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Last Updated on September 4, 2019 by Amy
In this post, we tackle a big project for our outfitting – solar panels. Solar panels are the most popular method of gaining power for a cruising boat and on a catamaran, there’s tons of room for solar panels.
First of all, massive thanks go out to another Helia owner, Tad on Bisou, who pioneered the solar approach that we’ve taken on Starry Horizons and was incredibly generous about sharing the details of his set up and answering lots of questions. Thanks Tad!
Table of Contents - Click to Jump
Determine How Much Solar You Want
This is actually fairly easy. After nearly five years onboard, we’ve learned that the answer is “as much as you can get”.
Solar panels are the most efficient way cruising boats can get power, and walkable solar panels are not intrusive to sailing and cruising life, and they look good on the boat. Put on as many solar panels as you can.
Even with an optimum set up, it’s unlikely that we would be able to run our navigation equipment and autopilot on solar panels. Which means that on passages with good sailing conditions, we end up needing to run our generator or engines for power.
Power Usage Spreadsheet
I found a generic form online and modified it for what I assumed would be our usage. You can download a copy of the spreadsheet to customize for your own usage here: Power Usage Calc.xlsx. I’ve got another post planned where I’ll detail out exactly how to use that spreadsheet, but the remainder of this post will focus on our solar setup.
Placing the Solar Panels
Next, we needed to figure out how many panels we could actually fit on Starry Horizons. Based on a suggestion from Pat, we targeted Solara solar panels, and thanks to Tad, I had a basic layout of solar panels that would work on the Helia. Since I was doing all this research before we had actually seen Starry Horizons and needed to figure out exactly how many Solara panels would fit, I did a bit of graphical wizardry. Using a graphics program, I traced a to-scale outline of the Helia and created to-scale panels that I could move around and see where they would fit.
This was immensely helpful and allowed me to mix and match all different sizes of panels, both from several manufacturers as well as the different size Solara panels.
Solar Panels We Installed
We installed 10 panels in total, eight 120W panels and two 50W panels for a total of 1,060W of capacity.
Purchasing Solar Panels
While we were in Miami, we were lucky to meet Rob Warren from Coastal Climate Control at the Miami boat show who distributes the Solara panels we were looking for. He was very helpful answering questions about the panels and helping us flesh out our set up. The Solara panels are classified as marine grade, “semi-flexible” panels and have a non-skid walkable surface on them. This was important to me as I was worried about how a “regular” panel would hold up in the marine environment and with the amount of real estate the panels would take up the boat, I needed to be able to walk on them.
Since the solar panels are set up to output at a higher voltage than ideal to charge the batteries, we also wanted to get solar controllers. There are two options, PMT controllers, which are the older generation and don’t do a good job of maximizing panel efficiency and Maximum Power Point Tracking (MPPT) controllers, which use an algorithm to find the best combination of voltage and current to deliver power to the batteries. As Rob explained to us, an MPPT controller can result in 10-20% more output from the same panel. That’s a lot!
Another concern we have is shading. If panels covered up by shade, their output drops. And if several panels are wired in series together, the output from all of those panels can drop even if only one is covered with shade! In order to maximize the efficiency of each individual panel, we elected to go with individual Genasun MPPT controllers for each panel.
Wiring Solar Panels
We ordered the panels and Pat was nice enough to let us ship them to him so they’d be ready for us once we got over to Palmetto. One of the first things we did when the boat arrived in Palmetto was put a plan in place for running all the wiring for the solar panels. This is one of those areas where it would have been great if FP had put a bit of extra thought into making this easier for aftermarket installation. They only have very small access points into the vertical supports in the cockpit (not nearly big enough to run all the wires we needed) and the headliner panels in the cockpit are glued in place so if we wanted to hide wires behind them, we’d need to tear them out and likely replace the panels.
So instead, we decided to do something pretty custom and once again Rian at Mondo Marine came to the rescue. For all the panels at the aft end of the boat, we either ran the wires into the traveller, or straight down into the cockpit. Rian and Aaron from Mondo then came up with a fiberglass conduit running from the traveller into the salon. And then from where the wires enter into the salon, they made up another fiberglass cover to hide the wires as they run back behind the oven. It turned out pretty slick and unless you’re really looking, you can’t even tell that these additions weren’t part of the boat from the factory.
For the panels on the forward part of the boat, we hid the wires in the “gutters” in the hardtop and dropped them through the salon ceiling behind the oven. We’ve kept a really close eye out for leaks and had to rebed things a few times to make sure we got it completely secure, but everything looks good (at the moment at least!). The wire for the solar panel on the hardtop gets run through the conduits in the hardtop, down the forward starboard leg in the frame and down into the boat that way.
All of the wires come together in the closet for the port aft berth where our electrician George wired in by-pass diodes (hot spot preventers) and then all of the Genasun controllers. Well, he did the first 9 and then I did the last one, thanks to all he taught me! George also wired in a kill switch for us just in case we need to isolate the solar panels and work on the system.
Solar Panel Monitoring
Now, all that detail and you probably think this saga is over, don’t you? Well, think again my friend. We needed some way to monitor how well the panels were performing, as well as more detailed monitoring of our batteries. Once again, I shamelessly stole Tad’s idea for a monitoring system and looked into a company out of Germany called Philippi. Their PSM monitor has the capability to monitor solar, batteries, tanks and a host of other features should we decide to expand the system someday. Tank monitoring was something I was interested in as FP does not provide any holding tank monitoring, even as an option. I was getting really tired of removing a panel to check the black water level!
Fortunately, Rob Warren and Coastal Climate Control also distribute Philippi systems. He and I spent quite a while discussing our setup and what components we would need. We set up the system so that we could have detailed monitoring of our house battery bank, the voltages of our port and starboard engine start batteries, solar output, and holding tank sensors. The detailed monitoring of the house battery bank also shows us the net charging input whenever the batteries are being charged by the battery charger (generator/shore power) or engine alternators, but we don’t currently have it set up to show the output from those sources.
For those of you who are interested, I put together a very basic schematic of the components that we’re using and the Philippi literature does a pretty good job of detailing out exactly which components are necessary.
The touchscreen monitor is a pretty cool display and I like the graphical representations it shows for the different options.
Solar Panel Performance
Most of our days since installation have been spent on shore power or under cloudy skies at anchor. During sunny periods, I’ve regularly seen 40amps being pumped out by the solar panels, all the way up to a max of 64amps! Even hazy clouds have cut this down quite a bit, but even on those days, we’re putting about 12-15amps into the batteries during sunlight hours. This doesn’t seem to be quite enough to have full independence, but as we have to run our Cruise RO watermaker every 3-5 days, and thus the generator, it should be fine for our purposes.
What We Would Do Differently
Three of the panels we installed are the semi-flexible walkable panels that are just aft of the traveller. If there is any place on the boat to put rigid solar panels, with higher efficiency, that’s it. We’ve also seen a lot of catamarans with solar panels in this position and extending off over the back of the boat.
Hypothetically, we could take off the three semi-flexible walkable solar panels (360 W total) and put on at least five rigid 150W Solara panels (750 W total).
Additionally, we could add a whole other 120 W semi-flexible walkable solar panel on our hardtop. It’s that big!
This would up our total solar capacity to 1,570W.
In 2018 we changed our batteries to lithium ion. Our solar controllers were not compatible, so we had to switch them too.