BZ Products MPPT500 step down voltage

Boyhowdy! You wernt kiddin. I read the advertised Specs. for both of them charge controllers you mention an theyre identical cept for one bein "optimized" for one specific brand/model PV module. Weird! Sounds like a lot a hooey to me. Snake oil salesmen kinda stuff. I wouldnta bought either one, for that reason alone.

Just out of curiosity, the PV modules your utilizin, are they that specific brand/model that the one charge controller is "optimized" for?

As for how to fix your problem without someone campin out next to the charge controller... It may be that your PV array dont have a high enough wattage for maximum efficiency. Other than that, I cant say. This sounds like a job for the BZ techies (if'n they got any that is), know what I mean Vern?

Jonny,

Thanks for the reply - and I almost grabbed the phone to talk this over, but instead decided to write this for the forum. This would also be something best pasted into a email for BZ Products, if you have contact information for the company. I would really like to hear their comments.

After making the initial post, I decided to go back out and re-wire one of the PV arrays into a 12 volt, rather than a 24 volt source. I did this after thinking about getting 11.5 amperes battery current from my two panels in series, giving 6 amps to the controller. Duh, I can get 12 amps in the parallel wire scheme - and I do.

I verified that the MPPT500 performs as one would expect charging a 12 volt battery from a 12 volt PV source. So, I don't believe that the unit I have is defective. If there isn't a functional difference between the MPPT500 and the "HV" variant, other than standing up to a 60 volt source, there is no point in persuing a exchange.

Based on my experiments, I have decided that I'm better off wiring the PV's as 12 volts. I have to place an order to get another 50-foot #10 awg cable with the whacko MC connectors the Evergreen panels use, and I have another order already in effect for #10awg marine twin-conductor cable from another source for the other panels. It isn't as elegant as using a 24-volt source, but it is (in my opinion) necessary for the MPPT500.

Final judgement on my part for the MPPT500: While it is "autoranging" and indeed capable of operating with a 24-volt PV array, it is not able to autorange out of early morning sunrise and shadows. Once it "determines" that it has a 12-volt array because of weak light, it won't relax the current draw enough to find a higher source voltage from the PV.

The MPPT500 is "capable" of 24-to-12 volt conversion, but it is not suitable for this application.

While it has DIP switches inside to determine the battery voltage (12 volt in my application) and type of battery (AGM for me), it has no user programming for the PV array voltage. It needs it.

For the specifics of my setup:
I have two Evergreen EC-110 panels as one array. Not six of them, as you had thought. I measured 38 volts open-circuited from these, when wired in series.
I also have another array of four Solarex 48-watt panels that I found used locally. As an aside, I can tell the MPPT500 "likes" the power curve on the Solarex better than the Evergreen from an efficiency point.
Each of these arrays are wired independently as parallel sources to the MPPT500's input. The total package is about 400 watts, capable of 23 amperes when wired for 12 volts.
The battery bank is four 12-volt 100AH AGM batteries in parallel. Inverter is a Xantrex (Trace) DR1512, which hums along happily through this whole ordeal.

Again, I am very curious to see what BZ Products has to say, once they read this thread. I selected a MPPT type charger with the capability of using an array of greater voltage than the battery as a primary consideration. The multi-point power tracking is a secondary consideration, which is why I have no qualms about using a mixed-panel array that may have a weird optimum curve with double-humps.

I believe there is a market for a specific 24-to-12 charger, for minimizing PV wiring losses. MPPT500 isn't it. This would be great for a manufacturer to step up to the plate and answer to.

-Victor

MPPT500 PV tracking error.

The unit described has a internal noise problem that was not detected during production. A production change has been implemented to correct this problem. The microprocessor is seeing noisy data and not tracking properly. Return the 500 to BZ Products for hardware and software upgrades.

MPPT500 VS MPPT500HV.

While both versions of the MPPT500 will accept a PV input voltage of 100 volts maximum. The efficiency of the MPPT500HV has been optimized for 48 volt PV input.

We like to hear back from our customers in order to continue improving our products. 

Frank Lewon BZ Products. INC.

Tom,

Assume you have some length of wire that you use to connect the PV panels to the charge controller. The length and the guage are arbitrary for this example; use the constant of a one volt drop in the wire at 6 amperes.

Wiring the panels in parallel for a nominal 17 volt Vpk @6 amps = 102 watts from each panel. The loss in the wire (1V x 6A) = 6 watts. 6/102 = 5.8 percent of the power is lost in the wire.

In the 12 volt example, this would require individual wire runs to each panel. So, with two panels, there are a total of four conductors used, to carry a total of 12 amps. It is still 5.8% lost in the wire.

Switching over to series (24 volt) wiring for the same two panels results in 204 watts available (34V x 6A). Using only two conductors results in 6 watts lost (1V x 6A), which is now only 2.9 percent lost in wire.

Bottom line: the 24 volt wiring scheme is more efficient, and the wire to connect it will cost half the money, since half the wire is used.

MPPT50HV specifications.

Thank you for pointing out the difference between the MPPT500 and MPPT500HV. Both controls operate over the entrie PV input range of 12 to 48 volts nominal.

The power converter components of the MPPT500 have been selected to provide optimum operation efficiency and current boost with a 48 volt nominal PV input. Power conversion efficiency is up to 2% higher in the 500HV as compared to the 500.

In the 500 watt power range most PV arrays will be 12 or 24 volts. So the MPPT500 has been optimized to the lower PV input voltage.

Some installations require very long wire run to the solar array. In these installations the MPPT500HV would be a better choice.

Frank Lewon BZ Products.

Maybe try relocating the panels for a shorter wire run.....

I am researching controllers now, I recently read that the MPPT 500 is preferred for 12 volt systems.  Higher voltage the better choice is the MPPT-500HV.
 This was from their Product descrition.
Best of luck: Bob