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

[Elie]

My 'made in China' MPPT controller is dead. I once sent it back once for repair in China once under waranty. Just shipping was expensive, the seller reluctant, repair delay very long. I was never happy with its performance ,so I this time it seems kapput,(no power!) and I will replace it.
I have a 600 watts mixed solar array with 24 volts. So I need a good quality real MPPT controller, capable of handling this kind of power, from a good responsable manufacturer. What is your experience, what would you recommand? Many thanks.

[CAELESTIS]

Well, I am happy with my Midnite Classic 150. MidNite Solar Inc. Renewable Energy System Electrical Components and E-Panels

Made in the USA by the former owner of Outback.

[socaldmax]

Originally Posted by Elie

My 'made in China' MPPT controller is dead. I once sent it back once for repair in China once under waranty. Just shipping was expensive, the seller reluctant, repair delay very long. I was never happy with its performance ,so I this time it seems kapput,(no power!) and I will replace it.
I have a 600 watts mixed solar array with 24 volts. So I need a good quality real MPPT controller, capable of handling this kind of power, from a good responsable manufacturer. What is your experience, what would you recommand? Many thanks.

Can you be more specific, how many, and what sizes of panels do you have? What is the Vmp of each panel?

You really shouldn't mix panels. Maybe there's a way to split it up so you cna make up 2 arrays of similar panels.

[Undadar]

Buy a name brand controller. My Morningstar TS-MPPT-45 has been working flawlessly for several years. This assumes you aren't being struck by lightening or something...

[Elie]

Originally Posted by socaldmax

Can you be more specific, how many, and what sizes of panels do you have? What is the Vmp of each panel?

You really shouldn't mix panels. Maybe there's a way to split it up so you cna make up 2 arrays of similar panels.

My pannels are 24 volts 275 watts each. I connected them in serie so the voltage is 48 volts. Why can't I mix 2 pannels, when they are connected in serie?.

[Celestialsailor]

Originally Posted by Elie

My 'made in China' MPPT controller is dead. I once sent it back once for repair in China once under waranty. Just shipping was expensive, the seller reluctant, repair delay very long. I was never happy with its performance ,so I this time it seems kapput,(no power!) and I will replace it.
I have a 600 watts mixed solar array with 24 volts. So I need a good quality real MPPT controller, capable of handling this kind of power, from a good responsable manufacturer. What is your experience, what would you recommand? Many thanks.

This is a typical story about electronics from China. I even avoided buying my panels from China and opted for Grape panels...a US based company who's manufacturing is in Taiwan. They were a good price and found at Glogal Industrial supply.
I have a Blue Sky 25A., 12 volt MPPT unit. I've had it for 5 years now without a hitch. I chose to wire my panels in parallel...that's just me though. I understand there are advantages and disadvantages to either way.

[socaldmax]

Originally Posted by Elie

My pannels are 24 volts 275 watts each. I connected them in serie so the voltage is 48 volts. Why can't I mix 2 pannels, when they are connected in serie?.

That doesn't add up.

How do you have 600w of panels with 275 watt panels?

The answer to your question is: if you connect panels in series (bad idea on a boat) and 1 panel is 200w and the other panel is 100w, the 100w panel will drag the other panel down to 100w, thus total output will be 200w instead of 300w.

If you connect them in parallel, their total wattage will add up, as long as they all have the same or very close voltage output. If not, you'll never get max power out of the string because the MPPT controller cannot set 2 different MPPs on the same line. The higher output panels will be dragged down slightly.

Now add a little shading to the scenario, and output drops even more, especially in series connected panels.

[Elie]

Originally Posted by socaldmax

That doesn't add up.

How do you have 600w of panels with 275 watt panels?

The answer to your question is: if you connect panels in series (bad idea on a boat) and 1 panel is 200w and the other panel is 100w, the 100w panel will drag the other panel down to 100w, thus total output will be 200w instead of 300w.

If you connect them in parallel, their total wattage will add up, as long as they all have the same or very close voltage output. If not, you'll never get max power out of the string because the MPPT controller cannot set 2 different MPPs on the same line. The higher output panels will be dragged down slightly.

Now add a little shading to the scenario, and output drops even more, especially in series connected panels.

275 plus 275 makes 550 watts, so 600 watts capacity is roughly good enough, since we are talking of nominal power output. Connecting identical two pannels in serie won't change de total power avalable. Voltage will double though. So the total volts may vary, up to 48 volts nominal. If one pannel reduces its output voltage because of shadows, to 12 volts, the total voltage will drop to 36 volts nominal. The total watts will also go down by 1/4th roughly. But since I use a MPPT controller, and my battery banks has 12 volts, a good controller would be able to push all possible amps to the batteries since the voltage provided to the MPPT is much higher than the batteries's. Built in Diodes blocks anyway any transfer of power(with loss) between the solars pannels.
In my understanding, an MPPT controller works with the any voltage inferior to its design limit, and convert it to the batteries capacity(12 volts|!).The MPPT controller receives watts(power) and convert all avalable power(watts) to output maximum amps under an acceptable voltage for the battery bank. this is how I see the purpose of an MPPT function.
By the way, why is it a bad idea to connect in serie pannels on a boat?...
Have a look at this!
Mixing solar panels – Dos and Don’ts • SOLAR PANEL SECRETS EXPOSED

[Stu Jackson]

This includes a discussion of controllers:

Installing A Small Marine Solar System Photo Gallery by Compass Marine How To at pbase.com

[socaldmax]

