PV+ Grid Voltage Monitor

zeupater

Hi

Just a thought .... further to the above, by externally overriding the G83 compliance of the inverter, I wonder whether being able to continue to export at higher voltages than the standard allows would be considered as invalidating the entire installation in the eyes of the DNO resulting in the potential for a pretty unwelcome letter dropping through the letterbox ? .... :think:_pale_

HTH
Z

Ectophile

So far as I can see, it's a transformer, with a slight voltage step down.

There can be a slight voltage rise in the mains cable between the incoming mains supply and the inverter, particularly if it's a long cable. So what could happen is if the supply is getting very close to 253V, then when the inverter tries to start up and push out current, the voltage it sees at its end of the cable rises too high and the inverter shuts down.

But if you never have that problem, then the gadget will achieve nothing.

If you have a monitoring system for your inverter, it should be very obvious if it ever happens, as the output will abruptly drop to zero. General rises up and down is probably just clouds passing overhead.

Merlin139

This is taken from the information sent by Saveheatenergy.

http://s32.postimg.org/cj16eawr9/Capture_energy_A.png

Without PV+

http://s32.postimg.org/6ddyw5nx1/Capture_energy_B.png

With PV+

I myself have never had a day when my production has fallen off a roof to zero!

http://s32.postimg.org/qsjjnmwr9/Capture_SHE.png

This is taken from my SolarEdge.

http://s32.postimg.org/9xv3jvdxx/Capture_Me.png

Obviously colours are not the same and his information runs from Jun 13 to Sep 15. October is only 8 days.
Mine runs May 14 to Apr 16. May was only 10 days so only Jun 14 to Sep 15 to compare but I think it looks very similar. I have no idea where in the country it was taken but was told it was facing south.

Their system is 3 kW and mine is 3.975 kW

They claim that the increase is due to PX+ me thinks its due to better weather and more sun.

I think to prove this works you need 2 identical systems on 1 roof. 1 with PV+ 1 without PV+

Not even looking at cost per kWh with a claimed increase in production of around 20% so for me 800 kWh per year.

pinnks

If their chart is real it suggests a 3kWp system achieving only 200kWh in June, July and August in year 1 which suddenly jumps to something more normal-looking for a system of that size in years 2 and 3.

Clearly something has changed but if my system had been performing so badly I would have had the installers back to check it out, not gone out and spent a shed-load of money on some gizmo.

My guess is that one string was not working/connected and the work to install the gizmo corrected that error because someone was tinkering with connections...

But I may be wrong...

Martyn1981

Little story from a few weeks ago, involving salespeople and SolarEdge kit.

Got a cold call, offering SE upgrade on my ESE systems. Told them it wouldn't be worth it, but said fine send a sales person, but they are wasting their time.

It was a complete waste of time.

But, regarding graphs, stats and numbers, and a rather fiery Mart when SalesLady pushed her luck.

She showed me a site not far away from me in Wales, with a SAP estimate of 3,500kWh and asked me what a SE kit would generate there.

I said, SSW coastal, 950kWh/kWp (she reached for a calculator) I said so 3,800, lets call it 4,000 with the SE kit as it works well.

She proudly showed me that generation was 4,400kWh.

I suggested she was a con artist, she was taken aback and asked why.

I reminded her of the previous hours conversation:-
1. She'd pointed out that SAP figures were very low, and S. Wales will do much better than the Sheffield estimates.
2. She'd pointed out SAP figures were an average, not year specific.
3. She'd pointed out that SE kit gave up to the minute information on a system.

I pointed out that the figure she'd shown me was for 2014 (it said so in the corner), so:
1. Not an average but a specific year.
2. 2014 was a +10% year.
3. If SE kit has upto the minute reporting, why in April 2016 was she showing me 2014 results.
4. Having chatted with me for an hour, did she really think I wouldn't notice the tricks to get from 3,500 to 4,400?

One last shot in the dark as she realised she'd blown it, was to say my ESE system had two inverters, so with labour at £700 a time, I could expect to pay £3,500 every 5 years.

I laughed, she packed up and left.

I assume, perhaps unfairly, that any firm that also has to employ salespersons, and telesales reps, must have high overheads, so they need to come in heavy.

Mart.

ely_ellis

Hi all,

I received a call from a guy with a 'Chesterfield' 01246 telephone number offering me a free demo. It is of course on hold.

From what I can gather from the information available and what I have seen on here including the video, all I can assume is that it is a simple (toroidal) transformer with a few more bits.
I'm guessing that the few bits just monitor the voltage and if it gets too high, then maybe operates a relay to switch the transformer in-line thus dropping the voltage and allowing the inverter to continue.
Could it be that simple?
I have a Solaredge system and have just looked at the AC voltage which very rarely peaks above 251vac with a minimum around 234vac (quite a range)!
I don't see any signs at all of the inverter switching off in any panic mode at all so unsure where this comes from. Does anyone have this problem?
From what I understand about inverters, they have to track the supply voltage and be 'above' in order to output a current and export to the grid.
Power = Voltage * Current
If the voltage of the inverter is the same as the grid, then no current flows and thus no power generated (or at least exported) regardless of how much sun bakes your panels.
Grid = 250v
Inverter = 250v
Current = 0A
Power = 250 * 0 = 0 Watts
So your inverter has to basically stay above your grid, just not sure how much but if your generating 4kw at 250v, then your pushing 16A.
If you go through a step-up transformer, lets say a 1:1.04, that's 250 at your inverter but 260 on the grid. Note that when you step up the voltage you step down the current so effectively the power output will remain the same but your inverter will now be operating at a lower output voltage and thus not cut out when grid voltage is high.
When the grid is low, if the transformer was still in line, then the grid voltage maybe too low for the inverter, so the transformer would need by-passing. This I assume is what the little circuit does, just operates a relay maybe to take the transformer out of line.
I have probably over simplified it (or complicated it for some) but it looks like that is the only way I can see it working.
It doesn't magically give you more generation just stops the over-voltage cut-outs which obviously some inverters suffer from!
In the video, he only shows the grid voltage and like mentioned already, how did he know it was just about to go over voltage, just right for the video.
And another thing, the graphs posted on here, I have seen on the site too. Solar PV+ say up to +25%, yet the graphs show something like +75% and above for June 2013 / 2015! (Maybe I am not reading the graph correctly).
Cheers

