Overall Classic efficiency at various step-down ratios

[JerryB]

Robin et al....

I have a boat mounted solar array (2.2KW) with a classic 150 driving a 12 volt 1200AH battery bank. The 9 panel array is 90 volt nominal (3 panels in series); 3 in parallel. On sunny summer days, the 150 runs at max output (if needed) for 6+ hours a day and runs VERY hot, e.g. 175+ degree (F) FET temp. It sometimes thermal limits even with an external 8" DC fan blowing on the case. My question is: Is it worth the effort to reconfigure the array to 30 volts nominal (cost and routing difficulty of big wire) in order to improve the efficiency of conversion and thus reduce operating temperature? Have you run any tests to determine overall efficiency at various in/out ratios and load? Other than this, the Classic is a killer product. Thanx for any info you might have.

JerryB

[boB]

Hi Jerry.

The Classic will run much cooler with a lower  input voltage.  I would expect it to
thermally protect with high input voltage.   Also I would think your cables would
be short enough on the boat that it shouldn't be too bad wiring for lower input
voltage necessary to do this.

I would certainly say to try this.   Then, maybe you can get rid of that extra fan, too.

boB

[JerryB]

Bob,

Thought I replied before.....oh well old timer's disease. Anyway thanx for your reply and I'm doing the reconfiguration as well as adding a second Classic. With fresh information regarding feeding two Classics from a single array (e.g. don't do it), I will run one classic (6, 240 watt panels) at 30 volts, and another Classic (3, 240 watt panels) at 90 volts. Why? Because I already had a #10 pair pulled and then added a #4 AWG pair which was a BEAR! I'm not pulling any more wire and a lightly loaded second Classic should be fine at 90 volts input. Make sense?

Jerry

[boB]

Jerry, that should work just fine.

boB