Question for the experts - Advantage or disadvantage of changing my array ?

danesol · May 23, 2012

We have a single array of 12 Sanyo HITs ( 240's ) all wired in series and connect to a SMA SB3000HF-30

We have part shade from the East in the morning till 9am, then shade commences again from the West due to trees at 4'sh...... these trees will be no longer very soon :gettree:

The inverter currently runs all the time at around 500vdc and I've never seen it lower than 450vdc, even when its producing approx 0.1a

The question is this ( I assume I have given enough data ) - would we of been better having the panels in 2 arrays of 6 panels each to cater for part shading for an hour or so or will the internal diodes be looking after this anyway ??

danesol · May 23, 2012

This may help..................

[ElectriciansForums.net] Question for the experts - Advantage or disadvantage of changing my array ?

methley · May 23, 2012

Here's what a completely unshaded south facing array of 12 HIT 235's looks like for comparison.

StuSpiers · May 23, 2012

You can certanly reconfigure the layout of the panels (put in two rows if it helps/you have room) but I would caution against reconfiguring the strings/array in any way, you can quite easily have two rows of panels on one string still.

Gavin A · May 23, 2012

before you do that, you want to install the optitrac global peak function to the inverter and test that out, as it could well sort this out for you providing the shading is oriented right for the panel bypass diodes to work. it's on the sma site I think, if not I can send it to you.

danesol · May 23, 2012

Gavin A said:
before you do that, you want to install the optitrac global peak function to the inverter and test that out, as it could well sort this out for you providing the shading is oriented right for the panel bypass diodes to work. it's on the sma site I think, if not I can send it to you.

Optitrac Global seems to be an option on the dc side, for which I can activate via Sunny Explorer - Do I just select YES or do I need to then restart the Inverter ??

danesol · May 23, 2012

BTW when I stated arrays - I meant strings :35:

danesol · May 23, 2012

StuSpiers said:
You can certanly reconfigure the layout of the panels (put in two rows if it helps/you have room) but I would caution against reconfiguring the strings/array in any way, you can quite easily have two rows of panels on one string still.

Sorry I think I've mislead you slightly here ..... my panels arent changing physically, they are staying put at - 2 high and six across in portrait mode.

What I find in the morning is that 1/2 the panels ie. the left 6 are in the sun till 9'sh and then all are fully exposed and then at 4'ish the reverse happens because of trees to the West of us..... (30ft)

Hopefully that explains better, why I was considering changing the wiring into 2 strings of 6 panels each.....

Eco Deal · May 23, 2012

so do you have one string I seem to recall you can have around 14 panel going into a 3000HF in one string ???

hence high voltage .....

I think it may help to go the two string option depending on sma 3000HF start up voltages

poheZ · May 23, 2012

Your HF wont deal with shading well as it is best as a single string inverter. Optitrac will only work effectivley with partial shading, 6 panels shaded is not partial shading.

danesol · May 23, 2012

poheZ said:
Your HF wont deal with shading well as it is best as a single string inverter. Optitrac will only work effectivley with partial shading, 6 panels shaded is not partial shading.

What is meant by the term partial shading then..... ??

Bit more insight into our setup..... these six panels gradually go into shade and out of shade as the case maybe - is that partial shading..... ??

poheZ · May 23, 2012

yes, partial shading of an array is hard to define. The OPtitrac software will scan for the global peak but that may not be very high anyway given that half the array is shaded. The only real answer is to use the Optitrac peak and monitor the results, or change the inverter to a twin tracker inverter (or 2 seperate inverters). The cost of that may be a problem

danesol · May 24, 2012

Gavin A said:
before you do that, you want to install the optitrac global peak function to the inverter and test that out, as it could well sort this out for you providing the shading is oriented right for the panel bypass diodes to work. it's on the sma site I think, if not I can send it to you.

I may be a bit premature here but after day.1 i'm impressed - this does appear to have made a difference !!

Thanks