vac problem

[dave992]

hi, im an electrician but haven't done my solar qul or never installed solar equipment,i still live with the parents but my dad had a solar system installed but when the inverter working nearly flat out was have a error come up saying VAC failure, then the inverter turns off and take time to restart. The inverter is a ever solar inverter, any help would be good.

thanks dave

 

[dansk]

Voltage AC problem, either grid is too high or inverter isn't set for UK

 

[Earthstore]

Or the old chestnut, AC cable too small.
If you are a sparky, do the VD calc and post what it is in %.

 

[dave992]

hi thanks for the reply, the company installed the solar equipment. with guard the voltage different the company have use voltage optimiser to control the voltage range, should this control the vac problem.

 

[dansk]

Not if done correctly as PVshould be connected before VO unit.

Check the inverter is set to G83 UK, power down the unit then power up and look at the screen it should tell you,if not take a note of the serial number and post in here that will.

 

[dave992]

Hi earthstore, i haven't done the calculation because im not sure if it a different formula. It a 80m run, 4 kw system and in 3 core swa buried in the ground, some could help me would be good.

thanks

 

[dave992]

hi dansk, the v/o is place on the incoming tails, this is the one we got Eversol TL4000. Thanks for your help

 

[dansk]

VO isn't my bag, but as I understand it PV shouldn't be connected the VO unit, I'm sure someone on here will know for sure.

i haven't done the VD calc, for yours, but last 80m ish run I did was in 16mm.

 

[dansk]

Also FYI most inverters are manufactured for a global market and sometimes the settings aren't set for the uk and therefore other country's voltage range canbe stricter than ours. for example I fixed a system the other week, omnik invert which is same as ever solar and that was set to NL (holland) top voltage range was 250, incoming grid was already high at 247 so when the system was generating good levels it didn't have much scope for movement in terms of voltage.

 

[dave992]

Dansk thank you for all this help, just wanted to clarify a little with guard the cable cac, solar panels wires come off the roof straight into to interver then travel 80 m back to th hose and db board, how would I know if the inverter was set up correctly? Thanks

 

[dansk]

as post #5

the chances are its ok and it could be as earth store said about VD and incoming voltage etc.

 

[Earthstore]

hi thanks for the reply, the company installed the solar equipment. with guard the voltage different the company have use voltage optimiser to control the voltage range, should this control the vac problem.

No.

There could be several reasons why this is happening, my first question is who installed it and have you spoken to them yet? (Oh that's two questions)

What size is your PV system? What size is the SWA cable? What make of VO have they installed? How and where have they connected the PV to your supply? Is it before or after VO, on shared RCD.

A good pic is quite often worth a thousand words.

 

[dave992]

Try and do my best describe to installation, So we have two systems on the same roof, both 4 kw systems, comes off the roof straight into the inverter, Then from the inverter we have one system going to the house and seconded system going to the farm. From the inverter we have a length of 80 m and from the inverter to the farm a length of 100 meters. Both are wired in 10 mm 3 core swa cable and are both on 32 amp breaker. They have placed a voltage optimer between the both DB and the incoming tails. Tried my best and question please ask.

We have a ever solar tl4000 inverter
Voltage optimer is a vphase one

Want to say again very grateful for any help.

 

[BruceB]

Is the pv connected to the output of the voltage optimiser?
If so, not allowed. VX1 instr manual here, see page 5
http://www.vphase.co.uk/getattachme...loads/HS12059_VPhase-Instruction-Manual_E.pdf

 

[dave992]

The main tails come out of the meter reader, straight into the voltage optimizer then from there to the DB, so would say yes.

 

[BruceB]

Then it is wrong. You are probably getting away with it whilst house consumption is more than pv generation, but as soon as the pv starts trying to push power the wrong way through the vphase then as it is not designed to work like that, the voltage rises and pv cuts out out, voltage falls, pv restarts, voltage rises, pv cuts out..........................................

 

[Earthstore]

There you go, Bruce is spot on.

 

[dave992]

Thanks for your time and explaining, the reason we had a voltage optimizer was because the incoming voltage was very high but within regs and this is why the company installed it, would like to say, that the quality of there work was **** poor!! thanks

 

[Earthstore]

A V phase only goes on dedicated curcuits too, sounds like they did not read the instructions.

Just get a sparky to disconnect the unit.

 

[BruceB]

I am not generally a fan of VOs, but your situation might still be a good reason for you to have one. But the pv must be connected the other side of it. If you are working G83 rather than G59 then your inverter does not have to cut out until it gets to 264V, so you should still have a good margin for it to work. You need an installer who knows what they are doing.

 

[dave992]

That our problem, the company who installed them doesn't know how or what to do to sort this out! Thanks for all your comments!

 

[Earthstore]

Just out of interest, and this is not a dig, but what made you choose this company to do your install?

 

[dave992]

Thanks again, the reason my dad choose the company was that we knew people who had installed and all was ok. just want to stress on one point, ill remove the voltage optimer but the vac problem still there, how can there mend this problem, just want to stress that i will not be doing anything with the solar equipment because im not qualified and haven't done work in this field
thanks

 

[Earthstore]

What is the normal supply voltage without the PV running?
When the system is running check the voltage again at supply, and also at the inverter.

This could show you whether you have an install or supply voltage problem, there is also the possibility that the inverters have not been set to UK spec.

You can contact the DNO and ask them to turn down the voltage, however you need to check that your house is in order first.

This does have a risk though, if their system is within tolerance (216V-253V) and your PV system is pushing it over they can order you to shut your system off, even if you have the correct approval from them to install in the first place.

 

[Worcester]

The installer's worlmanship warranty should cover this - insist that they come out and sort it.

In addition workmanship is covered under their scheme they are registered with - so if you still don't get satisfaction a call to Elecsa / Napit / NICEIC etc or however they are registered with may kick them into action...

Voltage Drop is also probably one of your issues, a 4kWp systems south facing with giood quality inverter with 80m run from inverter to DB would need a 25mm2 SWA cable just to cope with the allowed 1% voltager drop, the 100m run will also need 25mm2, - what size did they install?

(We work on 20m max 6mm2, 35m max for 10mm2, and 65m max for 16mm2)

Cable sizing
The grid impedance of the AC cable must not exceed 1 ohm. Otherwise, the inverter will disconnect at full feed capacity due to excessive voltage at the feed-in point.

The conductor cross-section should be dimensioned such that cable losses do not exceed 1% at nominal power

The conductor cross-section required in individual cases depends on the following factors, among others:
• Ambient temperature,
• Routing method,
• Cable losses,
• Valid installation requirements of the respective country (installation location)

(PV systems only allow 1% not 3% or 5% VD to cope with the way inverters monitor and power the grid)

If the installer won't sort it (which they should foc - part of their warranty on workmanship), then as you're in Gloucestershire, someone like BruceB or ourselves could come out and sort it out for you on a paid for basis and then take the installer to the small claims court to sort it. (I'm not pitching for the work by the way )

 

[jason121]

The installer's worlmanship warranty should cover this - insist that they come out and sort it.

In addition workmanship is covered under their scheme they are registered with - so if you still don't get satisfaction a call to Elecsa / Napit / NICEIC etc or however they are registered with may kick them into action...
None of the above will be interested. All they do is pass the problem on to each other, and you end up going round in circles.:cuss:

 

[Worcester]

I'm NOT suggesting he goes down the Gemserve / RECC (nee Real) route that is a waste of time. Workamnship quality should be of interest to their electrical certifying body though.

 

[Earthstore]

Be great if we could see some pics, it might not be too bad, there again it might be.

Any pics Dave992?