Bifacial solar panels

G

genehelfman

Member
Joined
Nov 16, 2024
Messages
7
Fluid Motion Model
R-27 (Outboard)
I'd like to install bifacial panels on a 2023 R27, replacing the factory installed panels. Anyone have relevant experience or recommendations? Thanks.
 
I installed a 300W bifacial panel from BougeRV in place of the stock panel. It was almost plug and play on my 2024 R25 LE. I selected the panel because its max open circuit voltage was within the limitations of the factory Kisae DMT1250 Abso 50 Amp DC/DC charger. I did not want to install a Victron MPPT 100A charger. Maybe I will someday if I add even more solar. I used the mounts from the old panel. I think they are Seadog.

The panel has been great. I leave house power on at all times and never need to turn on the battery charger unless we have a long stretch of cloudy weather (uncommon in Southern California). The panel keeps up with the fridge and all 24/7 house loads. I leave the Garmin and associated electronics "sleeping" so they draw minimal power.

Even with relatively smart battery chargers I question whether it is a good idea to keep the shore charger on with lithium batteries 100% of the time. My unproven theory is that relying on the solar panel 99% of the time will add longevity to the house batteries.

Panel.png
 
Solar sizing starts with knowing what you actually consume.

I built a spreadsheet for this exact question — covers the R27, R29, and R31 with real Pacific Northwest solar production data by season. January fog through summer peak. It'll tell you exactly what you need based on your actual usage patterns.

I have 420 watts of solar on Channel Surfing. Last season, I unplugged from shore power on May 20 and didn't plug in again until Sept 1. Whether we were on the boat or not, we ran off solar. I have several tabs in this calculator that show what output one can expect with different solar configurations. Let me know if you have any questions.

Free download here: https://csurf.co/power
 
Another recommendation, no matter what panel(s) you go with, make sure they're waterproof in case you go full-submarine.
I have a pair of Custom Marine Products 210 watt panels, wired in series. They're waterproof, Johnstone Strait approved.

Here's one of my favorite solar panel photos of my boat. 😀

But did we sink 2FX.jpg
 
Last edited:
JMarshallR25 said:
I installed a 300W bifacial panel from BougeRV in place of the stock panel. It was almost plug and play on my 2024 R25 LE. I selected the panel because its max open circuit voltage was within the limitations of the factory Kisae DMT1250 Abso 50 Amp DC/DC charger. I did not want to install a Victron MPPT 100A charger. Maybe I will someday if I add even more solar. I used the mounts from the old panel. I think they are Seadog.

The panel has been great. I leave house power on at all times and never need to turn on the battery charger unless we have a long stretch of cloudy weather (uncommon in Southern California). The panel keeps up with the fridge and all 24/7 house loads. I leave the Garmin and associated electronics "sleeping" so they draw minimal power.

Even with relatively smart battery chargers I question whether it is a good idea to keep the shore charger on with lithium batteries 100% of the time. My unproven theory is that relying on the solar panel 99% of the time will add longevity to the house batteries.

View attachment 27046
Click to expand...
Thanks! I'm pretty sure we have the Victron MPPT but have to check its amperage rating (weather a little challenging at the moment). Then I can go to BougeRV to see which unit is compatible. I like the "almost plug and play" nature, but almost often carries a wide range of possibilities.
 
Submariner said:
Solar sizing starts with knowing what you actually consume.

I built a spreadsheet for this exact question — covers the R27, R29, and R31 with real Pacific Northwest solar production data by season. January fog through summer peak. It'll tell you exactly what you need based on your actual usage patterns.

I have 420 watts of solar on Channel Surfing. Last season, I unplugged from shore power on May 20 and didn't plug in again until Sept 1. Whether we were on the boat or not, we ran off solar. I have several tabs in this calculator that show what output one can expect with different solar configurations. Let me know if you have any questions.

Free download here: https://csurf.co/power
Click to expand...
ChannelSurfing comes through again! It's obviously time for me to get educated. Thanks!!!
 
genehelfman said:
Thanks! I'm pretty sure we have the Victron MPPT but have to check its amperage rating (weather a little challenging at the moment). Then I can go to BougeRV to see which unit is compatible. I like the "almost plug and play" nature, but almost often carries a wide range of possibilities.
Click to expand...
Ha! The “almost” was that the factory panel is hardwired, so I had to cut that and add MC4 connectors to plug in the new panel. A bonus is now it is literally plug and play if I want to swap this panel or add more.
 
JMarshallR25 said:
Ha! The “almost” was that the factory panel is hardwired, so I had to cut that and add MC4 connectors to plug in the new panel. A bonus is now it is literally plug and play if I want to swap this panel or add more.
Click to expand...
That was definitely worth knowing. Thanks! I'm headed to the boat as soon as the weather lifts to check controller specs and existing panel size.
 
genehelfman said:
That was definitely worth knowing. Thanks! I'm headed to the boat as soon as the weather lifts to check controller specs and existing panel size.
Click to expand...

The easiest way I've found to get MC4 connectors on the boat is to buy a 3' MC4 extension off Amazon. Cut them in half. Then use 10awg butt connectors and 3:1 heat shrink to splice them on. I show this in the very beginning of this video.

 
I just replaced the factory 90W panel, two battery controller and remote display with a 400W BougeRV bifacial panel and Victron 100/50 smart controller. It was pretty easy and works perfectly for me. I had to remove the extra (+) and (-) 10GA wires going to the starter battery since the Victron only has connections for one (house) battery. The ACR will spill any extra needed voltage to the starter battery. Accessing and removing the old controller wasn't easy as I had to remove the teak bulhead in the cave. I had to cut and reconnect the wires going to the lamp behind the bulkhead in the cave as they were short. I installed the new controller where the old remote display was on the bulkhead and ran the wires thru the small hole that was behind it. I also had to install two MC4 connectors on my old panel wires that come out near the base of the mast atop the cabin. I used the mounting hardware from the old panel but had to drill new holes in the frame being careful not to damage the panel. Also had to loosen the small allen set-screws on the SS rack hardware and slide it where I needed it as necessary.
 
