Power meters and Solar Power

...and the ever present threat that the guaranteed FIT rates being abandoned by the current or a future regime leaving you with a roof full of shiny PV's that pay bugger all.

Reply to
The Other Mike
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The "Generate 10KWh, consume 10KWH, pay nothing" was in relation to an earlier post discussing payments made to the electricity SUPPLY company.

Dependent on the timing of your daily usage this necessary payment can vary anywhere between nothing and the full amount of your normal electricity bill. PV suppliers typically suggest that about half the PV energy will count towards reducing the size of your electricity supply bill. With the old reversible supply meters this was a credible estimate.

With the new non reversible digital meters it is wildly optimistic. With most power consumption outside daylight hours it would be hard to reach even a 25% reduction in your electricity bill.

The export and Feedin Tariff payments are quite different and account for the major part of the cost saving.. They occur at a different time and are made by one of the approved Energy Acceptance companies.

Overall the scheme is very attractive and offers a good return on cost of the installation.

Jim

Reply to
pentagrid

The type of meter and whether they are reversible matters little. It's 3p extra export payment compared to 41.5p paid for ANY and ALL generation, 7% extra per kWh is hardly going to be a deciding factor in making the scheme pay or not.

But import/export meters at the boundary are the only fair way. Every other source of generation is metered this way. That metering of generation sources *separately from the boundary* and in addition to that *at the boundary* gives rise to an addtional premium payment that has no place in a competitive market - it's green fudge at its worst.

By the way, the existing digital meters can be configured for measurement of import and export in a matter of minutes.

Reply to
The Other Mike

The type of meter fitted makes a significant difference to the return on a PV investment.

Take the limiting case - ALL consumption outside daylight hours.

This means that, if an export meter is fitted, all PV energy qualifies for the 3p export payment

Reversible meter

1 KWh generated , 1KWh consumed - electricity bill nil Feedin tariff +41.3p export - +3p Net income +44.3p per PV KWh

Non reversible meter

1KWh generated, 1KWh consumed - electricity bill -12p Feedin Tariff +41.3p export- +3p

Net income +32.3p per PV KWh

If an export meter is NOT fitted the assumption is made that half the PV energy qualifies for the 3p export payment.

Reversible meter

1 KWh generated , 1KWh consumed - electricity bill nil Feedin tariff +41.3p export - +1.5p

Net income +42.8p per PV KWh

Non reversible meter

1KWh generated, 1KWh consumed - electricity bill -12p Feedin Tariff +41.3p export- +1.5p

Net income +30.8p per PV KWh

This is an extreme case but even with the most optimistic assumptions on daylight power usage much of this reduction will still occur.

Jim

Reply to
pentagrid

One question on my FIT application form was to ask if the import meter had started to run backwards since installing my PV system. It has not as I have a newer digital meter by I expect that If I had said yes, they would have been round like a shot to fit a uni directional meter. I'm sure that they do not want cases 1 and 3 above to occur.

Do you have a PV system installed Jim?

Bob

Reply to
Bob Minchin

SNIP

Many of the comments made in the recent posts arise from difficulties I encountered in obtaining accurate costing information on my PV installation.

My PV supplier simply said that the usual assumption was that about half the PV energy resulted in a corresponding direct reduction in the electricity bill. If I needed more detailed information I should take it up directly with the supply company.

This I did. but it took just over a month to get a straight answer to the relatively simple question " how does the timing of consumption affect the electricity bill "

The normally helpful call staff of the supply were not briefed on this subject but I eventually succeeded in contacting the technical department. The following extract from their final email is the basis on which I have made comments to the group.

"With regards to your points below, the following require correction.

The electricity meter registers total power consumption minus total PV power generation.

Your supply electricity meter (that is read for your bills) will record only the excess electricity that you use (buy in from us) when your system is not generating enough for you needs at the time, or not generating at all.

If, in a 3 month period, total PV generation exceeded consumption the meter reading would decrease.

It is illegal for your supply electricity meter to run backwards, therefore the reading should never decrease. The meter should stop and not record any consumption when your generation is greater than any consumption in your property. But if the meter run's backwards you must inform us immediately and we will exchange it for a meter that won't run backwards. " Jim

Reply to
pentagrid

You could tell them you have blocking diodes to prevent reverse flow, and see how long that delays them.

jsw

Reply to
Jim Wilkins

Please name and shame them so we all know who this shower of shit outfit are!

Reply to
The Other Mike

I did not name them as I have no axe to grind with either. Pretty well all PV supply companies make the same optimistic claims on reduced electricity bills and apart from this I am satisfied with my suppliers performance

The electricity supply company is simply implementing nationally agreed supply arrangements.

Jim

Reply to
pentagrid

Oh dear so you *really* think they are doing that?

Reply to
The Other Mike

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