Solar panel upgrade questions

[Ted Rathjen]

The SunSaver duo is a PWM style controller. Just switching to a MPPT style controller (more efficient) will result in 20% more power from sunshine on the existing solar panel you have. The PWM style controllers were really designed for low wattage solar arrays as the PWM controller uses very little power. An MPPT controller also uses little power, but it uses more than a PWM consumes.

Most MPPT controllers that I've seen available only output to a single battery bank. The SunSaver Duo is configured for 90% to the house, 10% to the engine battery. Personally, I don't think this is necessary. On a NW edition boat using all AGM or FLA batteries.. those SI-ACR's, with enough sunshine, a charge voltage is created causing the ACR's to close, which means sunshine will get to all three battery banks. On folks with a Luxury Edition (using LiFePo4 batteries), then the output of the MPPT controller just goes to the house bank. EPever makes a MPPT controller that will send 90% to the house and 10% to the engine battery. This is what's standard on the NW editions today that Fluid Motion is selling on the new boats (A 20amp EPever is what the factory uses today). Again, I don't think it's necessary to have dual outputs (house and engine). It doesn't hurt to have dual-outputs.

When I re-wired Channel Surfing and converted my NW edition to LiFePo4 (LFP), I went with a 100/30 MPPT Victron SmartSolar controller. I've since replaced it with a 100/35 Victron controller. I have two 210 watt solar panels (420 watts total). It serves us well, with no generator on board. My MPPT controller outputs to the House bank and that's it. My thruster and engine battery get charged on shore power or when the engine is running. I figure, my car sitting in my driveway for the 55 days we were gone to SE Alaska, started up fine upon our return. The only use case I can see where maybe having the MPPT controller with dual outputs to the engine and house battery is if we trailered our boat and stored our boat for long periods of time on the trailer without shore power. But then again, if that was storage on a trailer without shorepower, I'd probably bring the engine and thruster battery home to my garage for the off-season.

I also want to note the following. A PWM style controller requires that the voltage of the solar panel match the voltage of the battery bank. Our boat is 12volts, and the original solar panel that came on Channel Surfing was a 12 volt 160 watt panel. The 210 watt panels I put up are 24 volt panels. Larger panels most often are going to be 24volt (some are 48 volt). The MPPT controller is a battery charger, while a PWM controller is more like an on/off switch. Said differently, if you're going to upgrade solar on your boat, always start by upgrading the controller first since it's likely that whatever panel you go with, you'll need a MPPT controller for compatibility with the new panel you put up. I started by upgrading from PWM to MPPT, and 5 months later I did the solar panel upgrade.

I have a ton of info published all about solar on our website.

Solar Panels | LetsGoChannelSurfing

www.letsgochannelsurfing.com

And also over on YouTube. Here's a playlist of all our "Solar on a Boat" videos.

Solar Power on a Boat

Share your videos with friends, family, and the world

www.youtube.com

Thank you. It’s all coming together especially with my current arrangement charging my starting battery. Hey man I for one greatly appreciate your assistance to the Tug world.

 

[tendercaruso]

Wow. So much great information. We are lucky enough to have just purchased a 2020 R23OB. It comes with the factory solar setup. We like anchoring for several days/weeks on our boat so will need to upgrade the solar. I'm thinking ~400 watts of the two sided panels. I have 3 new acid based batteries for the house bank (was going to replace with agm but the existing acids are only 1 season old, maybe just add another acid?). It looks like I should be replicating Channel Surfings set up? Would love to hear comments. Thank you.

 

[cliffm]

We had upgraded our solar panel via factory change form, to single 280W CMP mono panel, but had the oem pwm controller, in March we swapped to victron 100/30 panel. We have been enjoying the 20% boost in performance since!

 

[freedomvango]

We had upgraded our solar panel via factory change form, to single 280W CMP mono panel, but had the oem pwm controller, in March we swapped to victron 100/30 panel. We have been enjoying the 20% boost in performance since!

It's a huge difference going from oem to a mppt controller.

And the other added benefit of system history and trends on how your solar is doing!

 

[GunkHoling]

What are others opinions of bifacial panels? On my C28 I already have a victron 100/30 installed with the original 160W panel. I'd like to retain some roof rack space for possible roof box or kayak storage in the future, so I'm leaning towards a single panel. I may add a some additional cockpit shade in the future and could mount a flexible panel to the roof of that with the panel in parallel.

CMP has a 280W rigid panel, but is currently $1300. I see bluemarine has a 220W bifacial panel from Lumera for $230. What am I missing on the price difference and performance? Has anyone installed bifacial panels and see a benefit? Is the price difference a true quality difference or possibly old stock from the tarrif exception on bifacial? I'd likely re-install any pannel with the gemini mounts which may give me a bit more reflection on the underside of the panel.

 

[Cutwater28GG]

i havent looked recently but the 340W panels split cell at platt are good value if you call around and get cheap delivery

 

[JMarshallR25]

There have been a number of posts suggesting that the Kisae DC/DC charger is only rated for one panel. Has anyone tested that to verify? Kisae's website seems to suggest it is capable of handling 800w!

https://www.kisaepower.com/wp-content/uploads/2021/06/DC-DC_Charger_brochure.pdf

I note the manual suggests 500w in a 12v system. https://www.kisaepower.com/wp-conte...nual_DMT12V_24V-Series_Rev-D_190612_Print.pdf
Max input voltage is 50.

Edit: well, I read the entire thread and answered my own question. Thanks to Martin for the clear explanation.

