Some time ago we bought a piece of land to build our future home there. The price was 'acceptable' (compared to other insanely expensive offers in the area), the place is very nice, but... As we found later, it's basically impossible to get a normal electric connection there.
The only option seems to be an off grid house, powered by solar panels.

There are quite numerous 'off grid topic' sites on the internet, suggesting this or that - usually the ultimate solution they sell. That's why I'm starting this thread - to get some fresh and unbiased ideas from the LG community that has already been helpful in some other cases.
Here's my reasoning so far:

1. It's very expensive, the house will have to be as small as possible.
2. Solar panels will be also on the barn and animal houses. (Small main house - not enough space for panels.)
3. Rated solar panels life is 25 years. The replacement will probably hit us when we're retired.
4. LiFePO4 batteries should last 8,000 cycles. But what's actually such a cycle (in a day with changing weather, part of the time charging, part of the time discharging...)
5. An older site suggested truck batteries as a cheaper starter.
6. It definitely must be an MPPT solution/inverter.
7. Lighting (using LEDs) is basically a negligible item. Computers must be power saving and turned off while not in use (or suspended to disk).
8. Motors (pumps etc.) are a bigger problem.
9. In the darkest part of the year with less than 8 hours of light and completely overcast skies, there'll be basically no power from panels (or something like 1% of the maximum). The fridge must be turned off at that time (fortunately it also means the outdoor temperatures are suitable for storing food.) A diesel generator will be a backup.
10. Washing machine must be modified for use with externally heated water (no electrical heating). Actually absolutely no heating of anything using the electricity.
11. The idea of a massive concrete base accumulating heat, compensating short weather changes seems interesting.
12. They suggest using the electricity directly from panels (if possible) without storing it. Need to pump up a lot of water? Do it in midday hours.
13. Another interesting suggestion is to tilt panels more than usual (it will lessen the summer performance but improve winter performance when the sun isn't too high above the horizon).

Have you done any calculations about estimated power usage per day? That would be a good way to start so you can then see how much panels and battery capacity you need. Like you've read, bigger power hungry tasks would be better doing at the time when there lots of power available from the panels. That way you reduce wear in batteries and save some electricity because no battery has 100% efficiency, there will be always some losses when storing energy.

I would suggest staying away from truck batteries as this sort of usage is way different from what truck batteries are designed for so you may get reduced capacity or lifetime. What comes to battery cycle, it means draining 100% of the charge and then loading full = 1 cycle. It's somewhat theoretical as you should never drain you battery completely empty (also important to remember while calculating needed battery capacity) and also it does not have to be done at one sitting, draining 20% then 40% and for the next day 40% still equals one cycle.

Just out of curiosity, what sort of heating are you planning to have?

What I have learned about Li based batteries, their aging/wear is not that much related to the charge/discharge cyckes, but to the time spent at different charge states (the extremes being the worst,...), tyen the temperature ("classic" each 10degC higher doubles the wear rate).

With lead acid, mainly when really significantly cycled, the life correlates more with the cycles.


The good thermal mass of a well insulated house indeed improves the heat management economy (allows to utilize colder nights in sumer heats, allow efficient use of wood burers,...), but it costs money and space to build... And often need active blowers/pumps to control the heat transfers, so if heating fuel is nearly free for you there, you won't need summer cooling, it would be better for you to stick with a simpler wood stove for heat and to utilize that money and space for something else.


The question is the use of that house, whether it is supposed to be a seasonal home, or permanent living.

And generally even when many "recommendations" seems to beconflicting each other, that does not mean they are wrong. All are some sort of a compromise, so it depends on which comfort aspects you are willing to sacrifice and what natural conditions are at that place.

Hi,
1) For heating purpose, you can mix geothermal heat pump with thermo solar panel (the first, can be reversed in summer for cooling, the second not, but can help heatpump in winter), floor heathing is a must.
2) You should install a lot of PV panels and batteries, you can use this calculator https://re.jrc.ec.europa.eu/pvg_tools/en/#api_5.2 for theoretical data.
3) Stay away from car/truck batteries: as told before, they are designed to do PEAK load, not continuous load and they will be trash in 1-2 years.
4) An array of proper built inverters (not low cost trash) includes all what you need (MPPT, ecc), so don't waste money on the cheapest option (there are some interesting option from Huawei model Luna).
5) Backup generator is needed in case of emergency: you should keep it in mind during planning electrical wiring (i won't use a battery powered option).
6) I don't think is a good idea to turn off the fridge: when you turn it off, it will gradually loose cold, which must be restored when turned on again; also you have to mind fridges, like ovens and other appliances, have a thermostat, so if it have reached the desired temperature, it will turn off the compressor until it sense a temperature raise.
7) If you plug your washing machine to hot water, you can't have wool, and also you need a constant source of hot water.
You will need a lot of insulation in your house to keep heat and cool in house during winter/summer and concrete is a thermal conductor.
9) Tilting panels is a good idea, but you need more space due shadows.
10) You should considering to install also solar optimizer in every solar PV module (in case there is a shadow in one or more PV module, solar optimizer will bypass this module).
11) At the end, you should consider into buying all efficient appliances (EU A label): they cost more, but will drain less battery.