Originally Posted by Elie

275 plus 275 makes 550 watts, so 600 watts capacity is roughly good enough, since we are talking of nominal power output. Connecting identical two pannels in serie won't change de total power avalable. Voltage will double though. So the total volts may vary, up to 48 volts nominal. If one pannel reduces its output voltage because of shadows, to 12 volts, the total voltage will drop to 36 volts nominal. The total watts will also go down by 1/4th roughly. But since I use a MPPT controller, and my battery banks has 12 volts, a good controller would be able to push all possible amps to the batteries since the voltage provided to the MPPT is much higher than the batteries's. Built in Diodes blocks anyway any transfer of power(with loss) between the solars pannels.
In my understanding, an MPPT controller works with the any voltage inferior to its design limit, and convert it to the batteries capacity(12 volts|!).The MPPT controller receives watts(power) and convert all avalable power(watts) to output maximum amps under an acceptable voltage for the battery bank. this is how I see the purpose of an MPPT function.
By the way, why is it a bad idea to connect in serie pannels on a boat?...
Have a look at this!
Mixing solar panels – Dos and Don’ts • SOLAR PANEL SECRETS EXPOSED

550 watts? Based on reality, I'd round down to 500 watts. So you DON'T have a mixed set of panels, you have a pair of matched panels.

Connecting panels in series on a boat is a really bad idea, you don't have to convince me.

I would recommend rewiring in parallel and using any good name brand controller in the 40 A or above range from Morningstar, Rogue, Victron, Midnite Solar, Apollo, Outback, etc.

[arsenelupiga]

a am not chinese fan but chinese made electronic goods are of superior quality from my experience.

they are cheap enough to risk give a go and so far paid off.

why would US controlled chinese factory be better ?

[Celestialsailor]

Originally Posted by Elie

My 'made in China' MPPT controller is dead. I once sent it back once for repair in China once under waranty. Just shipping was expensive, the seller reluctant, repair delay very long. I was never happy with its performance ,so I this time it seems kapput,(no power!) and I will replace it.
I have a 600 watts mixed solar array with 24 volts. So I need a good quality real MPPT controller, capable of handling this kind of power, from a good responsable manufacturer. What is your experience, what would you recommand? Many thanks.

Originally Posted by arsenelupiga

a am not chinese fan but chinese made electronic goods are of superior quality from my experience.

they are cheap enough to risk give a go and so far paid off.

why would US controlled chinese factory be better ?

You'll see the OP's post pointed out the results of that. If you want to buy from them, go for it. In a slip in the U.S., you merely go online and order a replacement and you're good to go in a weeks time. However, cruising in other countries where replacement products are often times impossible to find locally and paying duty on items ordered in country. That's if they ever make it to you.
My Blue Sky is built in the U.S. Blue Sky Energy Inc. - Industry Leaders In Solar Boost Charge Controllers and Maximum Power Point Tracking (MPPT) and has a great reputation. they can't.
I've tried Lee sails in the 80's and was very disappointed in the quality back then. Maybe they changed but left a sour taste for me. I've tried imported boat lighting only to have it continually blink off and on due to inferior electrical contacts. I had a friend who installed cheap Chinese fans in his boat while cruising Mexico in the early 90's and while asleep one night the housing caught fire. If they had not been onboard the vessel would have been destroyed.
Are there good products from overseas?...I suppose so if you can figure out the ones that are and the ones that are not.

[Elie]

Originally Posted by socaldmax

550 watts? Based on reality, I'd round down to 500 watts. So you DON'T have a mixed set of panels, you have a pair of matched panels.

Connecting panels in series on a boat is a really bad idea, you don't have to convince me.

I would recommend rewiring in parallel and using any good name brand controller in the 40 A or above range from Morningstar, Rogue, Victron, Midnite Solar, Apollo, Outback, etc.

Thank you for the info on good brands of controllers: Will try to find some controllers from Morningstar or Vitron.
I desagree with your comment about connecting pannels in parallele: The MPPT controller will never be aware of the type of connection, it just receive whatever voltage that is combined before reaching it.
Pannels are not affected electrically wise since diodes do their job.
Maybe this has to do with some esoteric thing specific to boat installations?...
By the way I'm not trying to convince you of anything, and you answered my main concern (What brand MPPT controller).
Have a good evening.

[socaldmax]

Originally Posted by Elie

Thank you for the info on good brands of controllers: Will try to find some controllers from Morningstar or Vitron.
I desagree with your comment about connecting pannels in parallele: The MPPT controller will never be aware of the type of connection, it just receive whatever voltage that is combined before reaching it.
Pannels are not affected electrically wise since diodes do their job.
Maybe this has to do with some esoteric thing specific to boat installations?...
By the way I'm not trying to convince you of anything, and you answered my main concern (What brand MPPT controller).
Have a good evening.

The problem with parallel vs series connections in terms of shading is one of electron flow, not MPPT performance. When 1 panel in a series pair is shaded, not only does it drop it's own performance, it also drops the other panel's output dramatically.

In a parallel pair, the shaded panel drops output, but the other panel continues to output max. power. Since shading is almost inevitable on a sailboat, this is a bigger concern than on a house or an RV.

I'm not trying win an argument: I'm trying to help you maximize your solar system output. You've already spent the money for the equipment, why settle for less than the most power out of it when you can make a simple change and immediately get better results? It's not my opinion, it's a proven fact. Check out this video for the amazing results from their real life testing of series vs parallel connections.

https://www.youtube.com/watch?v=1qD3mN8VotQ

[Celestialsailor]

That demonstration was pretty damming for series. When I was installing my system, I was advised to run the panels in series with my MPPT regulator. Now I'm glad I wired them in parallel. Thanks for that.