Electric meters

<Adding on to this thread:>

In the UK, schemes exist for "microgeneration" using either wind or solar energy collection at the home. When available supply exceeds local demand, the excess is exported to the local grid. Is it correct to state that the meter "runs backwards" when electricity is exported? And does it depend upon the meter type?

A very cheap electromechanical may turn backward, but it also might damage the meter, depending on the quality of the register gears. The better quality units had a latch & pawl or a brake to prevent reverse rotation.

I have several locations with co-generation. Before we went electronic, I would install two unidirectional meters, one for power in, the other for power out. That way the totals for both directions were always available. The meters we use now are micro-processor based, and have separate in & out registers for all parameters. The customer is billed only on net usage.

PWslack, its true, if you generate more power then you use, it will send the meter disc backwards, how ever many meters have a photocell to count the number of times a reflective spot on the disc passes over the photocell recording energy use. so it adds to your electric bill regardless of with way the disc rotates perry

I tried posting a response earlier but CR4 must have eaten it. Pre-apologies if this shows up twice.

Thanks for the responses to my original question. Unfortunately I have to flap again.

So assume a house had a mechanical meter. If there are a number of AC motors in the house and you put some power factor correction capacitors acrosss their inputs, this wouldn't affect the meter's reading in the homeowner's favor?

This is all purely hypothetical of course. This is not my house and there are absoultely no counterfeiting printing presses in the basement.

No. The meter reading will be the same regardless of the presence or absence of power-factor correction caps.

There is at least one lot of snake-oil salesmen in the US who sell power factor correction caps dressed up in fancy sealed boxes under the false promise of energy savings of up to 25% of the household electric bill, but these are generally regarded as a scam by anyone with an understanding of the concept of power factor.

Power factor correction will, of course, reduce the line current if the load is inductive, and there are some (very small) savings to be made as a consequence of reducing the i^2R losses in the wiring, but this is not going to make much of a dent in the power bill.