14.4 KW solar, 40.96 kWh backup, 2 solark 15k inverters, off grid family home, doable or delusional?

[Bop]

Funny you say that, to your point ... I've said it before I will say it again, it's all about DEMAND. I think part of this, and a big consideration if you're going off-grid, is how far we get pushed into electric vehicles. Compared to a HWH or Dryer an EV is an order of magnitude different. In particular if you want to run an EV and you are 'off-grid' it is likely you will be traveling a good distance when you do use it. At a generous 4.0mi.KWH driving back and forth to town 30 miles each way, it's going to eat 15KWH (a bit more likely). I split out a 100A panel for my entire all-electric home. This is a little tight if I'm charging my EV, however 125A will pretty much cover my needs, allowing a single car to charge without a potential demand issue. I will be upgrading as time permits. I'm running standard electric appliances, with an induction range, a third inverter is in my future.

Thus conservation is surely always important, but I would not build an off-grid power plant for a 2000 sqft home, without allowing for 150A of demand from the system no matter what the various components. This get's back to the ROI discussion on gas appliances. An EV is something I definitely have a great deal more control over when it get's charged. Since I would want to build out to be able to charge an EV the additional power to run an HWH/Clothes dryer must become a demand issue not an overall power issue. The two vehicles I have in an urban environment accout for about 1/5 of my overall power needs year round, higher in the winter, much higher in spring/fall, dramatically lower in the summer.

My "starter" solar system was built for 100A of demand, because I made that determination based on the fact that I moved everything into the 100A panel one thing at a time, and monitored it with sensors. The original intent was to shuffle loads with ATS's back and forth. What a PITA / dumb idea that was, though I did write the software to do it. IMNSHO if I'm going off grid, I don't mind maintenance, but I don't really want my power plant to have to stay at the top of my mind 24x7. I want the peace of mind and confidence to know it will perform without me being involved no matter the demand or power requirement.

It's funny- I am actually looking at getting an EV myself (despite being both totally offgrid here and in a very rural area) it makes good financial sense and even the cheaper end of the market has more than adequate range (especially when coupled with our extensive public charger system here- even my little country town (1500 people) now has a public charger, and there are 15 within an hours drive...
My 18kw of panels will be over 80kwh a day total generation (and with my 'normal usage' going between 7-10kwh a day, there is plenty of excess to run both my workshop and charge an EV)
Literally in the middle of this... 100% solar...

 

[wheisenburg]

Have you tried to use the Sol-Ark system sizing tool or the solar panel calculator? I found them very useful. FYI we live in southeastern Louisiana and have the following system that powers our whole house.

Link to system tool: https://www.sol-ark.com/calculator/

Link to panel sizing tool: https://www.sol-ark.com/solar-panel-sizing/SolarPanelSizing.html

2 x Sol-Ark 15ks in parallel
3 x EG4 Power Pro's
6 x EG4 LL V2's
4.8k watts of AC coupled solar
4.8k of DC coupled solar
(PV will soon be doubled its the only weak point in my setup)

Very nice build.

 

[ksmithaz1]

Found an article from a propane company, a bit dated, but it's the volumetrics that we are looking for. . .

Propane Gas vs. Electric Efficiency for Clothes Dryers

Propane can power many appliances, including your clothes dryer. If your house uses propane for heat, cooking, or to power other appliances, adding a propane gas clothes dryer could help dry your clothes more efficiently.

www.kauffmangas.com

"

• Gas dryers use about 15-25 gallons of propane per year. With the small amount of propane needed, the price per gallon is more expensive (currently about $4.22/gallon). But if you have more appliances running on propane and you order more, the price/gallon is lower (approximately $2.50/gallon).
  • Few gas appliances ($4.22/gallon): $4.22 (price per gallon) x 25 (gallons per year)= $105/year.
• Several gas appliances ($2.50/gallon): $2.50 (price per gallon) x 25 (gallons per year)= $62.50/year.
• Electric dryers use about 3.3kWH per load. At an average rate of $.093 per kWh, that equals $.31 a load. The average family that uses 5 loads per week will spend $1.55 per week, or roughly $80/year.

