Anyone running a "normal" household on solar?

I was wondering if anyone is running some normal appliances on nothing but solar. By normal I mean fridge, freezer, dishwasher, computer. Is it even possible with current solar and battery tech to run a "normal" house?

yes.  And, many people do.  A refrigerator/freezer, an regular efficient one is about 1kWh a day,  dishwasher is about the same, and a laptop is very little.  WHile I am grid interitie, I also have a battery bank and can go a few days on battery power powering the refrigerator/water pump/stereo and laptop.  I dont run the dishwasher then, I could.  I have a very small battery bank.   Many other people, people I have met, houses I have stayed at, have larger battery banks.  Anyway, the solar array needed is not that large, but depends on how many days you need to run off battery only.  If it is stormy for a week or two, well, more than my few batteries.

Technology has been here for a long time, my solar system is 20 years old.  When the grid power is out, which happens here frequently, I can run my well pump, refrigerator and various other things off the batteries.  I have never had very many batteries, used to have 4 Trojan 12V batteries.  Maybe L16's ?  At least a 4 day grid power outage.  So, anyway, yes inverter technology and batterey technology have been able to easily run regular appliances, it is all a matter of how much you have to spend on a system and battery bank.  For all the way off grid, you would want a larger battery bank than mine.  Or, you may rethink running the dishwasher during winter storms... or whatever tradeoffs you want to make.  

A "normal" household can indeed be run on solar. One just needs to size the solar system to the power needed. For the normal American, energy hogging, wasteful household, that means a rather hefty solar system. Such systems exist here in Hawaii. I have seen two, plus there are plenty of others.

Personally we opted to change away from our own glutinous energy habits when we went solar off grid.

C. West wrote:I was wondering if anyone is running some normal appliances on nothing but solar. By normal I mean fridge, freezer, dishwasher, computer. Is it even possible with current solar and battery tech to run a "normal" house?

My house started as purely on-grid when I built it in 2005. The area where we live is very prone to power outages, we watched for ten years as our town every calendar month had outages, every year. In 2015, we installed 4400 watts of photovoltaic panels and a 48vdc 600ah battery-bank [I can give details if requested]. We can shift breakers back and forth between power sources.

Our house has a fridge, chest-freezer, dishwasher, two computers, two ceiling fans, one wholehouse exhaust fan, a well pump and two septic pumps.

Over the course of 2019, I had continuing problems with the batteries, until they finally died completely this Fall. The individual cells went dead, cascading across all batteries. Now I need to buy an entire battery-bank, and we are strapped for cash.

All along I have been talking with neighbors who run solar-power systems and gaining from their advice, etc.

I blame two things for the early failure of our batteries.

1- Our charge-controller can not perform an equalize charge. I have spent hundreds of man-hours fighting with it to perform an equalize-charge. Next time I will have a separate free-standing charger here [output:53vdc/20amps].

2- My wife insisted on using solar power every day, while our electrical load grew more appliances.
[our market could not absorb how much pork we were producing, so we had to get more chest-freezers.
We fell in love with a hybrid plug-in sedan that re-charges from our solar-power system.]



If we were exclusively 1 fridge, 1 chest-freezer, 1 dishwasher, 2 laptops, 2 ceiling fans, 1 wholehouse exhaust fan, a well pump and 2 septic pumps. We would be fine, once again [if we also had a grid-powered charger for performing an equalize-charge once a month].

I pump over 1000 gal of water each sunny day with solar, with hurricane Irma I ran my fridge off it.      

I now have have 4 solar system setup, and I have created a wireless battery monitor system for both my 24 V and 12 volt systems so that it auto magically shuts down loads if the voltage drops too low.


My largest system I can run table saw off it, and it  runs the lights for my indoor plants.      At present I have more solar than I have batteries my plan is to buy an used electric car then dump the excess energy into the car for storage so that I will have portable power.      

I have run my bread machine, and insta pot off my system but as of now I only have 5 KWH of battery  so yes I have run my AC from this system but not my long term goal.

One of my smaller systems runs an air pump that pumps water into my filtration system it runs on a sunny day 7 - 9 hours.

The other smaller system is used for lights and keeps my phones charged.     I like multiple small systems because of redundancy if one fails the other can fill in the gaps.


Having the automation was key for me growing my first bananas this year as now that the system is automatic it just happens and I no longer worry about the battery going low as the safeguards in place keep it all safe.

Currently Hawaii, Maine and California uses less than 20kWH/day (600kWh/month) so a 6kWH solar system would cover their needs.
But you aren't the avg person in California. I am sure you could use less than 1/5 of that.

