Pearson Boats - Common Systems > Deck Mounted Hardware

Where to mount 15W solar panel?

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Dave:
I bought my 15w solar panel from Harbor Frieght for $70. They sell the mounting bracket that tilts for another $30 and a controller for $20. All of it is made in China. From what I have read it is all decent stuff. There is rumor that the US may put a tariff on solar panels coming from China because how inexpensive thay are producing them.

I think that would really set back the movement to use solar technology.

selene:
Dave - I'll be interesting to see how your project goes.  Harbor Freight is always a bit of a crapshoot - sometimes you get an unbelievable bargain, sometimes not so much. I hope in your case it is the former!

Richard - good point.  I had the same question when I was thinking it through a few weeks ago, and posted it on SailNet.  Here is a useful answer I received:
For a 15 or 20 watt panel, "overkill" with a small MPPT controller might very much be the way to go. They can provide a 20% boost in effective charging power, and while $120? for the Genasun might be as much or more than your panel, how else can you get 20% more power without buying a more expensive panel? Then there are the batteries themselves, the cheap controllers tend to be "all or none" affairs that turn on or off, period. That's not optimum for the batteries. The Genasun is a 3-stage controller, assuming your batteries can be topped off by it, it will keep them nicely formed with a 100% charge.

Of course, if you're just working with one WalMart Group24 battery...warranty replacement is the most effective way to go.

Unless your solar panel is a small percent of your battery capacity, in which no controller or regulation may be needed at all. (Except a blocking diode to prevent backcurrent at night. Not all panels are built with one.)

Like you, I am not looking to recharge a long-term cruising bank, and so am torn...the Morningstar range looks good, and could save some money; I have emailed them, and will let you know what products they recommend (as a datapoint).

Libations Too:
Thanks Selene!

I did look a bit more closely at the panel options themselves. The Sundance Solar option that I referenced appears to NOT have the simple j-box option. The result is that one ends up needing the proprietary MC4 cable connectors. In retrospect I think the SunWize panel that you initially selected may be the better of the two. I also measured my likely mounting location (port or starboard pushpit rail) and it appears that the 40 watt panel may be too large; I am now leaning toward a 30 watt panel.

I also did a little research on how to wire downstream of the controller, which adds more questions for me. Whether to wire directly through my master battery switch or directly to one of my two batteries is the question. Has anyone here researched this aspect of the installation? I think the simplest installation would go through the master switch...thus allowing me to charge either or both batteries without adding more devices. Another (more costly) option would be a panel and charge controller wired to each of my two batteries. This would double the cost, but would also double the total output. Or perhaps two 20W panels through one controller to my master switch (this option has the possible advantage of smaller, easier to mount panels with one panel on each side of the boat...but can one run two panels through the low-cost Morningstar controller?). And yet another possibility is perhaps one 20W panel, no controller, and through my master switch to both batteries...could this work?

Any thoughts or comments would be appreciated.

selene:
Response from Morningstar.  I asked for a suggested PWM controller for my boat - hopefully representative of others too (2 G27 lead/acid, 230AH total, single bank, possible 15-40W solar panel).  Their reply:

"I would suggest either the SunSaver-6 (3rd Generation), or the ProStar-15.  These are both PWM charge controllers, and are equipped with Three-Stage Charging.  (Bulk, Absorb, Float)    The Float stage is extremely important regarding battery life. Without Float, the charge controller will continually charge the battery at the absorption voltage.  There is the potential to "cook" the batteries.  During the Float stage, 12V batteries will be held at only 13.6 volts with minimal current.  This helps to preserve battery life."

The comments about the float stage reflects other research I have seen; not all controllers have it, and as our batteries tend to be expensive, it is an important feature. The SS-6 is around $45, the PS-15 around $85.

I would also welcome input on the wiring...AFAIK, you can run two panels though the controller in series (if it is a 24V controller) or parallel (if under max ampage).

selene:
Yeah, I'm still kicking this around.

So I came across a company called "Solbian" who make flexible solar panels (local boatyard had some flyers).  For example, they can be fitted to the top of the bimini/dodger (boom shade risk) using zippers or velcro.

It is relatively expensive - $400 for a 23"x21" 40W 8v panel - but could be mounted with less cost.  I *think* (still researching) that a Genasun MPPT controller GV5 will boost the voltage for a 12V battery ($75). Right now I have no idea as to the longevity or feasibility, but I thought I would throw it out there in case any of you have any experience or observations. (I also need to measure my dodger before I get too excited!)

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