Off-grid New construction

[greenware]

Looking to build a new 4000 sq. ft. house with a pool. Is it possible to produce enough power to run my house (which will be Net Zero) and charge an electric car? I live outside of Sacramento and we have a lot of sun. PG&E want $45,000 to run a line to the house. I figured for $45,000 I should be able to have a solar array and batteries to do this without being grid-tied. I will have a back-up generator run off of propane and possibly some wind power for the bad weather days and nights.
Where do I start?

 

[BentleyJ]

Start by estimating your total electrical demand in both Peak KW and KWhrs per day, week, month. But read below first.
1) Besides the generator, what other appliances will run with Propane. If space heating, water heating, clothes dryer & Range can be propane that reduces your electrical requirements a great deal. This is something you need to decide early on because it will have a MAJOR impact on the size and cost of your solar and battery system.
2) Electric vehicles, depending on your commute, consume large amounts of electricity. Determine how many KWh's your car needs on average per month. Generally, a vehicle uses 35KWhs per 100 miles.
3) Make a list of all the appliances that use electricity and their amperage draw. Add it all up and estimate how many hours a day they will run. Keep in mind its far cheaper to save a KWh than it is to produce one and store it in a battery. For example, A super high efficiency, variable speed HVAC system may cost $4,000+ more than a standard system but in your case it would be money well spent since it reduces the overall size of your solar. Likewise, with all the other appliances. Front loading washing machine, Heat pump type water heater (if you don't go with propane) Etc. Seriously, this is important. I know several people who had Solar Systems installed and are unsatisfied with still higher than expected utility bills because they never took the time to do an energy audit and replace their crappy pool pump with a permanent magnet Variable Speed product, for example.
4) When you construct your house use 2x6 construction and consider rigid 2 part spray foam insulation. Design the roof so the plumbing vents do not obstruct the prime South & West facing surfaces where solar panels can be located. Not sure of your lot size. Perhaps a large ground mounted system would work?
5) Bottom line: a house that size with an electric car is going to need a very large system. What comes to mind at the moment. 20KW of solar, 3 to 4 high quality inverters running in parallel and as much as 100KWh worth of batteries. Its probably going to stretch your $45,000 budget to the limit.
Lastly, Sacramento gets HOT so as the Summer temps go up, Inverter output goes down if they over heat and start to derate. The equipment should be in doors in a room with good insulation and something like evaporative cooling.

 

[OffGridEnclave]

Looking to build a new 4000 sq. ft. house with a pool. Is it possible to produce enough power to run my house (which will be Net Zero) and charge an electric car? I live outside of Sacramento and we have a lot of sun. PG&E want $45,000 to run a line to the house. I figured for $45,000 I should be able to have a solar array and batteries to do this without being grid-tied. I will have a back-up generator run off of propane and possibly some wind power for the bad weather days and nights.
Where do I start?

supplement solar with a wind generator if possible.
yes everything is possible, the only question is how many soccerfields of solarpanels you need..
charging the car during the day is rather doable, sizing batteries so it can also charge over night will be a nightmare/very pricy.
45k $ should buy a system to run a big house.
if you plan the setup as "offgrid" in other terms like water and food too there is many small details that should be done differently when doing construction compared to a "normal" ongrid house. (fire protection being a big factor for example).

https://offgridenclave.com/ <- got a website running to collect infos/knowledge/techoptions around the topic of offgrid /selfsufficiant living. bunch of reference projects and a ton of infos for newbros, you probably find knowledge/infos there you deem usefull for that livestyle.

 

[Rednecktek]

Well, I'll start the default answer to these questions and we can work from there. Here's you To-Do list:

1: Power audit! This will give you some important information on how big your inverter needs to be as well as how much battery capacity you'll need. There is a link in the FAQ section (I think, or someone here will post it shortly) so fill in the blanks and see what it comes up with. You'll probably need some sort of Kill-A-Watt to get accurate measurements. Are you going to be running a 12v system? 24v system? 48v system? What are the specs on your solar panels? VoC? Vmp? Being as this is a new build, throw together a wish list of what you want and estimate on the high side.

1a: Where do you live? Speccing out a system for Scotland is a LOT different numbers than Arizona due to the amount of light you actually get. Someone here can post the link to the PVwatts.com or JCR Solar Uber-Sun-Hours calculator sites to help figure out how much you'll have to work with. That will be a box in the Power Audit form.

2: Parts list: You don't need a make & model list, just a parts list to start from for reference. You'll need an inverter, a MPPT charge controller, fuses, shunt, buck converter, batteries, wire, etc. Once you have a basic list it can be fine tuned to make & models after that. If you're looking at the All-In-Ones check for correct voltage outputs (120v or 240v Split Phase for North America, 220v Single Phase for European type areas) and make sure it has enough capacity for a little bit of growth and fudge factor.

