Power at the farm

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Robson Valley

Full Member
Nov 24, 2014
9,369
2,139
McBride, BC
We have frequent power failures, summer and winter. Split second to 8 hours to a month or more ( big wild fire).
I installed a simple solar power system which can deliver 500W for 8 hours as
120VAC/ 60 cps

Solar panels, 2 x 75W connected to:
Charge controller to protect the batteries connected to:
Several 12VDC deep cycle batteries connected to:
Pure sine wave inverter to make 117VAC with max 1200 watts.

Most small electric motors are "universal winding" design. This means that the motor acts as a dead short for the instant you turn it on. The "inrush" current to get it spinning is about 2X the current needed for steady running.

Square wave and "modified" sine wave inverters stop at zero in the AC cycle. The motor thinks it has been shut off so asks for inrush current every 50-60 times per second. That sucks your batteries down fast and very hard on the motor.

If all you ever wanted to do was some lighting, fine, go ahead, it will all be OK.
However, to run any sort of a motor (electric drill, coffee bean grinder, whatever), you need to buy a pure sine wave inverter which can power everything.

My Harman wood pellet stove has 3 electric motors in it. Two run continuously, one pulses with pellet delivery. I need 500W pure sine wave to make it all go at -20C.

Power goes off. Solenoid drops out and my power alarm starts chirping.
Find my "touch light." Go downstairs and push one button to light up the inverter. Pull the pellet stove plug out of the wall mains socket and plug it into the operating inverter (NEVER start them under load). Stove clears itself.

Back upstairs, I have one dedicated quad 117VAC set of plugs coming up from the inverter. I plug in a 9W LED light and point that at the kitchen ceiling.
Lights half the house and many windows. Just to let other people know, if their heat dies and they get too cold, they can all come over to my house and bunk in the warmth.
 

Robson Valley

Full Member
Nov 24, 2014
9,369
2,139
McBride, BC
Afterthoughts:
You probably don't have to put up with the jackass unreliability of your mains power like we do.
1. When our power comes back on again, I want to juice up the batteries very quickly before another breakdown. If that's 4AM in winter, so be it. Dark and the solar panels are useless. So I bought a honking big smart battery charger. It looks at my battery bank and tells me how long it will take to jack the thing up again.
So that beast is plugged into the mains, I turn it on, and it refills my deep cycle batteries.

BTW, the Deep Cycle batteries will drive the inverter until the voltage gets down to about 11.5VDC. Then an alarm comes on and the inverter quits. Standard activity.

2. It's plate surface area that determines charge storage. Instead of single 12VDC batteries, I buy and wire 2 x 6 VDC deep cycle batteries for more power for longer. Those are what you put your money into = the batteries. Always look for sales (good luck). If anything, I want 2 more pairs of 6VDC (12VDC in series). Then ganged in parallel to see 12VDC. I know that I can buy big 12VDC cells, just 2 x 6 VDC cells under one skin. Ever try to lift one of those?
 
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Wayne

BCUK Welfare Officer
Mod
Dec 7, 2003
3,509
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49
West Sussex
www.forestknights.co.uk
The jackery or equivalent that is worth having retails around £1000 -£1200.
I looked into portable power stations for work. They are not cheap and don’t last forever.
However if you need 230v in a remote location they are the way to go.
a good solar system again isn’t cheap.
with power systems you get what you pay for. Cheap crap is often unreliable and short lived.
 
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Erbswurst

Bushcrafter (boy, I've got a lot to say!)
Mar 5, 2018
3,094
1,213
Berlin
Last Christmas my brother bought a couple of cheap solar Christmas tree chains from Aldi or wherever and we decorated the entrance way.

Most of them failed pretty soon. But one of them is constructed correctly and still works well. If it's totally dark around, they seem surprisingly bright. Approximatly like an old simple torch from the seventies. Bright enough to illuminate the way without disturbing the eyes. And they are so cheap that surely nobody will steal them.

As there are nowadays people who test and review all and everything one surely can figure out which models are the durable ones.

You just need to hang it so high that you don't cut through the cable in the summer if you cut back the hedge or other plants, what I managed to do of course. Now it's unfortunately a bit shorter and less bright.

;)
 

fingertrouble

Tenderfoot
Sep 6, 2021
64
43
48
London, UK
I'm really interested in this because I want to setup a studio in a place that doesn't have power, basically a modified shed - the only sticking point will be power for lights and charging. Nothing major, although heat might be a thing as well.

I was thinking 12V car or caravan battery with one of those solar trickle caravan panels to keep it topped up then those USB > 12V cigarette lighter converters. My drain unless I stick a heater on it would not be massive...I guess there are caravan heaters that work from 12V? Or indeed inversion units but those things cost hefty for 240AC.
 

fingertrouble

Tenderfoot
Sep 6, 2021
64
43
48
London, UK
Last Christmas my brother bought a couple of cheap solar Christmas tree chains from Aldi or wherever and we decorated the entrance way.

