Are there any write ups of people who supply all their energy needs (including transportation) via solar?

[dpilot83]

I’m looking at building a house and was thinking about how it would look to someday in the future meet all of the energy needs of not only the house but also the vehicles of everyone who lives there with solar.

Let’s say it’s a large family with 4 vehicles and those vehicles collectively travel 70,000 miles per year and if they were gasoline powered would use nearly 4,400 gallons of gasoline per year (two large pickups for working on a farm and a minivan for taking kids to school daily and a smaller car for random stuff).

If gas averaged $3.30 per gallon over the years you would be looking at your solar system paying you $14K per year on just the vehicle fuel saved.

You could have $140K invested in solar panels and batteries and inverters and charge controllers and still get a 10% return on investment.

If the house used 40 kWh’s plus the 4 vehicles could one build a solar system and battery setup that would service all of that for less than $140K?

I would think you would need 220kWh ($75K? Or could you do it with less for large systems like that with todays technology?) in batteries alone to be able to charge the largest vehicle (say they make an electric version of an F350 in a few years with a 200 kWh battery).

I would imagine you would need maybe $40K worth of solar panels to get 220 kWh charged in 4 hours.

Then you’d have $25K left over for everything else. You’d basically have to do the labor yourself to have any chance at making it happen I suppose.

Even if you didn’t pay yourself for any labor you’d still be looking at probably not having enough left over for buying everything else you need.

Just thought it was an interesting thought experiment but I don’t have quite the knowledge base in what solutions are available to make really great estimates.

 

[MichaelK]

To start out, you need to identify the three charging standards that are out there right now. You can then design from there.
Tier 1: 12A at 120VAC. Charging via a standard house wall socket (NEMA)
Tier 2: 20-50A at 240VAC. Charging via an electric stove/drier socket
Tier 3: 60A at 480V. Not realistic without specialized equipment requiring permiting approval.

Right now I have a LARGE solar system, and I know I could supply 10A at 240V for about 8 hours per day. That works out to be ~24kWh of power, which I have produced. That gets made with a 48V Schneider system with 4500W of panels, a Schneider XW+6848 inverter, and eight L-16 batteries.

If you want to assume that is enough to charge one vehicle, then scale appropriately for the total number of vehicles you need.

The one very important fact you should remember though is that off-grid solar is simply the most expensive way to make electricity. You will spend less money in the long run of you are grid-connected, and can charge at night when rates are lowest.

 

[dpilot83]

To start out, you need to identify the three charging standards that are out there right now. You can then design from there.
Tier 1: 12A at 120VAC. Charging via a standard house wall socket (NEMA)
Tier 2: 20-50A at 240VAC. Charging via an electric stove/drier socket
Tier 3: 60A at 480V. Not realistic without specialized equipment requiring permiting approval.

Right now I have a LARGE solar system, and I know I could supply 10A at 240V for about 8 hours per day. That works out to be ~24kWh of power, which I have produced. That gets made with a 48V Schneider system with 4500W of panels, a Schneider XW+6848 inverter, and eight L-16 batteries.

If you want to assume that is enough to charge one vehicle, then scale appropriately for the total number of vehicles you need.

The one very important fact you should remember though is that off-grid solar is simply the most expensive way to make electricity. You will spend less money in the long run of you are grid-connected, and can charge at night when rates are lowest.

Thanks.

I think the key of what you said is that grid connected night rates would see a much more rapid ROI. That is a wise point.

That being said, if one wanted to run through the whole scenario just for education and possibly the desire to not be reliant on outside energy sources regardless of cost, I’m afraid the 24 kWh you suggested may not be large enough.

When 3/4 ton and 1-ton electric vehicles are released I fully expect them to have batteries in excess of 200 kWh.

If they are kept between 20% and 80% charged that would look like being able to supply at least 120 kWh overnight. Chargers run at maybe 88% efficiency so the battery of the house would need to be able to supply 136 kWh to the vehicle in addition to the overnight house needs.

Maybe the house needs 20 kWh overnight so that would mean 156 kWh needed between charging one vehicle and supplying the house needs.

If you wanted the house batteries to stay between 20 and 80% (is that ideal just like it’s ideal for EV’s?) then you’re talking 260 kWh of battery capacity to be able to charge a vehicle at night plus run the house.

I was under the impression that the largest Tier 2 chargers could go up to 80 amps at 240V which is probably what I would shoot for since I would be dealing with larger vehicles at some point in the future.

