Tasting from the forbidden fruit

20/11/2013 12:34

[why electricity meters can(not) go backwards?]

Note: Before reading this, you should watch "tasting the forbidden fruit" on youtube www.youtube.com/watch?v=WDoiZzISc3Q&feature=youtu.be

What you will see is an electricity meter going backwards.

The setup for this was very simple. A medium size solar panel installation of 2.4kWp connected to the mains network (grid), with the sun shining and no main consumers running.  Since more power is being produced than is needed at this moment, the electricity meter is turning backwards accumulating credit. The moment there is higher consumption again, everything returns back to normal and the meter turns in the ordinary way.

However, even if the system is professionally installed and connected, this kind of setup is at present not exactly legal!

Is there any technical reason, why this should be the case?

-              Most modern electricity meters have been locked to only one direction, or might even be electronic meters that can be remotely red by the electricity company.

But in reality, there are many electricity meters still installed that have no problem counting backwards (in Greece still very common, in remote areas, but also in the UK).

-              Meters that run backwards are not calibrated and hence certified in this direction is a frequently used argument by the electricity companies.

Although this is true, there is actually no practical reason why it needs to be. Physically, it runs with exactly the same accuracy in both directions. It is a bit like led trimming the wheels of a car. They are balanced for both directions.

-              The created electricity could somehow tint or mess up the grid.

All modern Inverter,  work in a similar way. They first listen to/analyse the existing current and only when they are perfectly synchronized with it, do they start to feed in. The moment the mains power fails, they detect this as well and stop feeding in. (Also, all PV-installations  with a 20 year contract work in exactly the same way)

-              The created electricity might not be needed.

If the meter is turning backwards, than there is a need for this electricity somewhere up the line. If there wasn't, the meter wouldn't turn at all. Electric power is only flowing actively trough the electricity lines, when there are consumers running. The fact that one measures 230V at the outlets, is only the value of the electric potential and does not turn the meter at all. (Also, the same comment applies as to the item above)

-              There is a possibility to overload the grid.

As long as the maximum output of the installed system is smaller than the maximum consumption one has, there is no problem at all. If the lines can withstand 25A running into your house, they can withstand the same power going out. (And so can the rest of the grid)

A problem would only be created, when your system can produce much more. Here at SoLenium-technology, we would recommend no system bigger than about three quarters of your typical use.

So, if you use about 25kW/h a day, your system should not produce more than 18.5kW/h a day. Which system this would be, is very much dependent from your location and is somewhat  different from place to place, but a 2.4kW/h system in Greece, produces a good 15kW/h on a sunny summers day.

-              The main reason why this is illegal (at least in Germany and Greece), is that when you produce energy, you have to pay VAT. The fact that there is no contract and the feed in is not perfectly measured, makes you a tax-evader and this is nowhere really a good thing.

The truth is however, that for as long as your system is producing less electricity (in average) than what you actually need, you are only producing in a way of credit. Everything that you feed into the grid during the height of the summer or during the day, is used up by yourself at a later time or date.

In total, you are still consuming more than you produce, which means, that over a period of time, there is no VAT to be plaid.

SoLenium technology has seen such systems running, and they work just in the described way. We believe that it should be made possible through legislation changes, that these systems can be installed, of course within a proper framework and the knowledge of the electricity company.

Until then, this is only an urgent proposal, and if you want to learn more about how such a system can be extremely cheap to install and benefit everybody in many ways, "read on!"