"

5 loads / week . . . Bwahahahahah. More like 5 loads a day . . . I digress, using 10 for a household with teenagers, 33KWH/week. In normalizing the apples and oranges above 52 * 5 = 25 gal / 260 loads = .0.961 * 10 = ~0.95gal/week. Assuming an abysmal week always implies the need to run the genny for the boss's underthings, and we have 10 abysmal weeks / year, we would need to generate or store an additional ~330 KWH over 10 weeks. Just ~double it for the HWH and range, call it 700KWH of production /10weeks vs about 50-60 gallons of propane/year.

Generator Cost Per kWh: Diesel, Propane, Natural Gas, Gasoline

The US national average cost of electricity from the grid is about $0.15/kWh. How does the cost per kWh from generators compare? Obviously, the generator cost per kWh will be higher, otherwise everybody would be using generators for electricity. But how much higher? $0.20/kWh? $0.40/kWh? Even...

learnmetrics.com

Claims about 0.45/KWH from a propane genny. About $300 for 10 weeks converting propane to electricity to run electric appliances during a worst case winter with 10 weeks of ZERO sunshine. About 50 gallons of propane to just run the gas appliances year round about $150 @ $3/gal.

The ROI is clearly better for all gas, so if the object of the exercise if to do it as cheaply as possible go all gas if you are going to have 10 weeks of no sunshine and you can't store the solar. The opex falls lower for electric if you can cut the window down closer to 5 weeks, and you're never going to own an EV, but it will never pay you back. These numbers are all so small it almost seems irellevant.

Personally, I'd rather not have gas lines running in my house, and my goal would be self-sufficiency not $$$. I would probably not opt to go "off-grid" with solar, in a place that had even 5 weeks of zero production. If +$40K over 20 years is +$2K/year to be self-sufficient, and able to function normally with minimal outside help, I'm in.

 

[ksmithaz1]

Literally in the middle of this... 100% solar...

18KW of panels may not cut it with an EV unless you plan on frequenting those charging stations frequently . I have right at 18 now, going to push up closer to 23, that should provide the edge I need to get over the hump. The problem is not zero days its extended periods of low production/high use, and the ability to have the EV plugged in during the times you have excess you can't store. YMMV if your overall needs are really low. I keep playing with charging rates, times, and roll-off

Nice location...

 

[Zwy]

Found an article from a propane company, a bit dated, but it's the volumetrics that we are looking for. . .

Propane Gas vs. Electric Efficiency for Clothes Dryers

Propane can power many appliances, including your clothes dryer. If your house uses propane for heat, cooking, or to power other appliances, adding a propane gas clothes dryer could help dry your clothes more efficiently.

www.kauffmangas.com

"

• Gas dryers use about 15-25 gallons of propane per year.

I will have a spare 500 gallon propane tank after I get my gasification wood boiler running along with 2 heat pumps for heating.

If I fill it (80%) and hook it to a gas dryer, use 20 gallons a year, I will be able dry clothes for 20 years.

Propane truck was here this week, I had prepaid $1.30/gallon. That means it would cost me $26 per year for dryer use, about $0.50 per week.

Right now the electric takes about 6Kwh per drying cycle, my wife runs it on average twice a week so 12Kwh x 52 weeks = 624Kwh

I always use $0.20/Kwh. That comes to $124.80 per year for drying clothes.

I think I'll buy a gas dryer now instead of a heat pump dryer. Thanks.

 

[Bop]

18KW of panels may not cut it with an EV unless you plan on frequenting those charging stations frequently . I have right at 18 now, going to push up closer to 23, that should provide the edge I need to get over the hump. The problem is not zero days its extended periods of low production/high use, and the ability to have the EV plugged in during the times you have excess you can't store. YMMV if your overall needs are really low. I keep playing with charging rates, times, and roll-off

Nice location...

18kw of panels gives me about 80-90kwh a day here- I could recharge the EV I am looking at (BYD Atto 3) 60kwh battery pack from empty to full with 450km range and my normal usage of 7-10kwh a day, and still have ample power left for the workshop even...
Considering that mileage is over an entire weeks worth of driving for me, and could be recharged in one day, I suspect I will rarely if ever need to visit the local charger...
This is my 'retirement home' so I really don't have the need for that much travelling these days-- the workshop will consume far more power than the EV will...

 

[ksmithaz1]

I will have a spare 500 gallon propane tank after I get my gasification wood boiler running along with 2 heat pumps for heating.