3: Budget!: Steak is great but doesn't mean anything if your wallet says hamburger. Figure out what you're able to spend now vs what you'll have to cheap out on now and upgrade later.

4: Tape measure! Figure out where you're going to stick all the stuff you'll need. A dozen 3000AH batteries sounds great until you're sleeping on the floor because there's no room left for a bed. Is there a compartment that can house all this stuff? Will the server rack batteries fit? Are you going to have to make space? Physics can be pretty unforgiving.

5: Pencil out what you think you need and throw it at us so we can tell you what you've missed (because we ALL miss stuff the first go-round ) and help figure out which parts and pieces you're going to want to get.

 

[houseofancients]

@RayfromTX can may be pitch in here on keeping the home as net zero as possible, thus leaving more power available for appliances and cars to charge

 

[RV10flyer]

Even if you DIY, $45K will not be enough using new, high quality, reputable equipment. You’ll need at least $60K. It’s all worth it. I’d downsize, purchase high eff equipment (20 SEER+ HVAC) and build a well insulated home for starters. I did without the $80K truck/SUV, dining out, multiple vacations, etc. It’s all about priorities.

 

[Quattrohead]

You need to chat with the local town and see if they will even let you go off grid for power.
Then somehow ask the electric company the same thing.
After getting that info, yes you can do a good system for $45k.
Heat pump water heater, variable speed HVAC 20 SEER Mr Cool type system, net zero from day 1 you can make it happen for sure.

 

[chrisski]

I think the plan for solar is possible, but incredibly expensive. This is the site to get questions answered for solar.

For wind, I’m not sure its worth it. I could not get a wind turbine where I live and have it produce any significant power, but where I camp about 30 minutes from here where the mountains meet the flat valley, I could make a little power. An active wind forum is Fieldlines.com.

 

[greenware]

Start by estimating your total electrical demand in both Peak KW and KWhrs per day, week, month. But read below first.
1) Besides the generator, what other appliances will run with Propane. If space heating, water heating, clothes dryer & Range can be propane that reduces your electrical requirements a great deal. This is something you need to decide early on because it will have a MAJOR impact on the size and cost of your solar and battery system.
2) Electric vehicles, depending on your commute, consume large amounts of electricity. Determine how many KWh's your car needs on average per month. Generally, a vehicle uses 35KWhs per 100 miles.
3) Make a list of all the appliances that use electricity and their amperage draw. Add it all up and estimate how many hours a day they will run. Keep in mind its far cheaper to save a KWh than it is to produce one and store it in a battery. For example, A super high efficiency, variable speed HVAC system may cost $4,000+ more than a standard system but in your case it would be money well spent since it reduces the overall size of your solar. Likewise, with all the other appliances. Front loading washing machine, Heat pump type water heater (if you don't go with propane) Etc. Seriously, this is important. I know several people who had Solar Systems installed and are unsatisfied with still higher than expected utility bills because they never took the time to do an energy audit and replace their crappy pool pump with a permanent magnet Variable Speed product, for example.
4) When you construct your house use 2x6 construction and consider rigid 2 part spray foam insulation. Design the roof so the plumbing vents do not obstruct the prime South & West facing surfaces where solar panels can be located. Not sure of your lot size. Perhaps a large ground mounted system would work?
5) Bottom line: a house that size with an electric car is going to need a very large system. What comes to mind at the moment. 20KW of solar, 3 to 4 high quality inverters running in parallel and as much as 100KWh worth of batteries. Its probably going to stretch your $45,000 budget to the limit.
Lastly, Sacramento gets HOT so as the Summer temps go up, Inverter output goes down if they over heat and start to derate. The equipment should be in doors in a room with good insulation and something like evaporative cooling.

I can guesstimate the demand, yet without building the house not sure of actual usage.
Everything will be low voltage lighting and energy efficient.
We will only be driving 40-60 miles every other day since we are retired
The only use of propane will be for backup generator and gas fireplace and BBQ. Water heater will be a heat pump along with geothermal
The house will be entirely built with ICF construction. so no issues with air conditioning or heating
$45,000 is not the budget. Just a starting point since I would like to eliminate PG&E and not be grid tied.
Also looking at adding a wind generator during the stormy overcast days.

How much battery do I need and what is the best system out there.
We will probably go with a 48 volt system.

