To Fit Export Meter or Not ?

[rawpilot]

Hello Chaps,

firstly forgive me, I'm not an electrician, but I have a fascination for what you guys get up to.

I'm having a Solar PV system installed soon (3.76KWp). My electricity supplier is Southern Electric who do an optional free export meter.
I am after your advice as to whether to ask them to fit one or not since I have an old consumer unit which I believe may run backwards. This no doubt would outweigh all benefits of any extra export payments above the assumed 50%.

If I do ask them to fit an export meter are they likely to replace the old consumer unit with a combined Import/Export unit or would they just fit a stand-alone export meter and leave me with the old import meter ?

Thanks

 

[mmccx]

if you are fortunate enough to have an import meter that runs backwards then the DNO will most likely come and change it anyway. In regards to the export meter it will only be worth it if you are out all the time and have hardly any base loads running in the house or you will be doing yourself out of money! The export tarriff is deemed 50% of your total yearly generation at the moment. So its better not to have one if you think you will be using most of your generated electricity and it will be better to have one if you think you will be exporting more than the deemed 50%

Also if your meter does run backwards then it will be better for you as you will be getting your money back for electricity you have already bought! unfortunately the DNO's tend to catch on quickly and will come and change it, but you dont have to get on their backs to come and do it once they have been informed of your meter number via mcs then the onus is on the DNO to change it

 

[Mark.W]

I think it's best to stick with your old meter! The reason for this is you get paid 41.3p per unit generated irrespective of whether you use it or not! You will also get 3p (on top of the 41.3p) on 50% of what you have generated! If you have a new meter installed and you use all the power generated and export nothing, you won't be paid for it!

Hope this helps

 

[rawpilot]

Thanks Guys,
You've convinced me. I'll not get one fitted.

 

[Des Platt]

This was really interesting folks thanks because I was looking for the answer to precisely this question. I am still a bit confused because Green Sun said that I should opt for the default half unless I used a lot of electricity. Well I don't do that ; single man , no home computer , pay about £28 per month with Southern Electric and I'm sure I could pay less if I was more disciplined with immersion . Also I have only just replaced a really old and probably inefficient tumble dryer.However, I'm in very little especially in the day so surely I would export more than half of what is produced? However, my meter is going backwards in the day so is that the definitive answer until they make me change my meter?

 

[Worcester]

Sorry guys,

If a meter is running backwards, and you don't report it, it is theft and you can be proesecuted.

Question though, why are the so happy to accept 50%, I reckon that if you actually monitor your usage (and see the charts here) you may be suprised how imbalanced your usage is compared to your generation:
MPANs, Meter Point Administration Numbers explained

Before you decide why not get one of the free energy monitors (i'm sure southern will give you one if you ask) or better still get one of these,
Current Cost - Reducing your energy bills so you can live a greener life! along with this Current Cost - Reducing your energy bills so you can live a greener life!
and hook it up to either their site or Google Power Meter

monitor your whole daily consumption for say two weeks

then hook it up to the output from the inverter and monitor that for a simliar period and compare the two.

Current Cost are actually working on a twin input device at this very moment to monitor generation and consumption, you'll then be able to make an informed decision.

After all you can always ask for an export meter to be fitted at anytime, though asking for it to be removed - unlikely!

 

[mmccx]

Sorry guys,

If a meter is running backwards, and you don't report it, it is theft and you can be proesecuted.

Question though, why are the so happy to accept 50%, I reckon that if you actually monitor your usage (and see the charts here) you may be suprised how imbalanced your usage is compared to your generation:
MPANs, Meter Point Administration Numbers explained

Before you decide why not get one of the free energy monitors (i'm sure southern will give you one if you ask) or better still get one of these,
Current Cost - Reducing your energy bills so you can live a greener life! along with this Current Cost - Reducing your energy bills so you can live a greener life!
and hook it up to either their site or Google Power Meter

monitor your whole daily consumption for say two weeks

then hook it up to the output from the inverter and monitor that for a simliar period and compare the two.

Current Cost are actually working on a twin input device at this very moment to monitor generation and consumption, you'll then be able to make an informed decision.

After all you can always ask for an export meter to be fitted at anytime, though asking for it to be removed - unlikely!

you know when you record the serial number and type of import meter and then send it off to your supplier as part of your FIT request, thats you telling them what kind of meter you have! they will then come and change it if they want. The customer does not have to chase the supplier to change it as you have already informed them of your meter. So no its not theft and you wont be prosecuted

 

[moshun111]

For a small solar power system like you have, you are very unlikely to generate more power than you actually consume.

 

[Worcester]

@mmccx

I may be wrong, however if, as a consumer, you know it is running backwards, and you don't tell your supplier, then you are knowingly defrauding them, and as such may be liable.

