Put your solar panel questions to the Energy Saving Trust

cheap_skate

Hi I'm just looking to have a system fitted and have 5 companies give me 5 different quotes ranging from the 9k to 14k. The best price I have had is 10,500 for a 4kw system using siliken panels. Does anybody know if these panels are anygood as I have been told that the sharp hit are the best but quite a bit more money. So my question is it worth spending the extra for the sharpe panels?

Thanks for any help

grumpyoldsteve

Cardew wrote: »

I think you have misunderstood how solar works.

A 2.45 kWp system in your location will generate I suspect less than 2,500kWh pa - you should have the prediction.

Even if you used all of that electricity in the house - which is impossible - that would mean you would save 2,500 x the tier 2 rate you pay for your electricity say 11p? which would come to £265.

However all tests - according to the EST and others with export meters - that very few people manage to to use 50% of that electricity, and many much less.

The 206kWh you have generated would be worth about £23 if you could use it all, but you will have done well to have saved £10 in the month.

It may be that you have a backward running meter that is distorting figures - but that won't last.

You don't say if you bought the system, but the main income will be from the FIT and export tariff and that 206kWh will earn £92.39

Yes, I have bought the system and I realise that the main income will be from the FIT (I got that calculation right:). I see your point with your calculations and I have the prediction which is actually 2087 - and as my calculations were based on actual meter readings (showing very few units accumulated since the system was installed) then I guess the meter (which is a rotating wheel mechanical one) it must be distorting the figures big time.:embarasse
Thanks for pointing this out. I did ask British Gas if I could have a smart meter as I was having solar fitted, but they said I would have to wait my postcodes turn. I guess they might change their mind when they realise how little I will be paying at my next quarterly bill going by the readings.
Oh and another thing that is probably distorting the bill reducing capacity of the solar, is the fact that all this awareness of consumption and energy saving prompted by generating our own power is that I have changed some bad habits so would have reduced consumption a bit regardless of the solar PV system. I have a whole list of power ratings from electrical and electronic gadgets used in our house and will be doing some calculations to see how much having them switched off whenever possible could be saving. I guess the biggest culprit for my false optimism will be the meter though.

Cardew

grumpyoldsteve wrote: »

However, as a solar newbie I only know what I was told about Sharp panels being some of the best and have no idea about other makes at all really, only that monocrystalline silicon (as per the Sharp ones) are the most efficient!

Just to point out what efficiency of panels means in this context.

You have 245Wp panels - they will produce the same as any other 245Wp panels under the stipulated test conditions in a lab.

Essentially the efficiency comes from the size of the panel - less efficient panels than yours will be bigger, more efficient smaller. The main advantage of higher efficiency panels is you will fit more on your roof is space is tight.

orrery

Cardew wrote: »

You have 245Wp panels - they will produce the same as any other 245Wp panels under the stipulated test conditions in a lab.

But double check the way they are specified - there will be a range around that figure.

-5 / +10% means that it could deliver within a range of 5% less to 10% more than specified. So -0 / + 10% would be good.

grumpyoldsteve

I had previously said that I had a backward running meter, which would seem to explain unfeasibly high forecast of savings on my bill.
However sat here writing this on a beautiful sunny day, with my energy monitor registering approximately 1 kWh going out to the grid, my meter is not budging in either direction. The big wheel is static (except when I put the kettle on for a cup of tea a few minutes ago).

So my question is are there some mechanical type meters that don't actually go backwards?

energysavingexp

grumpyoldsteve wrote: »

I had previously said that I had a backward running meter, which would seem to explain unfeasibly high forecast of savings on my bill.
However sat here writing this on a beautiful sunny day, with my energy monitor registering approximately 1 kWh going out to the grid, my meter is not budging in either direction. The big wheel is static (except when I put the kettle on for a cup of tea a few minutes ago).

So my question is are there some mechanical type meters that don't actually go backwards?

yes they are called ratchet meters and it looks as if you have one
if you look at the meter it will show a ratchet symbol:beer:

grumpyoldsteve

Cardew wrote: »

The 206kWh you have generated would be worth about £23 if you could use it all, but you will have done well to have saved £10 in the month.

It may be that you have a backward running meter that is distorting figures - but that won't last.

It seems that I have a ratchet type meter, and if it was going backwards, it isn't any more - is that what you meant by it won't last?

:beer:

Cardew

grumpyoldsteve wrote: »

It seems that I have a ratchet type meter, and if it was going backwards, it isn't any more - is that what you meant by it won't last?

:beer:

No, Smart metering will be coming in some time.

In any case even if it were running backwards, the utility company can still chase you for estimated 'lost' revenue.

grumpyoldsteve

Do ratchet meters ever go backwards then?
It's just that I thought I had seen it going backwards when we had a lot of sunshine (and lots of solar power) just after they had installed my system back in September.

Cardew

grumpyoldsteve wrote: »

Do ratchet meters ever go backwards then?
It's just that I thought I had seen it going backwards when we had a lot of sunshine (and lots of solar power) just after they had installed my system back in September.

I think it depends on the make/model of meter.

There is one anti-tamper meter made by Siemans that actually runs the meter forward i.e you generate say, 6kWh use 2 from the mains and the meter advances 8kWh.