For a very large battery bank like 260 kWh, am I right in assuming that would cost around $75K to $80K?

 

[cods4]

I’m looking at building a house and was thinking about how it would look to someday in the future meet all of the energy needs of not only the house but also the vehicles of everyone who lives there with solar.

Let’s say it’s a large family with 4 vehicles and those vehicles collectively travel 70,000 miles per year and if they were gasoline powered would use nearly 4,400 gallons of gasoline per year (two large pickups for working on a farm and a minivan for taking kids to school daily and a smaller car for random stuff).

If gas averaged $3.30 per gallon over the years you would be looking at your solar system paying you $14K per year on just the vehicle fuel saved.

You could have $140K invested in solar panels and batteries and inverters and charge controllers and still get a 10% return on investment.

If the house used 40 kWh’s plus the 4 vehicles could one build a solar system and battery setup that would service all of that for less than $140K?

I would think you would need 220kWh ($75K? Or could you do it with less for large systems like that with todays technology?) in batteries alone to be able to charge the largest vehicle (say they make an electric version of an F350 in a few years with a 200 kWh battery).

I would imagine you would need maybe $40K worth of solar panels to get 220 kWh charged in 4 hours.

Then you’d have $25K left over for everything else. You’d basically have to do the labor yourself to have any chance at making it happen I suppose.

Even if you didn’t pay yourself for any labor you’d still be looking at probably not having enough left over for buying everything else you need.

Just thought it was an interesting thought experiment but I don’t have quite the knowledge base in what solutions are available to make really great estimates.

I think you need to do your ROI calculations differently.
I suspect 70% of your $14k savings would be made by moving to electric vehicles alone. You will still be paying for the electricity, but it is going to be a lot cheaper than buying gas.

Here are some quick calculations on how much your power for the EVs will cost without any solar or batteries
70,000 miles / 3 miles per kWh (dont know how accurate this is for electric pickups / minivans, but it's my best guess)
= 23333kWh
23333 kWh x $0.2 per kWh (you might want to put your actual electricity cost in here)
=~ $4,700 pa

If you then do your ROI investment on the solar/battery install, I suspect it wont look nearly as good.

BUT! Try doing the calculations again based on solar only (no BESS), and assume that you can charge one or two vehicles at home each day off the solar (surely that is achievable with 4 vehicles). Based on that you should be able to come up with a reasonable sized solar system that you can fully self consume from.
This should give you a pretty good ROI.

Then you could also consider V2H to supply your house loads over night which might let you go off grid without having to spend huge money on a BESS.

 

[timselectric]

Charging EV's at night from solar, is just not going to give a good ROI. Wait for the technology to get better. Or, figure out a way to charge during the day.

 

[timselectric]

Build your own gravity battery. Then, it might be doable.

 

[edcoopered]

Hopefully one day we'll all be able to use the grid to shuffle energy about, put the power in at home, and use that to charge your car at the office.

 

[cods4]

Hopefully one day we'll all be able to use the grid to shuffle energy about, put the power in at home, and use that to charge your car at the office.

Certainly possible, but it will never be free (or if it is, we will be paying for it in some other way). It costs a lot of money to build and maintain the electricity grid

 

[timselectric]

That's why I am trying to never need it, again.

 

[HRTKD]

To manage costs, I would try to charge the EV during the day. I charge my EV at night because the rates are lower and I don't have solar at the house.

I think a full EV 3/4 ton (or larger) truck is a few years off. But that's a different discussion.

 

[timselectric]

I think a full EV 3/4 ton (or larger) truck is a few years

I've been thinking about converting my 1 ton, crew cab, dually, to a diy EV. But, it's going to be a very large project. Maybe, I'll have time when I retire. lol

 

[Ampster]

I would imagine you would need maybe $40K worth of solar panels to get 220 kWh charged in 4 hours.

I think you may wish to examine your assumptions. I have been driving EVs for ten years and can easily put 200 miles of range into one of my EVs overnight. That is a very reasonable 75kWh. Most of the time I charge from solar during the day and can add 100 miles of range from an 9kW solar system during the six months after the Equinox. Less in winter.

 

[summit]

My household is almost there with 4 EVs, 4-ton Heatpump for main furnace, portable electric radiant heaters for spot heating, Geospring HP water heater, several electrical cooking gadgets (Instant Pots, induction stove, microwaves...) We still have propane, mainly used by the women who are stuck in the old ways of cooking (though last propane fill in 2013). The roof-top is currently only about 7kw, a one-day max record was 40kwh last summer, we're in Northern CA, Santa Cruz Mountain. The grid is currently my battery, but there's a lot of pushing back from utility companies and the writing on the walls is not good for the current configuration in the near future.