Thanks, guys! Yep, we've got a pretty large mind map (I use good old FreeMind) considering all variants, relations and calculations.

@Roi_hartmann
The estimated daily consumption (after applying all energy saving measures) should be between 7kWh and 8kWh. Thanks for explaining the cycles. I wasn't sure as they suggest recharging smartphone batteries when discharged to 15% and those who recharge on every occasion (like using public recharges in buses), several times in a day, shorten live of their battery. That's what I've read.
I know the truck batteries are far from optimal for this purpose. They were meant as a cheaper 'starter' and replaced by something better later.
As for the heating - probably wood (as a cheap option) or pellets. Gas isn't an option in the area.

@Medved
The motivation for moving is the fact we have some animals and while they're only 3km away from our current home, it's quite time consuming to get there two times a day. The road is very bumpy and one must drive very carefully. Moreover, that land isn't ours and the rent might end one day.
So it's meant for permanent living.

@marcopete87
They don't recommend geothermal heat pumps for off grid houses. They drain too much energy.
As for the fridge - the key was keeping the food in a box outdoors. In the dark part of the year, the temperatures are low enough for storing most products. Moving the fridge to a sheltered outdoor and keeping it running so that the thermostat would intervene very rarely is another option.
The concrete base would be possibly under the house for compensating shorter temperature changes. The walls and the roof must indeed be made of well insulating materials.

One thing about turning off the refrigerator is not recommended due to that it takes lots of energy to process the cold in the fridge.  It would really regulate the temperature and it will use it as needed.  That would take less energy than turning off and on.

Hi Merc,

Hopefully my reply is not too late. I've lived off grid for a while. Let me try and address some of your questions:

1. It's very expensive, the house will have to be as small as possible.

In regards to solar, don't worry about making the house small. It just needs to be efficient. Although smaller will save you a lot on construction costs, heating, and cleaning!

2. Solar panels will be also on the barn and animal houses. (Small main house - not enough space for panels.)

If you have space on your land, ground mount the panels. Mounting them on the roof makes cleaning and maintenance very difficult. Also imagine having to strip the entire array off the roof if the roofing materials need repairs or replacement.

3. Rated solar panels life is 25 years. The replacement will probably hit us when we're retired.

This rating is not a lie. Don't fall into the trap of thinking they will last for ever. Even with the best quality panels you will see a noticeable reduction in output after only 10 years let alone 25. You will certainly have to replace them by 25, which will of course be a lot easier if you follow my advice from number 2. 

4. LiFePO4 batteries should last 8,000 cycles. But what's actually such a cycle (in a day with changing weather, part of the time charging, part of the time discharging...)
5. An older site suggested truck batteries as a cheaper starter.

Lead acid (truck batteries) has been a mature and proven tech for a century. They don't randomly burst into flames. They easily last over a decade if treated properly. They're cheaper and can be sold for scrap for a reasonably sum at EOL, at which point they can be fully recycled into new lead acid batteries with minimum environmental impact. I'm still not sold on lithium for a stationary application where weight is irrelevant.

6. It definitely must be an MPPT solution/inverter.

Correct.

7. Lighting (using LEDs) is basically a negligible item. Computers must be power saving and turned off while not in use (or suspended to disk).

Lighting just needs to be efficient, not necessarily LED. Fluorescent is also okay. It's a fairly negligible load in terms of kilowatt hours per day, but has more impact than you think as it's only run at night when the system isn't charging. Night time loads are the worst so focus your main attention on reducing these. While the sun's shining it's not such a big deal.

8. Motors (pumps etc.) are a bigger problem.

Yes, especially larger induction motors as your inverter will need to be large enough to handle their starting current which is usually 6 - 7 times the run current. For your pump use a variable speed drive if possible.

9. In the darkest part of the year with less than 8 hours of light and completely overcast skies, there'll be basically no power from panels (or something like 1% of the maximum). The fridge must be turned off at that time (fortunately it also means the outdoor temperatures are suitable for storing food.) A diesel generator will be a backup.

Definitely need the genset. The trick here is to tilt the panels for maximum winter output, NOT maximum kilowatt hours per year as you would in an on grid system. Summer output will still be good enough and it will fill in your winter lacking. The impact of overcast days is best reduced by installing more panels since panels are so cheap these days. Even when it's overcast they still produce something, and if you have enough you will find you can just scrape by most overcast days.

10. Washing machine must be modified for use with externally heated water (no electrical heating). Actually absolutely no heating of anything using the electricity.

Correct, make sure you buy a washing machine with two pipes (separate hot and cold feed) so it doesn't have to heat it's own water. Hopefully they exist in your part of the world.

