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Solar charge EV from inverter... no batteries (yet)

chateau_nomad

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Joined
Jun 22, 2023
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Lancaster
Ohio native here. We have a 2022 Chevy Bolt EUV. We bought the car new and had a 50 amp outlet installed in the garage, which has been our primary charging source. Wife & I are now both retired, so the car is often parked during prime daylight hours in the garage. We are semi-rural, and often do 100 -150+ mile "day trips". In addition, we add a fair amount of miles just puttering around town with errands etc. Being retired, we have the uncommon luxury of planning our charging.

I have a roof area adjacent to the garage I roughly estimate will hold ten 400 watt panels. I have easy access to the garage for cabling, etc. Since we don't need storage (at least initially) I would like to start with installing the panels and a capable inverter to directly charge, using a manual transfer switch to convert from grid to inverter as needed. This would be a start... then maybe at a later date add a bank of LiFePO4 batteries for storage. But for now, we have the luxury of direct charging from solar and want to start there.

Obvious questions: Does this sound viable? What would I expect to pay for a "STARTER" setup like this... which could be expanded later if needed? This would be a self-install. I haven't killed myself yet installing solar and lithium in our motorhome!

Thanks!! Suggestions and critiques (and criticisms) welcome!
 
400 watts is like a single panel. Are you really that short on roof space?
In general, your proposed ideas doesn't work well.

The specs for EVSE has a minimum charge rate of 6 amps. So, 6 amps at 120 volts is 720 watts. You'd need more PV.

Second is the lack of communication between the solar and car/EVSE. If a cloud rolls past and output drops down to 40 watts, the inverter browns out and will likely cause EVSE (or worse case, faults on the car side)

The way I do it is grid tie solar and EVSE, then some communication and smarts in the background to actively adjust car charging to match available solar.
But I've got over 7,000 watts of solar.

At 400 watts, your probably charging at a out 1 mile of range per hour. I don't know Ohio's numbers, but maybe 4 hours of sun. So, 4 miles of range per day for your proposed, 400 watts of solar. Even at 800 watts (to meet the min spec for the EVSE communication), that's only 8 miles per day. Would take a long time to recharge after a 150 mile trip.

I'm all for charging from solar, but your an order of magnitude from the amount of solar I'd go with.
 
Well, that's much better! Makes so much more sense and is a lot more feasible.

Do you have an reason not to do grid tie solar? With grid tie, you can power other portions of the house when the car is not charging. With a system dedicated to the EVSE, it's just idle with lost production any time the car is not charging or once full.
 
Mainly cost and complexity. I want to DIY and keep it simple... solar panels, charge controller, inverter and associated cabling/mounting hardware etc. At nearly 70 years of age I have no interest in recouping investment over 25 years.

We have lost power here maybe twice in seven years, and I have a 6.5k generator to cover that. Although lithium is cheaper than ever, battery storage of reasonable amount for home use is still quite expensive... and unnecessary if I'm dumping directly into the car battery.

A typical charging session with the grid 50 amp is usually less than three hours, often less. Even though a grid tied setup would pay me for those "wasted amps", the recovery of initial expense would take several years. If anything I would set up a trickle charger for my (much less driven) Jeep Wrangler, and also charge power packs for lawn tools.
 
So ultimately what would I expect to pay for 10 400 watt panels, a capable charge controller, inverter, mounting hardware and manual transfer switch? I realize cable will be dependent on run length. Just trying to ballpark a budget.
 
No charge controller, panels hook directly to the inverter's integrated MPPT(s).

You don't really have any option that will work without a battery and some communication. Even a single small battery to keep the inverter alive/awake overnight and cover any multi second delays between communication and action (the car changing charge current)

For example, if your PV output is 3200 watts one moment, then some clouds roll past and your doing 300 watts, something needs to change.

50 amps of charging is 12kW. You're looking at more like 13-16 amps.
Remember that even on a perfectly sunny day, solar production is a curve ramping up from 0 in the morning to only hit the peak for a short period in the afternoon, that will rarely (more than likely never) hit the name plate rating on the panels. Then you have clouds or shade from trees.

To make it work, you'll need an inverter that can communicate with something (possibly Home Assistant, Emporia, etc) and an EVSE that can take external control/input from the same system (Home Assistant or Emporia)
Then the bare minimum, smallest 48 volt battery you can find to cover the gaps and keep things awake overnight.
 
There is one more option, you could wait for something like this to exist in the real world.
This is an EVSE/charger that directly takes in PV input.

