Charging from my Solar panels

I use an envision solar arc, which is a stand alone solar charging station with battery backup. When you crack it open it is essentially a residential battery backup system that uses the load to power the charging station. It disables the system when battery capacity reaches a preset amount.

When watching the solar production stats, the energy generated fluctuates quite a lot throughout the day, I'd be curious to learn how the clarity handles asking for 3-4kw but when solar array is generating a random value from .3 to 4kw in a given hour. (The EVarc subs this with battery power and works well)
It would be nice to have the ability to charge when PG&E leaves us all in the dark again this summer and fall.

 

There are some with lots of solar expertise here (not me), but I believe that most solar / micro-inverters are designed in a way that they cannot function without the grid being live (for synchronization). It is of course possible to have off-grid configurations, but they are much more specialized.

 

I have a solar system w/ micro inverters (Enphase M215). As @MrFixit stated, most microinverters are designed to be grid-tied, which means they don't function unless they're connected to the grid. If you want to charge exclusively from your panels, you will need to run a micro-grid to keep your panels producing power. But then you also need a way to sink the excess energy, so you would also want to get a battery back up to soak up any excess energy that's generated while it's off the grid. Otherwise, you'll need to throttle down the energy production to match the load (newer Enphase IQ series microinverters can do this.. my old M215's can only turn on/off, and it takes several minutes for them to turn back on each time, so it's not really practical in my case). But why would you want to throttle down your panels to match the load? That's just wasting solar energy that you could be generating.

A better approach is to just take advantage of being grid-tied. Let your panels generate as much power as possible, and feed the excess to the grid. If you wish, there are certain EVSEs that can tailor the energy draw to your solar output. So you could set the EVSE to charge your car only with whatever excess energy your panels are currently producing (basically, use the energy, instead of feeding it into the grid). This kind of setup is particularly good if you want to charge your car on purely solar power during the day.. say your solar panels are generating an excess of 3kW at a certain time.. the EVSE would automatically limit the charge to 3kW. However, there's a caveat.. J1772, the standard that the Clarity uses to talk to the EVSE, has a lower limit of 6A. So you can't set the EVSE to lower than 6A, so you can't tell the car to consume < 1440W @ 240V. An example of an EVSE that can self-adjust to solar output is OpenEVSE. However, it takes some expertise to set it up, and you have to have an external energy monitoring device to measure the net output of the solar, and feed that number to the EVSE.

I prefer to just let my solar panels run my electricity meter backwards during the day, and charge my car in the middle of the night. This has benefits for both the environment and my pocketbook. The panels feed power into the grid during the day, when electricity demand is higher,so the grid has more green power, and I am helping my utility to avoid firing up a dirty peaker plant to meet demand. By charging my car in the middle of the night, when demand is low, its high energy demand is less likely to contribute to making the utility fire up the peaker plant. Also, since I'm feeding the energy in during the day, when the cost/kWh is higher (off-peak and peak rates), and charging my car during super off peak rates, my energy cost is lower. Every utility has a different policy for electricity generation, so YMMV w/ the cost/kWh.

 

I also charge my Clarity using my solar panels that are tied to the grid. I just use the EV charger Time of Use feature to ensure charging happens only during the operation of my solar system. The EV charger is set to allow charging from 11 AM to 3 PM and the EV charger is set to allow only enough amperage to keep below the 5KW maximum of my Solar inverter. Attached is the image of my charge today against my solar production. Makes me feel good to know that my miles are solar-powered and also it maximizes the return on my solar system since I save more by using my solar power than I get by selling to the grid.

My advice is just to get devices with good software and set it up that way.

My power meter showing charging against solar production today.



My EV charger history:

 

I do charge the Clarity directly from the solar panels but only because I also have a Tesla Powerwall. So with the Tesla battery fully charged and over 3Kw being actively generated by the panels in the middle of the day I can fully charge the 17 kw Clarity battery at the highest Level 2 rate. Usually takes a little over 2 hours.

I have an Kia Niro EV also which usually is charged at night using whatever Powerwall capacity is left and TOU low rate grid power. When I am bored I also will add charge to the Kia during the day for a limited period if the Clarity isn’t charging and I have some Powerwall capacity. But I have to watch the declining capacity in that Powerwall to shutoff charging before the grid power kicks in.

Yes I am a retired engineer


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I have Solar panel installed by SolarMax, and uses the Enphase inverter for the unit.
currently SolarMax have new product for the Inverter that can also charge the EV - basically the inverter have EVSE unit build in.
But this new product can not work with Enphase Inverter, it's different brand ( Solartech if not mistaken). which has less warranty than Enphase - 12 years vs 25 years for ENphase.
If you plan to install Solar Panel and buy EV maybe can check this Product.
Electric Car Charging (solarmaxtech.com)