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Voltage Optimisers

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    1 vote (100.0%) for: Has anyone else had experience in the installation of voltage optimisers like matt:E. Do they work and give a better inverter performance or is it just an £800 gimmic

#1 Oct. 4, 2016 15:19:19

Roger F Mortimer
Registered: 2011-11-10
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Voltage Optimisers

Has anyone else had experience in the installation of voltage optimisers like matt:E. Do they work and give a better inverter performance or is it just an £800 gimmic?

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#2 Oct. 6, 2016 11:14:51

prodigymad
Registered: 2015-02-06
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Voltage Optimisers

From what I've seen it's an expensive gimmick for a normal domestic property.

It depends on the type of equipment you have at the house. If you have electric space heating or cooking then voltage optimisers do nothing to lower consumption.

The biggest savings appear to be mainly for motor based equipment such as compressors, washing machines, etc. So it's probably useful for air-conditioning or potentially even heat pumps.

http://www.yougen.co.uk/blog-entry/1948/Is+domestic+voltage+optimisation+all+it'27s+cracked+up+to+be'3F/

“However, we would urge residential customers to be wary of voltage optimisation technology sold purely on the basis of energy saving in appliances.

From our initial studies, the savings do not arise for most residential end-users, and are minimal where they do occur. ”

https://www.ofgem.gov.uk/ofgem-publications/58457/energy-saving-trial-report-vphase-vx1-pdf

“The mean saving in electrical energy consumption, attributable to the VXI devices, was determined from the trial as 5.2%, with a confidence limit on the mean of ± 1.4%. ”

Edited prodigymad (Oct. 6, 2016 11:15:17)

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#3 Oct. 6, 2016 13:23:06

bhommels
Registered: 2011-10-03
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Voltage Optimisers

A quick google search confirms the suspicion that these are only intended to serve the consumption side of the household, they will not adjust the voltage seen by the inverter.

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#4 Oct. 31, 2016 08:51:25

guava090
Registered: 2011-12-14
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Voltage Optimisers

Suggest you read the tech spec on the solaredge site. Useful if you have any shading issues.
Also by using them it makes the inverter simpler, so they can offer a longer warranty than others.

guava090.

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#5 Nov. 4, 2016 10:08:04

Roger F Mortimer
Registered: 2011-11-10
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Voltage Optimisers

This is very interesting and confirms my thoughts although there are variable answers as to whether any of the Microgen contributors have had one installed. If I can increase output to the grid by 6% then potential savings are there it seems. Roger

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#6 Nov. 6, 2016 14:40:09

pnews99@hotmail.co.uk
Registered: 2015-06-03
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Voltage Optimisers

i fitted one before i had solar pv i noticed about 6 per cent saving,at the time the unit cost £250 and was able to fit myself.
givan my monthly bill for gas end elect has dropped to under £30 it may not be cost effective to buy one now.
i have seen these fitted in large office blocks where the savings can be larger

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#7 Nov. 7, 2016 10:17:12

bhommels
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Voltage Optimisers

@guava, Roger,
Hope I am not confusing power optimizers with voltage optimizers - are we talking about the same thing?

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#8 Nov. 7, 2016 16:23:22

Roger F Mortimer
Registered: 2011-11-10
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Voltage Optimisers

Yes I believe it to be a voltage optimiser since we have voltage increases which automatically cut out the inverter which is set at 260v. It should not really happen but we live in an rural area with grain dryers and the like and we also live within a flood plane. The YED up the voltage at the substation to combat these issues and then forget to turn it down again so its a right pain. The number of kettles we have been through is just amazing.

I been quoted £800 fully fitted and although it fairly expensive if we were to get another 6% from the output of the inverter it would give an extra £90 in return and therefore pay itself back in 9years. It might also give a longer life to the inverter as well so another saving.

That's my interpretation so any additional thoughts welcome Roger

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#9 Nov. 8, 2016 10:17:53

bhommels
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Voltage Optimisers

Thanks Roger. I would like to see cast-iron guarantees from the sales people that the optimiser copes with power flowing in the reverse direction. On all connection diagrams I have seen the voltage optimisers sit between the supply and the household consumption side, with optional solar PV arrays always connected at the supply side of the optimiser, which would not help you much. Oh well, if it saves you a few kettles a year I guess it is worth it.

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#10 Nov. 16, 2016 11:57:50

BackYardSolar
From: Surrey, on Gatwick flight path
Registered: 2015-05-30
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Voltage Optimisers

Ok, bit late to this party, but have you considered the following.

The law in the UK currently states that the mains supply voltage must be 230 V +10% / -6%, so I make that a max voltage of 253 V or min of 216 V. So if you are getting 260V, then you should be complaining to your electricity supplier.
They should come out and put a monitor on your supply for a period of time to measure the voltage range. And if it is excessive then they should correct it.

This may not be your supplier but UK Power Networks. Ring them up and discuss your problem they do monitor their circuits and should be able to see if there is a problem. Often they don't know they have a problem unless it is pointed out, or maybe they ignore it as nobody has complained.

My SolarEdge inverter SE4000 is supposed to work up to 265V according to the handbook.

Things to consider that are not understood by many of the firms installing PV systems.

The AC volt drop between the inverter and the grid connection point should be less than 1%.
A 4kW inverter is capable of 16A so at this current the volt drop should be less than 2.3 V (2300mV).

This is important as the inverter has to be in synchronisation with the supply frequency and supply voltage, so the closer electrically to the grid the better. This can cause the inverter to trip if it cant match the supply.

VOLTAGE DROP PER AMPERE PER METER (mV). Conductor operating temperature: 70ºC and a two core single phase AC cable.

2.5mm cable has a 18mV drop at 1A per Metre, so at 16A the maximum run length would be just 7.98 meters. i.e. 2300mV / 16A x 18mV = 7.98 Metre.

4.0mm cable has a 11mV drop, so at 16A the maximum run length would be just 13.06 meters. i.e. 2300mV / 16A x 11mV = 13.06 Metre.

I argued with my installer who thought the volt drop was 5% as most domestic wiring is. My run was 15 meters so I paid extra for 6mm cable.
6.0mm cable has a 7.3mV drop, so at 16A the maximum run length would be just 19.69 meters. i.e. 2300mV / 16A x 7.3mV = 19.69 Metre.

Don't forget between the inverter and the grid connection point as well as the cable there are two isolators, a circuit breaker and a kWh meter all adding to the resistance. SolarEdge say a 16mm cable should be used in their installation handbook.

Long DC cable runs can also be problematic and a max voltage drop here should be less than 3%, As the DC side runs typically at 360V then you have a more manageable 10.8 V here to play with.



SolarEdge SE4000 inverter, 16 x Romag powerglaz 235W panels. South facing at 30 degree angle in Surrey just East of Gatwick and under the flight path.

ESS AC coupled system using a Victron Multiplus 24V/1600VA Inverter/Charger - 8.16kW Trojan 875 battery bank.

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