 
Bear with me while I try to wrap my head around all this... :)

Here's some stats:

Average daily miles driven = 28.5
Bolt battery capacity = 65kWh
Average insolation hrs. = 4
Typical kWh used per mile = .325
kWh needed per day = 9.26 (round up to 10kWh)

I have initially looked at a hypothetical setup as follows:
10 x 400 watt solar panels (4kW) $1,200 ??
LVX6048 (6KW 48V) hybrid solar inverter + MPPT solar charger $1,100
14 AWG cable and associated connectors, hardware, manual transfer switch etc. $300 ??

So, something around $2,600 but under $3,000 ??

I know it's not apples to apples, but comparing a relatively low power level 2 EV charging setup to my RV setup...
I have 600 watts solar on the RV roof; a 40 amp 12 volt MPPT controller and 300Ah of LiFePO4 batteries. If memory serves, I typically get between 20 and 25 amps @ 12 volts into the batteries in decent sun. Obviously at night this is 0 amps. When the sun comes up again and the amperage is sufficient, the controller again starts dumping amps to the batteries.

I'm not understanding the "keeping things awake" for the EV setup. Wouldn't the inverter simply start charging again when the controller starts receiving sufficient PV input? I futzed around a few years ago with Home Assistant using an Arduino Mini using MQTT and geofencing for an automated garage door opener... so I can probably hack through a communications protocol, but I'm wondering if that's really necessary for such a simple system? While I do have a 240v 50A grid tied charger outlet, I believe the most the Bolt draws is around 32 amps.
 
I have a set up which is something like you are looking for but it's 230/240v here in France. I imagine it would work the same on 110v in the USA. I have 8 x 415w panels and a 230v 7.2kw Orient Power inverter which does not need a battery to operate. 110v/120v version here https://www.opsolarbattery.com/product-page/LV6548 I run a simple plug from a socket on my grid power for the mains in and a power outlet is connected to my mains out on the inverter. I plug my EV slow charger into the power outlet whilst the sun is out and it charges my EV at around 2.6kw charging speed. If I get clouds the inverter takes the shortfall in power from my grid feed. You can easily install this yourself as the inverter cannot back feed into the grid so it's just a simple plug from a wall outlet into your mains in on the inverter. When the sun goes down I turn the inverter and charger off. Total cost for me was around €2500 including professional ground mounts.
 
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Bear with me while I try to wrap my head around all this... :)

Here's some stats:

Average daily miles driven = 28.5
Bolt battery capacity = 65kWh
Average insolation hrs. = 4
Typical kWh used per mile = .325
kWh needed per day = 9.26 (round up to 10kWh)

I have initially looked at a hypothetical setup as follows:
10 x 400 watt solar panels (4kW) $1,200 ??
LVX6048 (6KW 48V) hybrid solar inverter + MPPT solar charger $1,100
14 AWG cable and associated connectors, hardware, manual transfer switch etc. $300 ??

So, something around $2,600 but under $3,000 ??
Don't forget mounting rails and associated hardware. I'd wager it is significantly more expensive than you expect.
I know it's not apples to apples, but comparing a relatively low power level 2 EV charging setup to my RV setup...
I have 600 watts solar on the RV roof; a 40 amp 12 volt MPPT controller and 300Ah of LiFePO4 batteries. If memory serves, I typically get between 20 and 25 amps @ 12 volts into the batteries in decent sun. Obviously at night this is 0 amps. When the sun comes up again and the amperage is sufficient, the controller again starts dumping amps to the batteries.
Sure, that works great because there aren't two computers between the solar and batteries, just the battery charger that is integrated into the inverter, directly connected to the cells.

The charger is on the car, it converts AC to DC to charge the battery. The minimum rate it can do is 6 amps AC (at 120 or 240 volts, still 6 amps)
This charger has no idea how much power is available other than what info you provide it from the EVSE. It's also slow to respond, it takes a second or two to adjust to a new command.

Based on what you're proposing, the sun would come up, PV inverter would turn on and start powering the AC, and let's say there is 50 watts available. Well, the car/EVSE don't know that, so the car tries to start charging at whatever it's set to, somewhere between 720 and 7,680 watts.

Obviously, that's not going to work.
That's why you need to set up something to command the EVSE.

The battery gets you two things:
Buffer to make it through clouds
Better info on available solar power (it's difficult/impossible) to know how much solar power is available with our trying to use it. Having a battery helps the inverter have somewhere to put solar energy that the inverter is directly connected to.
 
EVSE? Please explain/clarify. I am now using the charger which came with the car. It has a changeable plug... one for 120v 15 amp outlet (not using) and a 240v 50 amp plug, which I am using. Is the EVSE the charger I'm describing? If not, could you give an example of the equipment (including a typical battery) which would work?
 