If I fill it (80%) and hook it to a gas dryer, use 20 gallons a year, I will be able dry clothes for 20 years.

Propane truck was here this week, I had prepaid $1.30/gallon. That means it would cost me $26 per year for dryer use, about $0.50 per week.

Right now the electric takes about 6Kwh per drying cycle, my wife runs it on average twice a week so 12Kwh x 52 weeks = 624Kwh

I always use $0.20/Kwh. That comes to $124.80 per year for drying clothes.

I think I'll buy a gas dryer now instead of a heat pump dryer. Thanks.

Don't forget a 'gas' clothes dryer DOES have an electric motor. ;-)

 

[Hedges]

One can certainly get by with less, like 30A, 7500W, if not much in the way of electric heating (or cooling) appliances.

My sister's house had 30A service, I think. Probably my mother's did originally.
My mothers had been upgraded to 100A, with electric ovens and dryer outlet, outlet for range as well but has gas cooktop.
Remodeling my sister's, I installed 100A. She remodeled again decades later, adding A/C, and put in 200A.
Now that my mother's is mine, I'm in the process of putting in 200A.

Could get by with less, but upgrade required by 120% rule given the PV wattage I'm installing (15kW), with an eye toward banking credits for electric heat.

We can get panels for 100A, 125A, 150A, 200A, 225A. Standard sizes are what's most economical, and when doing an upgrade much better to aim higher than needed. The point is never having to say, "Oops, it tripped. Need to turn something off."

Living with an inverter, managing peak watts and SoC/kWh is key.

Propane truck was here this week, I had prepaid $1.30/gallon. That means it would cost me $26 per year for dryer use, about $0.50 per week.

Right now the electric takes about 6Kwh per drying cycle, my wife runs it on average twice a week so 12Kwh x 52 weeks = 624Kwh

I always use $0.20/Kwh. That comes to $124.80 per year for drying clothes.

My San Jose rates, electric dryer would cost you $3.60/week ($7.20 peak hours.)
DIY PV would knock that down to $0.36/week.

It seems like propane, at your prices, is good to have. But PV, especially at the panel prices we've been seeing lately, is also good.

Have one dryer of each kind, one water heater of each kind, one furnace of each kind.
There are a few heat pumps with gas backup, most use resistance.
But given PV costs, I think simplicity of resistance heat not heat pump is the way to go, except possibly for winter heating if PV + heat pump has a chance.
Rebates and tax credits may make now a good time to buy heat pump something.

 

[Bop]

LPG (propane to the yanks) is a poor choice where I am in Australia- close to one of the most expensive ways there is to power a home...
LPG is currently $1.19 per litre, so a 40kg tank costs close to $100 a tank, and would last a house with a gas stove and hot water service about 2 to 3 weeks per tank...

A 500 gallon tank is 2300 litres, at $1.19Au a litre to refill here where I am, (in Brisbane it's cheaper), is just over $2700Au per tankload (plus delivery fee)- five of those tanks and you have paid for my LYP battery bank and have some left over...

 

[ksmithaz1]

We can get panels for 100A, 125A, 150A, 200A, 225A. Standard sizes are what's most economical, and when doing an upgrade much better to aim higher than needed. The point is never having to say, "Oops, it tripped. Need to turn something off."
...
It seems like propane, at your prices, is good to have. But PV, especially at the panel prices we've been seeing lately, is also good.
...
Have one dryer of each kind, one water heater of each kind, one furnace of each kind.

Agree. and I want my solar to handle whatever the panel will handle from a demand perspective.
...
If I could get propane for a buck a gallon, I'd probably re-think a few things. That is REALLY cheap.
...
"Kewl" best of both worlds, across all appliances, lousy ROI but nice if you can do it from a redundancy POV.

But given PV costs, I think simplicity of resistance heat not heat pump is the way to go, except possibly for winter heating if PV + heat pump has a chance.
Rebates and tax credits may make now a good time to buy heat pump something.

I'm all in. If you already had propane and you are retro-fitting that's one thing, but building new off-grid, I'd have propane, but only to run a generator in a big tank behind my power plant. You pretty much have to run electric for a modern structure no matter what. It really simplifies if you wire up and use it for everything, and when properly installed is much more forgiving than piping gas into your home. As much as people talk about "cooking with gas" I prefer electric. My induction range boils water in no time flat, and gas ovens are annoying IMNSHO. And before you say it, commercial enterprises prefer gas because it's cheaper. That does not make it better per se.

