Upgrading the MPPT SC for Suitcase Solar

[jd1923]

Working on adding Suitcase Solar, one without built-in SC, in the range of 220W to 400W. I need to upgrade our MPPT SC to handle additional solar amperage.

We have 340W rooftop Zamp panels and a Blue Sky MPPT 25A SC and this system has worked flawlessly during 14 months of our ownership. Recently upgraded to 600AH Epoch LiFePO4 and Victron 3KVA MP2 inverter. We boondock more than camp on shore power. Want to be able to run A/C on inverter occasionally during afternoon hours.

The common route would be to replace the Blue Sky system with a higher amperage MPPT SC. If we add 220W in solar a 50A SC would work. If we go with the beastly 400W suitcase, it would just be over the 50A spec and would have to go to 70A. Upgrade would be a Victron product.

Here's where I would like opinions. I can scrap the Blue Sky but had another thought. What if I left the OEM install as-is, been working fine for 8 years, and just added another MPPT SC for the suitcase. It would just be off when suitcase not attached. This would be a redundant system so if one was to fail the other independent system would not be affected.I'm not into fancy integration. No Victron Lynx or Cerbo or Victron displays in our hull. I will just use the VictronConnect app as I do for the SmartShunt BM and VE.bus connection to the MP2. I am not interested in any Wi-Fi connections for remote monitoring, Bluetooth range is fine. If I go to an independent system, all I need is 10 AWG cabling, Anderson PowerPole connectors, a fuse/breaker and smaller 30A MPPT SC would do for much less money. My understanding is two MPPT SCs can work in parallel just like the SC and DC converter on shore power can charge simultaneously.

This model is $260 less than the 70A version. What do you think?
Amazon.com: Victron Energy SmartSolar MPPT Solar Charge Controller (Bluetooth) - Charge Controllers for Solar Panels - 100V, 30 amp, 12/24-Volt : Patio, Lawn & Garden

[Rolind]

I think either of your two options is acceptable and I have used both methods on different trailers. With two separate charge controllers you get less expense and system redundancy in case one solar system goes down. I suppose you could argue that using only one charge controller would be a “cleaner” installation, I don’t really think so however. One other thing to consider, if you run only one charge controller, solar panel outputs need to be very similar or you won’t get full charging from the higher power panels.  There are great videos available on YouTube explaining mismatched solar panels. Happy Trails.

[mountainoliver]

John, that’s approximately what I do for my suitcase solar. I wasn’t real pleased with the SAE plug being used for repeated connection disconnection so I added a secure two prong Cnlinko socket to the outside of the trailer. The Cnlinko plugs have a stainless latch that secures the connection.The Cnlinko socket is connected through a 10 amp fuse directly to the shunt for the Blue Sky solar controller. The Blue Sky IPN Pro remote displays all of the battery input information such as roof mounted solar, shore power battery charger, and the suitcase solar panels. I removed the solar controller that came with the suitcase panels and plug it in to the trailer and then plug the panels into the controller using the generic solar plugs. This allows a little bit higher voltage from the panels to travel the long distance from the panels to the controller. The wires from the controller are only about two feet long so less loss. All wiring is #10. The box that the controller is in is not waterproof so I just set it on top of the tire under the fender skirt. This idea was originally developed by John Davies.