off grid noob, please help

[ABCDE]

Hi guys,

wanting to build a house in Hawaii, and wondering if someone can delight me in some questions

-can I be able to run a house with charging EV's off grid, or is it going to draw too much power? Planning on getting a couple EV's and couple EV motorcycles.

-I notice I drive about lets say a cushion of 60 miles a day here. what size solar and how many powerwalls do you think I would need to run off grid ( I wouldn't be in house much as I'm out most the day at another house ) ( house size is about 1,000 square foot as of right now )


just starting my idea, as I can run power to the house, but electric company says it runs about 30k to hookup the lines, so really that's quite an expense and thought to apply that toward running a bigger solar array. Also not sure but I believe in Hawaii we get double credits for anything solar????? one federal and one state I believe? making the system a lot cheaper than most.

please also keep in mind, I don't mind costs as long as this doesn't run upwards of 100k as really at that point it kinda looks silly to run such a big system then pay for it, but our electric here is .31 cents so...


thanks guys, looking forward to hopefully being able to run an off grid solution

 

[2012MS85]

Are you paying cash for the home? Most mortgages require proof of utility service to the home before they loan money. Truly “off grid” homes are rare, and often not allowed by many governing bodies (city, county, HOA). But I have no idea where in Hawaii you are or what their laws/rules/regs are. Also, if you’re not planning to be “home” during the day during peak solar, you’ll need lots of batteries (Powerwall2s) to store the juice and time-shift your use.

 

[gilscales]

you can get a sizable off grid system for a little over 30k
The Ranch 16.74 kW 54-Panel Mission Solar Off-Grid Solar System - Wholesale Solar

Throw in 3 power walls and this would probably be way overkill for your needs and parts would be less than 50k

not sure what this would cost to install or if you need anything like this or if you even have room for this but it can be done for under budget

after tax credits you are better off than spending 30k to get wire ran from the utility company

 

[cwied]

Make sure you do your due-diligence on using the Powerwalls off-grid. As far as I know, this is not supported yet. There used to be a section on Tesla's web site that said support for off-grid operation was "coming soon." I can't find that any more.

 

[2012MS85]

If you’re an electrical engineer or simply brilliant, then perhaps you can install your own solar system I, however, possess no such skills and had to pay a contractor, who subcontracted the electrical work, for installation. The materials (panels, micro-inverters, and all other hardware) was one-third of the $50k cost of my 16.1 kw ACPV system. And I agree that TESLA is unlikely to work with a homeowner vs a pre-approved solar contractor/electrician. So take the wholesale cost of your desired system, then multiply by 3...because professional installation is likely to be twice the cost of materials.

 

[gilscales]

If you’re an electrical engineer or simply brilliant, then perhaps you can install your own solar system I, however, possess no such skills and had to pay a contractor, who subcontracted the electrical work, for installation. The materials (panels, micro-inverters, and all other hardware) was one-third of the $50k cost of my 16.1 kw ACPV system. And I agree that TESLA is unlikely to work with a homeowner vs a pre-approved solar contractor/electrician. So take the wholesale cost of your desired system, then multiply by 3...because professional installation is likely to be twice the cost of materials.

Well in some cases I agree with what you are saying but the likelihood of $100,000 being the price to install this system is way beyond reality.
Today the average install is around 2$ to $3 a watt for a grid tie system, prices have come down on both sides considerably lately and will continue to fall.

I am not sure what you have but 16kw with micro inverters and all associated equipment should be closer to 25K not less than 17k

 

[ewoodrick]

Multiple cars and bike as well as the house isn't going to be a small feat. You've got to build enough storage for multiple cloudy days and decide just how much driving that you are going to do. It's doable, may not be cheap.

 

[2012MS85]

Well in some cases I agree with what you are saying but the likelihood of $100,000 being the price to install this system is way beyond reality.
Today the average install is around 2$ to $3 a watt for a grid tie system, prices have come down on both sides considerably lately and will continue to fall.