Lighting = 0.5kWh (4hrs/night * 10W/LED * 12LED bulbs)
TV = 0.4kWh (2hrs/night * 100W/TV * 2 TV)
Laptop/All in One = 0.5kWh (4hrs/day * 30W/device * 4 device)
Washing Machine: 0.3kWh (avg is 0.3kWh/day)
Refrigerator-Freezer (17-20 cubic foot): 1kWh (avg is 7kWh/day)
Microwave/Toaster: 0.5kWh (avg is 0.5kWh/day)
Central Air Conditioner (2 ton): 0kWh (avg is 50kWh/day)
Water Heater (4-person household): 0kWh (avg is 10kWh/day)
Electric Clothes Dryer: 0kWh (2.5kWh/day)
Oven Range: 0kWh (avg is 2kWh/day)

Total = 3.5kWh/day
Which could be powered by a 1kW solar array assuming 4hrs per day.

"Normal"is a loaded word. I designed several dozen systems now and no two household loads were ever the same. Where are you is usually the first question as it determines solar availability. Next would be what kind of life do you lead? Are you willing to adjust your life or do you just want to duplicate everything only use solar? Do you have a grid connection already? If so a grid connected system is an option with no lifestyle changes.  Generally for off grid solar the main appliances in a house are covered. Heat appliances like hot water and cooking are usually covered by Gas or propane. Home heat can be a gas or propane furnace but many solar homes usually have a wood heat or low energy propane heat source like radiant floor or wall mounts. Air conditioning in the south gets tricky but can be done with a larger solar array. Passive construction helps there. Usually it starts with a lot of questions.
Cheers,  David

We maintain two houses on our off grid solar, that includes 2 refrigerators, 1 freezer, a washing machine, well pump, a desktop, a laptop, numerous TV's, dishwashers, microwaves, essentially everything that you find in a typical American household. We have an extensive battery bank and a backup generator that recharges the battery bank if it gets too low. But as someone else has mentioned, cooking and heating are propane, or wood.

thanks for all the replies, i have a renewed hope for using solar

I’d look up the archives of Home Power magazine articles archives about energy systems. Home Power stopped publishing recently but they had lots of great articles

Home Power magazine was the best.    I literally started a subscription with issue #3 .  
Can't recommend them enough!

I probably don't qualify for what you'd call a "normal" household in that I use very little power.  I do have an electric water heater, fridge, well pump, lights, computer, and such things.  I use a laundry mat for washer/dryer or do it by hand at home, and I don't use a dishwasher, microwave, or TV.  That said, I'm also using an off-grid solar system in one of the worst areas in the US for solar.  

I just finished posting a blog article talking a bit about my system and the challenges I have around the time of the winter solstice.  If interested here is a link:  https://theartisthomestead.com/off-grid-solar-living-when-there-is-no-sun/

C. West, "normal" depends on where you are.  Solar is about location, location, location.    There are a lot of threads here to look at, we've discussed this a lot.    If you mean completely off grid, there's a lot to know beyond whether it's sunny or not.

Solar equipment is expensive, and it needs to be maintained.  Deep cycle batteries are very expensive, and if you know what you are doing you might....might make the best ones, the most expensive ones last 8-10 years, then they have to be bought again, all at once, because one battery that isn't new will drag the others down to its level, that's a tragic waste of money.   10 years ago we spent $2500 on 8 batteries for a small system.  We just replaced the same batteries for $3500.  So that's $1,000 more than we paid the first time.  It's an expense that won't be the same, and it's quite high for a repetitive household expense.

At some point everyone using battery power, including electric vehicles, will find out that nobody actually recycles batteries.  Batteries have a few of the internal parts that can be recycled, but there are only a few places that do that, and it takes freight to get them there, which is expensive.  The last time I looked there was only one company in Germany that dealt with the other, more toxic components of a dead battery, and shipping it there by dirty, diesel-spewing fuel doesn't seem very green, and I don't think other countries do that.   Maybe this will change when the world has a lot more batteries to recycle, but as of now, when we hand off 8, 10, 12 old batteries, or large electric vehicle batteries for recycling, odds are the worst parts of them are just dumped somewhere very unfortunate.

