At 18:38 -0800 29/11/11, jay peltz wrote:
Hi Kent,
You can't parallel them.
They each must have their own load.
But you can connect two Tristars to the same battery, each with its
own load and this is normal recommended practice.
The two controllers may not agree exactly about when to move to the
float stage, but when you think it through that doesn't actually
matter at all.
At 18:30 -0800 29/11/11, Kent Osterberg wrote:
The Tristar 60 manual says to keep diversion loads below 45 amps (or
somewhere close to that).
Load sizing is very confusing, but no, you can use any resistive load
that will not exceed 60 amps (at EQ voltage). The 40 amps is the
maximum renewables input (source current) if you are going to conform
to the NEC requirement that the dump load must be sized to 150% of
the maximum rated current of the solar, wind and hydro sources
combined.
In short you can use a 40 amps source provided that you have the
capacity to dump 60 amps, and this depends on finding a suitable
load. (In reality a load that dumps 60 amps at 60 volts will only
dump 54 amps at 54 volts float so you are down to a 36 amp source
current but this may be built into the safety margin already, who
knows?.)
I normally choose a big wire-wound resistor. In this case one ohm
4kW would be suitable. In reality this would be built from several
1kW or whatever I could find. For example 4 resistors at 1 ohm and 1
kW, configured in two pairs series/parallel.
More about the subject here. http://scoraigwind.co.uk/?page_id=637
Best wishes,
--
Hugh Piggott
Scoraig
http://www.scoraigwind.co.uk
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