325 Watt Shade Tolerant Flexible Solar Panel with Polycarbonate & J-Mount Brackets - Sunpower A+ Grade 24.4% Efficient Cells
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325 Watt Shade Tolerant Flexible Solar Panel with Polycarbonate & J-Mount Brackets - Sunpower A+ Grade 24.4% Efficient Cells
Take your off-grid power further with the 325W Shade-Tolerant Flexible Solar Panel, built with premium SunPower A+ grade Maxeon cells delivering up to 24.4% efficiency - among the highest in the industry. Designed specifically for marine and van applications, this panel provides exceptional output even in challenging, partially shaded environments.
Unlike conventional panels, this 325W design is engineered with a multi-section cell layout that helps maintain power production when part of the panel is shaded. Whether it’s a mast, boom, AC unit, or roof vent casting a shadow, the panel continues generating power where others would drop off significantly. Video on them here.
Built for real-world installations, this semi-flexible panel conforms to gentle curves, making it ideal for:
- Biminis and dodgers
- Van roofs
- Boat decks and cabin tops
- Curved surfaces
The low-profile, lightweight construction reduces wind resistance and eliminates the need for bulky mounting hardware, perfect for clean, efficient installs.
Installation Note:
For best performance and longevity, mount the panel on a stable surface or between support bars to prevent stress on the solar cells.
✅ Solar panel kit includes:
- PV solar panel module
- Sheet of twin wall polycarbonate backing
- Two J channel mounting extrusions
- Owner’s Manual
📦 Ships Next Day UPS Ground from Denver or Michigan.
Key Features
- High Power Output – 325W of solar charging with industry-best 24.4% efficient SunPower A+ grade Maxeon cells.
- Shade-Tolerant High Efficiency – Four-quadrant design keeps energy flowing even when part of the panel is shaded.
- Built for Marine & Mobile Use – Lightweight, semi-flexible, and rugged enough for boats, camper vans, and curved surfaces.
- Easy Setup – Includes mounting grommets, blocking diodes (silicone-protected), and 3 ft. #10 solar cable with MC4 connectors for fast installation. Comes with Poly and J brackets for secure setup.
-
Secure Mounting Options – Works with bolt kits (recommended) or strong magnet kits (wind-tested to 55 knots). Video on them Here.
- System Ready – Pair with a solar controller and solar wire with MC4s pre-attached for a complete off-grid setup.
Specifications
| 325 Watt Shade Tolerant Flexible Solar Panel | |
|---|---|
| Model | CMP23325FX-STP |
| Rated Power | 325 Watts |
| Peak Power Voltage (Vmpp) | 58.1 Volts |
| Peak Power Amps (Impp) | 5.6 Amps |
| Open Circuit Voltage (Voc) | 70.9 Volts |
| Short Circuit Current (Isc) | 6.0 Amps |
| Cell Conversion Efficiency | 24.4% |
| Dimensions | 40.7" x 59", 1035 x 1500 x 4 mm |
| Weight |
22.7 lbs, 10.3 kgs |
| Cell Layout | 6 x 17 (17 are half cells) |
Installation of 4x 260 Watt Flexible Shade Tolerant Solar Panels on "Mariah":
I ordered the CMP23115FX-120-ST panel for a special project on my Toyota Tacoma to create an on board solar generator to charge the main battery and a lithium battery. The first panel I received was defective, it generated random voltage and no current so I pretty much chalked it off to the protective diodes in the junction box. I contacted Tom and let him know everything I could tell him without disturbing the sealant in the junction box. He quickly put me in touch with Cindy to arrange a replacement. I have received the replacement and am very impressed with the improvement of quality in the new junction box which has cable restraints and better cable which is easier to work with when installing. The new one also seems to have upgraded solar cells. Guys thank you very much for looking after me in my custom truck generator! Also to everyone else, you’d be taking a chance if you don’t obtain your solar needs from these guys!
Brenon
I did a search for a solar panel system for my Bavaria 35 and Tom's website was the most clear and straightforward website I found. And Tom was extremely helpful in helping analyze my electrical load needs. He put together a great system of semi-flexible panels to be located on my bimini, two 145 watt panels and two 55 watt panels. They work great. I highly recommend Tom and his company, Custom Marine Products.
did just what I wanted; kept the batteries up over the winter
Easy installation and it’s pushed us over the line in sustaining our demands to run the boat’s loads through the day in the Bahamas!
We installed two 155 watt panels, and two 120 watt shade tolerant panels one year ago. These have generated more than enough power to run refrigeration overnight at anchor. The panels are bimini mounted with the shade tolerant versions near the boom. I highly recommend the shade tolerant versions as in practise they perform as well as the higher wattage panels.
Harold Beer, Lansing, MI
March 25, 2025
I bought and installed this unit with Tom's help and advice over email back in 2020 and it has been a huge help ever since. It makes our battery bank seem twice as big and has taken a decent amount of abuse occasionally getting walked on.
Couldn’t be happier.
Our New 4 Quadrant Design
The diagram along side illustrates how these amazing panels work. Instead of the normal 2 quadrant design we use a new split cell design allowing the panel to have four quadrants of solar cells linked in series and isolated with inner panel blocking diodes. If one or two quadrants are shaded, the other quadrants perform at normal output. This can increase shaded panel output by 3 times that of a standard shaded panel.
SunPower Maxeon Shade Tolerant Series
Solar panel shading is a major issue on many boats. Shading can reduce a standard panel performance by over 60%. Custom Marine Products has developed a series of semi-flexible shade tolerant solar panels that have superior performance when partially shaded by boat equipment or nearby objects. These solar panels have high performance SunPower Maxeon cells. The diagram to the left illustrates how these amazing panels work.The junction box is mounted in the center or the edge of the panel enabling the panel to have four quadrants of solar cells linked in series and isolated with diodes. If one or two quadrants are shaded, the other quadrants perform at normal output. The result is a panel that will provide up to three times the output of a standard panel when shaded. These shade tolerant panels are ideal for bimini and dodger mounting where there is boom, mast and instrument pole shading. Patent pending
What Makes Our Panels Superior
- Our Semi Flexible Shade Tolerant Panels use only SunPower Maxeon A+ Cells.
- The SunPower cells we use in these panels are 24.4% efficient.
- We use an ETFE laminate coating that won't delaminate or go milky for 10 years.
- The ETFE laminate is applied with a prismatic finish to direct sun energy into the cells.
- Panels use internal blocking diodes to isolate the quadrants unaffected by shading.
- We build 6 grommets into the panels edges for easy installation with our mounting kits.
- All panels come with 3 foot pigtails and MC4 connectors.
- Our junction boxes are filled with Non Gassing Silicon RTV for maximum electrical waterproof insulation and corrosion resistance.
Solar System Design and Installation
We have put together a collection of helpful information for our customers on everything to help you design you perfect system and installation instructions.
SHOW ME HOW TO PUT TOGETHER MY SYSTEM
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Shipping
Products ship the day after payment (domestic).
- Free shipping on orders over $1,500 (Lower 48 US states).
- $65 flat-rate shipping for orders between $500–$1,499 (Lower 48).
- International shipping takes longer. No tariff charges added — call for pricing.
Custom Designs & Custom Made Panels Available on Request
Our engineers will work with you to design a solar system specific to your needs including Lithium Batteries if you like. (Batteries are 10% off w/ solar system purchase).
If you'd like a custom solar panel, we can do it at $10/watt, more info here: Custom Solar Panels
Call Us: 248-712-1526
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