It's very important to understand DC and AC electricity, the difference, and what to do when things go wrong.  Birds cling to wires with their feet and damage the wire coating, or rodents eat wires coming from the panels if the wires aren't in something protective.  If the panels are on your roof, you have to go up there and clean them, wash off pollen, leaves, pine needles,  tip them at different seasonal times into the sun as it lowers and raises off the horizon.  I prefer to have them on the ground, but they have to be in the sun for a minimum of 6-8 hours a day, no trees, no building shade during those hours at any time of year.

Knowing the difference between a 12 volt, 24 volt, 48 volt system is important.  If it's just installed and they walk away, you will need to know how many circuits you have, how many appliances can be on at one time, and what to do if the alarm goes off on the inverter.  We have yet to find an electric company that wants to work on a solar system that has a problem.  We just had a really good inverter break down, and there's no one to fix it.  I really, really don't want it to go into a landfill somewhere, so I'll probably end up shipping it, expensively, somewhere, if I can find a place.

It's very important to know the wattages of all appliances and how much they will use on a daily basis, including all of the high-wattage appliances like a vacuum, coffeemaker, dishwashers use heaters to dry, printers running for any length of time, hot water pots.  An electrical hot water heater did not work for us in our situation, it just took the batteries down too much when it had been overcast.  We had to have a backup system for hot water, and what's the point of two hot water systems?  An electric dryer runs on 220 volts, instead of the regular 125 volts, and that's huge for a solar system with a special 220V circuit.  I wouldn't even attempt it.  

Most appliances these days look like they are off, or turn themselves off, but there is something called phantom power, they are taking trickles out of the system to be up and running sooner when you push a button.  This is not good for a solar setup.  Trickling power out of batteries when there's been overcast is just using up very expensive batteries.  All of our appliances are on power strips and everything is off overnight, except the refrigerator.  They also act as breakers and protection.

Companies that sell the panels want to tell you about your yearly solar number of hours, and that that somehow fits on a chart for what works.  We live day by day in the real world.  In the winter there are fewer hours that can have sun on panels, yet it's the time of year when we need more power, lights are on sooner, we cook more inside and for holidays.   So the kinds of solar totals they try to sell you on may be questionable, unless you live in San Diego where it rains something like 3 days a year and is sunny the rest.

Two shed expenses... there has to be a shed for the batteries separate from a shed that has the controlling equipment in it because the batteries off-gas hydrogen and sulfur dioxide, which can eat the wires inside very expensive electrical components.   The batteries need distilled water once every 1 month to 6 weeks, and should be added in a dry location, not with rain blowing into them, or snow or dust, blowing sand....a real shed you can stand up in to work on them, and several gallons of distilled water on hand.  You'll need of storage space for corrosion spray, broom, paint brush for dusting them off, a funnel for the water, paper/pen to keep track on, manuals, tooth brush to clean off corrosion....

You can't just set it and forget it.  It's important to know going into darkness at what stage of charge the batteries are each and every day.  This is easier in the summer when you know it's sunny most of the time, but even 2 days of overcast change their circumstances.  We burned out a refrigerator when we first put in the system because we didn't have enough panels to get the batteries up fast enough in non-sunny conditions.  It's something I've got on my mind every day, how much sun was on the panels, and how much overcast was there.  Do we run the vacuum tonight, or do we wait until the sun is on the panels at noon the next day?

We downsized the refrigerator and do not have an electric stove.  

And where is the nearest solar parts distributor?  Will you have to have everything shipped -- (probably) -- which could take 8-10 days, with no refrigerator, as an example.

And this is just the beginning of what someone needs to know to have basically an alternative electrical system that ost likely they will be required to maintain themselves.

It's a kind of serious commitment that if you like that sort of thing, and the power goes out a lot, and there just isn't any other source of electricity, there's motivation for it.  Just because it seems cool, well, I guess that's up to each individual.  :)

I have had a different experience running a normal household on solar, for example

Cristo Balete wrote:C. West, "normal" depends on where you are.  Solar is about location, location, location.    There are a lot of threads here to look at, we've discussed this a lot.    If you mean completely off grid, there's a lot to know beyond whether it's sunny or not.

Solar equipment is expensive, and it needs to be maintained.  Deep cycle batteries are very expensive, and if you know what you are doing you might....might make the best ones, the most expensive ones last 8-10 years, then they have to be bought again, all at once, because one battery that isn't new will drag the others down to its level, that's a tragic waste of money.   10 years ago we spent $2500 on 8 batteries for a small system.  We just replaced the same batteries for $3500.  So that's $1,000 more than we paid the first time.  It's an expense that won't be the same, and it's quite high for a repetitive household expense.

