Solar Panel Mounting

[Roy 845]

The past 3 seasons here in Connecticut I've had a standard 100 watt Solar panel lashed to my Starboard lifelines supported by the deck up near the forward hatch of my 1977 O'Day 22. "Penelope" resides at a floating dock at My Boat Club and while there is fresh water available there is no electric. I access her from the Main dock using my 9.9 West Marine Tender. The current Solar Panel does a fine job of keeping my Deep Cycle Battery charged but it is in an annoying location not only physically but aesthetically as well. I've seen various solutions for mounting on railings or hanging off the stern none of which I particularly care for. I'm beginning to lean to mounting a flexible panel or two, 1 Port & 1 Starboard, high up on the Hull forward of the Keel and I'm just concerned with the salt water causing problems or maybe something else I haven't thought of. Supposedly the wiring junctions are very well protected but I'm open to listening to all other opinions, criticisms, thoughts and musings that members can toss my way before I make a final plan. I'm not concerned with drilling mounting points through the Hull as I have had lots of experience repairing damage to her already to get Her seaworthy to begin with. I'm wanting to add a second battery to the system as a back up and for extra capacity as well in case I want to do an overnighter somewhere. The electrics I have on board are;
1. VHF Radio
2. Required nav lighting
3. Cabin lighting
4. Am/Fm/ Sirius Radio
5. Power ports for cell phones etc.
6. Bilge Pump
7. Tiller Pilot
8. Raymarine Sonar, GPS Unit
All comments are appreciated

 

[dlochner]

I think you are correct to be concerned about the saltwater dunking. On deck or on an arch the panels get sprayed but not dunked. The panels are weather proof, but I doubt they will survive many submerges especially at speed.

Another factor is sun angle, on the sides of the hull the sun will hit the panels at an oblique angle which will not provide much power.

 

[Ron20324]

Another factor is sun angle, on the sides of the hull the sun will hit the panels at an oblique angle which will not provide much power.

 

[Timm R Oday25]

As an owner whose boat resides on a mooring all summer, I understand your concerns . We use a 20 watt solar panel mounted on the stern railing . It's completely out of the way all the time. It is held with quick clamp connectors that allow for easy tool less removal come fall . At 22' ,you are going to be hard press to have the space . We also have two group 31 batteries with a "Sun" brand controller .
With led lights our electrical consumptions is minimal . The auto pilot is easily our biggest user of amps. With a 20 watt solar panel and a 8 horse outboard that puts maybe 2.5 amps back into the batteries ,we can easily stay out for a week .

 

[Benny17441]

Your equipment list does not tell us anything about the usage. The fact that you have a single battery and you seem to indicate that it keeps fully charge gives an indication that your usage is not that intensive, but in order to nail down your need it would be best if you conducted a Power Survey. Every unit or fixture on the list should indicate in a label how many Watts or Amps it consumes. Using the formula Amps= Watts / Volts list the number of Amps every unit uses. That unit will be assigned to the number of Amps drawn in one hour or (Ah). Deep cycle batteries are rated in Ah. The normal wet cell Group 24 will have about 90 -95 Ah and the Group 27 about 100-105 Ah. Prepare a template indicating 1) name of fixture 2) Number of Ah it is rated at, 3) Approximate time it is used in a 24 hour period, 4) Multiply Ah by hours or fractions of (a microwave oven may use 66 Ah but if only used for 3 minute to heat a cup of water then its use is 3/60 * 66 or 3.3 Ah. Estimate the usage for every item and calculate the Ah draw for each of them. 5) Add all the Ah calculated and you will have a very good idea of your actual daily usage. In order to extend the life of wet cell batteries they should not be drawn down to more than 50% of their capacity. In other words a 100 Ah battery should only be discharged to 50Ah before being recharged. If your usage survey exceeds the 50 Ah then you surely need a 2nd battery. The thing about battery health is that they should be charged to 100% every time after being used. A 100W panel considering efficiency losses renders about 7.5 Amps in optimum sunlight conditions. Given that you only have an average of 5 hours daily of good sun you can only replenish approximately 37 Ah per day. Since good sun conditions cannot be guaranteed day after day then you must use a weekly average which resembles the conditions in your area. Let's say you only have 4 days of good sun and 3 days of partly cloudy so you can get 148 Ah for those 4 days and perhaps 60 for the other 3 days for a weekly total of 208 Ah or a daily average of 30 Ah. Panels that are not pointed directly at the sun or at an angle will not deliver an optimum output. The placement of the panels should be in a location where it can catch the most optimum sunlight for the longest time. Check the resting voltage on your battery with a digital multimeter. With a battery at rest (no charge, no loads) for at least two hours a fully charged battery should have a voltage of 12.7V Anything less is undercharged. It is understandable that with a solar panel it may take 2-3+ days to attain full charge instead of 5 to 6 hours from a shore power charger and that is the sacrifice of battery life we make. If it is taking more than 2 to 3 days then the solar panel is not being adequately pointed or has lost efficiency. Consider the adequacy of the solar panel to charge two batteries.

 

[TimFromLI]

My boat is on a mooring, I use a 160 watt flexible solar panel mounted on the cabin top under the boom. I drop the dodger and bimini when we race so they were not good options for mounting. Sure it's not ideal but it's not that bad. The boom only shades it if the boat is pointing directly at the sun which is rare. I used velcro fasteners- I don't like putting holes in my boat. I have had a little corrosion in the connectors hopefully some dielectric grease will fix that. The 160 watt is undersized for my bank, I need to add more for cruising - they'll go on the dodger next summer.

 

[RitSim]

When we had our C30, it came with a semi-flexible solar panel( approx 15" x 48" +/-). When we left the boat for the week, the panel was put out on the cockpit seating. For sailing, the panel was stored below in the aft berth. The panel had sufficient wire run to allow placement, movement and storage. Worked well for 10 years. Toward the end, the seagulls caused a few dings from dropping shellfish.

 

[jssailem]

I have had a little corrosion in the connectors hopefully some dielectric grease will fix that.

I would suggest something better. ACF-50 by Lear Chemical Research Corp out of Ontario CAN.

Lear Chemical Research Corporation

Lear Chemical Research developing and compounding anti corrosion lubricants and greases, ACF-50, Corrosion Block, Corrosion Block Grease, Rust Block, effectively solving corrosion related problems in the Automotive, Aviation, Industrial, Marine, Motorcycle and Recreational industries.

www.learchem.com

Very good stuff for the purpose you propose to fix. It only takes a little dab to give you multi-year protection.

 

[Roy 845]

When we had our C30, it came with a semi-flexible solar panel( approx 15" x 48" +/-). When we left the boat for the week, the panel was put out on the cockpit seating. For sailing, the panel was stored below in the aft berth. The panel had sufficient wire run to allow placement, movement and storage. Worked well for 10 years. Toward the end, the seagulls caused a few dings from dropping shellfish.

I understand the seagull thing. They were sitting on the Piling that holds my Slip Finger and were pooping on my cockpit so I put spikes on the piling....now they're sitting on my outboard Some Terns were nesting nearby and keeping the Gulls away but once the Terns leave it turns into a mess.