 

[BentleyJ]

I can guesstimate the demand, yet without building the house not sure of actual usage.
Everything will be low voltage lighting and energy efficient.
We will only be driving 40-60 miles every other day since we are retired
The only use of propane will be for backup generator and gas fireplace and BBQ. Water heater will be a heat pump along with geothermal
The house will be entirely built with ICF construction. so no issues with air conditioning or heating
$45,000 is not the budget. Just a starting point since I would like to eliminate PG&E and not be grid tied.
Also looking at adding a wind generator during the stormy overcast days.

How much battery do I need and what is the best system out there.
We will probably go with a 48 volt system.

Insulated concrete forms is an excellent choice for home construction. So you are starting out in a good position efficiency wise.

The car is 30 miles a day so figure 10KWhrs minimum per day to charge it up and a Tesla home charger is a 5KW appliance.
For the house since its all electric the total demand would be in the 35 to 40KW range and up to 50KWhrs of usage. Of course, you will probably not have everything on all at once but it adds up. The pool pump is a big factor, consider a Pentair Intelliflow VS.
I just did this guestimation exercise for an average 3 bedroom house in Southern Calif. and came out with 35KW peak demand.

For a high demand Off-Grid situation like yours I would definitely install something like a Span or Leviton Smart panel that could help manage and monitor load control otherwise you will have to constantly worry about your peak demand or stack even more Inverters in parallel.

There is no way to answer the question of what is the best system out there. There are so MANY choices, from full proprietary (expensive) to partial generic to full DIY etc. You really need to sit down with a consultant (not a contractor that only has a couple of options to sell you) and design a complete solution, top to bottom. Based on the description you have provided so far, I know what I would do in that situation but my hands-on approach would not be appropriate for someone who doesn't want continued interaction or the burden of personally maintaining the system.

Going back to my first post yesterday. I would do the following.
1) 20KW of Quality solar panels on the roof, if space is available, or ground mount. I'm assuming 5 solar hours a day but this falls off rapidly in cloudy conditions and seasonal production varies. I would use fixed panel locations with NO tracking or other mechanical means of optimizing the panel direction, too much maintenance.
2) Include a dedicated mechanical room in the home design where the Smart panel and 5 or 6 parallel Inverters can be mounted and kept below 90F in the summer. Something like Outback or Schneider Conext XW Pro.
3) 100KWHrs of LFP battery storage. Probably rack mount type from Signature Solar or equivalent. Located in the same mechanical room. Personally, I would seriously consider DIY batteries, maybe wall mount but this is definitely a big job, not for everyone and I'm not recommending this in any way, just sharing some thoughts.

Let me know if I can help, you have a very interesting project.

 

[Quattrohead]

I am also building an ICF house in Florida and whilst not targeting netzero, will hopefully come close.
I have been monitoring my power use with an Emporia system and it has been very useful to understand our use of power. I doubt it will change too much, probably swapping AC for pool pump use !!!
I discovered a highest use day on Thanksgiving due to cooking and cooling for a house full of people of 57kWh. I think peak current was 70-80A
Average daily use over the year was 31kWh with a low of 19kWh and a high of 45kWh.
I want to have 3 days of battery backup with some power conservation and genny as a last resort.
I am thinking of 12-18kW of inverter, 50kWh of batteries and 9-12kWh of panels.

How does your expected consumption look against my figures ?

 

[BentleyJ]

Thanks for electrical usage info that helps quite a bit. I recently removed an older TED5000 energy monitor and installed an 8 CT Emporia system. I'm still waiting for the firmware upgrade so I can get NET metering from my Subpanel with the 50A CT's as well as from the mains.

The system you are proposing would most likely work but I would consider it as the bare minimum and not comfortably sized.
For example, 10KW of solar panels will produce up to about 50KWh per day, less during the winter, BUT that can easily drop to 10KWh or less with clouds. In this circumstance you would still need about (3 days x 20KWh) 60KWh from batteries. So your 12KW of solar panels figure is probably more realistic.

Keep in mind you are proposing to be Off-Grid so reliability and redundancy are important.
I would go with 3 Inverters (Conext XW Pro for example) in parallel which will give you 21KW continuous and still 14KW if one goes down and you need to wait for repair parts.
Batteries, one 25KWh battery for each Inverter (they would be in Parallel) but in separate racks or cabinets. Again this allows you take one battery off-line leaving 2 instead of just having 1 BIG battery with no back-up. With 75KWh of batteries, that's 60KWh usable.

Lastly, you mentioned that electrical consumption in the new house is not expected to be much different. Make sure to take into account any upgrades such as a double oven vs. single, Spa and/or saunas etc.

