[RE-wrenches] Adding similar but updated modules to same inverter

[August Goers]

Dave,



Good point - we definitely can't go with a transformerless non-isolated
inverter here because of the positive grounding requirements with the
original 230s. Another Wrench member sent me a PVSyst analysis off-list
using the "electrical behavior tool for heterogeneous arrays" and the
losses were minimal. I think we'll stick with the original SunnyBoy. I
wasn't aware that PVSyst can analyze these different scenarios and it seem
like a very powerful tool in the right hands.



Best,



August



*From:* re-wrenches-bounces at lists.re-wrenches.org [mailto:
re-wrenches-bounces at lists.re-wrenches.org] *On Behalf Of *Dave Click
*Sent:* Saturday, July 13, 2013 11:49 AM
*To:* re-wrenches at lists.re-wrenches.org
*Subject:* Re: [RE-wrenches] Adding similar but updated modules to same
inverter



I think that the 230s required positive grounding, so you can't swap out
the inverter for a TL unit. These two circuits in parallel will be fine for
your MPPT, you'll have essentially the same voltages but slightly higher
current in your new second string.

DKC

On 2013/7/12 19:27, August Goers wrote:

Hi Wrenches,



I have a client with a small system consisting of 6 SunPower 230s and a SMA
SB 3000. Anyway, he wants to add another 6 modules but the closest we can
get from SunPower these days is a 245. The new six modules would go on a
second string.



Do you think that the slight difference in tracking voltage and current
will be significant enough to justify the cost of adding or swapping the
inverter? Here is the info for the modules:



SunPower 230 WHT

Vmpp    41.0 V

Impp     5.61 A

Voc        48.7 V

Isc           5.99 A



SunPower 245NE WHT

Vmpp    40.5 V

Impp     6.05 A

Voc        48.8 V

Isc           6.43 A



I imagine that the tracker in the Sunny Boy will be a little off and
perhaps the result will be that both strings will be running a few percent
lower than they are capable of?



Best, August





*August Goers*

Luminalt Energy Corporation

o: 415.641.4000

m: 415.559.1525






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