News and Info about Solar Panels for Sailboats

Sailboat Solar Panel News---Information
Cruising Sailboat - Solar Panels
Sailboat solar panels
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Sailboat Solar Panels 
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Morningstar controllers
The preceding discussion of PWM vs. MPPT may cause some to wonder why a PWM controller would ever be chosen in favor of an MPPT controller. There are indeed instances where a PWM regulator is a better choice than MPPT and factors which will negate advantages the MPPT may provide.  The most obvious consideration is cost. MPPT controllers will cost more than their PWM counterparts.  When deciding on a controller, the extra cost of MPPT should be analyzed with respect to the following factors.

Low power (specifically low current) charging applications may have equal or better energy harvest with a PWM controller. PWM controllers will operate at a relatively constant harvesting efficiency regardless of the size of the system (all things being equal, efficiency will be the same whether using a 30W array or a 300W array). MPPT regulators commonly have noticeably reduced harvesting efficiencies (relative to their peak efficiency) when used in low power applications. Efficiency curves for every Morningstar MPPT controller are printed in their corresponding manuals and should be reviewed when making a regulator decision.  (Manuals are available for download on the Morningstar website 

As explained in the Environmental Considerations section, the greatest benefit of an MPPT regulator will be observed in colder climates (Vmp is higher). Conversely, in hotter climates Vmp is reduced. A decrease in Vmp will reduce MPPT harvest relative to PWM. Average ambient temperature at the installation site may be high enough to negate any charging advantages the MPPT has over the PWM. It would not be economical to use MPPT in such a situation. Average temperature at the site should be a factor considered when making a regulator choice (See Appendix).

Systems in which array power output is significantly larger than the power draw of the system loads would indicate that the batteries will spend most of their time at full or near full charge. Such a system may not benefit from the increased harvesting capability of an MPPT regulator. When the system batteries are full, excess solar energy goes unused. The harvesting advantage of MPPT may be unnecessary in this situation." 
Don Casey
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When shopping for solar controllers you will find three different types:

"Shunt"  The cheapest and the least sophisticated.  It simply turns the the circuit on and off to regulate the charge.  These are the cheaper controllers you see advertised on the Internet at very low prices.  At times they are even mislabeled as PWM or MPPT. Buyer beware.  They tend to be the least reliable as well. Because of their poor performance, we do not recommend this type.

"PWM"  A more sophisticated and reliable controller, it monitors the batteries state of charge and can adjust the charge going to the battery.  This will give you a faster charge.  Typically they have three or four charging "profiles." 

"MPPT"  The most sophisticated controller, it can take the "extra" voltage that's above what the battery needs and turns it into additional amperage.  These are generally thought to be the "best" (and most expensive).

We feel the PWM is a good choice for our size of panels.  Our feelings seem to have been affirmed after reading the MorningStar's report: "PWM over MPPT" that we have linked to.                                                                                       

Another important point: If you have two isolated batteries/ banks, there are controllers that are designed to charge both, automatically. They can also give you additional options as to charging each battery.  One type that we recommend is the MorningStar SSD-25RM Sunsaver Duo.  The RM model also comes with a remote meter that makes it easier to check on your system's performance.  It also has a temperature sensor to help regulate the proper charging profile.
MorningStar Duo
Sailboat controllers
"There is greater danger for boats that connect to AC shorepower: destructive, low-voltage galvanic currents (DC) passing through the shorepower ground wire. Normally, AC is not a corrosion problem, but because the boat, pier, and wire are all connected, or due to a leakage, there can be direct current (DC) also present. This is potentially very damaging and requires additional protection."  Quicksilver Marine
"Electrical Connections" by Don Casey / BoatsUS
"Types of Marine Corrosion" Don Casey Library / Quicksilver Marine
             "Solar Panels"             BoatUS
Sailboat brands
alberg  beneteau  c&c cal catalina  hunter irwin  jeanneau  macgregor  morgan  pearson  precision starwind
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Coastal Solar Sales - Sailboat Solar Panels with Mounts
 * NTN Certified - No Tools  Needed to mount panel to rail.
A few sailing related sites:
  When Does 20w not equal 20w?
An adjustable panel, pointed properly, can produce more power than a rigid mounted, stationary panel. This is beneficial whether your boat is on a trailer, a slip or even while underway. 
The 3/8” lock nut helps to keep the adjustment lever in place so it's not lost overboard. Usually it isn't tightened fully, so you can easily make adjustments to the panel. If you want a little extra security for the panel when you leave the boat, the nut can be tightened against the adjustment lever, so that a wrench would be required to remove the panel.  We also have a lock kit available if needed.

A black plastic adapter is included in the clamp for the use on 7/8” rails unless you confirmed that you have 1” rails. If using this panel on 1” rails you will not be using this adapter.