You had lead acid batteries, There are other options for batteries, for example, for longest life, nickle iron based batteries.  https://ironedison.com/nickel-iron-ni-fe-battery  "....Nickel Iron batteries use Nickel plates and an alkaline electrolyte, they don’t experience the plate degradation and short life of a lead plate in acid. It is common to see 50+ year old Nickel Iron batteries still in service today, with some dating back to the 1940s! ..."

At some point everyone using battery power, including electric vehicles, will find out that nobody actually recycles batteries.  Batteries have a few of the internal parts that can be recycled, but there are only a few places that do that, and it takes freight to get them there, which is expensive.  The last time I looked there was only one company in Germany that dealt with the other, more toxic components of a dead battery, and shipping it there by dirty, diesel-spewing fuel doesn't seem very green, and I don't think other countries do that.   Maybe this will change when the world has a lot more batteries to recycle, but as of now, when we hand off 8, 10, 12 old batteries, or large electric vehicle batteries for recycling, odds are the worst parts of them are just dumped somewhere very unfortunate.

They DO recycle the lead cores of lead acid batteries.  Then, there are ones like the ones I use that are totally recyclable, non toxic materials,  Aquion batteries http://aquionenergy.com/

It's very important to understand DC and AC electricity, the difference, and what to do when things go wrong.  Birds cling to wires with their feet and damage the wire coating, or rodents eat wires coming from the panels if the wires aren't in something protective.  If the panels are on your roof, you have to go up there and clean them, wash off pollen, leaves, pine needles,  tip them at different seasonal times into the sun as it lowers and raises off the horizon.  I prefer to have them on the ground, but they have to be in the sun for a minimum of 6-8 hours a day, no trees, no building shade during those hours at any time of year.

I have never changed the tilt nor washed off my solar panels on my roof, way too much trouble.  Yes, sometimes they have pollen on them.  Eventually the rain washes it off, still get plenty of power.  But, yes, you want to eliminate or minimize shading.

Knowing the difference between a 12 volt, 24 volt, 48 volt system is important.  If it's just installed and they walk away, you will need to know how many circuits you have, how many appliances can be on at one time, and what to do if the alarm goes off on the inverter.  We have yet to find an electric company that wants to work on a solar system that has a problem.  We just had a really good inverter break down, and there's no one to fix it.  I really, really don't want it to go into a landfill somewhere, so I'll probably end up shipping it, expensively, somewhere, if I can find a place.

It's very important to know the wattages of all appliances and how much they will use on a daily basis, including all of the high-wattage appliances like a vacuum, coffeemaker, dishwashers use heaters to dry, printers running for any length of time, hot water pots.  An electrical hot water heater did not work for us in our situation, it just took the batteries down too much when it had been overcast.  We had to have a backup system for hot water, and what's the point of two hot water systems?  An electric dryer runs on 220 volts, instead of the regular 125 volts, and that's huge for a solar system with a special 220V circuit.  I wouldn't even attempt it.  

Most appliances these days look like they are off, or turn themselves off, but there is something called phantom power, they are taking trickles out of the system to be up and running sooner when you push a button.  This is not good for a solar setup.  Trickling power out of batteries when there's been overcast is just using up very expensive batteries.  All of our appliances are on power strips and everything is off overnight, except the refrigerator.  They also act as breakers and protection.

Companies that sell the panels want to tell you about your yearly solar number of hours, and that that somehow fits on a chart for what works.  We live day by day in the real world.  In the winter there are fewer hours that can have sun on panels, yet it's the time of year when we need more power, lights are on sooner, we cook more inside and for holidays.   So the kinds of solar totals they try to sell you on may be questionable, unless you live in San Diego where it rains something like 3 days a year and is sunny the rest.

Two shed expenses... there has to be a shed for the batteries separate from a shed that has the controlling equipment in it because the batteries off-gas hydrogen and sulfur dioxide, which can eat the wires inside very expensive electrical components.   The batteries need distilled water once every 1 month to 6 weeks, and should be added in a dry location, not with rain blowing into them, or snow or dust, blowing sand....a real shed you can stand up in to work on them, and several gallons of distilled water on hand.  You'll need of storage space for corrosion spray, broom, paint brush for dusting them off, a funnel for the water, paper/pen to keep track on, manuals, tooth brush to clean off corrosion....

