MPPT Solar controller: What is the good, the bad, the ugly

[slowpoker]

Elie;
Since you are looking to replace your solar controller, keep in mind the maximun voltage that those panels can generate, even in optimal conditions and compare that maximum voltage to that which the solar controller you choose, can safely handle without burning up and voiding the warranty.
In my case, with Blue Sky MPPT, their absolute max. voltage is 50 Volts. Also, that might limit you to wire them only in parallel because doubling the voltage, if in series, might exceed that maximum voltage that the controller can handle.
Three (3) of my Chinese controllers of different brands, have stopped working at some time or another. Buy U. S. made goods when possible.

[jeepbluetj]

I have a midnight solar kid in my motorhome. Works perfectly.

What about bypass diodes on series wired arrays? (i.e if one panel is completely shaded, the current will just flow through the bypass diode)

[socaldmax]

Originally Posted by jeepbluetj

I have a midnight solar kid in my motorhome. Works perfectly.

What about bypass diodes on series wired arrays? (i.e if one panel is completely shaded, the current will just flow through the bypass diode)

According to that video, they don't work. They keep the panel from hot spotting, but if one panel gets shaded in series, almost all of the power of the pair is gone.

[richwest3]

We replaced our Blue Sky controller (after the second one failed - two failures in two years... not good) with Victron Energy controllers and have been using them for two years now. They are GREAT! We're getting more power out of the panels than we ever did before.

The Victron controllers say their "fast" MPPT controllers. I thought that was probably just sales hype but after seeing their performance, I think there must be something to it. I mainly notice the difference in lower light conditions like mornings, evenings, or with cloud cover.

Since installing them two years ago, I have not touched them. I often had to reset the Blue Sky controller, maybe once a month, when they'd hang. The HF radio would often hang the Blue Sky controllers, even hanging the replacement that was supposed to be more RF tolerant. (It's never been a problem for the Victron controllers.)

As I remember, the Victron controllers model numbers represent the max voltage/max amps. I bought two (for two banks of panels) so I'd have redundancy and if one failed, I could switch the surviving controller to the highest output panels. So far, this has proven unnecessary.

I also bought the PC programming tool for about $75 USD, as I recall. This also has proven unnecessary as the company I bought them from offered to set up the programming as I wanted it. I have not had to use the tool since installation.

I know it sounds like I work for Victron but I don't. I'm just really thrilled to find such a great product!

[Celestialsailor]

Two failures in two years sounds odd to me since mine has been marching on for 5 years now. I'm not saying it didn't happen. Just wondering why? How many amps are your panels putting out? And is there a lot of RF from your SSB?

[Elie]

Originally Posted by slowpoker

Elie;
Since you are looking to replace your solar controller, keep in mind the maximun voltage that those panels can generate, even in optimal conditions and compare that maximum voltage to that which the solar controller you choose, can safely handle without burning up and voiding the warranty.
In my case, with Blue Sky MPPT, their absolute max. voltage is 50 Volts. Also, that might limit you to wire them only in parallel because doubling the voltage, if in series, might exceed that maximum voltage that the controller can handle.
Three (3) of my Chinese controllers of different brands, have stopped working at some time or another. Buy U. S. made goods when possible.

I agree completly with your statement, Slowpoker: Voltage from all pannels should never exceed the max voltage of the MPPT controller, or else... Trouble. But each MPPT controller as a clear voltage limit and the total voltage should never be more that that limit. This is also true for the max amps. In fact I thing it is a good precaution to have a controller that has much more capacity then strictly required. That is why I was talking about a 600 watt capacity when my pannels put out in theory 550 watts.