 

[Quattrohead]

Yes some good points and indeed those are my beginning requirements and I will expand as I find necessary. I have considered running the pool pump off its own little system that will only run during the day...not a big pool so 1hp or less.
Also thinking about critical loads and regular loads panels, possibly 120v panel and 240v panels too.
Ultimately it will all be UL and local code complaint and able to be connected to regular PoCo if ever needed, solar or not.

 

[Stiffmeister]

You absolutely need to find out ASAP if you're allowed to build a house without being connected to PG&E. My mom was having Tesla Powerwalls installed and the guy said it was not legal to be off grid (who knows).

If you're allowed to go off grid, congrats and you need more than $45k. You can always add panels (need roof space and angle) but you'll need large inverters.

I'm trying to go off grid in Cabo San Lucas. Obviously AC is the most important so I have R60 roof and R22 walls. Windows aren't great but I needed them to be hurricane proof. I'm around 25kw in panels but remember they never make what they are quoted. The upstairs inverter feels small to me at 7200 watt (Outback) but downstairs is 12,000 watts (Outback Radian). So that's all great and grand, replacing some charge controllers with Victron 150/100's.

So sure we can bring in a ton of power during the day and invert to AC, but off grid is all about battery power. That's where I'll really be throwing down the cash.

You may be hit by NEM 3 if you don't get it finished and are stuck being connected to PG&E.

 

[Ampster]

You absolutely need to find out ASAP if you're allowed to build a house without being connected to PG&E. My mom was having Tesla Powerwalls installed and the guy said it was not legal to be off grid (who knows).

I live outside of Sacramento and we have a lot of sun. PG&E want $45,000 to run a line to the house.

I assume what @greenware was implying was that grid service is not currently provided to that lot. He most definitely would need to check with the Authority Having Jurisdiction, which is most likely the building department of his City or County. As far as my understanding of the state building code, grid service is only required if it is available to the particular site in question. I do not know the details and I am sure they differ around the state.

 

[50ShadesOfDirt]

Just a thought exercise:

0. assuming AHJ buy-in, and they need site plans, designs, etc., which means architects/engineers/EE/electricians ...
- get property site plan finalized as much as possible, with all of the players
- coordinate with GC, to ensure their buy in (to temporary power arrangement)

1. you'll need onsite power (generator) for construction, and will want to transition that power to "backup" status:
- onsite fuel source (propane)
- a "utility" site/structure (integrated propane tank, utility shed, etc.) close enough to house to tie in
- factor in ground-mounted panel farm in the utility area siting, with overall site plan

2. onsite generator (EE sized):
- a liquid-cooled behemoth (propane), in the 20kw on up range; lower rpm, longer life, massive power, etc.
- must be automatic, must run for 1000's of hours with no problem, must be serviced/serviceable by someone
- will serve as temporary construction power

If you stop right here, there is any amount of construction power needed; genny has to run whenever power is needed. Serves as the "backup" component in the off-grid solar setup, so not "wasted".

3. inverter/charger/battery-bank, to meet EE's calc's of what's needed:
- a bank of linked magnum 4048 inverter/chargers
- battery "bank" of LiFePO4; possibly a bank of ampere time 24v or 48v batteries (highest ah available)
- a decent solar installer, if not the electrician (who is a solar installer)

4. car charging facilities:
- car vendor passes on details to EE, who sizes, ties in to the rest of the design
- a decent solar installer, if not the electrician (who is a solar installer)

If you stop here, still unlimited power; genny only runs to refill battery bank. Note that no power demand can be exceeded, because of the behemoth above (should turn on automatically when battery bank exceeded).

5. solar panel farm, mppt(s), (EE sized):
- add enough ground-mounted solar panels (site plan & utility site integrated, site permitting) to meet 50% to 90% or more of power, served by battery bank; tie in via mppt(s) ... I couldn't begin to calculate if the EE can hit 100%, but either they will, or genny makes it up.
- a decent solar installer, if not the electrician (who is a solar installer)
- genny makes up power not provided by panel farm; otherwise in standby mode for emergencies

Get an EE involved early, to design "everything" ... sizing of all components, inter-connections, even down to electrical panel layout (one or more 4x8 sheets of plywood worth). Coordinate with electricians to get buy-in before a body or a component shows up on site.

I'd still work hard to reduce all non-essential power loads, if they can be served by propane, etc., and if no inconvenience that you can't live with. But, with a behemoth of a generator, no power need that can't be met, by throwing more power at it (backed by propane); genny will just come on more often.

Hope this helps ...

 

[Smokin]

Pay the $45,000.

 

[WYtreasure]

Welcome to the party Greenware. Please don't feed the trolls. ?

