Voltage optimisation

[Jay_Benson]

I have had a look around the site - well the search function has - and I didn't see anything about voltage optimisation. So to explain what it is:

A voltage optimiser (VO) normally aims to reduce the voltage of the mains system in a property to around 220V - the benefits are claimed to be a reduction in electricity bills of between 10-19% and a reduction in the wear on systems such as compressors for fridges / freezers and washing machines / dishwashers as the voltage going to the motors are lower so the motors spin slower.

The context for the question arising is that we have solar panels and we have been approached by a company to carry out routine maintenance on them on an ongoing basis with the company picking up liability for replacing any components that die. One of the key components is the inverter, this converts the DC from the panels to AC at mains voltage - our inverter is around 11 years old so is close to the top end of its expected life (8-12 years). They have stated that the VO would reduce the likelihood of the replacement inverter failing and so they want to include it in the contract - the benefit to us is the reduced energy bills.

My bull shit detector is singing out loudly as the energy savings are not really savings to my mind as they just make things run slower - sure the fridge / freezer / washing machine / dishwasher will be slightly cheaper to run their motors but other things will just take longer to heat up.

Am I being overly cynical or is my cynicism justified?

[John63]

Always healthy to be cynical 😀

Is the VO changing / reducing the voltage or simply reducing fluctuation?

A more consistent supply would presumably give smoother operation of electrical items so less wear and tear.

[Jay_Benson]

In our case reducing the voltage - it is sat at around 249V today - down to, from my limited understanding, 220V.

[Energy58]

No idea if it works re extending life but what normally matters is the amount of work done (kWh) and if you reduce the voltage then to do the same amount of work the current must rise (work = voltage x current) and the heating losses (which are the big ticket items) are determined by the square of the current (which is one of the reasons why electricity is transmitted at 400kV and not 240V) so I can't see a mechanism whereby reducing the voltage improves efficiency.

Regardless of that your inverter is deffo getting towards the end of its life though so you need to budget for its replacement

[Stig]

I've also had calls from companies that have figured out I've got solar panels, I generally don't give them enough time to start their sales spiel or I don't answer the phone at all.

A lower voltage won't generally make electric motors run slower, a fridge probably has an induction motor who's speed is set by the main frequency, a washing machine has a fancy speed control system for the (probably DC) motor anyway. It is true that 220V would put any power electronics under a bit less stress than 249V but then the current will have to increase by the same proportion so you'd get more heating effect in wires and semiconductors so that's an increase in stress. Pretty much what Energy58 just said.

In summary, I also call bullshit.

[MarkA]

I have had a look around the site - well the search function has - and I didn't see anything about voltage optimisation. So to explain what it is:

A voltage optimiser (VO) normally aims to reduce the voltage of the mains system in a property to around 220V - the benefits are claimed to be a reduction in electricity bills of between 10-19% and a reduction in the wear on systems such as compressors for fridges / freezers and washing machines / dishwashers as the voltage going to the motors are lower so the motors spin slower.

The context for the question arising is that we have solar panels and we have been approached by a company to carry out routine maintenance on them on an ongoing basis with the company picking up liability for replacing any components that die. One of the key components is the inverter, this converts the DC from the panels to AC at mains voltage - our inverter is around 11 years old so is close to the top end of its expected life (8-12 years). They have stated that the VO would reduce the likelihood of the replacement inverter failing and so they want to include it in the contract - the benefit to us is the reduced energy bills.

My bull shit detector is singing out loudly as the energy savings are not really savings to my mind as they just make things run slower - sure the fridge / freezer / washing machine / dishwasher will be slightly cheaper to run their motors but other things will just take longer to heat up.

Am I being overly cynical or is my cynicism justified?

I think your BS meter is working fine.

Agree with what Energy58 and Stig have said.

If I remember, the UK standard for household voltage is 230V +10% -6%. Any new equipment should show that it covers 220 to 240V on the nameplate. Low voltage can also cause issues. We have an oven that below 197V it stops working. The control board not the heating elements.

On the industrial equipment I used to work on we would tap the transformers to get the correct secondary voltage. Some stuff used go bang if it was a little high. We used to use a UPS to feed the computers, but generally this caused more problems than it solved. So we stopped using the UPS. Where the supply is really scabby a UPS may have been useful.

[Tens]

In the UK the standard is 230V -6% +10%.

[wibble32]

I am baffled by these claims. The unit you are interested in using and are billed by is the kWhr base on kW of load. The kW is a constant and as pointed out by Energy58 is a function of Volts and Amps with increased Amps due to lower voltage which brings an increased waste heating effect in its transmission.

If they claimed a UPS style buck and boost of the voltage and or regeneration of the waveform to clean up spikes and sags then I would think about it as extending operational life of appliances I had bought. Such as boiler circuit boards etc. Info is lacking as to their claims.

Rgds

[MarkA]

In the UK the standard is 230V -6% +10%.

Thanks for the correction

[Jay_Benson]

Much as I thought. It is good to get confirmation that I was not being overly cynical. Thanks all.

When I think about it if it were such a fanatic energy saving machine then given the current , sorry about that, energy situation the government / green lobby would be all over a simple easy system of reducing the power requirements. But they aren’t.

[nigel hewitt]

Lighting would be a saving but how much of your bill is lighting?

[Energy58]

We have an oven that below 197V it stops working. The control board not the heating elements.

Plus this ^ if any controllers are depending on mains voltage (stepped down) you might get issues if you start sailing close to the wind with your non-standard domestic voltage. And you shouldn't really be bothered by spikes in the waveform unless you have super sensitive machinery and are at the A***end of nowhere connected by 3 bits of wet string with huge motor loads or an arc furnace next door - the UK is a pretty small place!

[jb2cool]

On the flip side to most of these comments I know at work we have a series (at least 4, maybe more) PowerPerfector units installed that adjust our voltage and maybe do other things too. These have been around for about 15 years and one of their benefits was claimed cost savings.

We are a large government laboratory site with lots of sensitive equipment but also lots of heavy duty plant machinery.

[Stig]

On the flip side to most of these comments I know at work we have a series (at least 4, maybe more) PowerPerfector units installed that adjust our voltage and maybe do other things too. These have been around for about 15 years and one of their benefits was claimed cost savings.

We are a large government laboratory site with lots of sensitive equipment but also lots of heavy duty plant machinery.

Maybe they're correcting the power factor which can be an issue with having lots of electric motors as the grid load. Business premises would get charged a higher rate if their power factor was too far off 1.0

[Stig]

When I think about it if it were such a fanatic energy saving machine then given the current , sorry about that, energy situation the government / green lobby would be all over a simple easy system of reducing the power requirements. But they aren’t.

You're assuming there's anyone in the government that understands science or engineering.