I have just had solar electric fitted. Currently it is producing around 600watts of power, and according to the output meter it is exporting around 300 watts to the grid. My energy meter shows I am using about 300 watts currently (this is my usual "ambient" load). Now, as this energy meter is fed by a current transformer on the tail from the meter to consumer unit, I would have expected a negative reading while it is exporting, But it is reading as normal. Why?
Solar Energy
- Thread starter maltaron
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Well, for a start, unless it is specifically designed to deal with this situation, it's pretty likely that your 'energy meter' doesn't understand about different directions of energy flow. Do its instructions have anything to say about use with solar installations?
Kind Regards, John
Most installations don't have a meter that goes backwards, there is usually an estimate made that 50% of the power generated will be exported and you are paid an allowance based on that. Check your contract.
Why not ask the people who installed your solar panels?
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No harm trying - but I suspect that they might well not know whether the OP's particular 'energy meter' is capable of detecting direction of energy flow and displaying negative figures. I strongly suspect that most such meters don't/can't, unless they are specifically designed with solar installations in mind.
Kind Regards, John
If they don't know enough to satisfy the OP then one has to question their competence to install such systems.
Hmmm. Maybe we're interpreting the question differently, but it seemed to me to be a question about the behaviour of his energy monitor. However, as I said, it's worth a try, and they might get asked the question sufficiently often that they know the answer, even though it relates to someone else's product!
Kind Regards, John
Are they paying you more for that electricity than they can sell it to somebody else for?
If they are, how do you think that comes to make economic sense for them?
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You of course raise a valid question. With a smart meter it can work out if power is being imported or exported but any other meter will likely charge you for energy you export and it relies on your solar panel dedicated meter earning you more money than the standard meter charges you for and tariffs are adjusted to cater for the problem.
So the behaviour of people with smart meters will be very different to those without in order to gain as much as they can monitory wise.
There are systems for using excess energy to heat water and until a smart meter is installed you have to aim at exporting as little as possible. The problem is non of us know when the smart meter will be installed so paying for the equipment to use excess to heat water will only pay for its self if there is some time before the smart meter is installed.
So the behaviour of people with smart meters will be very different to those without in order to gain as much as they can monitory wise.
There are systems for using excess energy to heat water and until a smart meter is installed you have to aim at exporting as little as possible. The problem is non of us know when the smart meter will be installed so paying for the equipment to use excess to heat water will only pay for its self if there is some time before the smart meter is installed.
Well, the OP is talking about his "output meter", rather than an extra energy monitor. I assumed he meant the supplier's meter. If a solar installation company doesn't understand how those work or cannot explain that to their customers then they have no business installing microgeneration.
I think you may be muddling two parts of the OP. It started by saying....
...which is what you are talking about, and I think is non-contentious - i.e. the OP accepts that the 'output meter' is telling the truth. However, he then went on to say:
I took that all, including the OP's question, to relate to his clip-on 'energy meter'. Do you disagree?
Kind Regards, John
Ah yes. 
However I would still expect the installer to be able to explain what is actually happening.
However I would still expect the installer to be able to explain what is actually happening.
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A suitable 'energy meter' (e.g. the Wattson) has two separate clamps, one on a cable for the consumed power and one for the generated power. The clamps can't detect the direction of power flow, but the meter knows to subtract one from the other.
This relies on the wiring being such that these two wires are separated at a Henley block. Many installations aren't connected this way and make the sort of measurement you want to do much harder.
This relies on the wiring being such that these two wires are separated at a Henley block. Many installations aren't connected this way and make the sort of measurement you want to do much harder.
As I said, that's quite possible, although I suspect that their 'explanation' might well b much the same as mine - namely that many/most of these energy meters can't/don't distinguish between energy flowing one way and energy flowing the other way.Ah yes.
Kind Regards, John
Yes, I agree, but they shouldn't leave their customer feeling he has to ask on an internet forum.As I said, that's quite possible, although I suspect that their 'explanation' might well b much the same as mine - namely that many/most of these energy meters can't/don't distinguish between energy flowing one way and energy flowing the other way.Ah yes.
Kind Regards, John
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