Interesting Lesson

[RichardKB]

Hi Richard

My panels chinese ones have diodes inside the connection box on the rear of the panel.

Rich

[linesrg]

Good Morning All,

As I continue to 'battle' with my 'underperforming' 2.56kW of panels I'm getting a batter understanding (I think). Having studied my new BP380's I believe the bypass diodes are SMD as I can see two rectangular pimples in the traces to the connection box and using a DMM in diode test mode I get the expected result. I can only assume that if one of the SMD diodes fails you'll need to revert to a moe convenional one hooked up in the junction box.

I have no deployed my 3rd SMA inverter which I bought as one which had been used with a wind turbine and it is marked as a Windy Boy thus when I interrogated it I was surprosed to see it tell me it was programmed for MPPT!!

Thus my 48 panels are now 3off 16 panel strings into the SMA's with MPPT set at 250V.

Given to date my original tracker based set-up is giving the best results it might be time to 'accidentally' wire them into what I hope will be the FIT' able TGM. At this point in time it looks like my tracker based system is delivering way more than the fixed arrays. If this is the case I'm reluctant to spend too much erecting them 'expensively' on the outbuilding roofs if I need to look at constructing another tracker system.

Regards

Richard

[linesrg]

Good Afternoon,
Apologies for answering my own queries but this thread may prove of use to somebody in the future?
After much fannying about it is clear that one of the SB2500 isn't doing all that it should despite the LED's indicating nothing is wrong.
Effectively I have 3 equal strings yet the one attached to the 3rd SB2500 doesn't seem to do very much.
I do have a clamp meter but I find that observing the LED flash frequency rate on the Elster's is a pretty good indicator. Thus the Elster fitted to the tracker array is flashing about once every three seconds.
The other two SB2500 are feeding the one Elster and it was flashing about once every 3 and a 1/2 seconds. When I connected the two strings in to the top inverter the Elster starts flashing every 2 seconds.
Anybody any experience which could indicate if the lower SB2500 is at fault?
Regards
Richard

[StBarnabas]

Richard
interesting stuff. I sadly have had very little time to spend on the Forum the past few months. I am also thinking about shading at the moment and gradually I think understanding a bit more. I'm also looking at the effect of shading on my array. Hopefully in the near future I can put numbers into my model at which time I would be very happy to look at your array also.
Sean

[linesrg]

Good Morning,

If I knew it was possible to attach a wee Excel spreadsheet I'd show my results from a moderately sunny day where I took hourly output readings from both generation meters. For the purposes of determining the 'losses' in the 2.56kW fixed array against the 1.28kW tracker array I assumed that the fixed array would producd twice as much power as the tracker but allowed a 10% reduction to allow for the mismatch of panels on the fixed array.

Over the day the fixed array made 5.9kW and I made the calculated loss to be 5.6kW using the above 'formula'. What was obvious was the fact that between about 1330 and 1700 the fixed array was almost bang on my estimated output but it lost out hands down from sun up until 1330.

I have read in the past that it was cheaper to fit extra panels than have a tracker. I am losing 48% power with the set-up as current and that is a lot of extra panels.

The message for people with less then ideal roof orientations is you may see some considerable loss of output although quite a bit of mine is also shading related.

Regards

Richard

[linesrg]

Good Evening,

Following on from my last posting I have been comparing output readings from my two solar set-ups over the last two days.

I can report that follwoing the same simple formula i.e. calculating the output of the second system at 180% of the other (which will be conservative) I have a seen a 37 and a 43% loss in projected output on the static array against the tracked array.

Assuming I do qualify for the full FIT rate I have 'lost' £3.59 over these two days alone.

My measurements to date seem to support the upper end of suggested benefits of using a tracker i.e. 40%.

I need to emphasise there are issues of SSW orientation and shading contributing to my results currently.

Regards

Richard

[linesrg]

Good Evening,

I'm back again. OK so the system has been running since 1st April and I came back onshore on Thursday and went out and read various meters at lunchtime. The following figures still assume the currently static 2.56kW are accepted under FIT.

The tracking array has made 192.7kW and the fixed a mere 164.4kW (which by my conservative calculation means I have 'lost' 182.5kW a tracked system would have given me).

Thus 192.7 at £0.09 = £17.34 earned and £67.90 from the 'FIT' panels (by the above figure I have 'lost £75.36!!!)

Of the total 357.1kW generated 200kW have been exported.

Thus the 157.1kW used on site has saved me £21.53 (this based on Sept 2009 prices at £0.1309 per unit) The 200kW exportd at £0.03 makes £6.

Thus in total I am £112.77 better off but this could have been £188.13 if I eliminate the losses on the 'fixed' panels.

Thus it looks like the MkII tracker will have to be built. I was building a scale relpica this afternoon with cardboard and an overhard light in the kitchen to determine how much clearance thr 5.75 x 3.4metres of panels will require. 3metres all round is the answer.

Regards

Richard