Solar Panel for Benetau 321

[rsotomayor]

Good morning:
What would be a good choice for solar panels for a Benetau 321?

Requirements are very basic. A battery for starting,house battery, 12 V fridge(only used while sailing) and bilge pump. Basically only need it to recharge batteries, as shore power not yet restored. And for weekend trips,anchor lights etc.
I have a battery charger uses 110V.
I would like to have it mounted on the deck forward of the companionway. Have heard of systems that are flexible and can withstand standing on them.
Any general orientation will be appreciated.
Ramon Sotomayor

 

[Andrew 321]

I hung a single 100 v panel off the stern lifeline of my 321 for a couple of seasons and it seemed to manage fairly well in PNW climate. To be even more covered I now doubled up to two of these panels hung on the lifelines amidships. This way my batteries can stay functional for a Couple of days at anchor without running the engine.

 

[rsotomayor]

The question really is because if it is mounted on the deck below the boom, there will be time when it will have a shadow. So, I am not clear how nuch this would affect it.

 

[Andrew 321]

That's why I hung the single panel off the stern and the two I have now on the rail. Some shadowing but not as much as under the boom. If you are worried about output, you should also make sure to use a high quality controller (SMPT).

 

[dehler25]

Even a small shadow has a big impact and a boom would cast a large shadow. The extra effort to create a mount that gets even the one into clear sunlight would be worth the effort. I have been seeing where some have removed wind generators because they cast a shadow which negated their value.

 

[Ron20324]

On my B32-3 I mounted two 40 watt panels between the mid and aft bows of the bimini.

 

[stevemitchell]

I have been considering doing this in 2018 on my 311. I had considered @Ron20324 's approach of putting them on the bimini. I am considering flex panels similar to this setup: https://svviolethour.com/2017/06/28/harnessing-the-sun-solar-power-on-a-sailboat/

 

[rsotomayor]

Hi . Started this post last sunday, but have not followed up because internet has been very unreliable.

Is it very critical to have the sun perpendicular to the panels? If so then they would only function during noontime.
Shortest days in the caribbean are about 11 hrs. So I wonder if having more sunlight than in the PNW would overcome the time that the boom would cast a shadow on the panels?
RS

 

[Andrew 321]

My impression is that shade is much more of a problem than how perpendicular the panels are. Incidentally some folks say the longer days in the PNW summer give us more sunlight than further south. Hard to believe it though.

 

[Kings Gambit]

I have an 85-watt monocrystalline (fixed-frame) panel from Nature Power that lies on atop the cabin deck fwd of the companionway under the boom vang most of the time. It delivers more power than I need to keep the battery up while the boat is in the slip; but I also use it at anchor, sometimes along with a second one that I also have on the boat. I've noticed from the charge regulator that essentially zero charge is produced under clouds or when the unit is shaded. Low angle of incidence of sunlight produces some charge. But, of course, full on sunlight at high incidence delivers the highest charging rate.

At overnight anchor, with a fridge and various other things running, the one 85-watt panel is not enough to do the job over the long haul; that's why I have a second one, also 85 watts, that I pull out when needed. Usually I oriented these panels toward the sun as the day passes to maximize charging; so they do not lie in the fixed location fwd of the companionway. I reported some of the challenges with the panels under cloudy skies and short days in the thread at the link below; there is some good discussion from others included.

KG

https://forums.sailboatowners.com/i...lenges-keeping-batteries-up-at-anchor.182883/

 

[rsotomayor]

That is the position I am looking at perhaps with a single 100 watt.
According to Nigel Calder, the temperature also is important with decrease power as the temperature increases, so this may also be a problem in the tropics. I have been looking at different companies and found a flexible panel that seems acceptable for less than 200$ including the comptroller.

 

[Ron20324]

...Is it very critical to have the sun perpendicular to the panels? If so then they would only function during noontime,..../QUOTE]

Yeah, ideally- but not critical- the sun being straight up from the panels would be good. But it just does not happen. The panels will charge as long as the sun hits them from some direction. IIRC, mine charge on just daylight- no sunshine.