Daniel0807

Wish, I would have read this thread earlier.
Today, Andrew, Energy Consultant for Star UK Energy visited us reviewing our existing Solar PV installation (PV output 2.50 kWp, Fronius, Galvo 2.5-1 inverter) and convinced me to install their Solar Booster System for 1295£ with money back guarantee if the system would not perform:

1. Increase life span of inverter from 5 years to 25 years
2. increase output by upto 25%

He demonstrated that our AC voltage was around 244V and said this was way above what the inverter would be designed for (230V). Hence a lifespan of 5 years only and fewer units generated per year. :eek:
But, their clever Solar Booster System would protect the inverter, allow it to stay compliant for longer and so generate upto 25% more units of electricity. :j
With current total costs to replace an inverter of £2500 every 5-7 years and the increased yield, the Solar Booster System would repay itself really quickly.
It all sounded so logical at the time and the risk so low that I ordered it today. Since the order allowed for cancellation within 14 days. Also, ordering it while he was at our premise would spare us £250 for health and safety survey. Not to mention additional 20% VAT if ordered after 5 April, when Solar PV was no longer subject to reduced (?) VAT.
Now looking at the order, I fail to find any mention of the money back guarantee or of the assured features. All I am left with is the memory of pictures from his sales material. Seem to originate from page 2 of the brochure for Solar-PV+ from renewableenergyhub.

I guess, I can cancel the order, as long as the installation has not started, right?
Or, have I ordered solid gold?

Daniel

theboylard

Cancel!!!!

You've been had me old fruit, and the extra discount offered for ordering on the spot is definitely dodgy.
Oh, new inverters, like for like, less than £1k for your Fronius, plus £150 max for install.
I'd be inclined to ask Fronius about extended warranty, loads cheaper!

And his ludicrous claims about extending life, increased performance, and voltage variance - name and shame him. Did you get any pics of him?

What we need to start doing is encouraging people in this situation to take pictures of any literature they view whilst being sold something - last copy I have and new brouchures are at printers, oh really!! - the sales droid would soon change tack.

Oh, Daniel, if you're not sure, cancel anyway regardless of what I've said.
If anyone really wants to believe this snake oil solution is genuine, then there will be much cheaper variations even after accounting for the extra VAT (is that a thing btw?)

Martyn1981

Hiya Daniel, I would definitely consider cancelling.

I've found these tech sheets, which suggest a 211V to 264V range for a 240V setting (see page 50).

This sounds normal for the UK, and most inverters (certainly later installs) will shutdown at 253V anyway, to stop them pushing the grid voltage higher.

I note from the tech sheets that they give voltage range for 208V, 220V and 240V, but not 230V - I assume this is because the UK is a pretend 230V, as a compromise between our old 240V and Europe's 220V.

Also note that all inverters have to be certified for use in the UK, and that on installation the installer will tell it what country/settings to work to.

If you have any concerns at all, then just contact Fronius and ask them, I'm sure they will be happy to advise. I'd also ask if this reduction in voltage would lengthen life expectancy from 5 to 25 yrs. I suspect they will disagree.

Current cost to replace an inverter, well these seem to sell for around £800, but you'll need to add on the sparkie's charges. A like for like swop should be very quick.

3kW inverter from SMA about £800, or £500 for a 3kW Samil.


Regarding the higher output, I've never understood how this is supposed to work, or how it can work. Your inverter has an efficiency rating of 95% (see page 51), which is very decent, some domestic inverters get to about 96% or even 97% and some huge commercial models 99% - but if your inverter is converting 95% of what the panels generate, then even at 100% efficiency (won't happen) it could only increase production by 5%.

Martyn1981

Found a discussion on the electricians forum, and they are not impressed.

The only benefit being if your property regularly goes over the permitted UK voltage range of 253V, as the inverter will shutdown to meet UK regs, and to prevent it pushing the local voltage even higher.

If a property does regularly go over 253V, then the DNO has to fix this problem, even if there are SSEG's (small scale electricity generators) such as PV on the line.

In 6 yrs I'm only aware of my WNW system shutting down once, for about 10 mins due to grid voltage. I know this because my ESE inverters are older and prior to the reg change, and one of those displayed grid voltage at 253V, rather than the usual (around here) 238V-244V. This shutdown happened on a sunny Sunday afternoon, exactly when it's most likely due to low demand pushing up grid voltage.

Worth reading the comments on the electricians forum, several suggest that installing such a device between the inverter and the grid, may breach the regs that the inverter has to meet. Also, worth reading as I laughed so hard at this response to one comment:

"It is very big in Germany, apparently!"

"Something else was big in Germany in the 30's and 40's
That didn't end well."