 

[Submariner]

CMP has a 280W rigid panel, but is currently $1300. I see bluemarine has a 220W bifacial panel from Lumera for $230. What am I missing on the price difference and performance? Has anyone installed bifacial panels and see a benefit? Is the price difference a true quality difference or possibly old stock from the tarrif exception on bifacial? I'd likely re-install any pannel with the gemini mounts which may give me a bit more reflection on the underside of the panel.

I have a pair of CMP 210 watt panels hooked up in series to a Victron 150/35 MPPT controller. (35 amp controller, 420 watts of solar).

My only regret is I should have done a pair of their 225 watt panels as I have the available roof space.

I’ve field tested their 210 watt panels by subjecting them to submarine service crossing Johnstone Strait, shorting them out, and they still work (once I replaced the shorted out solar controller).

I’m also looking for someone with the new bifacial panels with a Victron contoller to compare output. The 2026 Ranger Tugs all come standard now with a 220 watt bifacial panels from Lumera. I've read their literature, and If I'm reading between the lines correctly... the bifacial claims are up to 30% gain, which may mean it's a 154 watt panel, with the added 30% potentially coming from the bottom of the panel. I need to see someone's Victron daily output off the 220 Watt Lumera panel to confirm.

The Gemini brackets are fantastic. They simplify adding the panels to the boat (less work). I paid $25/each in 2021 when I did my solar upgrade. Today, they're $45/each and a panel needs 4 of them. I also like the fact that they raise the panels up off the roof rack which allows us to open our aft hatches for more air flow even when raining since the port and starboard solar panels completely cover those aft hatches.

My pair of 210 Watt CMP panels in submarine service. They still operate great today. I broke our high score earlier this season. 2,770 watt-hours (about 216 amp-hours at 12 volts).

 

[Rode Trip]

I installed a pair of 200 watt bi-facial panels in parallel with a Victron 50 amp mppt. https://www.amazon.com/dp/B0DHZBLZSV?ref=fed_asin_title&th=1

I had no desire to put extra weight (beyond the solar panels) up on the roof, no cargo rack or anything like that for stability reasons, so I could have gone bigger but don't have a lithium bank to charge. With my small lead acid bank, soon to be AGM I think, my solar was capable of charging our overnight use back up by noon. On our 6 week trip earlier this summer we spent a little over 3 weeks of it at anchor but kept going somewhere every day, so the panels never got into float mode on their own. I think the latest we left was one day around 10:30 in the morning and I saw a peak of 382 watts on the controller. The way my panels are mounted on the outboard sides of the roof racks I felt like the bottom side was probably getting a bit of reflection off the water and white roof, and I suspected that I could have seen 400 watts or slightly more if the batteries were low at noon.

The one thing that surprised me about installing the panels was that the cost of the panels themselves was not much of a factor. I spent twice as much on all the other stuff: MPPT, aluminum roof rack mounts, aluminum flat bar for the panels to bolt to the rack mounts, 6 awg wiring from MPPT to battery, 30 amp breaker on input side, MRBF fuse, 10 awg from panels to mppt, and solar panel connections. Of the $700-800 I spent only about $270 was the panels (bought in Dec. pre-tariffs).

 

[Submariner]

II think the latest we left was one day around 10:30 in the morning and I saw a peak of 382 watts on the controller. The way my panels are mounted on the outboard sides of the roof racks I felt like the bottom side was probably getting a bit of reflection off the water and white roof, and I suspected that I could have seen 400 watts or slightly more if the batteries were low at noon.

When I bought my CMP panels they were 200 watt panels. 2 years later, they reclassified them and now sell them as 210 watt panels as they consistently over perform. So I purchased/installed 400 watts and got 420 watts.

Every year I see a peaks over 400 watts, many times.
Ironically enough though, the day(s) I hit like 2700 watt-hours (216 amp-hours), I may not hit peak wattage but definitely pour in the electrons to my house battery.

This screenshot of our solar array was taken May 10, 2025. As an illustration: 2,690 watts-hours with a peak of only 334 wats.

 

[scross]

I installed a pair of 200 watt bi-facial panels in parallel with a Victron 50 amp mppt. https://www.amazon.com/dp/B0DHZBLZSV?ref=fed_asin_title&th=1

I had no desire to put extra weight (beyond the solar panels) up on the roof, no cargo rack or anything like that for stability reasons, so I could have gone bigger but don't have a lithium bank to charge. With my small lead acid bank, soon to be AGM I think, my solar was capable of charging our overnight use back up by noon. On our 6 week trip earlier this summer we spent a little over 3 weeks of it at anchor but kept going somewhere every day, so the panels never got into float mode on their own. I think the latest we left was one day around 10:30 in the morning and I saw a peak of 382 watts on the controller. The way my panels are mounted on the outboard sides of the roof racks I felt like the bottom side was probably getting a bit of reflection off the water and white roof, and I suspected that I could have seen 400 watts or slightly more if the batteries were low at noon.

The one thing that surprised me about installing the panels was that the cost of the panels themselves was not much of a factor. I spent twice as much on all the other stuff: MPPT, aluminum roof rack mounts, aluminum flat bar for the panels to bolt to the rack mounts, 6 awg wiring from MPPT to battery, 30 amp breaker on input side, MRBF fuse, 10 awg from panels to mppt, and solar panel connections. Of the $700-800 I spent only about $270 was the panels (bought in Dec. pre-tariffs).

The panels have really come down in price. A solar installer in my town (Ashland OR) has 3 extra pallets of new Hyundai 390 watt bifacial panels for $100 each. They are narrow enough (40”) to fit on one side of the cabin roof just fine but are 80” long so they might overhang in the cockpit a bit. Still it’s a really low price for a quality panel!