Average Electricity Consumption

[Stan]

In the attached table of thermal conductivity, glass is 0.8 W/mK and polyurethane is 0.02 W/mK. The units are as for the Vitrex.




http://hyperphysics.phy-astr.gsu.edu/hb ... thrcn.html

[nowty]

In the attached table of thermal conductivity, glass is 0.8 W/mK and polyurethane is 0.02 W/mK. The units are as for the Vitrex.

http://hyperphysics.phy-astr.gsu.edu/hb ... thrcn.html

Yes I don't doubt that, I was going off the general quoted U value of a single glazed window which is usually around 5 or 6. I cannot really explain the discrepancies as a glass pane is of similar thickness to the 5mm underfloor board.

Maybe my U value calculation of the insulation board is wrong, happy for others to check my calculation.

[AlBargey]

Reading all the threads avidly, I see that a lot of you have quite large batteries and solar arrays but I often also read (or think its implied) that your batteries only get you through one or two nights without recharge, is that right? The reason I ask is I am trying to get an angle on my electrical consumption as to whether its low, medium or high. Not as a comparison to how well or bad I am doing compared to others but to see whats the right thing to spend hard earned money (and scarce time) on first.

So for example December to 5th January our daily consumption was 7.85kWh/d, this included all the vestiges of Christmas, running the tumble dryer a lot because the weather here was appalling, little to no input from the solar array - did I say the weather had been bad here ? and so I think its probably indicative of the cottages worst consumption behaviour.

So how does 7.85kWh stack up with others.

Moxi

We have a large (for a boat) amount of solar and large battery bank, which gives us 5-7 days in winter. Over the last year we used 9.9kWh/day average, for Dec to Jan 5th our average was 8kWh/day so similar to you. But as we have FLA batteries with an RTE of 84% we use 16% more energy than if we were on grid without batteries.. ignoring all the other inverter efficiencies for now.

We live normally as though it was a house, including electric shower, big modern fridge freezer etc, but being a boat we have standing loads of around 200w, quite a few which a 'normal' house doesn't, with extra switch gear and controls for the off grid stuff, a sewage treatment plant with 40w compressor which is on 50% of the time and just having an 8kVa inverter seems to suck up a constant 80W ish.

If we had lithium we'd save 14% of our power needs, but considering our 2nd hand 4 year old 26kWh usable bank was £1k and around £4k new, for an equivalent 28kWh of Pylontech would be £8k ish so a big outlay.

For us living on a boat and having off grid power is a necessity, so the usual cost benefit analysis for a grid tied house and payback is less relevant, because we have to function off grid, having said that I've installed all our solar, inverter, switchgear etc for around £6k to be over 80% self sufficient from solar, at an assumed 28p/kWh if we were on the grid. We're currently saving £1,000/year, so it would pay for itself in 6 years.. which is a no brainer really.

[billi]

billy the barge ? D

[AlBargey]

billy the barge ? D

There was another member on a barge from the other forum called Billy I think?

Us barge people get about though

[Moxi]

Yes I think Billy had a motor cruiser something like a Colvic Watson ? I know he had a leading edge 600 flying alongside his berth - I wonder where he’s got to these days ?

Moxi

[cojmh]

When I had the smart meter installed I left the PV system off to get some average consumption figures before I put batteries in.

So these figures were for the last week of Feb and the first two of March. We averaged 18.5 KWh usage per day over 3 weeks.

We have GCH and a gas heated hot water tank but pretty much everything else is electric (cooking etc.). We have traditional combustion vehicles too. We do use a tumble drier, washing machine and dish washer every day (despite my protests!) - so that is what I consider our "base consumption".

All appliances are in the A+ to A++ range when purchased.

I think we are too high for what we use - but I suspect the two main culprits of this are:

1. The Showers, both are electric and pull about 9KW ........ Something I intend to get rid of ASAP
2. Things on Standby - which I have been reading about on here .... so this is in the process of being tackled.

This is based on a 4 bed semi-detached with 5 of us here almost all the time (both my wife and I work from home most of the time and we home school at the moment)

If I scale this up it comes to about 6.752 MWh for the year. But this does not include all of our usage as somethings only come out in the summer.

My PV array consistently produces 4MWh per year so with the batteries I am hoping to get my self utilisation for electricity up to at least 75% and I would like to try and shave off 20%-25% off from the above two culprits.

But time will tell ....

[nowty]

When I go back to my 2010 pre PV age, my 4 bed house with 4 persons had a leccy import demand of 6.4MWh. At the time all heating and hot water was gas and that was an eye watering 25MWh of gas import.

With all this renewable nonsense , my gas import has dropped from 25MWh to less than 0.4MWh. My leccy import has increased though but only to around 10MWh or 11MWh. And that includes two electric cars to feed as well.

Once I offset the remaining 11MWh import with ripple WT1 and WT2 which might be as high as 16MWh generation we should be well negative, both in carbon and cost.