Wednesday, 2 November 2011

Are we making any money?

Thought you might be vaguely interested agog to know how we are doing with our new solar PV panels.

Well here goes, I've had to use the calculator so hopefully all figures are correct.  If you notice any glaring mistakes feel free to let me know, maths has never been my strong point.

The two weeks before we had the panels fitted we consumed:-
279
185 kWh

Then the two weeks after (I've disregarded the week we had them fitted as mid week) we consumed:-
137
119 kWh

No actual sunshine, but still generating.

For the full four weeks we've been 'live' we have generated:-
33.8
29.2
43.7
30.8 kWh respectively.

That's a total of 137.5 kWh units (not bad for October).  For each unit generated we receive 43.3 pence, plus a further 3.1 pence for any kWh exported back to the grid.  Our FIT electricity supplier calculates the export figure simply by halving the figure we generate.

That means in cold hard cash terms for this four week period we will receive a total of £61.67 tax free from the government, for both the kWh generated and exported under the FIT scheme.

On top of generating and exporting we are also of course reducing our electricity bill by using as much as we can when we generate, so for example I delay my washing machine to come on when the sun is up and plug in all mobile devices to recharge their batteries in the day.  The daytime energy consumption is helped by the fact that there are four of us at home in the day, throughout the day.  

How we work out exactly how much we are reducing our electricity cost is a little difficult to calculate as there could be times when we do not use absolutely all of the energy generated.  I thought instead, simply as an interesting exercise, I'd contrast last year's readings from our electricity meter against this year's readings.
 
October          1st Week      2nd Week         3rd Week      4th Week       Total Used
2010               183                223                    270               237                 913
2011               137                119                    135               203                 594

In short a saving of 319 kWh.  All the reduction of kWh usage in this comparison obviously cannot be put down solely to the installation of the solar PV panels, other variable factors should be taken into account.  For example; external temperature conditions, general home energy conservation strategies implemented, whether we were home in the evenings etc. Still I like the figures.

One last little thing.  I still haven't got used to seeing how our home energy monitor now sometimes goes down when we switch a light on. That's simply because when we are generating more than we are using the monitor reflects the credit available.  When we switch something on, the figure on the monitor reduces because that electrical item consumes some of the generated electricity available for free use.

The Inverter
IMPORTANT: Government reducing FIT payments soon?

There is a rumour that from December 12th 2011, the tariff payment will reduce to 21p/kWh for solar photovoltaic systems of up to 4kW.  I found this information on the energy saving trust website, note that this proposal is not final.

Falling costs in solar installation, (the Government) quoting a fall from £13,000 to £9,000 for an average system since the tariffs began, mean that homeowners should still see a decent rate of return on their investment, quoting figures of around 5% return. But that's well shy of the 10% return owners are currently getting.  In short if you are considering it ACT NOW.

Bear in mind too that it can take some time for your application for FITs to be received by your FIT licensee (FIT electricity supplier).  It will of course always be after the date on which your PV system is installed.  

3 comments:

Midlife Singlemum said...

That's interesting. We have solar heated water but not for generating electricity - although the school opposite had it recently installed. And there is also the sell-back system for those that do generate electricity. (writing from Israel).

Rob-bear said...

Oh, dear. Didn't know you were having a FIT over your solar panels.

But the numbers are, um, well, fascinating. Well done, lins and family.

And you're giving the economy a shock with your leftover generation! Yes, a good thing.

Preseli Mags said...

Well I applied - the week before they announced the reduction in FIT payments! Martin Moneysavingexpert Lewis says it's now probably too late to get free panels installed. So it looks as if we've missed the boat (this time). Next time there's something like this I'll be at the front of the queue! I was very impressed with your system (she says, bragging that she had the privilege of a guided tour!)

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