Solar MPPT Controllers to consider

[noelex 77]

Originally Posted by Jack C

So video shows PWM working almost as well as MPPT. Not a real test. Its a spot test.

Look a lot deeper

If you are using “12v” panels in warm or moderately warm conditions, the gain from the MPPT voltage conversion is not great. The second video is not unrealistic or unrepresentative, in fact it is pretty typical. The gain in cold conditions is considerably higher.

However, non MPPT controllers (sometimes called PWM) cannot be used with modern high voltage panels. It is also difficult to find quality adjustable PWM controllers these days (although they are available).

Given the typically high cost of solar installations on a boat, especially when mounting and installing costs are included, the extra costs of MPPT controllers is sensible even with “12v” panels in parallel.

[NorthCoastJoe]

I have a Morningstar that has been flawless for years. It was one of the first ones manufactured.

[mitiempo]

There are many good MPPT controllers - Morningstar, Bluesky, Midnite, and others.

But I do not know of a better combination of features and value than Victron. Their smart controllers with bluetooth not only let you adjust every parameter and see what is currently happening but also show history.

[noelex 77]

Originally Posted by mitiempo

There are many good MPPT controllers - Morningstar, Bluesky, Midnite, and others.

But I do not know of a better combination of features and value than Victron. Their smart controllers with bluetooth not only let you adjust every parameter and see what is currently happening but also show history.

The versatility of the Victron MMPT controllers is excellent. Almost every parameter can be adjusted. This allows altering the charging parameters to ideally charge the batteries. This is one of the most important features of any charge controller, providing you are prepared to adjust the default settings.

Another very positive feature of the Victron contollers is the continual software updates with significant additional features. When I first purchased my Victron solar controllers the degee of adjustability was far more limited. This has been updated at no charge to users such as myself.

Thumbs up Victron.

[GTom]

Originally Posted by Jack C

So video shows PWM working almost as well as MPPT. Not a real test. Its a spot test.

Look a lot deeper

The land-based tests forget something: radio/VHF interference. I recall someone complaining few years ago on CF can't remember the make of the controller. Definitely wasn't a Victron.

[Captain Bill]

I would not recommend a Morningstar MPPT controller. These controllers do not allow for a shunt to measure current flow into a battery and control absorption-float switch over based on actual charge acceptance. Do yourself a favor and buy another brand that does use a shunt such as a Bluesky. In addition my Morningstar Tristar MPPT default AGM profile has a programming error which destroyed a $1500 set of AGMs before I figured out the problem and built a custom profile with the error corrected. The unit has a feature called float skip. It is used to help a battery bank recover from a deep discharge by holding absorption voltage as long as there is sufficient power the day after a deep discharge and not going to float. This feature is supposed to only get triggered wen the battery bank drops below 11.5V (on a 12V bank). The default AGM profile actually had it set to 12.5V. It apparently is not timed either so even an instantaneous drop below 12.5V could cause it to skip float the next day. I often found my batteries sitting at 12.6V just before sunrise but the log showed a low voltage of 12.45 or something and it would skip float the next day. It severely overcharged my batteries. It uses only time to determine the absorption time and it starts a new absorption cycle anytime there is a dark period with no input from the solar panels. Even if your batteries are fully charged you are going to get a full absorption cycle anytime the sun comes up in the morning. This includes when you are plugged into the dock and sitting at float all night. I have to have a second custom profile for when I am plugged into shore power just so I don't fry another set of batteries.

[Celestialsailor]

I used a Blue Sky 2512. Cheap, no bells and whistles. Just worked.

[noelex 77]

Originally Posted by Captain Bill

I would not recommend a Morningstar MPPT controller. These controllers do not allow for a shunt to measure current flow into a battery and control absorption-float switch over based on actual charge acceptance.

This is a nice, but not essential feature to consider. It produces a more accurate transition between absorption and float and makes the set up easier. Only a small fraction of marine solar systems have this installed, but it can be fitted to most (not all) of the better quality controllers. It involves some extra equipment, the solar controller has to be able to “talk” to a shunt mounted close to the batteries. As an identical shunt is needed for a battery monitor, some companies solve the problem by providing a smart system to allow communication between the battery monitor and the solar regulator. This can be an excellent option but it often ties you in to using the same brand battery monitor, as well as adding a degree of complication and a violation of the KISS principal.

One word of caution is that the cost of the extras to allow this feature varies enormously (from nothing because the shunt is included with the controller to well over $500 just for the options)

Originally Posted by Captain Bill

The unit has a feature called float skip. It is used to help a battery bank recover from a deep discharge by holding absorption voltage as long as there is sufficient power the day after a deep discharge and not going to float. This feature is supposed to only get triggered wen the battery bank drops below 11.5V (on a 12V bank). The default AGM profile actually had it set to 12.5V. It apparently is not timed either so even an instantaneous drop below 12.5V could cause it to skip float the next day. I often found my batteries sitting at 12.6V just before sunrise but the log showed a low voltage of 12.45 or something and it would skip float the next day. It severely overcharged my batteries.

