“Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did do. So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover.” – Mark Twain


Solar Panels – Flexible Panels vs. Hard Bimini & Rigid Panels

So now that I have put the non-solar powering item to bed (at least for me), I plan to go with running the diesel instead of a small gas generator, it’s time to turn my attention to solar.

Since I had seen this post by the always helpful and inspirational MaineSail, I had planned on going with the flexible Solbian solar panels on my bimini.    At the Newport Boat Show I spent a significant amount of time talking to the people at the Solbian booth.  It was at this point that I began to think my plan for the Solbian panels might not work as I expected.

Sure enough, when I measure and planned out where the panels would be I couldn’t fit what I wanted.  I had hoped to fit two of the CP125 panels on my bimini with room to add some smaller panels down the line.  But I can’t fit those panels without crossing a bow for the bimini support which is a big no, no.  The panels can flex on the bow and break.  This means I would either have to go with the more expensive SP series panels or go for smaller sized panels than I wanted.

Since we are going to cruise in a smaller boat I know we can’t fit enough panels to be entirely self sufficient.   However, I would like to reduce the amount of time we have to run the engine to two hours or less per day.  With that in mind, I worked up the attached power consumptions to help me figure out what my max loads will be and how much solar I should try to add.  I included a watermaker in this analysis and I have played with the refrigerator amount as well because we plan to have a watermaker and a 12 volt freezer (leaning towards the Engel).  I am also in the process of verifying our current 12 volt use based on readings from my battery monitor.  I got the form I used from someone on Cruisersforum.com, I wish I could remember where so I could credit the person who created it.  A copy is attached.

Power Consumption worksheet 2

I divided my usage up into 3 areas, under sail which is the worst case conditions, on the hook and on the hook with no one on the boat (for when we go traveling on land for a couple of days).  I have estimated we will use between 55 and 165 amp hours per day while on the hook and as much as 200 amp hours per day under sail.  With my current alternator, 60 amps, assuming a 75% efficiency (I am not entirely sure what efficiency to use) I can get back 90 amps from running the diesel for 2 hours.  This would leave me with around 75 amps per day I would have to get back from solar (or more so I could run the engine less).

Solbian Panel Option

Under this option the first thing I would need to do is bring my current bimini to a canvas show to have some repairs made (rips and thin spots that have developed in the last 12 years since it was new).  I have estimated this at about $700 based on talks with the canvas shop that made repairs to my dodger last year. Then I would need to make the bimini frame more rigid.  It is currently 1″ thick wall stainless held in place with straps.  I would ditch the straps and then make the structure more ridged with some additional 1″ tubing.  The Solbian panels could then be mounted to the bimini with Velcro a la MaineSail’s method.  Here is what that layout could be.

Solbian Panel Option

If I went with the smaller SL90L panels that would put the cost around $3,700 for 37.4 amps per day.  With the SP125 panels it would be closer to $5,000.  Not a very cheap option.

Hard Bimini & Rigid Panels Option

Another approach would be to rebuild my current bimini with a hard, rigid cover instead of the canvas.  I research this and found a number of people who have done with the King Starboard, purpose made panels from Hard To Top, Azek exterior plastic for houses and expensive, custom made fiberglass hard tops.  The custom fiberglass is out due to cost.  Same with the Hard to Top.  Starboard would cost about $500 for enough material.  But the Azek would only be about $125 and I could make the hard top from one sheet.  Also at only a 1/4″ thick and made from plastic, it wouldn’t weigh too much yet with proper backing plates it would be able to support solar panels and a few other things.  You can work the Azek trim sheets just like wood and I do have access to a really talented carpenter that could likely help me make this look professional.  I could fit 3 large solar panels on this hard bimini (either 3 95 watt panels or 2 160 watt panels and a 95 watt panel).  The cost to constructed the hard bimini would actually be less than getting my canvas one repaired.  Here is what that layout would look like.

Hard Bimini Option

If I went with the larger 160 watt panels and a 90 watt panel I would get about 80 amps per day.  This would cost about $2,500.

NOTE: This is based on the Go Power! solar panels sold by Defender.  I need to do a lot more research to figure out if these are good panels or not.  I suspect I am not making a true apples to apple comparison and may need to update this when I have research solar panels more.  Please feel free to add any comments on these panels or recommend some good ones.

I am attaching a parts list for each approach.  Let me know if you think I have missed anything.

Solar Cost Evaluation

Based on this first bit of research it’s looking like the better way to go is the hard bimini.  I would love to here from others on which approach they think is better.

Cross posted on the C310 Owners Forum.