Do you own an EV and charge with solar?

[fatjay]

One of my biggest motivations of building out a solar system is getting truely off grid, and that means everything, vehicles included. Which means I need sufficient production to also charge a vehicle.

My current system I'm building is 4.2kw with a 3k inverter and 15kwh battery, but once that's done, I'm going to add antoher 9k solar with 3 more inverters for 12k of inverter, then scaling up to 90kwh battery storage.

Now i'm looking forward to getting my fisker ocean extreme in a couple weeks. I downloaded my driving trips from the jaguar app and since december, I've driven about 2000 miles, had 35 days where I didn't drive at all, and when I did, averaged 25 miles a day. So when I build my next phase, I'm debating adding a seperate 4kw array and piping it directly into the fisker.

So if you have an EV, have you taken it into account when planning solar?

 

[timselectric]

I don't have the EV's , yet.
They will come after the system is complete.
But yes, they are definitely part of my plan.

 

[Bkord]

You may be better off with one big system. It is easier to manage. I had an Ev 9 years before my solar so nothing really changed. Just have a small electric bill now.

 

[OffGridForGood]

EV charging for our system is the dump load, after the main ESS is full (or nearly full).
We have been building our system gradually over four years now, with more PV planned this year and next, but that is still never going to be able to run our home, business and charge the EV during October-January there is just too much foggy/cloudy weather that time of year in our area.
Spring/Summer we have lots of excess PV and it makes the most sense for our set up to have one big Solar/PV system with the EV just an extension of the ESS for charging when we can. Other times we use utility off peak ToU to charge at night, especially during winter.

 

[time2roll]

25 miles per day is fairly easy. The dedicated 4kW should work well as long as vehicle charging is during the day. But then a 90kWh battery could easily be dumped into the vehicle at any time. I would tend to make it one big system so all equipment supports the total load.

My previous house had a small 3kW system net metered so it helped but not near enough to be off-grid. System for the current house will be 16 kW and about 50kWh battery to fully support everything. Presently I charge mostly at work but the home system will easily support the 7kW charging of the I-Pace once installed. Vehicle battery is larger than the home storage so I would be looking to charge during the solar day to put power in direct.

 

[chrisski]

If you have a way of figuring your watt hours into the battery for that 25 miles, that’s a bit more helpful in planning than just miles driven.

I have solar and am grid tied and usually put around ~7 kWh of power in after 7pm, so that power is from the grid. I do try to charge during daytime, but can only do that on the weekend.

I have kicked around building a separate PV system for my Tesla, but at a daily cost of $1.71 for electricity, the pay back period is a but long for what I use.

So, if your separate system saves you $500 a year, may not be worth it. Theres other things besides the monetary costs like redundancy and being nice to have that could make it worth it.

 

[Ampster]

I am on NEM 2.0 and last year all I paid was $230 in NBCs. Charging overnight creates approximately $0.025/ kWh in NBCs. They covered the Minimum Delivery Charges. Some of the NBCs I cannot avoid because I am a net consumer in the winter. However in Spring, Summer and early Fall I do try to charge as much as I can from excess solar after my batteries are charged from solar. I use an Emporia EVSE which modulates my charge current to make that somewhat easy. I am now tracking NBCs and for the first six months I have acrued $90 in NBCs and I hope to accrue even less by my True Up in September. I will be happy if I can get the total down below $180 this year.

 

[400bird]

So if you have an EV, have you taken it into account when planning solar?

I do have an EV and charge from solar.
I agree with others that one larger system works better for me, vs a separate system dedicated to just the EV. This allows all your solar to be fully utilized. For example if you have two separate systems, when one battery is full, the PV in that system goes idle, even if the other battery needs more range.

I am on grid, so the car takes priority over charging the home battery. No big deal if the house battery goes below the threshold to run loads, the grid is there.
Being off grid, you may want to reverse that priority.

 

[fatjay]

If you have a way of figuring your watt hours into the battery for that 25 miles, that’s a bit more helpful in planning than just miles driven.

I have solar and am grid tied and usually put around ~7 kWh of power in after 7pm, so that power is from the grid. I do try to charge during daytime, but can only do that on the weekend.

I have kicked around building a separate PV system for my Tesla, but at a daily cost of $1.71 for electricity, the pay back period is a but long for what I use.

So, if your separate system saves you $500 a year, may not be worth it. Theres other things besides the monetary costs like redundancy and being nice to have that could make it worth it.

My garage is not tied into my solar system for the time being, it'll just be a subpanel that will power a handful of circuits. I'm not going to build the big system out just yet, but I can throw together a small system on the pavilion next to the garage easily. The bigger system will be ground mount further away. It's logistically difficult to get everything to the house.

 

[Redflyer]

I started with 12 panels (400w) and two inverters to provide 240v to a solar sub in the garage. I ran dedicated circuit to a NEMA plug specifically for the car. The charge controller is selectable on amperage....which helped. I would easily tax the small solar array and battery bank if I cranked it up. So I had to charge 5-10kw at a time and let the solar system recover. Was kind of a pain to micro manage the system, but that was my only option at the time.

Since then, I've added another 7 south facing panels (also 400w) and the system is much more robust. I top out my batteries easily during the Spring and dump load into the car. But I still don't have enough places to send the electricity too. I've always loved my gas water heater, but in my mind, I'm already switching it out to an electric model just because I need more loads. I went from famine to feast pretty quickly. First world problem I guess.

