connection to the national grid

he

Well in the Winter quarter, my PV panel generates a quarter of the electricity it does in the Summer quarter. But there are plenty of Winter days when it does very little. December is the worst month as you might expect.
A true real world example, not BS from TurNiP Dunno why he rabbits on about stuff he has zero knowledge of.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
harryagain wrote:

I published the insolation figures from a solar panel lobby. Who would be expected in anything to overstate the case. They don't as it happens. December insolation is 10 times less than July. So its up to readres to say whether you are lying, or they are.
I note you are still connected to the grid.
the way PV is paid for, you will still make money if 80% of your electricity comes from it.

--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Well, you'll get some power I suppose, for 6 hours a day. But nothing serious.
--
Tim

"That excessive bail ought not to be required, nor excessive fines imposed,
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Clive George wrote:

Not quite.
What I was pointing out was that the summer to winter variation of output is approximately 10:1.
That leads to two strategies
1/. Buy enough panels so that the 10% of summer output you get in winter is enough for winter needs (which are always far higher) and simply waste the excess in summer when you don't need it.
2/. Arrange to store summer electricity for the winter, in which case you need about half a million quids worth of batteries per house, with a lifetime of only 5-7 years.

That or 10 times as big a panel when you only need batteries to tide you over a dull week instead.

No, you are falling into the classic mistake of sloppy thinking.
You believe that the word 'could' has a single meaning regardless of context, so that the statement 'I could catch the 10:37 train to London' has the same essential truth value as 'I could go on a rocket to the moon'
I too hae a motorhome of advancing age and modest dimension. It too could hae all its meagre electrical needs met by a very large solar panel, even in winter. Of course it has a gas fire, and a gas cooker and a gas fridge, only 8 lights - of which I dare only use a single fluorescent or the battery is flat in two days..and that's in summer.
But if that's living, yes I COULD get all the electricity I used from sunlight.
As long as I have enough gas.
--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polar air effect. They are much more efficient in the cold and atmospheric moisture is low, a big help. Also 24 hour sunshine in Summer (and nilin Winter)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

They virtually stop working in rain and when covered in snow.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 05 Mar 2012 17:21:01 +0000, John Williamson

Off-gridders in the boondocks have been doing it for years. Once again TNP spouts bollocks.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 05 Mar 2012 17:02:47 +0000, The Natural Philosopher

<snip calculations>
My experience with a standalone solar system (not powering a house) is that you need about a weeks worth of capacity.
Met Office sunshine figures Northern England 1971 - 2000 *
http://www.metoffice.gov.uk/climate/uk/averages/19712000/areal/england_n.html
1348 hours sunshine per annum 112 hours per month average (above figure simply divided by 12) Worst month December 40 hours (1.3 hours sunshine per day) Best month July 176 hours (5.6 hours sunshine per day) Worst 6 months October to March (66 hours per month average) (2.2 hours sunshine per day average)
The conclusion?
Size an array for demand during the worst month and it will probably overproduce by about 4.4 times in the best month
Reality is that it's about 5.5 times according to the calculations at
http://re.jrc.ec.europa.eu/pvgis/apps3/pvest.php
Despite a number of quotes in the press and on here I don't believe that average household consumption is anywhere near 1kW. 400-600W is closer to the mark according to the statements I've seen of a number of electricity consumers recently.
Real world monitoring of the solar output on this off grid system I briefly mentioned above very closely tracks the published met office figures for the geographical area which can obviously be above or below the long term average.
To meet 1kW of average demand then you need (24-1.3) = 22.7 hours of reserve capacity in December
Assume a maximum discharge level of 60% of peak capacity to keep battery life to 5 years. That means a battery capacity of 38 hours to meet December demand
But the sun might not shine for a few days, four 24 hour periods in a row without sun is a reasonable assumption but without going below that the imposed depth of discharge
That increases the battery capacity required to about 160 hours, or about 1 week, like I said earlier :)
1000W average load x 160 hours
160,000 Wh of capacity
Or, at say 48v nominal, 3300Ah cells
It's around 1000 quid for a 4v 1600Ah cell, so that is 24 cells or 24000 quid
1000W load 24 hours a day for 31 days is 744kWh
To supply 744kWh during December needs about 11kW of solar pv in the north of the UK
(Using http://re.jrc.ec.europa.eu/pvgis/apps3/pvest.php )
Two 6kW systems on Ebay are 15k (because I can't be arsed to find a more accurate figure)
Solar array lasts for 25 years, five battery replacements during that time.
Total cost of ownership
5 x 24000 for the batteries + 15000 for the panels = 135k
All that to supply 1kW average load for 25 years
25 years x 365 days x 24 hours = 219,000 hours
at 1kW load, that is 219,000KWh
Cost of that electricity
61 p / kWh
In the situation I mentioned at the top of this posting the load is far lower and there is zero possibility of a grid connection, and if one were to be provided the cost would be in the order of many hundreds of thousands of pounds. A fossil fuelled generator is not permissible due to noise considerations, nor is a wind turbine for reasons that can't be specified here.
The solution when offgrid, is to be frugal and only use power when you really need to.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
">

