We have been testing our 150 and 160 watt solar panels for the past few years on extended cruises. While at anchor, on a sunny day, our battery banks are usually topped off by about 1 PM. We run our refrigerator/freezer 24/7. So why not use a smaller 100 or 120 watt solar panel and plug in a flexible panel on the rare occasion we need more charging power? This is what we will be testing while cruising this summer. It's a simple arrangement. We will carry a 100 watt flexible solar panel under a bunk cushion. If we need extra charging power we will simply plug it in using a T-branch connector at our pole mounted 120 watt panel and secure the flexible panel to the bimini top. That gives us 220 watts of power through our 20 amp MPPT controller. Several of our customers have reported using this configuration and are very satisfied with it. I'll report our results at the end of the season. Now, gotta go sailing and start testing.
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![]() Having warm water for showering and washing dishes while at anchor for an extended period can be a luxury for the cruising sailor. We at Custom Marine Products have come up with an easy and convenient solution; heating water using radiant energy from the sun. Here's how it works: Solar panels get quite warm on sunny days. The back of a solar panel tilted toward the sun may reach 140° F. Mounting a heat exchanger (collector) to the back of the solar panel enables the collection of radiant heat passing through the back of the solar panel. Circulating water from the water heater through the heat exchanger heats the water in the water heater. The water heater becomes a heat storage vessel. Water is circulated using a low draw circulation pump designed for this purpose so very little electrical energy is consumed. You no longer need to run your engine at anchor to heat water. Heat water to 115° F+ in an hour. Kits are available for all CMP rigid panels and many other brands Kits include: heat collector, insulation, panel backing, pump, tubing. Click here for more information. I have recently conducted seminars at boat shows on the West Coast. I am often asked who manufacturers our solar panels? Also, what is unique about our marine solar panels? These questions have several facets.
Our panels are manufactured to our stringent specifications by one of the most respected solar panel manufacturers in China. (China makes 87% of the world's solar panels) The company is a joint venture with a US company. The solar cells used in our panels are made by Bosch (German), Qcell (German) and SunPower (USA). Some of the sealants and backing materials are also made in the USA. The history of our solar panel manufacturer search: After considerable research and years of using solar on our Ericson 38 cruising for 6 weeks at a time, I developed a specification for how a marine solar panel should be made and for what qualities and features it should have. I then spent over a year searching for a US company to manufacture the panels for us. Unsuccessful, I then looked for a company overseas and found 4 companies in Asia who had good reputations and would manufacture the panels with the solar cells we wanted in the relatively low quantities we required. We purchased samples from all four companies, benchmarked them, put them on boats, tested them and selected the manufacturer with the best products. We have been working with this manufacturer for over four years now. As you can see from our CUSTOMER COMMENTS page, our diligence has paid off. Many of our customers report panel performance up to 30% higher than the label specification. Why? Because we use the highest grade of solar cell in our panels. Solar panel specifications are based on performance under an industry standard artificial light. When the panels are exposed to the full spectrum of sunlight, the cells generate more that their rated output. Quality solar cells are a bit more expensive but they really pay off for we cruisers who have limited on board space. Selecting a marine solar panel supplier isn't easy. Here are some ideas. Compare our solar panel performance specifications with others, read our customer comments to validate our quality, read my blog where I report on actual experience with the panels and look at price/performance/size ratios. Then, call me if you have additional questions or concerns. We are proud of our CMP solar panels but we recognize that our limited selection may not meet your exact needs so we will suggest alternative solutions where appropriate. We have all heard about tax credits for putting solar on our home but what about for our boat? Sure, why not?
