Who makes the most compatable PV charge controller for a Magnum Energy Inverter?

Re: Who makes the most compatable PV charge controller for a Magnum Energy Inverter?

One of the issues is how great the distance is between your array and charge controller. The longer the wire needs to be, the more sense it makes to increase the array Voltage.
The KD315's have a Voc of 49.2. Three in series would "max out" a Classic 150's input Voltage, and under cold conditions could exceed it causing the hyperVoc function to become very necessary. In fact up here such a configuration could hit 192 Volts, meaning it would only be feasible on a 48 Volt system (HyperVoc allows maximum input Voltage + system Voltage without damage to the controller).
So you could run three parallel strings of two in series on a Classic 150: Vmp 79.6, Voc 98.4, Imp 23.76, Isc 25.5
Or you could run two parallel strings of three in series on a Classic 200: Vmp 119.4, Voc 147.6, Imp 15.84, Isc 17

The first configuration is most efficient for the controller (array Vmp closer to system Voltage), the second would allow for fairly long wire run between array and controller without extremely large wires.

Re: Who makes the most compatable PV charge controller for a Magnum Energy Inverter?

vtMaps is technically correct: the greater the difference between array Voltage and system (battery) Voltage the less efficiently the charge controller will operate.

However, it is not some enormous figure like "20%" (it's more like 3% difference) and it will not generate tremendous amounts of heat resulting in premature failure of the controller. Likewise the heat generated in wiring losses isn't going to fry them either. You have to be pretty far off the mark to create that kind of trouble.

The trick is to balance the power loss in wiring against the power loss from reduced controller efficiency and see which way ends up being the least. And that is all for the sake of reducing wire size (and thus cost) for performance at maximum power output. That 3% loss in wire we aim to get below is not some rigid absolute dictum carved in stone that must not be violated under any circumstances.

It's not like either configuration is going to be the difference between "this works" and "this doesn't work". We're talking about a few percent power loss. If you're designing a system where that much is critical to operation you're doing it entirely wrong.

So for this application the only change to my recommendation in post #13 would be upping to 8 AWG as per vtMaps's suggestion, providing it's not prohibitively expensive to do so.

Re: Who makes the most compatable PV charge controller for a Magnum Energy Inverter?

Nothing wrong with Canadian Solar panels. I think that model has a Vmp of about 30 and a current around 8. The Voc would be 37-ish, so if you put ten in series you'd have 370 Volts and it would definitely not work. Furthermore the Vmp would be 300 Volts and pretty far away from any system Voltage. How did you enter the numbers?

Ten of them would be 2300 Watts and on a 24 Volt system would provide about 74 Amps peak charging current.

The main difference between the Classic and Classic Lite is that the latter has LED's to indicate status rather than an LCD readout. The readout, however, can be added later if you wish.

Re: Who makes the most compatable PV charge controller for a Magnum Energy Inverter?

No, it's not just your opinion. Here's why:

We use the panel Vmp & Imp ratings to determine maximum power into the charge controller. But that only works in theory because an MPPT controller will 'load' the array according to what it thinks will give the best output to the batteries for the SOC at the moment. It may in fact never pick Vmp * Imp even if it is available, instead opting for a higher Voltage (above the rated Vmp) and lower current (below the rated Imp). I have seen this many times with my own system. In fact I've seen the MX60 output more than the array's 700 Watt rating without reaching Imp on the panels; cold weather = high Voltage.

But it is always best to plan for "worst case scenario" or maximum strain on components/wiring. In fact the NEC requires it for anything deemed to be in "constant use" (thus the derating of some devices and conservative current numbers for wires, et cetera). One should not count on the system behaving in that way.

When we're working with initial design we're working with the theoretical. The practical is another matter.

Re: Who makes the most compatable PV charge controller for a Magnum Energy Inverter?

Fe-Wood wrote: »

Cariboocoot-
It was a dislexic moment... series of 1 with a total of 10 panels in parrallel. It looks like I will need to use #2 AWG, Am I right? for a >3% line loss. It seems to me that 10 panels @230W 29.6VMP and the Midnight Solar 150 Classic Lite is a decent system given my budget and battery bank. Am I in the ball park or still way out in left field?

Now you're off in the opposite direction!

Panels of Vmp 29.6 in parallel aren't going to charge a 24 Volt system; the Voltage is too low. A bit of wire loss, some heat, and soon you haven't got 28.8 Volts for the Absorb stage, much less 30 Volts for Equalization. In general a 24 Volt system needs Vmp of around 35 to work properly.

If you put two in series you get Vmp 59.2. The current from five parallel sets of these would be about 39 Amps. At that rate you'd be using 6 AWG. Better than 2 AWG, but still pretty big.

Note: one of the rules-of-thumb is that nominal array Voltage should be about 2X nominal system Voltage, so for a 24 Volt system you try for around 48 Volts in the array. Not written in stone, just one of the ways to get enough Voltage for charging.