In some climates a heat pump is sub-optimal, but they keep getting better, but I'm gonna likely want AC anyway, so burning something for me would be as a last resort.

Solar ain't cheap, and the ROI is not great when you scale it out to the edge case use, but production costs keep dropping, to the point it's more around the storage cost to pick up that edge, and there is downward pressure there as well.

 

[Zwy]

LPG (propane to the yanks) is a poor choice where I am in Australia- close to one of the most expensive ways there is to power a home...
LPG is currently $1.19 per litre, so a 40kg tank costs close to $100 a tank, and would last a house with a gas stove and hot water service about 2 to 3 weeks per tank...
View attachment 194563
A 500 gallon tank is 2300 litres, at $1.19Au a litre to refill here where I am, (in Brisbane it's cheaper), is just over $2700Au per tankload (plus delivery fee)- five of those tanks and you have paid for my LYP battery bank and have some left over...



View attachment 194566

Propane is a bargain here in the States, no doubt about it. It is byproduct due to processing natural gas which the States have an abundance of, even flaring off excess natural gas.

If everyone here switches to solar, then propane will end up once again at giveaway prices. 37 years ago I remember paying around $0.30/gallon.

 

[Hedges]

... even flaring off excess natural gas.

Because that is so much better in terms of global warming then letting people burn it for domestic heat or motor vehicles.

I suspect it has to do with oil leases, company wants to extract as many $$ as possible, no regard for wasting resources. If someone owned the resource, they might pump more slowly such that there was a market for the gas too.

If we can burn propane or NG in a generator to top off batteries during winter, also using the "waste" heat (CHP), we come out further ahead.

There are fuel cell CHP units, including high temperature reformer for NG, but don't know about cost effectiveness. Don't know if that would be possible with propane.

 

[Zwy]

Don't forget a 'gas' clothes dryer DOES have an electric motor. ;-)

Yes, but my electrical system for my house supplies free electricity.

Heat pump dryers take more electricity than gas.

The largest load in my house next to HVAC is the clothes dryer. I've looked for heat pump dryers in the larger size, never find any at a retailer around here or any heat pump dryer for that matter. It is always order one in.

Gas dryers are in abundance. I just checked and the Samsung 7.8 cu ft heat pump dryer I was interested in is now on sale with $700 off the price and is $1627 plus tax.

Gas dryer is around $700. The difference is $927 x 5% = $46.35

So I'd still have the $927 plus pocket an additional $20.35 in interest earned on the $927.

Compound that over 20 years of propane in the tank and I will have $2,459.61 extra.

However there is one thing that could change my mind. The High-Efficiency Electric Home Rebate Program will pay up to 50% of the cost up to $840 (income between 80 percent and 150 percent of Area Median Income) so that would be $813 rebate.

The heat pump dryer I'm looking at uses less than 1Kwh to dry clothes. It is a toss up, I could sell the extra propane tank (probably not) and it would fetch about $1500 in today's market.

 

[Quattrohead]

Propane is a very volatile material in terms of actuality and price, I would not want to rely on it long-term because people are turning against it because it's dirty and produces carbons. I buy my batteries, solar panels and inverters and I am done, I don't need to rely on anyone ever again.

 

[Zwy]

Propane is a very volatile material in terms of actuality and price, I would not want to rely on it long-term because people are turning against it because it's dirty and produces carbons. I buy my batteries, solar panels and inverters and I am done, I don't need to rely on anyone ever again.

It comes down to economics for me when it comes to some directions I've taken. I know propane will be available for a long time due to natural gas processing. This country will be using natural gas for a very long time, there is no way the world population can be fed without processing natural gas. I don't care what some might think, it isn't happening.

I hedge costs all the time, both in business and personal expenditures. I've installed solar as an example hedging against future energy costs once I'm retired. I hedge against fuel cost by buying fuel for business vehicles in bulk and at time when there is a dip in price. I hedge on propane costs the same, I need propane for the business heating needs and pre pay/summer fill in bulk. I own enough propane storage tanks that I can hedge a year in advance easily.

The clothes dryer is no different. On one hand you have proven reliability and long service life with gas. The operating expenses are ongoing but compared to an electric dryer whether on solar or not, the gas dryer is a bargain.

