Which MPPT solar controller for 6 x 100 watt panels hooked in parallel to 3 x 100 ah 12v deep cycle batteries?

[RickyA]

Which mppt solar controller should I get for 6 x 100 watt panels (check amazon.com/gp/product/B07MQJZQPY or see attached pic for specs) hooked in parallel to 3 x 100 ah 12v deep cycle batteries? So, 600 watts solar with 300 ah 12v deep cycle. I plan to upgrade the batteries to lithium later on, but for now deep cycle is what I have.

 

[MisterSandals]

Is there a reason you want to connect all 6 panels in parallel?
With 6 in parallel, you may need a distribution box because MC4 connectors are only rated to 30A and you'd be over that in terms of Isc. You'd also need to fuse each of the 6 panels.

Why not arrange in 3S2P with a single pair of MC4 Y connectors. That would be a nice ~75Voc x 11A array.

There are LOTS of SCCs to match most budgets and reliability requirements. How much do you want to spend and what kind of reliability/warranty are you needing?

 

[RickyA]

Why not arrange in 3S2P with a single pair of MC4 Y connectors. That would be a nice ~75Voc x 11A array.

Huh..?

 

[FilterGuy]

The two primary specs on an MPPT controller will be the Max PV voltage and the max output current.

Max PV Voltage:
The Voc is 24.3V. Since they are going to be hooked up in parallel, the input voltage of the MPPT needs to be 24.3V *plus* whatever is needed for cold temp voltage rise. I would be tempted to just build in a 25% buffer and call it good. 24.3 x 1.25 = 30.37V. This would cover you for almost any cold temp you would ever experience.


Max Output current.
The panels could produce up to 600W of power (In real-world conditions it is probably going to be 10%-20% less).
If I understand the setup correctly the batteries will be wired for 12V.
The highest current from the 600W of power will be when the battery is low so lets use 12V. That gives us 600/12 = 50A.

So....the controller should be at least a 30/50. In the Victron line of controller the closest match would be the smartsolar 100/50.


As our friend @MisterSandals said, with them all in parallel, you might find you run into other issues with the Isc current if they are all in parallel.
Also, if you have more than 2 strings in parallel, there should be fuses on each string. Unless there is a good reason for 6S, I would advise exploring 3S2P or at least 2S3P.

Note the xSyP nomenclature talks about the arrangement of the panels.

Examples:
3S2P means there are two strings of 3 panels in series and those two strings of panels are put in parallel.
2S3P means there are three strings of 2 panels in series and those three strings of panels are put in parallel.



BTW: Here are a couple resources you may want to review:

Adjusting Solar Panel Voc for temperature

When designing you solar panel system, it is important to adjust you solar panel Voc for temperature in order to ensure you do not over-voltage the PV inputs of your solar charge controller. This paper shows how to calculate the Temperature...

diysolarforum.com

Fusing & Wire Sizing guidelines for solar panels

To get the paper, click on the orange'' button at the top of the screen. This resource is intended to help the user understand when they need to add Over Current Protection Devices (OCPDs - Fuses or Breakers) to the solar panel array and what...

diysolarforum.com

 

[Rednecktek]

One of the big advantages to going to a MPPT controller is the ability to handle larger voltages coming in from your panels. If you can get panels in series then they hit the charging voltage your battery needs (15-ish volts) earlier in the day and stays there later into the afternoon. Another major advantage is the reduced connections required. If you do 6 panels in parallel, you're going to have 6 connections and 6 fuses and that's a lot of failure points to worry about, on top of that your power from all those connections is going to be upwards of 5.5a * 6 panels = 33a which is over the limit of the MC4 connectors on your panels.

If, on the other hand, you were to connect them into a 3s(eries)2p(arallel) configuration then you've only got 2 connections (which means no fuses needed), and only 11a of current through your joints and wires. The MPPT controller will need to be sized for your system, which would be 60a (really 50 but that would max things out and you never want to run anything at 100% capacity all the time) at 75v, so anything that was rated for 100v of MaxPV Input rating would be plenty.

You could go Victron, but if you're like me and work for a living, there are many other brands that will take Solar DC and convert it to Battery DC just fine for a LOT less money. Rich Solar, EPEver, SolarEpic, hell even PowMr will do the job. Granted, you're not going to have any of the fancy BlueTooth interfaces and online tracking and dog washing and espresso making that a Victron will provide.

Pro tip: when looking for a MPPT controller, outside of a VERY VERY FEW cases, if there's a USB port on the front/side, or it costs less than about $100, it's a FAKE controller and you're paying for a cheap PWM controller with a sticker that says MPPT.

 

[ianganderton]

Epever tracer 50A would be a good option if you get the right array voltage

2 strings in parallel, 3 panels in each string in series would be the most sensible option. Easy to get y connections for 2 strings

 

[RickyA]

So, basically like the diagram? I'm new to solar and didn't know you could wire them this way. Which controller and what else will I need to make this happen without breaking the bank? I'm not looking for cheap, just reasonable and reliable.

Thank you all for the replies! You guys are great!!

 

[ianganderton]

Looks good, that’s how my 4 x 120W panels are wired up

Have you sussed out how to calculate your solar pv voltage?

600W of solar / 12V nominal battery voltage = 50A of charge

So a 50A solar charger that will take the input voltage off your array (that you now know how to tune!)

Epever’s Tracer 50A is a good cost effective option that can work with the common battery chemistries

The Victron 100/50 would be a good choice. Comes in the very pretty (but addictive!) Victron blue that is super matchy matchy with a wide variety of othe excellent products to feed your new found addiction. The Bluetooth app is nice to have too

 

[Mattb4]

What is the intended purpose of your setup? You may be better off going with an off grid AIO (All in One).