Most of them failed pretty soon. But one of them is constructed correctly and still works well. If it's totally dark around, they seem surprisingly bright. Approximatly like an old simple torch from the seventies. Bright enough to illuminate the way without disturbing the eyes. And they are so cheap that surely nobody will steal them.

As there are nowadays people who test and review all and everything one surely can figure out which models are the durable ones.

You just need to hang it so high that you don't cut through the cable in the summer if you cut back the hedge or other plants, what I managed to do of course. Now it's unfortunately a bit shorter and less bright.

;)
You can 'ghetto waterproof' those things by wrapping sellotape over them, the problem that water gets in the cheap solar lights. I have a few hanging on, amazingly years later.

But yes, cheap solar lights are a good way of doing it, or those solar lanterns but not tried it.

When I go camping I take a little solar panel for the tent and an old 10000mah battery, I get at least a bar of charge when it's left up and the sun's out, or even if it's cloudy. Seems to be fairly waterproof also, my better Chinese one looked like a kid's electronic project and eventually failed, that was many small panels in series on a mat.

Worked great until, well, it didn't. I still have it, might get the multimeter out if that's still working and fix it. I suspect a connection has gone or rusted. I also suspected it was giving out too much current and fried my older battery...there should be protection for overcharging as not every charger gives out the correct voltage and wattage but that one made the battery whine which was alarming...
 
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Robson Valley

Full Member
Nov 24, 2014
9,369
2,139
McBride, BC
Don't try to "cheap" this out. Deep cycle batteries are meant for long steady draw downs, not at all like the battery that drives the starter in your car.
In 10 or 12 years, my little system has done as much as I have ever demanded.

Economics:
A Harman P38++ wood pellet stove cost me almost exactly 1/2 of what the equivalent forced-air, oil-fueled central heating furnace would cost.
So the pellet stove paid for itself from savings in less than the first 3 winters!
The little solar power system came out of savings in the next 2 winters. FREE!

When it's a windy winter blizzard, that shutty weather will blow the heat right out of your home. You can feel it. The pellet stove just kept chugging along (I mean -20C to -35C). The solar system meant barely a hiccup when the power went off.

Now that I have to run the oil-fired furnace for home heat, I have never needed to drive it (pressure gun & circulation blower) from the solar power system. That day will come out here. I'll report on my success.
 

Broch

Full Member
Jan 18, 2009
5,224
4,565
Mid Wales
I'm really interested in this because I want to setup a studio in a place that doesn't have power, basically a modified shed - the only sticking point will be power for lights and charging. Nothing major, although heat might be a thing as well.

I was thinking 12V car or caravan battery with one of those solar trickle caravan panels to keep it topped up then those USB > 12V cigarette lighter converters. My drain unless I stick a heater on it would not be massive...I guess there are caravan heaters that work from 12V? Or indeed inversion units but those things cost hefty for 240AC.

Lighting is easy and can be done cheaply using motorhome 12v technology; heating is another matter all together.

A100Ah deep cycle battery will run 10w of LED lighting for over 100 hrs without recharge.

You'll need at least 1kw of heating (probably twice that). 1kw is 1kw no matter what voltage you're working from but the current draw is the killer. At 240v, 1kw draws less than 5A but, if that's being drawn from a 12v source through inverters it will draw over 80A ignoring conversion inefficiencies. Even if you're battery could deliver that current continuously it would only last an hour. Consequently, you need banks of batteries and a lot of solar panels. No, stick to gas, wood, or oil for heating off-grid unless you plan to install a full system as RV says.

Whatever you do, even just for lighting, buy a deep discharge battery not an automotive starter one.
 
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SaraR

Full Member
Mar 25, 2017
809
502
Ceredigion
I like the idea more so of getting some outdoor lighting and being able to bring the battery and just plug it in, same as a solar panel, eventually have one on a building roof and plug in as and when I'm around/needed.
It would be nice to not have to worry about remembering to charge batteries every day for powertools, and be able to charge when needed if flat/ if others are around and also need to charge devices.
I can park on site, so hauling back and forth isn't an issue as iv been using a van and trailer so far for materials and moving wood- just takes forever charging anything via the van 12v with the engine running im sure its not economical?
Make sure you look into a way of keeping whatever you install safe from thieves and bored youngsters!
 

Robson Valley

Full Member
Nov 24, 2014
9,369
2,139
McBride, BC
Some local people here have bought generators. Usually no more than 3kW will let you limp along in any weather. I am amazed how quiet they are. I didn't elect to do that instead of solar as I have no really secure storage.

The RCMP (Royal Canadian Mounted Police) detachment here in McBride is a stand-alone building, set apart from others along that road. The last time we had a really big long power outage, they got up and running with a generator. Fine.
Somehow, somebody came sneaking along and stole the police generator.

