Hooking solar panels to MPPT Controller

I have two sets if panels, both of which are Renogy. They are very different though. One set of panels (2 panels) is pre-linked in series, the other set (4 panels) is pre-linked in parallel. All panels are 100 watts each.

My question is, what is the best way to connect them all to be able to use them at their fullest potential. I do have two charge controllers. The two panel kit came with a 20 amp PWM controller, while the second controller I bought independently. It is a 60 amp MPPT controller by LiTime. I have linked them all together using a splitter, but is this the best way to get the full potential out of them? Does the 2 panels kit (which is 24 volts because the panels are pre-linked in series) make the whole linked system 24 volts, or am I dragging it down to 12 volts by hooking up the 4 panel kit that is linked in parallel?

Below is an illustration of what I am talking about. One set of panels in series, the other in parallel. Now, can I use a splitter and connect all of the panels together, as in one set in series, the other in parallel? I appreciate any help, as I am new to all this. Thank you in advance for any help learning.

 

Can't hook them together in the manner which you're asking. Your wattages are the same, but you have mismatched voltages. The voltage of the set in series will be four times the voltage of the parallel set. Also, your charge controller will have an input voltage limitation, so depending on specs of the panels and of the controller, the series set might be more than the controller can handle. I have an off-grid well with 8 panels total. The deep well pump works on 90-360 volts AC or DC, so four of the panels are hooked up in series and put out a max of around 120 volts. That set is wired directly to the deep well pump through a switching circuit to pump water into a 2500 gallon tank. The other four panels are completely separate and charge a battery bank. The charge controller for those four panels is limited to 75 volts DC input, so those panels are hooked up in a parallel/series configuration. In other words two pairs of parallel panels in series with each other. The voltages of each set of two would be the same, so each paralleled pair is put in series with the other paralleled pair, for a max of around 60 volts. They charge a bank of 4 12volt 250Ah batteries in series for 48 VDC to run a boost pump that draws water from the tank to pressurize the house system.

 

All of the panels are 12 volt panels, so the two panels that are in series would be 24 volts total. The voltage of the four panel set would still be 12 volts because they panels are all in parallel. So yes, the voltage is different for the sets of panels. 12 + 24 volts. This is not even close to the maximum VOC for the MPPT controller I have, which is 150 VOC and the maximum amperage for the controller is 60 amps. I wasn't close to that limitation either, according to the controllers reading.

I have already hooked them up like I described and the batteries did show charging, but I am still unsure whether this will damage the system in some way or if I am limiting some part of the system by doing this.

 

Why not do three pairs in series/parallel so you don't have mismatched voltage?

 

Do you research into Voc and what your panels are. Lowest Voc will rule all the other panels and can have a drastic impact. Especially if you’re in shade and running series. I run all my panels in parallel that way I don’t have to worry about one panel being in shade and dragging down the total output of the others. Just another thing to research and mull over

 

I do too... partially for shading reasons, but once I decided on parallel I went with 200W panels so I no longer had a choice since I have an odd number of panels.

 

Yup. Unless you’re running a crazy massive array/battery setup I don’t see the benefit to running in series. For what most people do in a truck/rv I think parallel is the way to go. But I’m all a rookie at this stuff

 

About the only benefit I can see is series keeps your amperage lower so you can get away with smaller gauge wire. Yeah, it kinda' makes my eyes glaze over too.

That's why I paid a professional to do my system. (and the tax credit from putting solar on my house paid to put solar on my RV... seemed kinda' poetic to me.) I was very tempted to use the tax credit from putting solar on the RV to put it on my truck, just because.

 

Yeah, sorry I misread your original post about just two panels in series. Was going by the pictures, so not 4x the voltage.

I didn't realize you were referring to an RV setup, which is of course completely different from what I deal with. I have a 50 yard horizontal run from the panels to the pump house, and the pump sits 340' deep. The four panels charging the batteries are all in the same out building as the battery array. It's all been working for a little over ten years now.

 

The two sets of panels are pre-wired from the factory. The two panel set is wired for series, the four panel set came pre-wired parallel. Admittedly, I didn't exactly know what I was buying when I bought them. I just saw they were all 100 watt panels and thought that was the end of it. Companies don't advertise much beyond saying "this is a 12 volt 100 watt panel". I had to do a little digging to find out what I really had.

I can always just use the two charge controllers I have, one for each set of panels. I was just hoping there was a way to connect all the panels to the same controller.

These are the two sets I have:

$285 Renogy 200 Watt 12 Volt Portable Solar Panel with Waterproof 20A Charger Controller, Foldable 100W Solar Panel Suitcase with Adjustable Kickstand, Solar Charger for Power Station RV Camping Off Grid

https://www.amazon.com/dp/B07RFQVB9M

$530 Renogy 400W Lightweight Portable Solar Suitcase, Foldable Solar Panel Charger for Outdoor Activities, RV, Camping, Marine, Off-Grid，Fast Installation with Sturdy Kickstands

https://www.amazon.com/dp/B0D4LMVKYD

This diagram from Renogy looks as if there are two groups of panels that are different voltage hooked together. The upper pair is connected in series with the bottom panels exactly like mine. The upper group will have 24v, as they are run in series, the lower group will be 12 volts. I hooked mine up identical to this, but not sure if it is right.

 

Upper group 200w panel is parallel as it has an open circuit of 24.3v. The 400w panel is in series\parallel and has an open circuit of 47.2. Your best bet is to run two separate charge controllers as you stated. I see there is one built into the 200w suitcase style panel. Can your second charge controller handle 47v? Many cannot.

best of luck and any additional questions just keep asking


Edit: just saw your upgraded diagram. Yes, you could run a single charge controller but would need to buy another set of those 200w panels and run it in series to bring the voltage up from 24 to 48. You’d have a total of 800w at that point. Just look at the voltages listed on the back of the panels you have and do whatever it takes to make the voltages match. If you have one panel with 48v then you need two panels @24v run in series to match

 

I just found this, so I believe my idea is shot down.

Just using both the controllers is clearly the easiest thing to do,but I do still want to develop and understanding of what can and what can't be done. Also, just in case it is pertinent info, be it known that all individual panels in both sets are 12v 100w each.

 

I saw this on Renogy's website in the description if the 4 panel kit I have. I added the red boxes myself to show the different volts and amperage involved within the strings of panels.

 

I think I just realized something. This 4 panel suitcase has to be comprised of 48 volt panels. They are definitely wired in parallel, but all strung together in parallel, they do indeed have a VOC of 47.5 volts. The manual says 40 volts and 10 amps is optimum. Please someone tell me I'm not crazy.

This would explain the photo of the diagram showing them wired to another 2 sets of 2 panel kits.

 

Bingo. As mentioned, look at the tag on the back of the solar panel. Then take all your solar panels and do whatever you need to do to make all the voltages match