11. The idea of a massive concrete base accumulating heat, compensating short weather changes seems interesting.

I would like to try this next time for sure!

12. They suggest using the electricity directly from panels (if possible) without storing it. Need to pump up a lot of water? Do it in midday hours.

Yes that's what I was getting at in number 7. Set your washing machine, dishwasher, etc... on a timer to run while the sun is shining. Try and move as much consumption as possible to the daylight hours.

13. Another interesting suggestion is to tilt panels more than usual (it will lessen the summer performance but improve winter performance when the sun isn't too high above the horizon).

Yes 100% do this. Ignore anyone who tells you to set the tilt to your latitude!

Feel free to PM me if you need any more help

I'm rather interested in this, although we can't really live off grid here as we're in council housing, but it's a fascinating topic. If we were able to consider it, the thing that would not be possible is a washing machine with separate hot and cold water feeds, they simply don't exist any more, none have been made for years 

Rommie they're definitely still made (for example most of the higher end Miele models) but certainly not as common as they used to be

They may be made somewhere, but I've not seen any available for sale here in the UK for some years. Certainly when we replaced our old machine a couple of years ago we couldn't find one.

 I would recomend two system voltage one for 48 volt large loads inverter loads as it work best and lower current draw
 On batteries on large loads.    There some adjustment to life
 Style to make but nothing major.   One find every thing that u can run with out a inverter that  can run on DC.   Well DC air condition uint have been made now.  I have 48 Volt DC rapid
 Start F40T12 ballast. So I am running F40T12s.  Now u need ditch phantom loads that draw power that even if it off.  Such as
 Stuff that have wall warts,  radio with built in clocks with remote
 Features.  For heating u want propane  central air furnice or use a wood stove .  Just change out electric blower motor out to a DC motor for blower motor.  And 48 volt relay.  And just need a small inverter custom made for 24 volt AC for control board.
  It best to use a forklift batteries.  And those batteries are  u can  get them rebuild.  Plus if a cell goes down u can take that dead cell out of service and get by until u  can replace it .  Yes stock up on any MR16 bulbs cause there 12 volt and there getting  banned.  Yet they dont think about off gridders.
  Now here where 12 volt system comes into play.   This one
  I use more for incandescent lighting,  running a car radios, 
 More F40T12  using 12 volt DC  rapid start ballast.  12 volt TV
 tV monitor,  the wifi router ,  and yes running 18 volt power tools on 12 volt.  It works just takes slightly longer but get job done.  I also would  go to scrap yards  regulary for  lead acid batteies that is still good and some can be reconditioned
 Those batteries.  I keep around charge them up and make 120 volt DC just to run 120 volt vacumme cleaners and 120 volt tools
 Just to run anything that had a universial motors.   Like circular saws drills , vacs.  Blender for cooking.   I would recommend wind power too and  use your charge controller as a dump load
When your batterie are full.   U might as well convert that extra power to heat .  So u heat up the heating element in electric water heater.   It best  each week to set up a large load days
This where gas powered generator comes into play or when u have  cloudy  days for days  and lacking wind power.   Large load days would be doing laundery using washer machine,  large
Appliances,  charge up your batteries ,  and other large loads
  For water wells u can set up large water tank and set it up
  To pump water getting power from solar with out having a battery bank.  Or use a windmill for water pumping.

While I wouldn't ever want to live somewhere where off-grid was the only option (I'm spoiled by the convenience & would only want to live near(but not in!) a big city), there are parts of this that interest me.

For example, as it is, I would love to do solar to run certain loads I have that run everyday for hours - mainly lights for houseplants & fishtanks... but what I really want there is a setup that would run said items on solar, and a system without batteries , but also not be directly tied into the house/grid power either.
The ideal setup would be where you have your solar panels/inverters/controllers/etc then a wire ran to each of the couple rooms where the lights are and have some sorta plug-in module that would run off the solar, and only if that was unavailable switch over to grid power. (running shorter 'daylight hours' for fish/plants in winter would be fine too)
I'm not sure if something even remotely like that exists(even eliminating the switching module part), I've tried various searches & it seems everything solar systems talks about batteries...the one part I'd really like to eliminate!

In addition to what I mentioned above, it might some day be nice to have a small off-grid cabin in the mountains. (in that case a more traditional off-grid system for electric. & heat would be propane/wood)

Two things I've picked up from the conversation. 
Firstly, why wouldn't you want to have solar panels charging batteries, and have them running lights etcetera.? 
Using batteries as the power source will give a much more reliable voltage, and with the solar panels charging them you can carry on through the hours of darkness.

Secondly, remember that a fridge is essential a heat converter, and unless designed for use outdoors will struggle to reduce the temperature enough to keep the food chilled or frozen (in the freezer)

For a lighting in off-grid solar installation, I can't think of any good reason to use anything other than LED.

Personally, I can't think of a better use than my oily lampses, heat and warmth.