An 'off grid' house

shalomebony

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CashStrapped

Non-off gridder here.

Firstly, I would say there are a lot of variables involved. Mainly the efficiency of the diesel generator and how much load it is taking on a daily basis. They are apparently most efficient at the around 70% load. So if it is oversized and only works at 20% load, it may not be working as efficiently as it could. If it is undersized and works at 90% load all the time, it may be similarly inefficient. Then you have the age, how well serviced etc.

From a quick bit of research, I have seen figures that suggest a diesel generator on average may produce around 2.5-3.5kwh per litre of fuel.

That is the figure you need to look for in terms of making your own calculation. What it the rough output per litre of burned fuel.

If we divide your previous usage by the best scenario. 4800/3.5 it means that you would need 1371 litres of fuel to power the house for a year.

What prices can you get fuel for? If we take fuel at the pumps, around £1.18.

1.18x1371 = it would cost around £1600 to fuel the house for a year. In comparison to on-grid tariffs.....very expensive.

At the other end (2.5kwh for each litre of fuel).

4800/2.5 = 1920 litres.

1920 x1.18 = £2265

Obviously a big factor is fuel cost.

So that is just a perspective trying to look at the figures. A normal domestic tariff using 4800kwh at around 12p per kwh would cost around
£580 for the year.

That is just some rough calculations based on a quick bit of research. If you get more accurate information such as the generator efficiency, fuel costs etc. That would make the calculation more accurate.

DigForVictory

Just how off grid for water & sewerage? You'll need a few more kilowatts to run a UV filter for incoming drinking water & and few more pounds (about £150 but literally your mileage may vary) every other year keeping the sewage tank happy.

There are several things sewage tanks do not get along with, so your lifestyle may need a little adjustment to cope - I'm thinking disposable nappies & coffee grounds as the two main sources of sewerage contention I've experience of.

Getting snowed in, with a sick child, running through bricks of disposables & having to bag them to go whenever we could finally get out was a bad time.

dogshome

Only a thought, but I think fuel for a generator that supplies Electricity to an off-grid dwelling would be entiled to use 'Red' diesel, which doesn't carry the Road Fuel tax, but only HMRC can tell you for certain.

CashStrapped

dogshome wrote: »

Only a thought, but I think fuel for a generator that supplies Electricity to an off-grid dwelling would be entiled to use 'Red' diesel, which doesn't carry the Road Fuel tax, but only HMRC can tell you for certain.

I was thinking that, I think you can indeed. You need to check up on the regulations though

Price for Red diesel is around 56ppl at the moment so using that in my rough calculations.

0.56x1371 = £767 (assuming 3.5kwh per litre)

0.56 x 1920 = £1075 (assuming 2.5kwh per litre)

So that reduces the cost an awful lot obviously.

molerat

Red averaged around 52p in December

Norman_Castle

https://www.gov.uk/government/publications/excise-notice-175-motor-and-heating-fuels-relief-from-excise-duty-oils-used-to-generate-electricity/excise-notice-175-motor-and-heating-fuels-relief-from-excise-duty-oils-used-to-generate-electricity

Can your friend or the current occupier advise you?

macman

Am I missing something here? You will need a minimal amount of electricity to power the circuitry in an oil-fired CH system (basically the pump and the ignition system). Most of your electricity will be used for cooking, lighting and appliances (I'm assuming that the oil boiler also supplies the DHW).
By far the greatest energy cost will be the oil, which will be influenced by the tank size and the location and access.

dogshome

Hmmm - Looked at the HMRC regs on Red diesel, talk about a palaver.

28second burning oil used in domestic heating systems is also dyed Red, for the good reason that Diesel engined road vehicles, particularly older ones, will happily run on it.

So there is a fuel readily available also with 5% VAT, that does not have the Jump thro' three hoops paperwork trail, and the heating oil tank holds a bulk supply

reeac

Fuel oil of the 28 second variety is currently 44 pence per litre incl. tax. I would have thought that a fixed diesel powered generator is clearly not a vehicle and so it should be ok to use red diesel. Boat owners are charged a reduced tax for diesel fuel based on an assumption regarding the percentage of the total energy used for propulsion as opposed to heating and electricity generation etc. The former is taxed whilst the latter is not.