I am not sure what you have but 16kw with micro investors and all associated equipment should be closer to 25K not less than 17k

Please document any professionally installed residential solar system for $2 per watt. That would be a first that I’ve seen. I read yesterday on this forum that TESLA is currently quoting about $3 per watt. Some are less; others are more. I did my ACPV system in two phases. Every professional solar contractor in Iowa in 2016 was about $3.20 per watt. I installed 40 panels, which was the max my utility would allow until I had greater usage (that came the next year as I bought 3 EVs). For phase two (20 more panels in 2017), I got the rate down to $2.50 per watt. But those prices also excluded all the cosmetic costs to bring in rock around my three ground mount arrays, plus repairs to my torn up yard (which cost a couple grand extra). All told, my system cost $50k, or an average cost of $3.10 per watt. People make the mistake of reading dumb articles written by bozos who never installed solar and yet they have captivating headlines about the “50% DROP IN SOLAR PANEL COSTS!” Okay, so a Chinese panel that was 80 cents per watt in 2016 dropped to 40 cents in 2017. So what?!? Panels represent only a tiny fraction of the total cost; the majority is labor and expertise/profit of the professional solar contractor.

And @gilscales states my system should cost $25k, which would be a mere $1.55 per watt installed. That might be a world record Please share the # and website of the professional who would quote that.

 

[gilscales]

Please document any professionally installed residential solar system for $2 per watt. That would be a first that I’ve seen. I read yesterday on this forum that TESLA is currently quoting about $3 per watt. Some are less; others are more. I did my ACPV system in two phases. Every professional solar contractor in Iowa in 2016 was about $3.20 per watt. I installed 40 panels, which was the max my utility would allow until I had greater usage (that came the next year as I bought 3 EVs). For phase two (20 more panels in 2017), I got the rate down to $2.50 per watt. But those prices also excluded all the cosmetic costs to bring in rock around my three ground mount arrays, plus repairs to my torn up yard (which cost a couple grand extra). All told, my system cost $50k, or an average cost of $3.10 per watt. People make the mistake of reading dumb articles written by bozos who never installed solar and yet they have captivating headlines about the “50% DROP IN SOLAR PANEL COSTS!” Okay, so a Chinese panel that was 80 cents per watt in 2016 dropped to 40 cents in 2017. So what?!? Panels represent only a tiny fraction of the total cost; the majority is labor and expertise/profit of the professional solar contractor.

And @gilscales states my system should cost $25k, which would be a mere $1.55 per watt installed. That might be a world record Please share the # of the professional who would quote that.

Sorry you misunderstood my post, I was referring to cost of equipment with micro inverters, panels and all associated equipment costing closer to half of your total install or approx. $25,000 that to 1/3 or less than $17,000

 

[2012MS85]

Phase 1 of my solar system is 40 panels (2 ground mount arrays) facing south...

Phase 2 was installed a year later (2017) and those panels face southwest to capture more peak energy when my utility rates double (to $0.16 per kWh from 4-9pm, every day)...

So I’m sharing real-world solar installation costs from an actual solar system at my Iowa home

 

[2012MS85]

Sorry you misunderstood my post, I was referring to cost of equipment with micro inverters, panels and all associated equipment costing closer to half of your total install or approx. $25,000 that to 1/3 or less than $17,000

No worries. I just try to always include the total installed cost, as too many folks quickly see a number and then have the false assumption that they can produce their own solar energy for that “materials only” cost. What really matters is the all-in cost that includes installation, tax, etc. Cheers!

 

[Bigtanuki]

Phase 1 of my solar system is 40 panels (2 ground mount arrays) facing south...
View attachment 375040

Phase 2 was installed a year later (2017) and those panels face southwest to capture more peak energy when my utility rates double (to $0.16 per kWh from 4-9pm, every day)...
View attachment 375041

So I’m sharing real-world solar installation costs from an actual solar system at my Iowa home

Ahh, what I wouldn't give for $0.16/kWh peak rates. Our EV rate for this part of California is about $0.48/kWh (peak) and ~$0.12/kWh for off-peak. Yay California.

 

[gilscales]

Phase 1 of my solar system is 40 panels (2 ground mount arrays) facing south...
View attachment 375040

Phase 2 was installed a year later (2017) and those panels face southwest to capture more peak energy when my utility rates double (to $0.16 per kWh from 4-9pm, every day)...
View attachment 375041

So I’m sharing real-world solar installation costs from an actual solar system at my Iowa home

you installed yours in 2 phases and 2 years ago, costs for labor and equipment have come down, micro inverters are still more expensive so you do not have the cheapest priced components.

If you priced that install today you could expect to shave off 20% if installed all at once for todays prices is my guess but I am not positive.