RT23 Kingfisher said:
I just replaced the factory 90W panel, two battery controller and remote display with a 400W BougeRV bifacial panel and Victron 100/50 smart controller. It was pretty easy and works perfectly for me. I had to remove the extra (+) and (-) 10GA wires going to the starter battery since the Victron only has connections for one (house) battery. The ACR will spill any extra needed voltage to the starter battery. Accessing and removing the old controller wasn't easy as I had to remove the teak bulhead in the cave. I had to cut and reconnect the wires going to the lamp behind the bulkhead in the cave as they were short. I installed the new controller where the old remote display was on the bulkhead and ran the wires thru the small hole that was behind it. I also had to install two MC4 connectors on my old panel wires that come out near the base of the mast atop the cabin. I used the mounting hardware from the old panel but had to drill new holes in the frame being careful not to damage the panel. Also had to loosen the small allen set-screws on the SS rack hardware and slide it where I needed it as necessary.
Click to expand...
Thanks! We already have the Victron but I'm not sure which model (weather is keeping me from playing on the boat). The Bouge 400W seems to be the panel of choice, and the MC4 connectors seem to be what everyone has to install, so thanks for telling me what to expect replacing those. I've fought with those allen screws before when repositioning the existing panels; I recall it being awkward. Much appreciated.
 
Swinging on this post to see if anyone has thoughts on JMarshalls’ hypothesis that keeping the battery charger running all the time while on shore power might lower the longevity of the batteries.

I’ve been thinking the same, and have started turning the battery charger off. It’s been 3 days and the batteries never get below 94% overnight (and fully charge by the late afternoon in the sun).

Is there a good reason to keep the battery charger on if the solar panel seems to be keeping things topped off?
 
Interesting... I recently noticed my dock neighbor doesn't connect his R27 to shore power so I asked him about this. I thought with flooded lead acid batteries, any amount of cycling would take it's toll on the longevity of the batteries. He told me he leaves nothing on so there is just very minimal parasitic current draw... probably doesn't get below 94%. I on the other hand always connect to shore power with the battery charger on (when not on the hook). I leave my fridge on 24/7. My rationale is that the energy consumption/cost is negligible and I am not cycling the battery (as much). For those of us here in the Pacific Northwest that use our boats year-round, winter (and even some summers) can be a different story. No sun for solar and we use heat and/or dehumidifiers for interior moisture control. Those with lithium batteries are in a whole different camp. We have an exceptional electric/battery shop/store nearby and I am going to get their opinion... I'll report back.
 
R23 Kingfisher said:
Interesting... I recently noticed my dock neighbor doesn't connect his R27 to shore power so I asked him about this. I thought with flooded lead acid batteries, any amount of cycling would take it's toll on the longevity of the batteries. He told me he leaves nothing on so there is just very minimal parasitic current draw... probably doesn't get below 94%. I on the other hand always connect to shore power with the battery charger on (when not on the hook). I leave my fridge on 24/7. My rationale is that the energy consumption/cost is negligible and I am not cycling the battery (as much). For those of us here in the Pacific Northwest that use our boats year-round, winter (and even some summers) can be a different story. No sun for solar and we use heat and/or dehumidifiers for interior moisture control. Those with lithium batteries are in a whole different camp. We have an exceptional electric/battery shop/store nearby and I am going to get their opinion... I'll report back.
Click to expand...

With 320AH of LFP and 420 watts of solar, last year I went from May 20 to Sept 1 without plugging into shore power. This year, I disconnected shore power on May 8th, and haven't plugged in since. (Pacific Northwest).

I turn off what's not being used, but leave the refrigerators running (both of them). By morning, the boat's usually down 20% SOC and sunshine brings it back up.
 
All very useful; thanks. I installed a Renogy 250W bifacial panel which seems to be working. The connection was straightforward, the challenge was drilling new holes in the panel frame to connect to the mounting hardware, which of course didn't align with the original mounting arrangement; always fun in a tight place. But I got to buy a right angle drill attachment, wrench, and hex-based cobalt bits to do it, so now I have those on hand.
 
Submariner said:
With 320AH of LFP and 420 watts of solar, last year I went from May 20 to Sept 1 without plugging into shore power. This year, I disconnected shore power on May 8th, and haven't plugged in since. (Pacific Northwest).

I turn off what's not being used, but leave the refrigerators running (both of them). By morning, the boat's usually down 20% SOC and sunshine brings it back up.
Click to expand...
So the only hiccup was that when I got on the boat this morning and looked at the victron number by the sink, it showed 91%, but the battery icon next to the 91% only showed one bar. So I panicked and turned the battery charger back on and the boat shows a full charge (well 99.7%) and a full battery icon.

Do we know why the battery icon would show empty even though the victron said the batteries were at 91% charge? Unfortunately I’m unable to post a picture of it.
 
It is my understanding that cycling (depleting/charging/depleting/charging) will not degrade lithium (LFP) batteries like it will lead acid. And also LFP can be nearly completely depleted before charging unlike lead acid. What I am unsure of is what extent of depletion (5%, 10%, 20%...) will result in any noticeable degradation of a lead acid battery. My guess is any, although maybe negligible for a small percentage.
 
I'm not on my boat or near my phone (Victron app) right now but are you sure that icon is the battery state and not the wireless signal strength?
 
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