Met office statistics are not very helpful. Your calculation falls down on the point that there is sunshine and sunshine. A slight haze can knock 15%-20% off the generating capacity. A passing cloud can knock off 75% of capacity. You need to work off actual figures. Local sunrise/sunset has an effect. Orographic and microclimates.
You need to work off an insolation map and even they are very poor. http://re.jrc.ec.europa.eu/pvgis/apps4/pvest.php
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
The Other Mike wrote:

thats averaged over a MONTH so you still need enough battery capacity to cover that month.

I take around 1Kw. Big house, needs a lot of lighting.
Others use much more.

And hope you don't get more than 160 sunless hours. Or that your winter electricity demand is average, when in fact its generally higher as you spend more time indoors with the lights on and the telly on.

Bad assumptions. Add in the cost of capital as the power companies do, and the cost of maintenance at around 15% of capital cost (in total O&M + interest) per annum,
so every year add on £20.25k O&M and interest
Going on the 1Kw average draw, over that year, that adds another £2.31 per unit
Bringing the total cost of the electricity up to almost exactly £3 a unit.
Whereas coughing up 50 grand to get connected over a 25 year period where someone ELSE does all the maintenance,adds 2 grand a year to the price of the total electricity bill - a mere snip at 22p plus the notional electricity cost of 10p - a grand total of 33p before interest, and we will put that on at 7.5% ..adding a further 42p to the cost per unit.
So.
To get connected: 75p a unit over 25 years
DIY approach: £3 a unit. And no guarantee of reliable large winter power.
And which house will have more resale value? The one that comes with a high maintenance bill, a set of solar panels on their last legs, and a lot of scary electronics and a frankly dangerously explosive battery pack in the cellar, or one that comes 'with mains electricity'

And have a lot of bottled gas.

--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 06 Mar 2012 11:06:53 +0000, The Natural Philosopher

December isn't dark during daylight hours for 25 days a month and dawn to dusk sunshine for the remaining six. You don't need 6 months battery capacity as you said before, and you even don't need a months capacity either. Systems installed in the UK and monitored for many years conclusively prove that you don't. Six months battery capacity would only be needed at the poles and it's far cheaper to fly in JP-8 in bulk than a battery bank.

Maybe they do but big house does not necessarily mean high electricity consumption. We use 4 MWh every year, 450W average and that is with near 100% tungsten lighting - there are only two compact fluorescents in the place.

Cost of capital currently and for the past three years has been close to zero. Maintenance on a fixed system is SFA. Obviously you have to move those batteries every five years or so, and get someone to fit them, but spend 24k on cells and there is sufficient profit margin for free fitting if you let the vendor take away the 'waste'

I'd never consider solar pv for a conventional house 'offgrid' , and I think FIT tariffs are immoral, but given what the fully monitored real world performance of small (sub 1kW) systems has been in practice for true offgrid situations then I'd have no worries about using such an approach in future.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

He can still get a "FIT" payment for it so he may consider it an investment. Though there is no FI obviously..
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 6 Mar 2012 06:13:41 +0000, furby2009

Is there not a wood burning stirling engine thing that makes electric? (The gas one was on that homes of the future thing)
--
http://www.voucherfreebies.co.uk

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 06 Mar 2012 06:13:41 +0000, furby2009 wrote:

An expensive way of getting a shiny roof? :-)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Jules Richardson wrote:

A fantastc aiming point for pigeons on bombing raids.
--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
tony sayer wrote

Bet it wouldnt if they get a reputation for shooting the thieves dead.
Or have an underground tank for it.
Or a fierce dog chained up near it on a long chain.
Corse it could eat the kids.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Well they did have some pikes turn up at one sited demanding that they give them some scrap for free;!..
So the site operator jumped into a rather large loading shovel and then drove up to their transit van and shouted that he'd crush it and they could then take that as scrap. They have left them alone at that site since.
Prolly word has got round;!..

Useless .. as the poor dog gets whacked with an iron bar usually..

--
Tony Sayer



Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.