The US Federal Government offers a solar energy tax credit, applicable to your second home. If you have a head and galley onboard and your boat is docked in the United States, your boat qualifies as a second home. This tax credit,extended to December 31, 2019, is a 30% credit on qualified expenditures to purchase and install solar panels placed in service after 2008. This credit can be retroactive – as long as the solar system was placed into service after January 1, 2006. The Department of Energy website gives a simplified description of the energy tax credit: http://energy.gov/savings/residential-renewable-energy-tax-credit. The actual IRS form is easy to fill out: http://www.irs.gov/pub/irs-pdf/f5695.pdf. It may also worth investigating your state government solar tax credit. Seminar Slides - Selecting the Proper Solar System Including a Simple Power Consumption Worksheet12/2/2015 ![]() On this web site under SUPPORT - MANUALS & INFO you will find a slide presentation I have used for Boat Show Seminars. You can also see the presentation by clicking on the image to the left. The presentation includes a simplified Power Consumption Worksheet and explains how to use it. You will also find some helpful overviews of solar panel and solar controller technology. I hope you find it useful if you are in the process of learning about solar and contemplating installing it on your yacht. ![]() We are often asked questions about how to wire a solar system. This can appear to be a daunting task for those new to the world of solar but it is actually quite easy and straight forward. In this blog I will walk you through the wiring process for our dual output controller step by step. First, the definition of a few terms: * MC4 Connector - A water proof connector used in solar wiring. Most solar panels come with MC4 connectors attached to 3 foot solar wire pigtail coming from the panel junction box. These connectors are easily disconnected. * Solar Controller - Except for small trickle charge systems, all solar systems should have a solar controller. The purpose of a controller is to prevent batteries from being overcharged, apply the optimal charging current to the battery bank and prevent current from back flowing from the batteries to the solar panel at night. Controllers are sized by their amperage capacity. Controllers designed for residential and commercial (lighting) use are generally overkill and not well suited for marine applications. * Temperature Sensor - This device is connected to the controller and senses the temperature of the battery bank. If the batteries are heating up due to heavy charging, the sensor signals the controller and the controller reduces the charge current appropriately. A temperature sensor is only useful for systems with larger solar arrays as smaller solar systems do not provide sufficient power to over heat the batteries. * Solar Wire - While most any wire can be used in a solar system, solar wire is designed for maximum conductivity and is well insulated with a UV resistant cover. It is typically single conductor and the insulation is .25 Inches in diameter. The wiring diagram below is taken from our dual output controller manual and illustrates the basic wiring required for a two panel system, a dual output controller and two battery banks. Most solar controllers are single output so charge only one battery bank. In this case, it is common to wire the positive wire to the common on the battery 1-2-both battery switch to select which battery bank is to be charged. A few things to note in the diagram: * The two solar panels are wired in parallel using an MC4 T-branch connector, If one panel is shaded, the other panel will still provide full power to the controller. * There is a switch in the positive wire between the solar panel and the controller. This is optional. The purpose of the switch is to turn off the panel should it interfere with the alternator output when the auxiliary engine is generator is running. It has been reported that some smart regulators are confused by the power coming from the solar panel. It sees the sum of the battery charge plus the panel output and senses the batteries are fully charged so goes into float mode prematurely. This is easily remedied by flipping the switch thus disconnecting the solar panel. * The optional temperature sensor is shown to the left of the larger house battery bank. It is simply taped on to the top of the battery. * If you have a battery monitor such as a Link or Xantrex 1000 or 2000, it is important to connect the negative wires from the controller to the shunt of the battery monitor. Otherwise, the monitor doesn't see the power coming in from the solar panel and will give inaccurate readings. * There is a sequence to follow in connecting the solar system. Connect the controller to the battery banks first. Then connect the solar panel to the controller. In an earlier blog post I described how a solar panel can be used to heat water using the sun's radiant energy (not the electricity generated by the solar panel). This year we put the concept of heating water by collecting the sun's radiant energy coming through the back of the solar panel to work during our 35 day cruise. I mounted a custom made heat exchanger to the back of our 150 watt solar panel, added some insulation and a new back panel. Water is circulated from the boat water heater through the heat exchanger and back into the water heater using a small circulation pump that draws less than .4 amp.