Well, the shed thing depends on what type of batteries.  When I used to have lead acid batteries, I had them in a plywood enclosure inside the garage and had venting to the outside, but it was never a seperate building or shed.  When I got the aquion batteries, I took out the plywood battery box as the Aquion batteries do not have any discharge, and they are out in the open in the garage, directly under the inverter and electronics.  If I had Iron Edison batteries, I would likely have them in a lean 2 right on the outside of the garage and just pass the cabling into the garage as they need more venting.  But again, not a bunch of buildings.  

You definitely want to conserve electricity and change how you do things before installing solar.  For example, myself and most people I know, especially including the ones with solar just do not own a clothes dryer and hang clothes up to dry.  

Sue, thanks for the info on the Nickel-Iron batteries.  

The saltwater batteries, I'm glad they are working for you.

The only thing about storing batteries in a garage is if they are near a sparking type of device, like a gas heater with electronic ignition. the hydrogen gas  (from lead-acid and Nickel-Iron batteries) is dangerous.  It can cause an explosion.  I can't imagine hydrogen gas does much good to a car paintjob.  

Apparently there's some issue with compatibility with home solar equipment and nickel-iron batteries, as mentioned below.

Solar News
Disadvantages of Nickel Iron Batteries
22 November 2017

By Mario Santini

Nickel-Iron (Ni-Fe) batteries, also known as Nickel-Alkaline or Edison batteries are rechargeable batteries with a long life expectancy, high Depth of Discharge (DoD) and a reputation for durability. The battery can withstand overcharge, overdischarge and short-circuiting and yet last 20 years or more.

The disadvantages however outweigh the advantages.

Cost:

The initial cost is at least 30% over a high-end Lead Acid battery of comparable size (considering usable energy) and also still a lot dearer than Lithium-ion batteries.

Efficiency:

Nickel-Iron batteries have lower energy density and lower specific power compared to lead-acid batteries (or in layman's terms are less efficient). The cells take a charge slowly, and give it up slowly (cannot supply sudden large power spikes). This means one would need more batteries and more solar panels to achieve the output of a 'standard' lead-acid based power system. In addition, Ni-Fe batteries have a significant self-discharge rate of 1% per day.

Ventilation:

They produce a lot of hydrogen, daily gassing is required to get the expected performance. Hydrogen gas is explosive, therefore good ventilation is imperative.

Compatibility:

The characteristics of Ni-Fe batteries are not supported by most solar equipment. The voltage window is so wide that standard inverters are likely to shut themselves down well before the battery is fully discharged. Hence claims like "100% usable capacity" are exaggerated which will further add to cost, size and maintenance.

Conclusion

While not as bad as Ni-Cd batteries, RPC strongly advises against Nickel Iron batteries for home solar systems. The initial cost is unlikely to pay off unless maintenance is conducted meticulously - for decades. If you need high quality deep cycle batteries, take a look at these Lead Acid or Lithium-ion batteries.

I think you mis-read what I wrote !  I said if I had nickel iron batteries, they would need to be in a lean-to shed outside of the garage, due to fumes.  Which is still a very simple thing to do, doesnt need a full seperate building.  The advantage of nickel iron is the longetivity.

I used to have "regular' batteries, lead acid, and they were inside the garage, in a plywood box against the exterior wall, with vents to the outside, and this worked very well, they do not need an additional structure built for them, if vented.  The venting was not powered, just upper and lower, one at either end, round holes in the plywood box with flexible duct to hole in exterior wall, and screen on outside of wall to keep out vermin.

I now have Aquion Batteries, and they do no vent any gases.  At all.  They are sitting right under my inverter and electronics in the garage.  At this time, you cannot buy these here in the USA, but hopefully they will return soon.  They were bought out by a chinese company.

I dont no anything about the person who wrote the article you quoted.  I dont know if he has any other motivations to say such things, it seems he is very liberal with that word "most" without giving any details.  The main disadvantage to nickel iron is the cost, even though that cost is actually not high when ammoritized over the life of them.  I would have bought them, they totally would work with my system, I have actually never heard of incompatibilities, so I would recommend that a person looking to buy batteries talk to the manufacurer and check this out for their own situation.  I didnt buy them as the Aquions were available at the time I was in the market and the aquions worked better for me at this time, mostly due to my strength issues.  Likely the Iron Edisons would have been a longer lived battery -- hard to second guess these things

The saltwater batteries are pretty new, and apparently the company is going bankrupt.  From their website....

"Thanks for reaching out to Aquion Energy. As a former customer of the company we are sure that you read in the press release dated July 21, 2017 that Aquion has “emerged” from Chapter 11 restructuring and bankruptcy. We have prepared this short FAQ in hopes of providing a clearer picture to our former customers.

