On Mon, Aug 14, 2017 at 05:01:38PM +1000, James Cameron wrote:
> When cabling DC from a solar array back to an inverter charger, with
> increasing design distance, what are the precautions for the cable
> design?

Some specifications have been filled in, and a quotation received from
my designer.  I'm pleased with it.

The system is to consist of;

1.  photovoltaic array, 10 kW, as 36 modules in four series strings,
each module Voc 39.9V, peak power 300W, Isc 9.64A, so each string
359.1V at 9.64A, (Trina Honey M Plus TSM-DD05A, see references),

2.  DC cabling, four runs of 400V DC cable, to a maximum of 1% loss
(not yet sure why), and any necessary array earthing cables,

3.  two inverter/chargers, each with two DC MPP inputs, one battery
connector for a 48V nominal battery, one grid interconnect, and one
emergency power output, (SolaX X-hybrid E series SK-SU5000E, see
references),

4.  two 10 kWh lithium-ion battery arrays, (LG Chem RESU10, see
references),

5.  contactors for switching loads to emergency power output of
inverter/chargers,

6.  current transformer monitored by the inverter/chargers to
minimise grid import and export.

My quick system diagram showing power limits;

http://dev.laptop.org/~quozl/solar-2017-09.png

Theory of operation; power from the photovoltaics (2.5 kW per string)
is taken by a maximum power point tracking input of an
inverter/charger, and depending on battery state of charge, policy,
and consumer loads, is delivered to either the battery (2.5 kW) or the
loads in synchronisation with the grid (4.6 kW).

When grid voltage collapse occurs, an inverter/charger will drive a
contactor to switch a set of loads to an emergency power output, which
will deliver up to 2 kW per inverter/charger.  Is specified to take up
to five seconds.


References:

Trina Solar DD05A.08 - Data Sheet
http://static.trinasolar.com/sites/default/files/Honey%20M%20Plus%20DD05A%2=
8II%29%20Australia%20Feb2017%20A.pdf

Trina Solar DD05A.08 - Install Guide
http://static.trinasolar.com/sites/default/files/PS-M-0434%20A%20Installati=
on%20Manual%20of%20Standard%20Module_IEC_UL_2016_A.pdf

SolaX X-hybrid E series SK-SU5000E - Data Sheet
http://www.solaxpower.com/wp-content/uploads/2017/08/Gen2-X-hybrid.pdf

SolaX X-hybrid E series SK-SU5000E - Install Guide
http://www.solaxpower.com/wp-content/uploads/2017/01/X-Hybrid-Install-Guide=
..pdf

SolaX X-hybrid E series SK-SU5000E - with LG Chem battery Wiring Schematic
http://www.solaxpower.com/wp-content/uploads/2017/01/SK-SUxxxxE-LG-Wiring-S=
chematic.pdf

LG Chem RESU10 - Data Sheet
http://www.lgchem.com/upload/file/product/ESS_LGChem_ENG[0].pdf

LG Chem RESU10 - Install Guide
http://solarjuice.com.au/wp-content/uploads/2016/11/RESU-48V_installation_m=
anual_R2_eng_2016-10-21-1.pdf

--=20
James Cameron
http://quozl.netrek.org/
--=20
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