The heat pump dryer may not last as long, repairs could be expensive and it requires more cleaning compared to the gas. It does have the advantage of lower energy usage than electric, so it fits solar well. Actual energy costs compared to gas- no clear winner except in winter with low sun hours, gas holds the advantage.

Cost is slightly less with gas than heat pump with energy rebates/credits from the IRA. Heat pump holds the advantage of recycling the heat and is ventless, gas will require makeup air into the building envelope.

I'll let it stew but when it's December with clouds for 2 weeks, gas would be the winner.

 

[Quattrohead]

100% agree, it will change depending on where you are in the US and the world.

 

[Doggydogworld]

I suspect it has to do with oil leases, company wants to extract as many $$ as possible, no regard for wasting resources. If someone owned the resource, they might pump more slowly such that there was a market for the gas too.

It's a lack of pipes. You drop some wells in the middle of nowhere, both oil and gas come out. It's easy to pump the oil into a tank and have a truck empty it regularly, but if you don't have pipes in place you just flare the gas. The gov't frowns on this, but wants to keep the oil flowing so permits it up to a point.

Eventually if your field produces enough gas, and is near other fields and/or a nearby pipeline, it makes economic sense to lay pipe and collect all the gas.

I saw a spot the other day about a company putting bitcoin mines and server farms at remote oil fields. They get free(ish) gas to generate electricity and the oil company gets the gov't off their back.

 

[G00SE]

When I first embarked on learning how to power our offgrid homestead my intent was propane for the range, water heater, and dryer.
My intent has now changed to electric range, heat pump water heater as well as heat pump washer/dryer combo. (I’ll just hang dry 6 months a year if needed)

We still intend on propane, but as a fuel source for the generator and potentially have a backup gas wh to boot.
It’s apparent that depending on one’s current situation and/or desires are will strongly influence choices.
The ones in here demonstrating a lack of cost benefit to replace perfectly functional equipment, or the ones that don’t have a priority of off grid sustainability seem entirely on point in sticking with gas.
If one’s starting from scratch, I don’t much see the point anymore. My initial rationale was cost. But if one shops around there are amazing prices for solar gear

 

[ksmithaz1]

Yes, but my electrical system for my house supplies free electricity.

Heat pump dryers take more electricity than gas.

The largest load in my house next to HVAC is the clothes dryer. I've looked for heat pump dryers in the larger size, never find any at a retailer around here or any heat pump dryer for that matter. It is always order one in.

Gas dryers are in abundance. I just checked and the Samsung 7.8 cu ft heat pump dryer I was interested in is now on sale with $700 off the price and is $1627 plus tax.

Gas dryer is around $700. The difference is $927 x 5% = $46.35

So I'd still have the $927 plus pocket an additional $20.35 in interest earned on the $927.

Compound that over 20 years of propane in the tank and I will have $2,459.61 extra.

However there is one thing that could change my mind. The High-Efficiency Electric Home Rebate Program will pay up to 50% of the cost up to $840 (income between 80 percent and 150 percent of Area Median Income) so that would be $813 rebate.

The heat pump dryer I'm looking at uses less than 1Kwh to dry clothes. It is a toss up, I could sell the extra propane tank (probably not) and it would fetch about $1500 in today's market.

For the complexity I like the gas unit, dirt simple, heat source, blower/drum motor. For the safety I like electric. If installed properly gas should be perfectly safe, and modern gas devices don't have pilots, and have shutoffs and flame detection, but I'm old and have had a few bad experiences. Propane is a bit hotter (temp) than NG, and I prefer cooking by regulating temperature rather than heat volume. It's a subtle difference, and a gas oven will handle the dissipation to regulate the temperature, I just find gas surface units annoying.

A big advantage of propane/NG is the ability to run a demand HWH. If I had gas that is the one thing I would definitely spring for. The electric units draw way too much demand power. I might re-consider if I build my plant out more.

 

[SilverbackMP]

I would probably not opt to go "off-grid" with solar, in a place that had even 5 weeks of zero production.

Cough. Southwest-SoCal bubble. Cough

Propane, in Missouri was $1.69 per gallon in October (cheaper in spring and summer),

Can’t be much difference in Louisiana (which may be even cheaper).

