Running house off grid

Breakthru · Mar 16, 2019

I intend to do something similar but will use Evacuated tube panels for hot water heating. I will have two one with a solar powered pump to circulate hot water round a radiator system and another to heat a hot water tank.
My crude calculations are that heating water is the biggest demand.
2 X 2m panels not particularly expensive and easy to install even vertical on a south facing wall.
Heats water to 80C even on a dull day claimed.
When power is out here I run the house on a 1.8kw Honda Genny.
Have to alternate the fridge and the freezer as the start up of both is a mega draw and use the low draw kettle from the motorhome.
Microwave no problem so two ping cordon bleu will keep me alive.
I have now got a 6kw generator for a bit of leeway.
Lots of insulation and Led lights key to the whole show I reckon.

Slowcow · Mar 16, 2019

Just that! We have a 500l thermo store in the house with a immersion for when the Genny is on and a 1500l next to the Genny ready for me to plumb in when the farming/toddlers allow....

upnortheast · Mar 16, 2019

Breakthru said:
2 X 2m panels not particularly expensive and easy to install even vertical on a south facing wall.
Heats water to 80C even on a dull day claimed.

How many litres you heating ?

ollie989898 · Mar 16, 2019

If you are going to run a generator you might as well run a CHP unit and your heating then becomes a free by product.

f0ster · Mar 16, 2019

if you are running a generator remove the exhaust and pipe the exhaust gases through a plate heat exchanger with water and a pump on the other side of it.

Slowcow · Mar 17, 2019

Yep, around 40-50% of the heat is in the exhaust, you need a tube exchanger rather than a plate, the plate will slow the exhaust too much and will soon soot up, a tube one can be dismantled and brushed pretty easy as a part of the service routine.

ollie989898 · Mar 17, 2019

f0ster said:
if you are running a generator remove the exhaust and pipe the exhaust gases through a plate heat exchanger with water and a pump on the other side of it.

Just buy a proper CHP unit which will recover the heat generated from the engine properly, not just the exhaust. Your only issue is that in the summer when you have no heating requirement you may need somewhere to dump the heat- like a hot tub or kids play pool or some other way of cooling the engine.

Slowcow · Mar 17, 2019

As both heat recovery from the water jacket and the exhaust have been mentioned in this thread I can't see where any more heat can be gained by a chp unit?

Out of interest how much is a proper chp unit? I realise not everyone is going to want to roll there own but its pretty easy to recover the heat from the water jacket and the exhaust.

A friend who is well involved in this stuff said some old radiators in the shade is a good way to dump excess in the summer, although the solar panels should be working well then so the Genny won't be on much.....

Kidds · Mar 17, 2019

Have we reached a point with renewable energy that a new build completely off grid is a sensible approach?
I am contemplating a new build in the future and wonder if it is the way to go right from the off. Biggest obstacle I can see is getting the missus onboard, any restriction on washing machine use is going to be a barrier.

YELROM · Mar 17, 2019

Kidds said:
Have we reached a point with renewable energy that a new build completely off grid is a sensible approach?
I am contemplating a new build in the future and wonder if it is the way to go right from the off. Biggest obstacle I can see is getting the missus onboard, any restriction on washing machine use is going to be a barrier.

This is basically the question i was asking
Back in 2006 i had an indicative price of £20,000 for an electric connection to this building, so would assume this would of risen significantly since then
I am just looking at the alternatives before we get an up to date quote

slackjawedyokel · Mar 17, 2019

This is my gut reaction rather than an informed and considered opinion, but I’d only be considering going off-grid if putting in a connection was going to be utterly impractical (eg on an island without any electric or something).
If it’s your own house, and you enjoy tinkering then why not, but if it’s for someone else then the restrictions it might place on the occupants may put some off. When/if it becomes unstable, do you really want the hassle of being called out to try to sort it out at all hours?
What would be the cost of the kit (batteries, genny, maybe wind turbine etc) compared to the cost of putting in a new connection?

A few years ago we holidayed in an ‘eco friendly off-grid house’. Bit of a joke really: the wind turbine kept tripping the fuse in high winds, the batteries were clearly past their best and you had to fire up the generator if you wanted anything more than a couple of lights on. Charming for a few days, but you’d go potty actually living there, and defo not eco friendly!
Batteries and leds have come on leaps and bounds in the past few years, but I doubt things like washing machines and kettles have!

Exfarmer · Mar 17, 2019

I would make sure your wife was completely on board before contemplating such a move. I know would have a divorce if I voluntarily moved to such a situation. Men are much more happy struggling against the elements than most of the fair sex in my opinion. Although sometimes it is the wife who is the driving force

slackjawedyokel · Mar 17, 2019

Also, if you get a connection, you pay (admittedly through the nose) for it once then you’re set- no expensive gennys, batteries etc to be replacing every few years!

Slowcow · Mar 17, 2019

You do still have to pay for the electric tho!
Our situation my wife has no interest in how the electric arrives at the house as long as its there, a modern inverter will start the Genny if the batteries get low and ours will do 10kva for a short while, dish washer and washing machine have been run at the same time, think putting the kettle at the same time might cause a blip!

A Genny is more reliable than a car as long as its serviced.

I was quoted £67250 for a 15kva connection that we wouldn't have been able to put a 'disruptive heating load ' on, in our case of grid is a no brainer.

renewablejohn · Apr 20, 2019

Kidds said:
Have we reached a point with renewable energy that a new build completely off grid is a sensible approach?
I am contemplating a new build in the future and wonder if it is the way to go right from the off. Biggest obstacle I can see is getting the missus onboard, any restriction on washing machine use is going to be a barrier.

This point was reached on a new build about 10 years ago. Technology has just made it easier and with the collapse of PV prices and improvement in battery systems it should really be the norm for a new build built to pasiv house standards.

gavztheouch · Apr 20, 2019

Agree passive House is a sensible way forward for future buildings you would have pretty much zero heat demand. Then you just need a small amount of electric from pv which you can store in your car or static battery.

Greenbeast · Apr 20, 2019

Breakthru said:
I intend to do something similar but will use Evacuated tube panels for hot water heating. I will have two one with a solar powered pump to circulate hot water round a radiator system and another to heat a hot water tank.
My crude calculations are that heating water is the biggest demand.
2 X 2m panels not particularly expensive and easy to install even vertical on a south facing wall.
Heats water to 80C even on a dull day claimed.
When power is out here I run the house on a 1.8kw Honda Genny.
Have to alternate the fridge and the freezer as the start up of both is a mega draw and use the low draw kettle from the motorhome.
Microwave no problem so two ping cordon bleu will keep me alive.
I have now got a 6kw generator for a bit of leeway.
Lots of insulation and Led lights key to the whole show I reckon.

i've had tubes on two houses but I thought they were less good these days with PV being so 'cheap' and excess-diverter devices so readily available

gavztheouch · Apr 20, 2019

A heat pump will multiply your solar PV output by as much as 3 if you are using it to heat water.

Exfarmer · Apr 20, 2019

gavztheouch said:
A heat pump will multiply your solar PV output by as much as 3 if you are using it to heat water.

Until it freezes up!

Greenbeast · Apr 20, 2019

Exfarmer said:
Until it freezes up!

They use antifreeze, just like evacuated tube thermal solar systems

Running house off grid

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100% I’ve had enough of farming!

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