EVSE? Please explain/clarify. I am now using the charger which came with the car. It has a changeable plug... one for 120v 15 amp outlet (not using) and a 240v 50 amp plug, which I am using. Is the EVSE the charger I'm describing? If not, could you give an example of the equipment (including a typical battery) which would work?
The charger is built into the car. The EVSE is likely what you are calling a charger, but it's really just a fancy extension cord with communication and a relay. However, the one that came with the car likely doesn't have the communication needed to actively change the charge speed.

As a quick pass, a shopping list (not top tier product) something like this:


I like going with better quality equipment than EG4 offers, but this is a starting point. You'll need to do something with home assistant (and maybe another piece of hardware to get data from the inverter) to pull data from your inverter, process it with some logic you define, and send the appropriate commands to th EVSE.

Or you could ditch the battery, go grid tie and add an Emporia View (energy monitor), in that case, Emporia handles all the background logic and communications.
 
The charger is built into the car. The EVSE is likely what you are calling a charger, but it's really just a fancy extension cord with communication and a relay. However, the one that came with the car likely doesn't have the communication needed to actively change the charge speed.

As a quick pass, a shopping list (not top tier product) something like this:


I like going with better quality equipment than EG4 offers, but this is a starting point. You'll need to do something with home assistant (and maybe another piece of hardware to get data from the inverter) to pull data from your inverter, process it with some logic you define, and send the appropriate commands to th EVSE.

Or you could ditch the battery, go grid tie and add an Emporia View (energy monitor), in that case, Emporia handles all the background logic and communications.
Thanks! Being retired has it's perks... one being having the car at home nearly every day to charge off-grid. Most of the time I could literally walk out into the garage and manually (old school) plug (or transfer switch) the charge cord into either the inverter or existing 50 amp outlet. Even cloudy/rainy days with low PV output I would just leave it plugged to grid. Easy peasy... no programming required. I'd like to stay with 240v considering the low charge rate of 120v.

The ideal setup would be to have both grid and solar feeding the inverter, then have solar the priority. If/when solar input falls below a certain threshold the inverter would switch to grid automatically. I believe that's what you were describing earlier? And I would STILL need the 48v battery you listed? I watched a video of those components built on a Harbor Freight two wheel dolly.
 
Thanks! Being retired has it's perks... one being having the car at home nearly every day to charge off-grid. Most of the time I could literally walk out into the garage and manually (old school) plug (or transfer switch) the charge cord into either the inverter or existing 50 amp outlet. Even cloudy/rainy days with low PV output I would just leave it plugged to grid. Easy peasy... no programming required. I'd like to stay with 240v considering the low charge rate of 120v.

The ideal setup would be to have both grid and solar feeding the inverter, then have solar the priority. If/when solar input falls below a certain threshold the inverter would switch to grid automatically. I believe that's what you were describing earlier? And I would STILL need the 48v battery you listed? I watched a video of those components built on a Harbor Freight two wheel dolly.
That's exactly what I do and I explained my set up in my reply. You don't need batteries or "grid tie if you use the same inverter as me :https://www.europe.opsolarbattery.com/product-page/split-phase-inverter-230vac-50hz-48v-7200w"
 
I would not call it "connected to the grid" as in "grid tied". I just supplement the solar feed with a simple cable from the inverters grid input to a regular 240v power outlet nearby. The same power outlet I would use to charge my EV in the regular way via the trickle charger which is adjustable from 1.9kw to 2.7kw. Like the OP I am retired and charge my car via solar only when the sun is out.
 
Yeah, it could switch back and forth from the grid. Does the charge or EVSE complain about the power blip when the transfer happens?

I guess chateau_nomad could the babysit the thing and make current adjustments or only plug in when they are sure the sun is high enough, there's other options. But, I can't imagine spending that much time just charging the car. I plug in and walk away.

I plugged in at 8 last night, the car just sat there all night waiting. When the sun was high enough this morning, it started charging. As PV production increased the EVSE cranked up charge speed.
 
I also plug in and walk away ! My inverter is set for SUB so uses solar first and if there is not enough to charge the car it rakes the "extra" from the grid. It rarely needs the grid as I set my charger to 1.9kw and as I have a 3.3kw array it's usually enough direct from the solar. There is no "power blip" or switchover as the inverter does not switch between solar/grid it just uses the grid to supplement the solar but only rarely.
 
Some / most off grid inverters in SUB mode will leak export/operate in parallel with grid. That is not legal in lieu of an interconnection agreement. Some POCOs have hair trigger happy detection thresholds for this kind of Unsanctioned equipment
 
In light of recent developments I'm VERY concerned about tariffs affecting the cost of my above mentioned "project".

