solar panel output/production questions

Martyn1981

Emjayjee, PM sent, now it's time for bed.

Mart.

supremetwo

As Martyn1981 suggests in # 11, enter your details in PVspot on Solargis.

This gives you daily predicted outputs based on satellite measurements of insolation and temperature at 5 minute intervals and has been within a few per cent of my inverter outputs since January.

http://pvoutput.org/list.jsp?userid=6813

albyota

emjayjee wrote: »

Hi albyota - thanks for that. I might need to take you up on that if they still failing to believe me.

I have sent them an email stating they cannot work on a monthly average to tell me there is correct production during the higher production months.

Secondly I asked if someone from the company could come and check or if they can tell me how to check that all strings are working and that the inverter can handle the 2 uneven strings.

Really annoying that they trying to get out of this (but I did think they would have tried as they probably know they are in the wrong).

Are you based/travel around the West Mids?

Thanks in advance

yes nationwide.....PM'd

Martyn1981

Just an update for anyone interested, as I've managed to blag a quick lesson on uneven strings and single MPPTs.

Apparently, given a set up such as this 5 + 10 panels, the inverters MPPT doesn't ignore the lower output from the smaller string, instead, it looks at both strings and tries to lock on at the highest common voltage.

In this scenario, the highest common voltage will be the amount coming from the 5 string. By locking on to that voltage, it will 'waste' the power above and beyond that voltage coming from the 10 string, effectively treating it as another 5 string.

As an example, if all panels were producing 30 volts, then the 5 string would be running at 150V, and the 10 string at 300V. The highest common point for the MPPT to lock on to, would be 150V. Thus it would only draw 50% from the 10 string.

I found this slightly alarming, because if my understanding of this is correct (note: it might not be), then two strings of 7 + 8, would perform similar to a 14 panel system, and that would be quite difficult to spot (14 v's 15) generation wise, after allowing for some shade variance.

Hope this helps.

Mart.

emjayjee

Thanks, seems like I really should take action now...

Seems like the best idea would be to get an independent person if they not agreeing to come and have a look and then take it from there

Martyn1981

emjayjee wrote: »

Thanks, seems like I really should take action now...

Seems like the best idea would be to get an independent person if they not agreeing to come and have a look and then take it from there

I'd try ringing some of the governing bodies, and asking them for advice (or action). Give MCS a ring, they are there to protect us (well they should be!).

Have a look at the documentation and letterheads from your company, and see what bodies they belong to. A quick google should give you phone numbers or contact e-mail addresses.

BTW I'm still annoyed at that '3 average months' reply. For various reasons I've been chatting with lots of installers recently, and they all seem good guys, but they are getting really fed up with the cowboys.

Please keep us informed as your 'problem' is probably a great learning exercise for the rest of us, and anyone with a similar issue.

Edit: MCS has a complaints and governance panel

http://www.microgenerationcertification.org/scheme-governance

try the 'contact us' tab.

Mart.

Martyn1981

emjayjee wrote: »

Thanks, seems like I really should take action now...

Seems like the best idea would be to get an independent person if they not agreeing to come and have a look and then take it from there

Just a quick update for you, though you may have sorted this already.

Suggested action, is to contact your installer's 'certification body', you may be able to work this out from the letterhead logos etc, but you can contact the installer and ask them for the name of their certifying body. You can even ask them for the phone number and address too.

Best of luck.

Mart.

emjayjee

I have contacted "Which" helpline, as we are a member and they have suggested writing them a letter and they have helped template a letter which I will be sending them. That hopefully should realise this problem is not going to go away, and should prompt some action.

If that doesn't work, then I will proceed onto your suggestion (as it seems perfectly reasonable to me).