As installers we (should ) have notified them of everything we need to when we send the forms in (MPAN etc).

 

[SolarCity]

This is interesting and I doubt a supplier would actually attempt to prosecute - especially as it would be virtually impossible to prove.

The supplier would have to prove that the consumer knew it was running backwards. All the consumer would need to say is "Well it wasn't running backwards when I checked it."

If I were the consumer, I would definitely keep quiet.

 

[Des Platt]

Thanks very much for your replies folks.

 

[SibertSolar]

Interesting thread......aside from the queries/ethics/legalitites of primary electricity meters running backwards, I'll comment on the viability of having export/reverse energy registration via a secondary generation meter.

Sibert provides a range of secondary generation meters such as the commonly used Elster A100C, or the L&G 5235. Both these meters are typically installed as "import-only" and I understand from talking to clients that most DNOs provide a generic 50% payment of the export tariff based on your total generated electricity from the PV installation. However, what I don't understand is why consumers are happy to accept this reduced payment without first considering whether they are actually going to be generating more energy than they typically consume. As Worcester has quite rightly indicated above, it's entirely feasible that there is actually some net exported/reverse energy being sent back to the grid, over and above what the property actually consumes. Surely if the consumer can measure this and avail of 100% of the export tariff then that's got to be a good thing, right?

Given that we can supply the full Import/Export configured L&G 5235 generation meter (we do have a 3-phase version too) at the same price as a standard, import-only 5235 meter, I always encourage our clients to take these over anything else. The LCD display just cycles between the import (generated energy) and the export (net reverse energy back to the grid) values - no calculations or rounding of kWh's needed.

PM me or visit our website for more details,

Andy

 

[Worcester]

@SibertSoalr / Andy

It's not just import / export, we also need a 'Total Generation Meter', i.e what the system generates for the Feed-in Tariff, so that still means an extra meter, or can it do all three?

So if it's one meter, that would HAVE to go before the consumer unit and so would mean an additional 'garage' CU, as to measure Import, Export, Total Generation, i.e it needs three connections, Grid, Consumer Unit (load) and SSEG plant (inverter).. so you can't hook it up to a spare mcb, or have I missed something.

Even then it still isn't telling me (unless I look at it) and measure what the status is - I would still need a monitoring system that means that I can look back at the actual figures over a period of time.

 

[Des Platt]

Thanks everyone. Must admit, despite obtaining a maths degree 32 years ago, my brain is nowhere near up to this! Actually I have agreat admiration for electricians as like motor mechanic it is a job you could never train to me to do ; I am practically useless. However, this is a more intellectual question and I'm still struggling. Is the energy generated during the day which is not used during the day all exported or does some of it get used in the evening? It seems to me that my use in the day is so miniscule that I must be exporting more than half of what is generated unless I can save it to the evening .As mentioned above, I have an old style meter and at the moment it is going backwards .They originally quoted me as saving half my monthly bill and earning about £70 per month.

Do the payments in show on separate statement or via or normal bill?

On another note, The Guardian was pointing out recently that you don't get paid until you've filled the form in ( I've done that and sent in all my proofs etc) but a reader pointed out that it doesn't really matter as you will still get paid for 25 years from the date it is registered.

 

[SibertSolar]

@SibertSoalr / Andy

It's not just import / export, we also need a 'Total Generation Meter', i.e what the system generates for the Feed-in Tariff, so that still means an extra meter, or can it do all three?

So if it's one meter, that would HAVE to go before the consumer unit and so would mean an additional 'garage' CU, as to measure Import, Export, Total Generation, i.e it needs three connections, Grid, Consumer Unit (load) and SSEG plant (inverter).. so you can't hook it up to a spare mcb, or have I missed something.

Even then it still isn't telling me (unless I look at it) and measure what the status is - I would still need a monitoring system that means that I can look back at the actual figures over a period of time.

Hi there,

Perhaps I have misled in my info, my apologies if I have. As far as I understand things, the 5235 Import/Export meter provides 2 readings on the display:

t-value = Total accumulated energy generated by the Solar PV installation (regardless of whether consumed by property of sent back to the grid)

r-value = Net accumulated reverse/export energy sent back to the grid (excess energy over and above that used by the property)

So, with an existing Primary meter (fitted/managed by the DNO/MOP) and an Import/Export configured secondary generation meter, you have 3 readings in total available to the consumer. The total generated energy, the reverse/exported energy, and the primary imported energy (from the DNO).

Does this help to clarify? Anyone can download the 5235 user manual from our website here L&G 5235 Import/Export Meter - Sibert - automated equipment manufacturer and supplier of process consumables - there is a document link underneath the picture. Section 3.4 within the document deals with how the meter can be configured for reverse/export energy registration.

Andy