"When can I buy Aquion batteries again?

"Rebuilding after a chapter 11 filing can be difficult and time consuming. There will be a period of time needed in order to regroup, rehire, and requalify the manufacturing process, supply chain, and sales pipeline. There are also improvements to chemistry and form factor of the battery which will take time and effort. All of these efforts will result in a better product for a future market."

Cristo Balete wrote:The saltwater batteries are pretty new, and apparently the company is going bankrupt.  From their website....

"Thanks for reaching out to Aquion Energy. As a former customer of the company we are sure that you read in the press release dated July 21, 2017 that Aquion has “emerged” from Chapter 11 restructuring and bankruptcy. We have prepared this short FAQ in hopes of providing a clearer picture to our former customers.

"When can I buy Aquion batteries again?

"Rebuilding after a chapter 11 filing can be difficult and time consuming. There will be a period of time needed in order to regroup, rehire, and requalify the manufacturing process, supply chain, and sales pipeline. There are also improvements to chemistry and form factor of the battery which will take time and effort. All of these efforts will result in a better product for a future market."

They went bankrupt.  And were bought by a chinese company right after that blurb you quoted was written, so a couple years ago.  The technology is no longer made here, it is overseas.  Hopefully it will be sold here again.  You can buy it in other countries. There are people from all over the world here.   I said they were no longer available in the USA, and hopefully they will get back to our market soon.  SO, I already said this, do you read what I write ? The technology is great.  They did not have enough funding.  They were extremely popular with the off grid homes in Northern CA, and other places I'm sure, but they did not have enough capitol, had a cash flow problem, decalred banktrupcy and had all assets bought out by a chinese company to be built overseas for the overseas market.

These are the most amazing batteries, for non-mobile uses, I have ever had.  They are maintanance free, they do not outgas at all.  They can be drained down to nothing, I have done so, and when they get power again, they just charge back up, no problems.  There are no equalizing charges needed, etc....  They would not work for mobile applications, like a car or cell phone, due to size, weight and that they give up the amps slower that others, which works great for regular grid type electricity uses.  

"....

Updated: Aquion as a saltwater battery is no longer available in North America having moved to China after being bought out. But we've heard about a Dutch company who are starting to commercialize something similar - subscribe to the EcoHome newsletter here and be the first to find out when salt water batteries are available for sale again in USA & Canada...."

so, the only reason to mention them is that the technology does away with many of the concerns you mentioned, even though we cannot get them in USA right now.  Maybe used, hopefully new sometime soon, no matter which company... it will be a different company name

Cristo Balete wrote:Sue, thanks for the info on the Nickel-Iron batteries.  

The saltwater batteries, I'm glad they are working for you.

The only thing about storing batteries in a garage is if they are near a sparking type of device, like a gas heater with electronic ignition. the hydrogen gas  (from lead-acid and Nickel-Iron batteries) is dangerous.  It can cause an explosion.  I can't imagine hydrogen gas does much good to a car paintjob.  

Apparently there's some issue with compatibility with home solar equipment and nickel-iron batteries, as mentioned below.

Solar News
Disadvantages of Nickel Iron Batteries
22 November 2017

By Mario Santini

Nickel-Iron (Ni-Fe) batteries, also known as Nickel-Alkaline or Edison batteries are rechargeable batteries with a long life expectancy, high Depth of Discharge (DoD) and a reputation for durability. The battery can withstand overcharge, overdischarge and short-circuiting and yet last 20 years or more.

The disadvantages however outweigh the advantages.

Cost:

The initial cost is at least 30% over a high-end Lead Acid battery of comparable size (considering usable energy) and also still a lot dearer than Lithium-ion batteries.

Efficiency:

Nickel-Iron batteries have lower energy density and lower specific power compared to lead-acid batteries (or in layman's terms are less efficient). The cells take a charge slowly, and give it up slowly (cannot supply sudden large power spikes). This means one would need more batteries and more solar panels to achieve the output of a 'standard' lead-acid based power system. In addition, Ni-Fe batteries have a significant self-discharge rate of 1% per day.

Ventilation:

They produce a lot of hydrogen, daily gassing is required to get the expected performance. Hydrogen gas is explosive, therefore good ventilation is imperative.

Compatibility:

The characteristics of Ni-Fe batteries are not supported by most solar equipment. The voltage window is so wide that standard inverters are likely to shut themselves down well before the battery is fully discharged. Hence claims like "100% usable capacity" are exaggerated which will further add to cost, size and maintenance.