I'm thinking I need to make a decision to purchase the major components now... and worry about install next spring.

I'd like specific recommendations (brand/model, etc.) for components to accomplish an "off grid" EV (2022 Chevy Bolt EUV) NOT grid tied for simplicity.

I have room for 10 x 400 watt panels. Brand? Source? Recommendations?

Inverter? Specific brand? Specific features?

I also understand a battery is required? 48 volt? What is minimum required/recommended for a workable starting point?

If anyone can point me to links/videos I would greatly appreciate it! I have some experience with solar/inverter/LiFePO4 batteries by installing 600 watts solar, a 3kW Sungoldpower inverter/charger and 3 x 100Ah batteries in our motorhome.

Any suggestions welcome!!
 
Inverter: growatt 3k. I have one, and I'm using it to charge my electric ocean. I plug in the charger at 7am, using 15x 240w panels in strings of 5, and unplug as the sun sets. I have grid as backup.

I got my panels from marketplace, used for $20 a panel. I got the inverter for $500 from watts247.com.

Red is grid, blue is load, yellow is solar.

image.png
 
The two takeaways I'd like to stress are I'm trying to keep within a "starter" budget of around $3,500 - $4,000 all inclusive. I'm in a unique situation being retired and can either leisurely charge from off-grid solar OR my existing grid-tied 50 amp outlet, using the charger which came included with the Chevy Bolt EUV. A single battery for a 48 volt system are would essentially double the cost of the entire setup, and (unless necessary), and would add no value to a DAYTIME EV charging setup. However, battery storage for home backup use may be a consideration in the near future. But that just isn't in the budget for now.

Opinions on the following items appreciated...
Hyperion 400W Bifacial Solar Panels $1,280 for 10 panels
Lux Power EG4 6000XP Off-Grid Inverter $1,400
Mounting/Cables/Misc. $1,000 ???

Is this realistic??
 
Fellow EUV owner here -- and while we can all appreciate your excitement to get some solar power into your car (it's awesome) doing it without battery or grid backup is putting the car at risk since a cloudy day means an inordinate amount of charge initiate cycles that in the long run the car will not like. It's an express way to screw up the contactors that cycle each time power is initiated, in this case imagine its initiating a charge and cloud pops in the way killing all juice right in the middle of the contactors clicking over. Sure, it won't kill it instantly but 100X a day? not good.

The other major issue I see - the Bolt doesn't have selectable amperage when you are level 2 charging, neither on the car, or on the OEM charger. If you are level 2 charging it will automatically try and pull 32A off the circuit and overload the 6000XP. (I have one it's a nice unit) You'd have to use the level 1 (120V) pigtail for the OEM charger, from there select 8 or 12A on the car menu itself) it will be butt slow and even under absolute perfect weather/cloud conditions you might get 35/mi of range added in 7 hours (assuming you got 7 hours of sun that would allow 1500W to be sustained.

Solution -- buy a selectable amperage Level 2 charger, amazon has some solid ones, I use a Sophtrans 10A to 40A selectable charger.

Also if you are using the stock EVSE charger that came with your EUV, it going to brown out condition over and over isn't going to make it last. It's already a rather jank piece of hardware from chevy. I ditched mine after experiencing the phantom overheat issue most of those units suffer from.

The main issue is no battery and no grid backup. I think you are in for an overall bad time if you try to EV charge. Based on your comments I think you need more research as well on how/why batteries exist even on a system designed for daytime use. For a situation like you describe the batteries are there to smooth out any gaps in solar production, clouds, birds, whatever.

With fall/winter, the amount of kwh you'd be able to effectively put into the cars battery is highly diminished if you are relying on sun that far north.
 
Since my first EV (Nissan Leaf) I've thought about this too.

My main concern with running an EV charger w/o a battery is what happens at sunrise and sunset or when clouds roll in. Take for example at sunrise. Each morning as the sun rises, you'll get increasing voltage and current from your solar panels. The inverter will start working and begin providng power to your EVSE. As power is provided, voltage will drop. For several minutes or maybe an hour, it may cause the EVSE to connect, try to charge your car, and then disconnect due to lack of voltage or current. All this turnining on and off may cause a relay to malfunction. When you charge your car normally through the mains power, you'll hear several clicks as it starts charging. I suppose that's a relay of some sort. It could also be the J1772 socket mechanically locking in place. What happens if it does that two dozens times in the morning, two dozen times in the evening, and several times during the day as clouds roll in. And it does that every day you charge with solar. I suspect that might damage something in the car. And repairs to electronic components in a car is always going to cost thousands $$$$$. It's an expensive experiment that I do not have the resources to attempt.

I am highly interested to find out of this could work.
 

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