For heating a shed-sized building, I'd go for simple wood heat. Don't screw around trying to do something exotic which isn't a realistic use of electricity. That slow, steady, even heat is kind of addictive. My pellet stove was like that = the little fire box was in flames 24/7.

We can't buy 60W or 100W incandescent light bulbs any more. Lots of LED at different color temperatures even. Diffuse, focussed, all kinds of options. For the power they pull, they are magic in a a small solar system.
 
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TLM

Native
Nov 16, 2019
1,951
906
Vantaa, Finland
I have at the cottage a 10kW 3phase diesel generator, runs the whole thing or just part (I am normally connected to the grid). I am taking the waste heat from water cooling to heat the basement, in practice I get about the same amount of energy as heat as I get as electricity. Not a difficult conversion, I guess it did cost me some eur 300.
 

fingertrouble

Tenderfoot
Sep 6, 2021
64
43
48
London, UK
Lighting is easy and can be done cheaply using motorhome 12v technology; heating is another matter all together.

A100Ah deep cycle battery will run 10w of LED lighting for over 100 hrs without recharge.

You'll need at least 1kw of heating (probably twice that). 1kw is 1kw no matter what voltage you're working from but the current draw is the killer. At 240v, 1kw draws less than 5A but, if that's being drawn from a 12v source through inverters it will draw over 80A ignoring conversion inefficiencies. Even if you're battery could deliver that current continuously it would only last an hour. Consequently, you need banks of batteries and a lot of solar panels. No, stick to gas, wood, or oil for heating off-grid unless you plan to install a full system as RV says.

Whatever you do, even just for lighting, buy a deep discharge battery not an automotive starter one.
Yes it's a 'nice to have' but I'll just use paraffin or little gas heater. It would be a small space - a shed - so it wouldn't need a lot of heat.

I know you can get those greenhouse heaters which might stop it getting to freezing point? It's more a case of using the space in winter, I can wear more clothes but don't want it that cold. Wood fires wouldn't be possible, although those places sometimes allow fires, it wouldn't be a good idea in a wooden shed! (and yes I am aware of the risks with small heaters, ventilation, fire etc, we used to use parrafin heaters at my parent's old cottage, and gas heaters at the mobile home my partner had).

But it would be just while I was there working, not all the time. Lighting and device charging (USB/radio/phone/ipod etc) is the main one, although even the latter I carry an Anker battery so not a biggie.
 

Broch

Full Member
Jan 18, 2009
5,224
4,565
Mid Wales
Yes it's a 'nice to have' but I'll just use paraffin or little gas heater. It would be a small space - a shed - so it wouldn't need a lot of heat.

I know you can get those greenhouse heaters which might stop it getting to freezing point? It's more a case of using the space in winter, I can wear more clothes but don't want it that cold. Wood fires wouldn't be possible, although those places sometimes allow fires, it wouldn't be a good idea in a wooden shed! (and yes I am aware of the risks with small heaters, ventilation, fire etc, we used to use parrafin heaters at my parent's old cottage, and gas heaters at the mobile home my partner had).

But it would be just while I was there working, not all the time. Lighting and device charging (USB/radio/phone/ipod etc) is the main one, although even the latter I carry an Anker battery so not a biggie.

I've just put a log burner in a wooden shepherd's hut but I know what you mean; you do need space to step back from it for a start!

I'd be inclined to use a good gas heater. I've used paraffin in sheds in the past and found it a bit smelly. I'm lucky, my studio now has the luxury of mains :) - but I am planning on putting a full solar power system in there for the majority of our needs; we'll have to revert to mains for the cold peaks.
 

TLM

Native
Nov 16, 2019
1,951
906
Vantaa, Finland
That must be cozy = the lights are on, the kettle is about to boil and waste heat from the gen set makes the place shirt-sleeve in winter.
It works quite well, I do have a fairly large battery pack to run things when the gen is off. The cottage can be heated by burning wood or using air_to_air heat pump on mains power. The kitchen has a wood stove that also gives enough heat to minimize outside power down to about 0C.

Originally the gen set was all electric power we had but some 15 years ago we finally invested on mains too, it was not cheap but on a certain range of outside temps the heat pump works with high efficiency. Gen has been on reserve mostly since, except on major outages. So I have a choice of energy sources.
 

Bazzworx

Full Member
Mar 5, 2009
378
69
35
South Glos
It's also worth bearing in mind that the usable capacity of a lead acid battery is only about 50% of its nominal capacity and that to fully recharge the last 20% requires a float charge that takes a very long time. In my installs I tend to use LiFePO4 battery's, very expensive but you can use about 80% of the nominal capacity and you can bang loads of amps into it up to 100%. They're much better suited to leisure systems but maybe prohibitively expensive for some projects.
 

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