[RE-wrenches] Data System Puzzle

Philip Boutelle philboutelle at gmail.com
Thu Feb 3 19:20:18 PST 2011


Vince,
I had a similar experience a couple years ago with a Fat Spaniel string
monitoring box w/ Hall Effect sensors, on MODBUS comm, etc. The folks at FS
couldn't help at all, and like you I spent countless hours on the phone with
the technicians to no avail. Then I found out that their boxes were made by
DST Controls; once I got in touch with the people that actually made the
equipment, things were cleared up very quickly. I'd check with Energy
REcommerce to see if there is a third party involved and contact them
directly.
Good luck,

-Phil
Real Goods Solar

2011/2/3 Richard L Ratico <Richard.L.Ratico at valley.net>

> Hi Vince,
>
> I don't know anything about Energy Recommerce, but a search of their
> website did
> not result in finding an installation manual for their combiner box, only a
> datasheet. You stated countless hours were spent on the phone with their
> technicians. If it was my job, at this point, I would want my money back.
> If
> it's that hard to fix, it's worse than worthless, it's costing you bundles.
>
> Dick Ratico
> Solarwind Electric
>
>
> --- You wrote:
> Sorry for the long post. I don't know how else to communicate this issue.
> We installed an Energy Recommerce data system on a project last year that
> we have not been able get working properly. Everything works except the
> monitoring of the series string amperage outputs from the solar array.
> There are 3 pv source circuit combiner boxes with 11 series strings of 14
> modules and 1 with 10 series strings of 14. Each combiner box feeds one
> inverter with its own conduit run. The data system shows amperage from
> each circuit consistent within each combiner box, typically with a range
> of variance of about 1.5 amps DC between series strings.  Each combiner
> box will show totally divergent amperages. For example, combiner box 1
> might read 2 amps, combiner box 3 reads 10 amps, and at the same time our
> clamp meters are reading the actual amperage at around 5 amps consistently
> between every box for every circuit. The same combiner boxes will
> consistently read either too low or too high. The problem may be in the
> interface between the Hall Effect sensors that the circuit board in the
> combiner box uses to measure the DC current. The Hall Effect sensors
> deliver a calibrated voltage based on the strength of the magnetic field
> around the series string circuit as it goes through the box. The combiner
> box then calculates the amperage based on the millivolts that the Hall
> Effect sensor produces. For example 500 millivolts equals 5 amps.  The DC
> output voltage of the Hall Effect sensor varies by about 50 millivolts or
> more, so rapidly that it$E2s hard for our meters to follow it. We have
> spent
> countless hours on the phone with Energy Recommerce technicians trying
> everything that anyone could think of to trouble shoot the problem. Their
> system uses a MODBUS protocol for transferring the data and there seems to
> be no problem with the data transmission or connectivity.  I would love to
> hear from anyone that sees a pattern to this problem that might help us
> find a solution.
> --- end of quote ---
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