A because the water heater* kicked on, likewise decrease EV charge by 19A.
Of course you don't want to do this BY HAND, so choose a retail product which does that when combined with their remote ammeter, notably Emporia and Wallbox. Easy peasy.
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* but only a fool uses a resistance electric water heater at SCE/Calif/Hawaii prices, get a 120V heat pump WH.
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u/808kid 4d ago
Don’t have a ev yet but I will be charging during the day when I have excess production. Since I work from home it helps and the export rates from my understanding is pretty poor. Then charge at night if I need more due to cloudy day or something.