Conclusion

While not as bad as Ni-Cd batteries, RPC strongly advises against Nickel Iron batteries for home solar systems. The initial cost is unlikely to pay off unless maintenance is conducted meticulously - for decades. If you need high quality deep cycle batteries, take a look at these Lead Acid or Lithium-ion batteries.

Cristo, if you stick to the name brand manufacturers of equipment there should be no compatibility problems with nicad or NiFe batteries or lithium for that matter. The problem comes when the cheaper equipment is used without the programmable set points for absorb, float and low voltage disconnect...

I'm gradually getting my house on solar, which so far is working well.
I have the advantage of being in sunny New Mexico with a roof that faces dead south at an almost perfect angle for solar panels.
6, 235 watt panels give me about 1.2Kw, which go through an MPPT charge controller and into 8, 6volt golf cart batteries wired for 24 volts. This then goes into a 2500 watt pure sine wave inverter.
With this system I run a 12000 btu mini split A/C unit, which is also a heatpump.
During the day when the sun is on the panels I can cool or heat the house with no problem at all and still have enough power to fully charge the batteries. The trick is to crank the mini split up to maximum heating or cooling late in the day so the house will stay cool or warm all night without draining the batteries too much.
All the lights and ceiling fans are on a separate 12 volt system with 200 watts of panels and 2, 6 volt golf cart batteries.
Been doing this for over a year so far, and the best indication of it's success is that I keep forgetting the items that are on solar and just run them as if I was connected to the grid.
As a side note since I started doing this it has cut 25% off my power bill.

Sue, having maintained solar batteries and equipment for 20+ years, I much prefer to have them in their own shed, not a big one, or a shed with a wall down the middle, on the other side of the electronic equipment, so I can  stand up, out of the rain, out of the wind, out of blowing snow or pollen (and I'm referring to pine pollen here, which is extraordinarily thick and heavy for several weeks in the spring) or dust, to top them off, and store all their supplies.

Since this thread is about running a whole household on solar, it would require a very large number of batteries, so maintaining them will take time, much of that bent over, which is not my favorite way to spend even 20 minutes.  So having them and me under a roof, in a lighted shed,  where I can be relatively upright is a real plus.  Everyone seems so focused on, "How do I run my appliances on solar?" there isn't much mention of all the maintenance involved.   I just think people should be made aware that batteries need maintenance, and be reminded about the offgassing.   From participating in previous threads at this site, people don't seem to realize that it even happens.

Yes, hopefully in the future there will be more planet-friendly batteries.  But for now most of us will need to have a local source of deep-cycle, lead-acid batteries, especially when it comes to electric cars, which is another huge user of batteries that will hopefully be recycled properly.

I also have aquion batteries, and have a stack of replacement batteries as well. My main issue right now is finding someone able to help me with the battery systems should a need arise. The solar people that I had come inspect the system and walk me through some things have no experience with these batteries. My bigger issue is the backup generators, how to keep the main one from coming on so often. I don't like the amount of diesel that we use on that generator or the amount of propane that we use on the property in general, but given how difficult things have been lately, I don't want to harp on people's habits. It's been a painful, difficult thing, I don't want to make things worse.

Stacy Witscher wrote:I also have aquion batteries, and have a stack of replacement batteries as well. My main issue right now is finding someone able to help me with the battery systems should a need arise. The solar people that I had come inspect the system and walk me through some things have no experience with these batteries. My bigger issue is the backup generators, how to keep the main one from coming on so often. I don't like the amount of diesel that we use on that generator or the amount of propane that we use on the property in general, but given how difficult things have been lately, I don't want to harp on people's habits. It's been a painful, difficult thing, I don't want to make things worse.

Stacy, what kind of ags system are you using? I.e. what triggers the generators? There is a lot of tricks that can be used to lower genny time. The Aquions have unconventional set points and the standard ags settings would not cut it you would have to tweak them a bit...

I dont remember having to do anything special on changing set points for the Aquions.  That said, maybe I did but just dont remember as it was a couple years ago.  

But, the solar people realy should not have a problem, or be more open minded, as they are easy batteries -- do you have their spec sheet ? If not go online as it is likely still up on their old web site.  So, they are 48 volt batteries... When I bought them, I just checked the specs myself from their data sheet and my charge controllers/inverter.  But, we do have the same problem out here no "solar install people" will give me the time of day as it is an old system that they did not install.  I just talked to the Tech's, by phone, at Real Goods store, hopland CA, for advice, and they had sold me the Aquions. and then had my local electrician, who does not do solar, hook up the batteries to new inline fuses and to the existing combining box I had, there was alot of room.   He is better at fat wires than me, has all the tools, and is old school enough to not be fazed by new things or worry about it.  It is just another electrical connection, after all.  It was pretty easy to see that instead of strings of 12V batteries in series I moved to 48V batteries in parallel.  

