upgrading from cheap PWM Solar Charge controller

[Hars]

After one season with a cheap PWM charge controller on my 212QBW I am looking at upgrading to a MPPT charge controller. Currently have 2 100W and one 40W portable panels in parallel.
Need help deciding on the charge controller and size, as well as location of components and where to connect the MC4 cable connectors.
Controller size: looking at 30A EPEVER , but will that be large enough if I go to 400Watts of panels?
Looks like it would be a good idea to install the charge controller inside (likely under the bed)
Also wondering where others have put the MC4 connections for the solar panels. Is there a sealed box for the ends from the controller that the portable panels can connect to?

[pconroy]

400 watts at 12V is 33 amps, so nope. You'd need their 40A version. I tucked my MC4's under the panels. I do have a plastic "combiner" box up on top too.

[ChiToones]

I'm using a Renogy Rover 30 Amp MPPT charge controller with two 200W solar panels on my roof. The spec sheet for this unit shows the maximum solar input power is 400W at 12V, 800W at 24V. I installed it last year and it has worked as expected.

My MC4 connectors are on the roof. I ran the cables from the roof inside the awning channel and drilled a hole into the front storage compartment. The charge controller is in that compartment. Most charge controllers are not waterproof.

[Hars]

I like how you brought the cables into the trailer.
I’m still planning on using portable panels.
Do you have a pic of where you mounted the charge controller inside?

[sciencenerd]

Originally Posted by Hars

After one season with a cheap PWM charge controller on my 212QBW I am looking at upgrading to a MPPT charge controller. Currently have 2 100W and one 40W portable panels in parallel.
Need help deciding on the charge controller and size, as well as location of components and where to connect the MC4 cable connectors.
Controller size: looking at 30A EPEVER , but will that be large enough if I go to 400Watts of panels?
Looks like it would be a good idea to install the charge controller inside (likely under the bed)
Also wondering where others have put the MC4 connections for the solar panels. Is there a sealed box for the ends from the controller that the portable panels can connect to?

I was actually in a similar boat earlier this year, having 240 W of solar panels with a PWM controller, and wanting a little more. The decision was between $80 for another 100 W solar panel, or the same money for a MPPT charge controller. I decided the better bang for the buck was to get another panel. Here is why:

My 100 W panels at 16.7 V give about 6.2 A current (at max power point). At 13.6, the typical lead acid charging voltage, that's 84 W, or 16% loss of energy. A MPPT controller is 95% efficient, so that would give me 95 W from a 100 W panel, or a 11 W gain over a PWM controller. 11 W x 2.4 is a 26 W gain over PWM, but adding another 100 W panel gives me an additional 84 W. Easy decision. To corroborate this, there is a video from Will Prowse on youtube comparing MPPT vs. PWM for 18 V panels, and the efficiency gains from MPPT are really not significant. You need a bigger array with higher voltage panels for MPPT to make a difference.

As to the connector, I have a SAE connector for solar on the side, which makes it easy to connect my portable 100 and 40 W panels (in parallel). The additional two 100 W panels are on the roof.

P.S.: My charge controller is mounted in the front storage compartment.

P.S.2: This is the link to the video I mentioned comparing PWM vs MPPT:

https://www.youtube.com/watch?v=kF_cVEYxj3E

[JimD]

I use the Renogy 30 amp controller for my 400 watts of solar and it works great. I love the bluetooth feature where I can monitor the solar operation from my phone.

I wouldn't go with anything less than 30 amps because some day you will add another panel. Mark my word! I started out with 200 watts, then 300, and now 400. That is the capacity I want for my boondocking.

I observed just today (am camping) that it was putting out almost 17 amps. I don't believe you will ever get the max that a panel is suppose to put out. Maybe at the equator with the sun directly overhead.

A 100 watt panel's spec for absolute max (short circuit) current is about 6.5 amps. So my 4 panels would only put out a max of 26 amps into a dead short which ain't about to happen. I probably could add another 100 watt panel and still not hit the 30 amp controller spec.

You lose some power in the wire run from the panels to the controller. The heavier the gauge, the less loss. Always overbuild for you application.

[Hars]

Originally Posted by sciencenerd

I was actually in a similar boat earlier this year, having 240 W of solar panels with a PWM controller, and wanting a little more. The decision was between $80 for another 100 W solar panel, or the same money for a MPPT charge controller. I decided the better bang for the buck was to get another panel. Here is why:

My 100 W panels at 16.7 V give about 6.2 A current (at max power point). At 13.6, the typical lead acid charging voltage, that's 84 W, or 16% loss of energy. A MPPT controller is 95% efficient, so that would give me 95 W from a 100 W panel, or a 11 W gain over a PWM controller. 11 W x 2.4 is a 26 W gain over PWM, but adding another 100 W panel gives me an additional 84 W. Easy decision. To corroborate this, there is a video from Will Prowse on youtube comparing MPPT vs. PWM for 18 V panels, and the efficiency gains from MPPT are really not significant. You need a bigger array with higher voltage panels for MPPT to make a difference.