 

[BrendanK]

I'm looking into adding an EV charger to my off-grid house setup and appreciate all the thoughts on this thread.
I have an EG4 18K powering my main house with 8kW of PV and 60kWh of battery. Everything except the range is electric in the house.
I don't personally own an EV but we are airbnb'ing the house and I think an EV charger would be a huge perk, seeing as how we are pretty far from anywhere with a charger. My worry is taking too much from the house batteries but I suppose we could say not to use the charger except for during the day when the sun is shining.
I have been considering a stand alone system for the EV, since I have 5 extra panels and 15kWh of batteries that could be utilized, but there would also be the cost of an array and an inverter.

 

[BrendanK]

I started with 12 panels (400w) and two inverters to provide 240v to a solar sub in the garage. I ran dedicated circuit to a NEMA plug specifically for the car. The charge controller is selectable on amperage....which helped. I would easily tax the small solar array and battery bank if I cranked it up. So I had to charge 5-10kw at a time and let the solar system recover. Was kind of a pain to micro manage the system, but that was my only option at the time.

Since then, I've added another 7 south facing panels (also 400w) and the system is much more robust. I top out my batteries easily during the Spring and dump load into the car. But I still don't have enough places to send the electricity too. I've always loved my gas water heater, but in my mind, I'm already switching it out to an electric model just because I need more loads. I went from famine to feast pretty quickly. First world problem I guess.

I got an AO Smith hybrid water heater that works incredibly well. The heat pump sips electricity. In hybrid mode it will ramp up with the electric element but once the water is hot it maintains the temp with the heat pump and is super efficient. Highly recommend

 

[400bird]

I'm looking into adding an EV charger to my off-grid house setup and appreciate all the thoughts on this thread.
I have an EG4 18K powering my main house with 8kW of PV and 60kWh of battery. Everything except the range is electric in the house.
I don't personally own an EV but we are airbnb'ing the house and I think an EV charger would be a huge perk, seeing as how we are pretty far from anywhere with a charger. My worry is taking too much from the house batteries but I suppose we could say not to use the charger except for during the day when the sun is shining.
I have been considering a stand alone system for the EV, since I have 5 extra panels and 15kWh of batteries that could be utilized, but there would also be the cost of an array and an inverter.

I'd recommend setting up some brains/automation behind the EVSE and running from the main system (probably still add more PV to it). For example, only allow it to charge when the house battery is above say 80% SOC.

Just imagine how "well" a renter would take it if the house battery went flat, that's a good way to get some bad reviews and refund demands. You're going to want to set up a generator with auto start and figure out a way to avoid charging their EV from the expensive generator.

 

[G00SE]

When I started considering an EV the most drastic system change was battery bank.
I did double my panel count, but may have eventually anyways as they are far cheaper than batteries.
I figure most of the time I want to charge at home, the sun won’t be out (except weekends) which means I’ll need to rob Peter to pay Paul. Peter can be the house battery and Paul can be the EV battery.
So if I need 20kwh a day of “fuel” I figure an additional 30kwh of home bank should suffice most of the time, which is where the additional panels come into play

 

[time2roll]

I'm looking into adding an EV charger to my off-grid house setup and appreciate all the thoughts on this thread.
I have an EG4 18K powering my main house with 8kW of PV and 60kWh of battery. Everything except the range is electric in the house.
I don't personally own an EV but we are airbnb'ing the house and I think an EV charger would be a huge perk, seeing as how we are pretty far from anywhere with a charger. My worry is taking too much from the house batteries but I suppose we could say not to use the charger except for during the day when the sun is shining.
I have been considering a stand alone system for the EV, since I have 5 extra panels and 15kWh of batteries that could be utilized, but there would also be the cost of an array and an inverter.

Yes at some point there would need to be a limit or your entire battery could be depleted into a vehicle. I would limit charging by placing on a 20 amp circuit with the evse limiting to 16 amps. This is about 4kW and should be time limited.

Most EV drivers will understand the limits and understand the need for primary charging elsewhere. Best to locate and direct them to the closest L3 charging. Your convenience charging would be mostly to not get them stuck if they arrive low on charge.

Or you need 200+ kWh battery. May need more solar.

 

[BrendanK]

I'd recommend setting up some brains/automation behind the EVSE and running from the main system (probably still add more PV to it). For example, only allow it to charge when the house battery is above say 80% SOC.

Just imagine how "well" a renter would take it if the house battery went flat, that's a good way to get some bad reviews and refund demands. You're going to want to set up a generator with auto start and figure out a way to avoid charging their EV from the expensive generator.

is that something that is accomplished through hardware or software?

 

[rustythorn]

if you want to go down the rabbit hole for peak efficiency you can check out my blog. my planned system is close to your current system. i need to squeeze out every last watt since this is a mobile setup

 

[chrisski]

I don't see how you could offer off grid EV charging for an Air BnB customer in any affordable fashion.

I would plan on 350 wH per mile for vehicle charging, and driving 100 miles a day, so 35 kWh of power per EV vehicle per day. Doesn't matter if this power is delivered at 1.4 kw per hour level 1 or 11 kW per hour at level 2 charging or in between, I think this is what your customers will expect.

Worst Case electric rates of 78 cents per kWh comes to 19.50 per day, but building a battery pack to cover 35 kWh, is expensive.