The thing about the aquions is there is no maintanance or equalizing cycles.  So, they work or they dont.  The solar people should be able to hook up a meter to them, same as any other battery, if they suspect a problem, they can check if there is a charge etc... same as any other battery.  

Good luck.  I also do get frustrated that unlike any other household system I have, there arent just solar people you can call.  I can call a electrician,  plumber, etc....  When we reroofed 12 years ago, and had to take the panels off then on, I also COULD NOT get any local solar company to come out.  The roofers took them off.  Then I had a friend that worked back office of a large install company who asked 2 of the guys if they would re-put mine on, off book on Saturday, I paid them of course, so they did.  But, the company would not do it at all.  

I have had solar and batteries for 21 years now, which is why the new companies are not who put mine on.  Mine were put on professionally, although if you are comfortable on roofs, and have a stron friend or 2 who also are, you can do it yourself

The off-grid solar people that I have talked to just don't have any interest in dealing with my battery system, I'm not sure that I could convince them otherwise. And they are considered by many as the best off-grid solar people in southern Oregon. I need some time to gain enough knowledge to deal with things myself.

I was looking into what was triggering the generator, but then my grandbaby died, and life has been in standstill since. Some think it is a problem between the outback charge controllers and the xantrex inverters, but I don't know.

Stacy Witscher wrote:The off-grid solar people that I have talked to just don't have any interest in dealing with my battery system, I'm not sure that I could convince them otherwise. And they are considered by many as the best off-grid solar people in southern Oregon. I need some time to gain enough knowledge to deal with things myself.

I was looking into what was triggering the generator, but then my grandbaby died, and life has been in standstill since. Some think it is a problem between the outback charge controllers and the xantrex inverters, but I don't know.

Sorry to hear about your loss... First off usually if its a xantrex inverter the AGS controls work through that. What model? green and white rectangle? the older SW? I know one of the problems we face in the solar industry is its growth rate. As it grows so fast the real "money" is in install. Tweaking and upgrading is finicky and time consuming. Then if you" fix" something on an older system and an equally old component fails you all of a sudden "own" the problem. It is so common the former company I consulted for stopped doing upgrades and concentrates only on full systems now. I like to tinker so its a good niche for me. If I were you I would carefully read over your Aquions manual especially about the absorb time required. Usually absorb time on the xantrex AGS has a default amount of hours that is set up for Lead acid. Lead acid requires several hours of absorb to get from say 75 percent to 90 percent"full" The Aquions do not. So right there a good solar company wanting you to get max life out of their gear sets up the generator to give maximum life to the batteries and damn the fuel usage... for lead acid, Aquions are new, not lots of experience out there so it would be easy to miss. Lots of savings there. Next comes the trigger points for the AGS. Dive in and see at what voltage it is set to turn on the generator and how long it waits to see if that voltage holds or bounces back. Aquions can take 80 percent discharge according to their literature with no problem but their max amperage draw is fairly low so something big comes on, the voltage drops fast, the Older Xantrex AGS triggers too soon and you have a wasted generator cycle. Once an AGS is triggered it runs through a full cycle it does not care if it triggered 2 minutes before the sun came out. Outback controllers are invisible to xantrex inverters and vice versa so a generator turning on 2 minutes before the solar array powers up is common since the AGS and the charge controller do not talk. The trick there is to program in a "quiet time" window in the AGS that matches the sunny parts of the day... AGS' are dumb and are a last resort failsafe that cannot match the smart human in the loop...
Lots to think about.
Cheers,  David

FWIW...
Many "solar" applications are better being ran directly rather than through photocells, Hot water directly via solar is a winner, passive solar gain to dark flagstones has a looong payoff but if designed intentionally from the start acceptable.
If your question is "Can a conventional house with marginal insulation be adapted to run entirely off solar?" Then the answer is "Anything is achievable if you throw enough money at it!".
But for reasonable returns, if you build deliberately.....in a favorable section of the country........ with adequate, measured solar input....... using passive solar techniques honed over the last fourty years......Your costs of construction will be 20% to 60% higher than conventional, your fights with county building officials will be exponentially higher, but your costs of living, can be driven very low.