 

[FilterGuy]

Epever tracer 50A would be a good option if you get the right array voltage

My 2 cents: A lot of people really like the Epever units and they are certainly lower cost than Victron...... but a lot of people have had problems with them. It seems to be a bit of the roll of the dice on whether they will work or not so I would avoid buying them.

 

[ianganderton]

My 2 cents: A lot of people really like the Epever units and they are certainly lower cost than Victron...... but a lot of people have had problems with them. It seems to be a bit of the roll of the dice on whether they will work or not so I would avoid buying them.

interesting, they are really popular here in NZ and I haven’t heard of any problems.

They just aren’t as pretty as the blue stuff ?

 

[augiedoggy]

Ive ben running my 30a EPever since 2013 with 580w of panels on my pop up camper with no issues.

 

[Browneye]

I have two of the EPever Tracers, a 10A and a 20A, and think they're great. Cheap and good.
If you're flush with cash it's hard to beat anything from Victron. If anything Tracer was unreliable I'd swap them out for Victron - they're just twice the price.
And yes, with mppt, double up your panels for higher voltage. The controller will best use what it gets for charging.

 

[FilterGuy]

So, basically like the diagram? I'm new to solar and didn't know you could wire them this way. Which controller and what else will I need to make this happen without breaking the bank? I'm not looking for cheap, just reasonable and reliable.

Thank you all for the replies! You guys are great!!



View attachment 125064

Yes, That works.

Let's look at the two primary variables for selecting a controller:

PV input voltage:
The array Voc for this would be 3 x 24.3 = 72.9V. Once cold-temperature rise is factored in, this would be too high for a 75V controller. However, a 100V controller would handle even the coldest temperatures.

Controller output current.
The potential controller output current does not change based on the panel array structure so it would remain right at 50A.
The panels could produce up to 600W of power (In real-world conditions it is probably going to be 10%-20% less).
The highest current from the 600W of power will be when the battery is low so let's use 12V. That gives us 600/12 = 50A.

So, a 100/50 MPPT controller would work well.

Another benefit of 3S2P is that since the PV current is 1/3 of what a pure parallel set-up would generate, the wiring between the array and the controller can be much smaller without suffering a large voltage drop (Energy loss).

 

[Minimoose]

Which mppt solar controller should I get for 6 x 100 watt panels (check amazon.com/gp/product/B07MQJZQPY or see attached pic for specs) hooked in parallel to 3 x 100 ah 12v deep cycle batteries? So, 600 watts solar with 300 ah 12v deep cycle. I plan to upgrade the batteries to lithium later on, but for now deep cycle is what I have.

Check out the 40amp and 60 amp HQST mppt controllers. Built in bluetooth and $125 and $279 respectively.

Products - Charge Controllers - MPPT - Page 1 - HQST

hqsolarpower.com

 

[FilterGuy]

Check out the 40amp and 60 amp HQST mppt controllers. Built in bluetooth and $125 and $279 respectively.

Products - Charge Controllers - MPPT - Page 1 - HQST

hqsolarpower.com

With 600W of panels, the charge current to the battery could be as high as 50A if the panels produce at the specified rating. However, panels almost never produce at the specified rating. Consequently, a 40 amp controller would function fine, but may or may not harvest all of the energy from the 600W of panels. A 60A controller would harvest all the energy but is more expensive.

 

[Minimoose]

With 600W of panels, the charge current to the battery could be as high as 50A if the panels produce at the specified rating. However, panels almost never produce at the specified rating. Consequently, a 40 amp controller would function fine, but may or may not harvest all of the energy from the 600W of panels. A 60A controller would harvest all the energy but is more expensive.

Best I've ever seen on a perfect day with 600 watts was about 37 amps from my 40 amp controller. 12 volt system. It made no difference when I over paneled to 800 watts.

 

[FilterGuy]

Best I've ever seen on a perfect day with 600 watts was about 37 amps from my 40 amp controller. 12 volt system. It made no difference when I over paneled to 800 watts.

That is interesting. It kinda says the real limit on the controller is 37A.

Do you see the charge ramp up sooner in the morning and ramp down later in the afternoon after you over-paneled?

 

[Minimoose]

That is interesting. It kinda says the real limit on the controller is 37A.

Do you see the charge ramp up sooner in the morning and ramp down later in the afternoon after you over-paneled?

It was an experiment. I put a large load on my 3000 watt inverter and aimed the panels exact. The first was three 200 watt panels in series and the second was 4 200 watt panels in series/parallel. I was trying to see if I could over panel for crappy days and to see if it made any difference. It didn't on a sunny day, but probably would on a cloudy day ?

 

[FilterGuy]

It was an experiment. I put a large load on my 3000 watt inverter and aimed the panels exact. The first was three 200 watt panels in series and the second was 4 200 watt panels in series/parallel. I was trying to see if I could over panel for crappy days and to see if it made any difference. It didn't on a sunny day, but probably would on a cloudy day ?

If the charger is already maxing out, aditional panels will not typically give more power at the peak. However, more panels will typically make the charge start and rise earlier in the morning and drop/stop later in the afternoon.

You may have seen this:

Overview of Over-paneling an MPPT controller

To get to the paper, click on the orange button at the top of the screen. There is a misconception that putting more panels on an MPPT controller than the controller is able to use will damage the controller. However, in almost all cases it is...

diysolarforum.com