The charging algorithms used by solar controllers varies enormously and very poor outcomes such as the problem mentioned above are not unusual. This can make a huge difference to battery life.

The best system is to buy a controller with completely adjustable parameters where any “features” such as “float skip” can be disabled if they are not appropriate. The default setting rarely produces anything like the correct charging profile.

[DanielI]

Is Victron the only controller that is NMEA 2000 compatible? I would have thought this is a desirable feature, but I haven’t seen any other companies that include it. Are marine applications such a small market share, or is this a less useful feature than I thought?

[Capt Y Knot]

I have an Epever BN Series, 20A for my modest sailboat system. The MPPT controler is no toy. Its built strong with plenty of heat disapating fins, the whole controller sheds heat.

You can torque down number 8 AWG wire. The weak spot in other more expensive controllers. Check out Will Prowes video above.

My controller is mounted out of the way and is connected to a MT-50 remote display. Very flexable mounting options. Ours is mounted in a small wooden box the sits on the navigation table.

I have attached a picture of a Epever BN Series 20A controller.

[Jon Hacking]

I'm really surprised that nobody's talking about what features to look for in an MPPT. IMO as an EE & 25-year solar user, Good MPPT controllers should have:

• Independent battery-voltage sensing wires (not current carrying)
• Independent current sensing (shunt) wires to correctly measure state of charge
• Preset profiles for your battery type
• Temperature sensor for the battery (lead/acid only)
• At least 1 fully programmable profile

Capt Bill recommends sensing the current into the battery, & I strongly agree. The only real way to know when a battery is full is when the current into the battery required to maintain the Acceptance voltage, drops to 1% of the Ah capacity of the battery. That is, when in Acceptance (at the Acceptance voltage) then the battery is full when the current into a 500Ah battery drops to 5A. Time-based solutions (like MorningStar) are seriously sub-optimal, especially if your batteries are already charged (say, from a marina) as then the MPPT will over-charge them for (typically) 2 hours. I've destroyed a $3,000 bank of gels by overcharging them for only 1 hour. And even LiFePO4 batteries will benefit from a (short) Acceptance cycle. We set our LiFePO4s to 13.9v, with tail-current, but use the "Equalize" function to take them up to 14.4v once a month to let the balance modules get the cells balanced.

There are several other "nice" features for an MPPT, like remote display, WiFi, CAN-bus, BlueTooth, & integration with an overall Battery Monitor/charging system, etc. And some of those are quite important to some folks (I much prefer a remote display to WiFi or BT, but others don't). But you should make sure that any MPPT you're interested in has the bulleted features.

Victron seems to be furthest along in integrating all charging systems (engine, AC, solar, wind). They still have several holes, but I think they're ahead of the pack so far. And their components communicating with each other over BT certainly makes setup easier, although I don't know how reliable that BT is.

And there may well be other important features - feel free to improve my initial list.

[Wireless1]

Originally Posted by noelex 77

+1

Especially with modern high voltage panels. It is important to check the suitability of the components especially between the panels and solar controllers where the panel voltage can be above the voltage rating of some of the common marine DC components such as fuses and circuit breakers.

Just use switches to isolate each panel for resetting the charge algorithm, service, etc. As long as the DC current handling of the switch is adequate. If a panel's wiring to the charge controller becomes shorted no harm will come to a single shorted solar panel. Using a circuit breaker is a waste of money.

[noelex 77]

Originally Posted by Wireless1

Just use switches to isolate each panel for resetting the charge algorithm, service, etc. As long as the DC current handling of the switch is adequate. If a panel's wiring to the charge controller becomes shorted no harm will come to a single shorted solar panel. Using a circuit breaker is a waste of money.

The maximum DC voltage should also be checked. Often this is a greater issue as many DC switches cannot handle the 60+ volts of larger panels. Suitable switches can be found, but you need to be careful assuming “standard” marine switches will be suitable. Often these are limited to 32v DC. There is a very real fire risk using these switches to interrupt higher voltages.

Some solar arrays need fuse or circuit protection on the input side of the solar controller (as well as the output side). This is not common in marine installations, but if required a circuit breaker is generally simpler and neater than a fuse and switch.

[wackerb]

I had two Victrons on my last boat and they worked fine, but will not buy another as long as their connecting blocks are too small to accept properly sized wire. What a stupid place to economize!

[mjscottinnc]

2 Epever 40 amp mppt. 2 315 watt 36 volt solar panels, 2 200a/h battery banks, 400 watt wind generator, 1 dual output 36 volt power supply for the dock. Power manager routes available power from any source to the bank needed it most based on priority. Starting bank has higher priority then house bank. That setup has worked flawlessly since 2017. Cruised the Bahamas in 2018 and 2019 never ran out of power. I prefer using the software and a laptop to monitor mppt performance.