Voltage Levels And Vo

[steptoe]

I needed some valve clearances for the '30

and got some spare smoke to keep in stock, 

 

[binky]

was at the Greenwich Meantime micro Brewer yesterday Guinness Guinness Guinness   a most excellent range of IPAs and in particular a dark IPA with 5 varities of hops - delicious

C'mon Matt give us some technical theory.

With PV, if it stabilises at 220V and grid is at higher voltage, don't quite see how you export anything, plus transformer losses even if you do, ergo how does that make a PV system work better as claimed by various VO manufacturers?

 

[matt hunt]

Sounds like my sort of place and apparently Steptoes

If the grid voltage was 240v then the inverter would see 225v, it would then say export at 227v which would be stepped up back through the transformer to 242v maintain its 2v increase, if the current was utilised in the property then it would circulate through the transformer and again reduce by 15v giving the house a beneficial 227v generated or/and 225v from grid.

This all sound very cosy apart from you cannot do it to comply with G83-2 if the upper voltage thresh hold is set at 262.2v at the inverter. Make sense ?

If the inverter were set at 253v then we could stop it tripping out as it would see a reduction in voltage and in essence kid it but stay within the 262.2v range under G83-2

 

[matt hunt]

Canoe, I get the distinct impression you have a real downer on the PV industry, there are quite a few systems out there and they are not all bad, the voltage tripping problem is not just down to 'muppets' as you put it

 

[steptoe]

Canoe, I get the distinct impression you have a real downer on the PV industry, there are quite a few systems out there and they are not all bad, the voltage tripping problem is not just down to 'muppets' as you put it

I have yet to see one that isnt down to bad install,

Ive installed a few hundred PV systems,

and Ive prob seen thousands, loads of good ones, but a helluva lot of bad ones too.

 

[matt hunt]

Seems like again we will have to agree to disagree, I take your point on the bad installs causing problems by under sizing cables, too long runs etc but the harsh reality is that micro-generation does and will continue to push up the voltage on localised grids even with good quality installs.

 

[matt hunt]

I thought I answered it !

 

[matt hunt]

Why would Andrex sponsor a hospital for constipated men :slap

sorry a megger add was at the bottom of the screen when I was asked

its now Kash Flow

 

[steptoe]

just because I wont buy bottled space doesnt mean some other idiot wont.

 

[matt hunt]

like it Steptoe, we prefer selling through education not vapourware or as you put it bottled space

Give me time and maybe just maybe I can get you guys to see the light

 

[NozSpark]

like it Steptoe, we prefer selling through education not vapourware or as you put it bottled space

Give me time and maybe just maybe I can get you guys to see the light

I think you've come to the wrong place then

 

[steptoe]

give me proof that you can make more energy from less and I'll be convinced.

like it Steptoe, we prefer selling through education not vapourware or as you put it bottled space

Give me time and maybe just maybe I can get you guys to see the light

 

[matt hunt]

Na, as long as you have open minds and are not closed to basic physics and maths then we all have hope. Lets put it this way, coming from a commercial aspect, if the DNOs were to say that you could fit as many PV systems in a street as you wanted as long as you controlled the Voltage at the connection point in all houses on that street via a VO device, would you turn the contract down?

 

[binky]

Sounds like my sort of place and apparently Steptoes

If the grid voltage was 240v then the inverter would see 225v, it would then say export at 227v which would be stepped up back through the transformer to 242v maintain its 2v increase, if the current was utilised in the property then it would circulate through the transformer and again reduce by 15v giving the house a beneficial 227v generated or/and 225v from grid.

This all sound very cosy apart from you cannot do it to comply with G83-2 if the upper voltage thresh hold is set at 262.2v at the inverter. Make sense ?

If the inverter were set at 253v then we could stop it tripping out as it would see a reduction in voltage and in essence kid it but stay within the 262.2v range under G83-2

ok so how come any VO unit I have seen, and I've checked quite a few, say to feed the PV into the meter tails BEFORE the VO. I have my own PV system, send me a VO unit and I'll fit it and report back...

Grid is rarely at 240V. more like 245+ aound here.

 

[matt hunt]

Hi Canoe Yes toroid my own design (always) auto configured ( depends on type and application) electronics on certain models dependant on clients wish list via sine wave mapping, size dependent on model, the basic model fully rated BS Tested to 8 hrs continuous 60amp current and smaller than an A4 sheet of paper (smallest on market) efficiency 97-98% (best on market) price dependent on what wholesaler you buy it from payback, quicker than anyone else's and even faster if you integrate it with a PV system

Hi Binky, it all depends on the inverter setting, if its a G83 install but is set at 253v then we can protect the inverter from tripping out (hence protection) unless the grid gets up to 262.2v where we will automatically stop the export in line with G83-2

 

[steptoe]

Id love to see actual results of some proper tests,

not sales hype figures

I probably live in the sort of typical property these things are aimed at,

ex council 3 bed semi,

>90% led or cfl energy saving lamps,

9 kW electric shower

24hr electric ufh in bathroom

gas hob/electric oven

gas combi boiler

if I buy one of these do I get a written guarantee as to % savings I will get in any given yearly period?

 

[binky]

Hi Binky, it all depends on the inverter setting, if its a G83 install but is set at 253v then we can protect the inverter from tripping out (hence protection) unless the grid gets up to 262.2v where we will automatically stop the export in line with G83-2

Inverters rarely trip out due to grid voltages,  I've had one in 3 years doing this, earth leakage from poor installation is the main culprit, and the DNO are pretty good at monitoring their networks. Having the inverter trip out is actually quite useful, as it flags to the customer that the grid has a local issue that needs reporting to the DNO before their other electrical equipment gets trashed.

Right so reading between the lines , your VO unit can handle back flow to the grid, and if I'm reading the rest of it correctly, what your unit actually does is drop grid voltage by 15V rather than target a specific voltage output like 220V?

 

[matt hunt]

Hi Binky, we do not target a specific stabilised set point, we either reduce the voltage by 15v and have an auto LV cut-out threshold so as not to go below CENELEC limits of just use a straight 18v non intelligent unit for stiff supplies.

We also do a basic 18v subtractive unit with a build in 16 amp RCBO for connecting your inverter into and also a build in MID approved meter, so the sparks only have to fit 1 unit instead of 3 items 

 

[binky]

20 amp RCBO is more appropiate - shouldn't really run at full tilt of an MCB

so your unit is simpler in design than other units as it isn't trying to hit a specific voltage?? I am assuming it is therefore cheaper :^O

like the sound of the combined unit, but again , how much??

serious question, do you have a unit I could fit and evaluate / report back to forum - ex-demo would do.

I was actually going to fit a VO unit in my own house, more for the equipment protection than energy saving, just never got around to it. I like to try equipment for myself before recommending to customers, and have access to some comprehensive monitoring equipment if it isn't being used in a factory somewhere.

 

[binky]

prefer not have RCD on inverter anyway unless forced by TT earthing. Usually no need anyway, as most cabling is surface or more than 50mm below surface of a wall / floor etc etc. My inverters normally go in a garage or on an outside wall close to incoming supply - means longer DC runs, but I can live with that rather than putting inverter in nice hot attic.