Keep PG&E as far away as possible. I think that sooner or later they will be taking your power and leaving you with a little bit of what you produce. Just a thought.
At what elevation will you be building?
The valley will be experiencing fog while the foothills will be sunny. There's something else for you to consider.

So, are you heading out of town towards wind or sun?

 

[greenware]

Just a thought exercise:

0. assuming AHJ buy-in, and they need site plans, designs, etc., which means architects/engineers/EE/electricians ...
- get property site plan finalized as much as possible, with all of the players
- coordinate with GC, to ensure their buy in (to temporary power arrangement)

1. you'll need onsite power (generator) for construction, and will want to transition that power to "backup" status:
- onsite fuel source (propane)
- a "utility" site/structure (integrated propane tank, utility shed, etc.) close enough to house to tie in
- factor in ground-mounted panel farm in the utility area siting, with overall site plan

2. onsite generator (EE sized):
- a liquid-cooled behemoth (propane), in the 20kw on up range; lower rpm, longer life, massive power, etc.
- must be automatic, must run for 1000's of hours with no problem, must be serviced/serviceable by someone
- will serve as temporary construction power

If you stop right here, there is any amount of construction power needed; genny has to run whenever power is needed. Serves as the "backup" component in the off-grid solar setup, so not "wasted".

3. inverter/charger/battery-bank, to meet EE's calc's of what's needed:
- a bank of linked magnum 4048 inverter/chargers
- battery "bank" of LiFePO4; possibly a bank of ampere time 24v or 48v batteries (highest ah available)
- a decent solar installer, if not the electrician (who is a solar installer)

4. car charging facilities:
- car vendor passes on details to EE, who sizes, ties in to the rest of the design
- a decent solar installer, if not the electrician (who is a solar installer)

If you stop here, still unlimited power; genny only runs to refill battery bank. Note that no power demand can be exceeded, because of the behemoth above (should turn on automatically when battery bank exceeded).

5. solar panel farm, mppt(s), (EE sized):
- add enough ground-mounted solar panels (site plan & utility site integrated, site permitting) to meet 50% to 90% or more of power, served by battery bank; tie in via mppt(s) ... I couldn't begin to calculate if the EE can hit 100%, but either they will, or genny makes it up.
- a decent solar installer, if not the electrician (who is a solar installer)
- genny makes up power not provided by panel farm; otherwise in standby mode for emergencies

Get an EE involved early, to design "everything" ... sizing of all components, inter-connections, even down to electrical panel layout (one or more 4x8 sheets of plywood worth). Coordinate with electricians to get buy-in before a body or a component shows up on site.

I'd still work hard to reduce all non-essential power loads, if they can be served by propane, etc., and if no inconvenience that you can't live with. But, with a behemoth of a generator, no power need that can't be met, by throwing more power at it (backed by propane); genny will just come on more often.

Hope this helps ...

This is my plan, just need to have someone like an EE run the calculations and state specifically what I need.
We can do a ground mount system with 50-60 or more panels if needed.
10 acres of open sloped land south facing.
Trying to sty away from Propane as an energy source other than back up or the occasional fireplace or Pizza oven heating.
We ordered a Rivian R1S so I should be able to get the numbers from them on usage.
I don't mind spending the money on cutting edge technology as long as it integrates together.
Especially the battery technology which is really evolving quickly.
I will be my own GC since I am a retired GC and know my way around a job site.
I will also be doing most if not all of the electrical work and solar system mounting.
Low ground mount should be really easy. Will most likely need two separate ground systems next to each other with that many panels.
I guess finishing my house design and do a energy audit and load calculations should be next.
Than hire an EE to design the system for my load.
This is going to be one hell of a project.
Thanks for the recommendations

 

[greenware]

Welcome to the party Greenware. Please don't feed the trolls. ?

Keep PG&E as far away as possible. I think that sooner or later they will be taking your power and leaving you with a little bit of what you produce. Just a thought.
At what elevation will you be building?
The valley will be experiencing fog while the foothills will be sunny. There's something else for you to consider.

So, are you heading out of town towards wind or sun?

We much prefer to keep the utility company away if possible.
Need to check with our local county bldg department to confirm that this is possible.
We are at 1400 feet and totally out of the fog zone.
Very rare for us to get the fog but we do see it in the valley.
Our morning temperatures are 10 degrees warmer than the valley since the cold air sinks in.
We are in a little micro climate. Does get hot in the summer hence the pool.
Also why we are building out of concrete. We get a little wind but not gail force winds.
Considering a wind generator as a back up during bad weather.
Everyone is open to their opinion, yet I prefer ideas rather than comments.