As to the connector, I have a SAE connector for solar on the side, which makes it easy to connect my portable 100 and 40 W panels (in parallel). The additional two 100 W panels are on the roof.

P.S.: My charge controller is mounted in the front storage compartment.

P.S.2: This is the link to the video I mentioned comparing PWM vs MPPT:

Thanks for the input. Interesting video about pwm and mppt. Would have thought there would have been a bigger difference between the two.

[Hars]

Originally Posted by JimD

I use the Renogy 30 amp controller for my 400 watts of solar and it works great. I love the bluetooth feature where I can monitor the solar operation from my phone.

I wouldn't go with anything less than 30 amps because some day you will add another panel. Mark my word! I started out with 200 watts, then 300, and now 400. That is the capacity I want for my boondocking.

I observed just today (am camping) that it was putting out almost 17 amps. I don't believe you will ever get the max that a panel is suppose to put out. Maybe at the equator with the sun directly overhead.

A 100 watt panel's spec for absolute max (short circuit) current is about 6.5 amps. So my 4 panels would only put out a max of 26 amps into a dead short which ain't about to happen. I probably could add another 100 watt panel and still not hit the 30 amp controller spec.

You lose some power in the wire run from the panels to the controller. The heavier the gauge, the less loss. Always overbuild for you application.

Thanks for your feedback JimD.
I wasn’t looking at the Renogy Rover, but it might be a good fit for me.
I was wondering what size wiring you are using from panels to the Chargé controller and from it to the battery?

[ChiToones]

Sorry, I don't have any pics of the controller and the camper is still in storage.

[Hars]

I installed a 30amp Renogy Rover Solar Controller inside between the window and the side cupboard. 20amp breaker to Solar and 30amp break from battery (inside the pass through). I instal a SAE connector underside to feed the controller

[Hars]

I installed a connector underneath the trailer close to the solar controller

[mini4mw]

If you plan on having this for a long time, I would go for Victron equipment. It is superior to other solar equipment and they have a large range of monitoring equipment that all ties in nicely together (specifically a MPPT, shunt/battery monitor, temp monitor). It does cost a little more, but its for a reason. I do use Renogy in my RV and it works fine, its just not as accurate with voltages and I only have 200W. My off grid uses 3600W and multiple Victron and if I had to do it again I would have started the RV with it.

MC4 connections are water proof so you can use them anywhere. Try to keep panels in series (higher voltage) instead of parallel (higher amps) as higher amps = more heat = requires bigger wires. Higher voltage is why you want a MPPT as well. PWM tosses extra voltage to heat where MPPT changes it to higher amps. This is also why you want to put your MPPT as close to the battery as possible. Those need to be big cables and you want them short as possible (big amps).

Divide your watts by 12 (12 volt system in RV) to get amps. 300 watts/12 = 25amps and that is your charging amperage. If you ever planned on putting more or thinking you want more you would need to change out the controller. 400W is 33amps.

When you put this all in place, make sure you have the proper disconnects and fuses so you can turn everything off and still work on it as well as ensuring something blows/turns off before starting any fires from over voltage/heat. Solar is cool and easy, but once you start getting into the higher wattages you need to make sure you are knowledgeable about safety as those amps will do more than put a hurting on you.

[ARoamer]

Originally Posted by Hars

After one season with a cheap PWM charge controller on my 212QBW I am looking at upgrading to a MPPT charge controller. Currently have 2 100W and one 40W portable panels in parallel.

You may want to take the 40W panel out and test output. Generally solar panels should be similar wattage / volts / amps / for best performance. Maybe get the 40w panel it's own controller?

Net info-
"If you connect solar panels without matching either the amps or voltages, efficiency will be drastically reduced. If your solar panels are not matched in size, the system will always choose the lowest value.
This is especially crucial for panels connected in parallel. But whether wired in series or in parallel, this holds true. Plugging in a solar panel of a lower power rating into your array will reduce the total energy output."

[Pauls72]

We have 1200W of solar (6 - 200W panels - 3 sets of 2 in parallel) and 720AHR of battery, Victron SmartSolar MPPT 150/100 and Victron Multiplus 3K. I know it's a lott, but we can run the AC for 5-6 hours no problem. It all fits nice under the bed.

If you put the panels in groups of 2 in series and then the groups in parallel they will be 24V and only produce half the current (16.6A) @ 400W. You just configure the charge controller for 24V in and 12V out. You need 4 panels to do this. I would have them all the same.