EVs by far are the heavy consumption, the household stuff is effectively 1-EV

The current plan is to add more cheap Santan PVs to charge the EVs daytime; plus a 100-gal hot water storage as a thermal battery for winter heating assist, and some mini-splits. DIY solar is definitely the way to go.

 

[schmism]

I’m looking at building a house and was thinking about how it would look to someday in the future meet all of the energy needs of not only the house but also the vehicles of everyone who lives there with solar.

Almost all off grid homes use backup power source (aka a generator). There will be periods of extended overcast conditions that render a solar only option useless. (yes there are some a-typical installs that have micro hydro or wind however thats far from achievable by almost everyone)

Do I think building an off grid solution for a home and EV charging to be doable without a generator. no. If your considering a SHTF scenario then most of your other assumptions are also going to be out the window.

Installs that require you to time shift with the grid may acomplish your goal while the grid is up. However if the grid goes down your system will fail fairly quickly without significant time and effort put into the design on the front end.

 

[OffGridInTheCity]

I'm in year 4 of attempting to offgrid my home in the city. One key issue is Solar PV can be severely depressed beyond what's practical for any home battery bank. Last Dec I had 14 days in row of <5% (of max) out of my 13kw PV array. Up till that time I've never had more than 2 days in a row which I cover with a large battery bank. 14 days just can't be covered - would need 400kwh battery bank for my situation and not enough sun to build it back up once depleted. I don't have wind or water options.

I do have 12kw PV 'emergency panels' I can pull out - but at 14 days of <5% (of max) a 13 + 12 = 25kw PV is still not enough. I would need 50kw or 60kw of PV and it's a matter of physical space / co-existing with neighbors to contemplate 150 or 200 panels!

So to me, it's a matter of degree. I'm closing in on 10mons out of 12mons being able to live reasonably with PV/Battery only guaranteed. Maybe 11 of 12 months with 'normal' weather. But it's that last bit! And none of this is cost effective in ROI terms - I have 11c/kwh grid and currently at 22yrs ROI

Still noodling... Saw a 'used oil' furnace recently. Energy Logic 75H - https://www.energylogic.com/waste-oil-heaters/el-75h/ Old/used oil should store as well as propane and looks a lot cleaner/easier than wood based heat.

Recap:
On the plus side, we put in rain harvest and can go 8months with no conservation. With some modest conservation, we could go all year with full water all thru the house. We also put in place a waste plan. With propane/generator to cover the bad 2 months - our home can absolutely function 100% off grid.

 

[Michaells]

We are in the middle of our first year attempting to get to net-zero with our household and one (recently purchased) EV. As mentioned previously, the EV requires more energy than anything we currently run. Charging the car takes more juice than running an electric clothes dryer, and one needs to do it for a much longer period of time.

Our system is a bit complicated: https://diysolarforum.com/threads/s...owatt-spf600t-4-eg4-lifepower4-in-rack.43053/

It is a combined grid-tied and off-grid system, each running different circuits in the house and with the ability to charge the EV from either. The off-grid is definitely not sufficient to charge the car at 32amps / 240v, but I will charge from that system some of the time, at a lower current and when the sun is shining, to get the most from those panels. We don't use a lot of juice or drive all that much and even so it will be a bit of a juggle to get all our miles from the sun--if we ever do--requiring a strategy to charge the car from the off-grid when we have the capacity and switch to the grid-tied system at other times.

The idea driving this project is that by moving loads to the new off-grid system I would be running my utility meter backwards even more to help cover the rest of my needs--including the EV--when the sun don't shine. All without having my grid-tied agreement with the utility changed to my disadvantage.

Living in the NE, and with a less-than perfect roof orientation, we will see how it goes as winter approaches. I am hoping to achieve net zero, but for me having the grid to act as a big storage device is key. Save that, I'd be buying a crap-ton more batteries!

 

[teal95]

They just put more chargers in at work. The biggest are 50kW. I'm pretty sure they're fed from 3 phase, or at least higher than 220v.

 

[Ampster]

They just put more chargers in at work

If in California they can soak up some of that mid day solar production.

 

[teal95]

The problem is that most working stiffs have their car sitting at work when the sun is shining.

 

[kromc5]

I'm working my way towards the same plan, No grid plus being able to charge an ev.