After installing the panel, rotate to check for clearance issues. If a panel were to become loose, it could rotate and cause damage if it contacted a railing, stanchion etc. If the panel touches a surface (coaming, vertical rail etc.) you want to protect, small stick-on protective, bumper pads are available at most hardware stores, Lowes & Home Depot. They can be applied to the backside of the panel's frame at point of contact. Another option for stanchions is to use a foam pad (water noodle or pipe insulation) held on with black (more UV resistant) wire ties.

Remember shadows will decrease the output of the panel. Mount the panel in an area with minimum shade. If the boat is on a trailer or in a marina, orientating the panel towards the south will give maximum output. While sailing you also have the option to adjust the panel occasionally for maximum efficiency.

If you trailer your boat, we suggest you remove the panel. If it became loose it could be damaged. It only takes a few minutes to remove it and disconnect the wiring harness. We also suggest in heavy weather the panel be secured / protected from large waves.

If for any reason you need to disassemble any of the mounting parts, be sure to reassemble the mounting fasteners in the same order. There should be a nylon washer between aluminum and stainless components. Do not over tighten the screws, it could damage the nylon washers. 

There is a special anti-corrosion paste between the stainless mount plate and aluminum bracket mount. Do not remove this paste. You may see some residue in this area, this is normal. You may wipe the excess off but do not use any solvents as they may wash some of this protective coating off.

Cleaning Panel
Cleaning anodized aluminum (frame and brackets) is easy with the right technique. Because anodizing is so hard, you may want to use an abrasive cleaning technique with a gentle soap. Do not use harsh acidic or alkaline cleaners because they may destroy the finish. Use solvents with care as they may stain the finish. Regardless of the technique, be sure to try a test area first. One recommended technique is to use an abrasive cleaning sponge with mild dish washing liquid. Always try a test small area first to prevent a widespread problem.  The glass surface can be cleaned with a mild soap or glass cleaner.

Remember a solar panel is always “ON” when exposed to a light source. Do not connect the panel to the included wiring unless you have verified the wiring is properly connected to the controller (We strongly recommend the use of a charge controller) or that the wiring is not shorted or able to be shorted. Although shorting the panel won't damage the panel, it could produce an arc across the wires. The arc could ignite volatile fumes if present as well a small shock to the installer.  If you purchased the optional fuse holder package, do not insert fuse until you have connected all wiring, from the panel, to the controller, to the battery bank.

The panel wiring connectors come with protective caps to seal the
connectors from water and contaminates if the connectors are disconnected. These will need to be removed before connecting your panel to the included wiring. Save these caps in case you remove the panel. By replacing the caps you will protect your panel's wiring from possible contamination and corrosion. 

The panel uses ABYC color coding. The red wire is POSITIVE and the yellow wire is NEGATIVE.

Clamps after Unpacking
The adjustment levers are installed upside down for shipping. Slightly “tighten” the lever (clockwise) to release the lock nut. The 3/8” nylon lock nut and lever must then be removed and the lever inverted before mounting. Remove and discard the clear plastic tubing spacer under the adjustment lever. It is only used for shipping. You may leave the lock nut off or you may want to reinstall it at the end of the threaded rod, so that the clamp's adjustment lever can't unscrew completely and drop into the water. (making another donation to Neptune) The nut also helps to protect the clamp during shipping.

A Few Mounting Tips
If you choose to use the optional 3/8” lock nut, unscrew it from the clamp's stud, reinstall it and make two full turns of the nut. That will give you sufficient clearance to fasten the moveable jaw of the clamp around the rail.

Open the clamp's moveable jaw(s) (20w panel has one clamp) and lower the panel down to the rail. Flip the moveable jaw into place and tighten the adjustment lever. After the clamp's adjustment lever is tight, you can then tighten the 3/8” lock nut until you feel it come into contact with the nylon locking threads. Or you can leave the 3/8” lock nut off until you have the panel mounted. Just be careful if you are on the water, so the adjustment lever isn't lost overboard. Trailer sailors may want to mount panel before launching.

On rare occasions, a down tube rail may interfere with tightening the adjustment lever. In that case, rotate the panel until it's vertical and tighten the adjustment lever until it's almost ready to lock. Then rotate the panel to the angle you chose and finish tightening.

There are inexpensive "shunt" type controllers being sold on Ebay as MPPT or PWM controllers. Buyer beware. If it looks too good to be true, it probably isn't. For quality and safety, please be cautious of some sellers on Ebay.
Do I really  need a controller?
Maine Sail /
Coastal Solar Sales
Sailboat Solar Panel Information & Setup Instructions
We can give you some tips.

Q-Cells polycrystalline modules have lower temperature coefficients than monocrystalline modules and therefore have the potential to produce more electricity per peak Watt in regions with high irradiation and ambient temperatures.

These polycrystalline modules use high efficiency cells with a low temperature coefficient and improved low light behaviour. They have the potential to produce more electrical energy than monocrystalline PV modules in a comparable area.

Q-Cells is a global business that manufactures photovoltaic cells and modules. Q-Cells also designs, installs and markets large scale photovoltaic systems.
Battery life is extended by not routinely discharging your batteries below 50% - 80%.