Gas is not expensive when you have it in abundance and not too expensive when you don’t blow the pipelines running to your area/country (ok UK, “countries,” lol).

 

[Bop]

We have gas in abundance here in Australia, but refining and transport costs add up (especially when the government isn't majorly subsidising the oil and gas industry (coughs USA)
When LPG/propane costs $5.70US a gallon, tell me it is still 'cheap to run' and you would still be using it...

 

[SilverbackMP]

We have gas in abundance here in Australia, but refining and transport costs add up (especially when the government isn't majorly subsidising the oil and gas industry (coughs USA)
When LPG/propane costs $5.70US a gallon, tell me it is still 'cheap to run' and you would still be using it...

The ORIGINAL POSTER is in LOUISIANA. I guess we have an Australia bubble along with a Southwest-SoCal bubble. (Side comment: Probably would have helped if Australia hadn’t of shitcanned most of their oil and gas industry except for that coal for that lovely Chinese money (and that dude with the blown 73 Ford Falcon trying to crack his own)).

Point being, use what makes sense in your locality. Me running 100% ethanol in vehicles in Missouri wouldn’t make sense but would sure in the hell make sense to a Brazilian.

 

[Zwy]

For the complexity I like the gas unit, dirt simple, heat source, blower/drum motor. For the safety I like electric. If installed properly gas should be perfectly safe, and modern gas devices don't have pilots, and have shutoffs and flame detection, but I'm old and have had a few bad experiences. Propane is a bit hotter (temp) than NG, and I prefer cooking by regulating temperature rather than heat volume. It's a subtle difference, and a gas oven will handle the dissipation to regulate the temperature, I just find gas surface units annoying.

I've always had a gas stove and will always have one. Back when the power would go out, we could use the oven for heat and still cook and heat water.

With my solar system, I still have no desire to switch.

A big advantage of propane/NG is the ability to run a demand HWH. If I had gas that is the one thing I would definitely spring for. The electric units draw way too much demand power. I might re-consider if I build my plant out more.

I run a powervent propane water heater, that thing is pretty good on gas. The shop has a tankless and it gets used often, even run the heated water thru a pressure washer. It does require flushing every year or two. Before I would put one in the house I'd go with an electric ahead of the powervent propane water heater as a dump load. Eventual plan is gasification wood boiler for middle of winter with 1400 gal of thermal storage with another small thermal storage tank in the basement where I can use air to water heat pump or the wood boiler for heat storage when it is shoulder season: spring and fall. I can add a heat exchanger from the wood boiler for hot water too. That gives unlimited hot water.

I want the ability to heat the house 3 or 4 different ways. That gives me option, I might be gone a month in mid winter in the future or take off for a week on a short trip.

 

[SilverbackMP]

I've always had a gas stove and will always have one. Back when the power would go out, we could use the oven for heat and still cook and heat water.

With my solar system, I still have no desire to switch.


I run a powervent propane water heater, that thing is pretty good on gas. The shop has a tankless and it gets used often, even run the heated water thru a pressure washer. It does require flushing every year or two. Before I would put one in the house I'd go with an electric ahead of the powervent propane water heater as a dump load. Eventual plan is gasification wood boiler for middle of winter with 1400 gal of thermal storage with another small thermal storage tank in the basement where I can use air to water heat pump or the wood boiler for heat storage when it is shoulder season: spring and fall. I can add a heat exchanger from the wood boiler for hot water too. That gives unlimited hot water.

I want the ability to heat the house 3 or 4 different ways. That gives me option, I might be gone a month in mid winter in the future or take off for a week on a short trip.

Working on pretty much the same setup.

 

[Hedges]

Eventual plan is gasification wood boiler for middle of winter with 1400 gal of thermal storage with another small thermal storage tank in the basement where I can use air to water heat pump or the wood boiler for heat storage when it is shoulder season: spring and fall. I can add a heat exchanger from the wood boiler for hot water too. That gives unlimited hot water.

If you get/store thermal energy from a givenn source, e.g. boiler & storage tank, using that as thermal input to heat pump, no extra energy is obtained.

Heat pump needs excess quantity of lower grade heat.

You would get as much energy using stored hot water directly. Only thing heat pump does is boost temperature, could make radiators put out more. What it can do is cool off the tank faster if you need higher grade heat.