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high voltage MPPT - Page 2

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Posted by m II on June 8, 2010, 2:25 am
David Lesher wrote:

Ask Outback whether they have ever put two MX 60s in series on the input
and parallel on the output. If it isn't recommended, you haven't lost
anything but time. I use an MX 60, but only have three series wired
panels on it. That's roughly 110 volts when sunny.

My other controller is a Morningstar 30 amp unit. That one is fed by 17
volt parallel connected panels. The Outback is superior and adds the
output equivalent of an extra 230 watt panel. It was 300 dollars less
than buying another panel. The comparison between the two regulators
isn't really fair. It's apples and oranges.

Why the need for a 250 volt input? If it's solar power, could you not
parallel some panels? They don't recommend the controller for wind and
if you use it on a water turbine, the flow has to be fairly consistent.


Posted by David Lesher on June 8, 2010, 5:31 am

As an EE; I'd consider such as insane. I'd get two dead MPPTs.

I'm using panels on an existing pump system.....4 panels in series.

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Posted by Jean-Marc on June 8, 2010, 6:59 am

Would it be stupid to consider a transformer?

Posted by Jean-Marc on June 8, 2010, 7:07 am

YES, YES, YES, stupid.
I assumed  ~250V meant 250V AC until I looked what exactly a MPPT was. The
whole thing makes sense now.

Posted by m II on June 8, 2010, 3:44 pm
 David Lesher wrote:

Please explain why. The units have a completely variable input, from
zero to about 150 volts. The laws of a voltage divider circuit will
apply to two in series. To me, that means roughly the same voltage
across each one.

If the outputs are paralleled, they should be both providing roughly the
same current. That means the input voltage would be divided almost
equally between the two units.

Having said all that, I *DID* say to check with Outback to see if it's
possible. A dumb question is one you didn't ask. No one is suggesting he
actually do it before checking.


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