Marine Solar Panel Grids

​Panel Type - There are many articles written on the two types of solar panels also referred to as photovoltaic panels (PV) ; monocrystalline and polycrystalline.  Monocrystalline panels are made up of single crystal silicon wafers.  Polycrystalline panels are made using silicon wafers that have a multiple crystalline structure.  There are pros and cons to each type of panel.  Monocrystalline panels have a higher output per square inch.  They can be sensitive to shading and output will degrade on cloudy days.  Polycrystalline  panels tend to have a lower output per square inch in direct sun , may not as sensitive to being shaded and are less expensive.  It is important to note that today's newer high quality polycrystalline panels perform within 10% of some monocrystalline panels in full sun.  The premium monocrystalline SunPower cells  and PERC cells used in our marine solar panels provide the best all around performance of any solar cells on the market generating the highest Watt hours of power per day.

Panel Solar Cell Quality - Because boats (and vans, and RVs) have a relatively confined space, maximum power output per surface area is very important.  The quality of the solar cells used in solar panels is a key factor in determining the panel output.  Solar cells are passed under a standard light source and graded as to their output (1-10).  Grades are grouped into classes.  Class A (and A+) solar cells are grades 8-10, Class B solar cells are grades 4-7 and so on.  Solar cell quality follows a bell curve; there are many more Class B solar cells than Class A.  We at Custom Marine Products specify only the best Class A-9 (A+) solar cells for use in our panels which results in a panel efficiency of up to 24%.   Less expensive Class B and C panels are often used on land based solar farms where space is not an issue.  Though a bit more expensive, our customers have reported that our solar panels often outperform the performance rating on the panel label. 

The Importance of Solar Cell Quality - Not All 100 Watt Solar Panels Are Created Equal - ​​High quality high performance solar cells will produce more power at various sun angles than lower quality solar cells; up to 30% more power.  An important consideration in determining how much solar power you need is how many watt hours or amp hours of power you can expect to generate in a 24 hour period.  Let's say you cruise in an area that receives an average of 5 hours of full sun a day.  The average is computed based on the seasonal sun angle and the sun angle from morning through evening.  A 100 watt solar panel with average efficiency solar cells may produce 100 watts x 5 hours or 500 watt hours of power in a day.  At 13 volts that's about 38 amp hours in a day.  A 100 watt panel with high efficiency solar cells will produce up to 30% more power in a 24 hour period or 100 watts x 6.5 effective hours or 650 watt hours of power in a day.  At 13 volts, that's about 50 amp hours in a day.  38 amp hours vs. 50 amp hours in a day is significant on a boat (or van or RV).  Add more panels in the mix, say 400 watts and we see 152 amp hours vs.200 amp hours, a difference of 48 amp hours. This simple analysis does not take into consideration the impact of clouds or shading both of which will make the disparity even greater.   Clearly, the higher the quality of the solar cells the more power produced over time.

Panel Shape - The largest market for solar panels is commercial applications where many many panels are mounted on a roof or in a field.  These panels are usually rectangular in shape often twice as long as wide.   This shape is often not ideal for marine application.  Often a more square shape is preferable, especially for pole mounting.

Marine Grade - It's no secret that the marine environment, especially salt water, can be tough on equipment.  To withstand the rigors of the marine environment, solar panels should have strong stout anodized aluminum framing, should be well sealed and waterproof, and have the electrical box on the back of the panel encased in an inert non-corrosive waterproof material (like silicone) to protect the electronic components.
Quality marine grade solar panels are designed with bypass diodes to stop power from cells not producing and draw more from producing cells. This significantly reduces the impact of shading that so often occurs on boats.  Properly designed solar panels using diodes eliminate the need for dedicated solar controllers for each panel.  Our solar systems often include many solar panels wired in series or parallel feeding a single solar controller.

Choosing the right panel for your needs will require study and/or discussion with PV panel experts.  Our staff at Custom Marine Products are ready to help you design the best solar system for your marine needs.  Contact us via email or phone for a free consultation.

Solar Tax Incentive - As long as there is a head, galley, and at least a bunk onboard and your boat is docked in the United States, your vessel qualifies. This Federal tax credit is a 15%-30% credit on all qualified expenses to purchase and install solar panels and a solar system (including any installation charges), with no maximum limit for equipment placed in service after 2008. Plus you may have tax credits in your state.