Energysage states that in 2019 the average for a 6kw install is $3.05 per watt and as low as $2.67 2019 Solar Panel Cost (Updated) | Average Solar Panel Prices by State so a system nearly 3 times the size one could possibly get as low a $2 per watt using the most economically priced materials and a good installer that does not have kids he has to put through college.

I am only a general building contractor and have no experience with solar but I had seen a friends 5kw install that took 2 people 2 days so I was really shocked at the cost of the install when he received the bill!

I just went on to Renvu.com who has some of the best prices on components and using the most economically priced stuff they have It still came up to just over $1 per watt for everything so when you did yours i'm guessing with the Enphase and the price of panels in 2017 that you could have been closer to $1.50 per watt just in materials alone

 

[miimura]

@ABCDE you should talk to local solar installers. In Hawaii, they know what works off-grid. Honestly, Tesla does not support off-grid. The main reason that Powerwalls are attractive is that they have the cheapest long life lithium batteries on the market. However, for off-grid you're probably better off with a large AGM battery bank. You just have to be aware that lead AGM batteries are a "consumable" and have a relatively limited life. You would need to budget for replacement every 5 years. You will also need to oversize your solar array to make sure that you can generate enough to get by, even when the weather is not optimal.

 

[Tgfam]

Hi guys,

wanting to build a house in Hawaii, and wondering if someone can delight me in some questions

-can I be able to run a house with charging EV's off grid, or is it going to draw too much power? Planning on getting a couple EV's and couple EV motorcycles.

-I notice I drive about lets say a cushion of 60 miles a day here. what size solar and how many powerwalls do you think I would need to run off grid ( I wouldn't be in house much as I'm out most the day at another house ) ( house size is about 1,000 square foot as of right now )


just starting my idea, as I can run power to the house, but electric company says it runs about 30k to hookup the lines, so really that's quite an expense and thought to apply that toward running a bigger solar array. Also not sure but I believe in Hawaii we get double credits for anything solar????? one federal and one state I believe? making the system a lot cheaper than most.

please also keep in mind, I don't mind costs as long as this doesn't run upwards of 100k as really at that point it kinda looks silly to run such a big system then pay for it, but our electric here is .31 cents so...


thanks guys, looking forward to hopefully being able to run an off grid solution

We installed an off-grid system at a house we are building in Southern Utah in 2017 and it works very well. I would also recommend that you research whether or not off-grid homes are allowed in your area because it will affect a lot of things (loans, insurance, tax credits). As I recall, you need to be at least 1/4 mile from the nearest utility to qualify for state and federal tax credits (don't quote me on this!).

We have a 3 kw system with lead acid batteries which ended up costing about $9600. This doesn't include the generator which we added later but haven't used much at all. This is only the cost of materials and we did all of the work ourselves. It's definitely a complicated DIY project but I don't regret it at all because I learned a lot doing it. We are in a very sunny area and the system works great. I can monitor it from my phone (we're about 3.5 hours away) and so far it just does it's thing. It easily runs all of the lights, well pump, refrigerator, and electronics but the mini-split heat pump takes quite a bit more energy and needs to be monitored closely. We have so much extra energy available in the summer that we added a hot tub last year.

We are slowly working on adding the main house - we only have the garage with a small living area so far. When that happens we will triple the number of panels (from 9 to 27) and either get a new larger system or add a new system and keep both of them. I looked into the Powerwall but it's not really an option yet so we went with the lead acids. It would be really nice to have lithium ion batteries because you can only really drain the lead acids to 50% without shortening their life a lot - that needs to be factored into to any cost comparison. I'm sure it will happen soon but right now they still cost too much.

I also helped a friend install a grid-tie system last fall (4.4 kw) with Enphase microinverters and it ended up costing him $1.45/watt before tax credits and he estimates it will be about $0.70/watt after tax credits are figured in. Again, we did all of the work and it ends up taking more time than you think when you factor in messing around with the building permit, fire department, and the utility as a homeowner. But it can really pay off if you're up for doing all that.

 

[Shygar]

Ahh, what I wouldn't give for $0.16/kWh peak rates. Our EV rate for this part of California is about $0.48/kWh (peak) and ~$0.12/kWh for off-peak. Yay California.

Those are summer rates though, winter rates are $0.33 peak:
Making sense of the rates

 

[Bigtanuki]

Those are summer rates though, winter rates are $0.33 peak:
Making sense of the rates

Agreed. Still damn high prices for electricity.

 

[Shygar]

Agreed. Still damn high prices for electricity.

Yep for sure!