solar pv

[Piff]

My inverter (SMS Sunny Boy 3600TL) has a built in relay which was I believe originally intended to switch an optional cooling fan.
We changed our immersion heater to 1.5kw and the relay has been programmed to switch on the immersion heater when panel output exceeds 2.0kw. The difference of 0.5kw assumed to be used by normal domestic loads such as fridges/freezers which are permanantly on.
The water heating then reduces the amount of time our heat pump runs.
Haven't got any cost saving figures, but the change of immersion heater & a few electric cables, etc cost less than £50 to buy/install

 

[trapperjohn]

So our system has been in three years now and to save you hoping back through the thread.

Installation cost £8K give or take. Feed in Tarrif is the "high" one at 48.07p.

Total income after 3 years is £1939. So another seven years to get the original cost back. If you look at it on outlay payback only.

 

[wemorgan]

^ that's an APR of ~8%. Very nice

 

[Charles Morgan]

No it isn't. It includes three years of payback of the capital (say £400 a year on a 20 year life) so the actual rate of return notional is an undiscounted 3% per annum.

 

[wemorgan]

It includes three years of payback of the capital (say £400 a year on a 20 year life

You've lost me there. Sorry.

 

[230K]

That seems clear.

So, you use your own electricity, sell the extra generated, and only pay for what you use, say, after dark...plus receive a payment for having the system?

Hi

Rules for NI are different.

For every unit we generate we get 4 ROC's. Each ROC is valued at 4.24 pence/kWh so you get 16.96 pence per unit.

For every unit we use that we have generated we save approx 18 pence per unit.

For every unit we export we get paid 5.59 pence per unit from PowerNI.

So if you generate and use it you save/make 16.96+18 ~= 35 pence per unit.
For every unit we export we make 16.96+5.59 ~= 23 pence per unit.

A 4 kW system on a south facing roof should generate 3000-3300 KWh and costs approx £5900.

Expect pay back in just shy of 6 years.

Hope this helps

230k

 

[Meldrew2]

I have a 3.92kw fitted (£11k)a few years ago, just before government cut back on the FIT rate, so far the FIT chq I received by my calculation is enough to cover my house annual gas/electric consumptions. I am happy! Just wondering if there's system where I could store the electric generated during daytime and use it at night?

Would a storage heater (yes, I know, old technology) be useful?

 

[whitenemesis]

Indirectly, via hot water storage. Or any load up to 3kw

PV Water Heating, Solar Hot Water Switch and Controller Supplier in Lincolnshire, UK | immerSUN

Would a storage heater (yes, I know, old technology) be useful?

Use with this, up to 3kw

 

[Piff]

Would a storage heater (yes, I know, old technology) be useful?

Only problem with a storage heater is that the time you generate most electricity is in the summer when the sun is shining and you would rarely want the stored heat on a summer evening.

You also need a system that uses your surplus pv generated electric and does not necessarily draw electric from the grid. You need some control so that the device only cuts in when you are generating over a pre-set level and the device (and other devices that are running - fridges/freezers/etc) draw less power than your system output.

 

[whitenemesis]

See the link I posted in #148 for an intelligent switch

 

[trapperjohn]

Winter income.

30 10 2014 -30 01 2015 £28.86. Thats two quid less than the same period last year. Missing heavy frosts and sunshine days this winter compared to last.

Thats a grand total of £1963 since installation in Oct 2011. Installation fee was 8K+ shrapnel. Yup I'm on the old FIT of 40 odd pence per KW. I have no data to show how much my electric bills have been reduced by since installation.

 

[nictry]

Winter income. 30 10 2014 -30 01 2015 £28.86. Thats two quid less than the same period last year. Missing heavy frosts and sunshine days this winter compared to last. Thats a grand total of £1963 since installation in Oct 2011. Installation fee was 8K+ shrapnel. Yup I'm on the old FIT of 40 odd pence per KW. I have no data to show how much my electric bills have been reduced by since installation.

£44.59 for my winter quarter, this with the .14p tariff so assume we must be seeing a very different level of sunshine!!!

 

[Piff]

So our system has been in three years now and to save you hoping back through the thread.

Installation cost £8K give or take. Feed in Tarrif is the "high" one at 48.07p.

Total income after 3 years is £1939. So another seven years to get the original cost back. If you look at it on outlay payback only.

Ours has now been in for 3 years.
Latest winter quarter up to 28/2/15 = £190.10
Total income over last 3 years = £5084.33 (10531kw/h)
Original installation cost just under £8k

 

[bolide]

Interesting discussion.

You could dump excess energy into a thermal store and use a heat exchanger to pull it out into your hot water or central heating system. These systems are getting more popular as people adopt heat pumps

I think solar might be a great addition to a new heating system as you could tie the systems together. It gives a different way of looking at capital costs - £8k on a central heating system to enable you to spend £100 / month on fuel vs £8k on a solar system to generate electricity… Most people would consider a new central heating system as an investment, or a necessary evil at worst, whereas solar systems have acquired a reputation as being a con.

The 25-year projection is meaningless & the headline £75k equally so. The system won't still be running in 25 years - maybe not even 10 - but it doesn't mean it won't be cost-effective

Is the FIT figure guaranteed or can the Government change existing tariffs in the future? If the latter none of the figures mean anything

Is VAT payable on the equipment & installation costs?

Nick Froome

 

[Piff]

The 25-year projection is meaningless & the headline £75k equally so. The system won't still be running in 25 years - maybe not even 10 - but it doesn't mean it won't be cost-effective

Is the FIT figure guaranteed or can the Government change existing tariffs in the future? If the latter none of the figures mean anything

Is VAT payable on the equipment & installation costs?

Nick Froome

Systems likely to need new invertor approx every 10 years - cost perhaps around £1k. Panels decay over time - mine are supposed to generate 3132 kWh in year 1, but in year 25 are supposed to generate 2506kWh.
Years 1 to 3 are supposed to generate a total of 9292kWh but have actually generated 10531kWh

FIT is supposed to be guaranteed rising with RPI or similar. Started at £0.433 + £0.031. Predicted to be £0.477 and £0.034 today but are actually £0.4807 and £0.0339 (tariff usually updated at end of March). Of course change of govt policy could change everything

VAT was at 5% on equipment/installation (have included this VAT in all the figures I have shown)

 

[trapperjohn]

Ours has now been in for 3 years.
Latest winter quarter up to 28/2/15 = £190.10
Total income over last 3 years = £5084.33 (10531kw/h)
Original installation cost just under £8k

Gulp. The joys of living in the frozen North and panels situated on a roof (our best option) North/East. The sun goes off them at around 6pm in Summer.

Just sent in today's reading for the end Jan to start May period. Getting £142 back. Bringing total income to £2110 Some 3k short of yours Piff.

(trapperjohn goes off muttering to himself)

 

[guydewdney]

Wash your panels, it helps.

 

[Piff]

Wash your panels, it helps.

Mine are not very accessible....................
I need a drone with a hosepipe

 

[guydewdney]

Most window cleaning companies have a 'long reach ' system. Basically a blooming long pole with a brush on the end

 

[Piff]

Would need to be a long pole to get to the top 6

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