Here is what we found during our 35 day cruise in northern Lake Huron: 1. Running the circulation pump for several hours midday on sunny days provided us warm water for showers and dish washing within two hours. 2. Water was heated from 60 degrees F to about 110 degrees F on sunny days. 3. Water was heated faster and to a higher temperature on calm days than on windy days. This is because the wind tends to cool off the front face of the solar panel. 4. We enjoyed warm water from the solar panel water heating system 12 days at anchor. Other days we either had warm water from running the engine to move the boat or the days were cloudy so no heat was collected. 5. The small circulation pump did not draw a significant amount of solar power. Besides, our batteries were topped off by early afternoon so we had plenty of excess power. 6. Having the system tapped into our boat's water system made it very convenient to take advantage of the warm water. 7. The added weight (10 pounds) of the water heating system was no problem for the pole brackets or stern rail. 8. I added a T and a valve in the solar heater tubing to make warm water available in the cockpit for showering or rinsing off after a swim. It worked perfectly. All in all, the system worked as planned and provided us with warm water conveniently when we needed it. Our next step will be to make a kit available to our customers to retro fit their solar panel systems or to order a water heating system with new installations. We will have kits available for both our larger 150-160 watt panels and our smaller 100-105 panels. We tested our new 150 watt polycrystalline solar panel on a 35 day cruise in the North Channel area of Northern Lake Huron. This panel was equipped with the prototype of our solar water heating system which will be addressed in another blog entry. The solar panel was mounted on our pole mounting system and was rotated toward the sun The boat equipment and cruising pattern was essentially the same as last year (See prior blog entries). We were powering a freezer/refrigeration system, instruments, laptop computer, radios, autopilot, windlass and LED lights. Data was gathered using the remote display on our EP 10 amp dual output solar controller. The solar panel performance met our expectations. Our house battery bank consists of three 120 amp hour flooded batteries.
Both battery banks were usually fully charged by 2 PM when at anchor and on mostly sunny days so we often had excess power. Data comparing the performance of the 150 watt solar panel with our 140 and 160 watt panels is presented below. Average amp hours per day produced under various conditions: 150 Watt poly 140 Watt, poly 160 Watt, mono 160 Watt, mono 2015 2012 2013 2014 Overall average output per day 49 amp hours 53 amp hours 48 amp hours 48 amp hours Sunny days 60 69 71 69 Mostly sunny days 56 50 50 56 Mostly cloudy days 36 35 37 39 Cloudy days 22 32 28 20 Avg. Output on days at anchor 60 62 61 51 Avg. Output when engine was used 42 43 44 45 Min amp hrs for a day 4 27 28 4 Max amp hrs for a day 84 74 77 76 Max amps output 11.8 amps 10.5 amps 11.5 amps 11.4 amps This data is intended to provide a general idea of what to expect from the solar panels under various conditions. The two primary variables are the amount of sunshine and the running of the engine (the alternator charges the batteries so the controller shuts off power from the panels). Because the panel was equipped with a water heat collector on the back, it may have run hotter on sunny days when the water circulation pump wasn't run thus degrading the performance by up to 10%.The average panel output on sunny days at anchor with no motoring was 67 amp hours. ![]() Several of our customers have recently attached their semi-flexible solar panels using nuts and bolts. Here is what they did: 1. Place the solar panel on the canvas and mark the grommet holes on the canvas. 2. Glue a vinyl disk about 2 inches in diameter to the underside of the canvas at points where attaching bolts will be placed. 3. Puncture a hole in the fabric through the vinyl. 4. Place a 1 inch diameter or greater plastic or stainless fender washer on a 10-24 or similar stainless bolt and pass it through the canvas. 5. Place another fender washer on the bolt on top of the canvas and secure with a nut. At this point, you have a reinforced canvas sandwiched between two fender washers. 6. Pass the bolt through the solar panel grommet and secure with an acorn nut. 7. Repeat for each solar panel grommet. See diagram below for details. On the installation shown above, the solar wires were run through the channel used to attach the canvas to the frame thus hiding most of the wiring. ![]() The excellent performance of our semi-flexible solar panels is opening up new ways to easily implement solar systems on cruising boats. There are several ways to attach our flexible solar panels to a canvas bimini top. Here are some creative ideas our customers have implemented: 1. Zipper solar panels directly to the bimini canvas - Stitch zippers along the sides of the solar panel using an industrial sewing machine. Stitch the mating zipper onto the bimini top with a flap to cover the zipper to protect it from UV rays. Zip the panel onto the bimini and run the wires as necessary. See picture to the right. 2. Attach solar panels to canvas and zipper canvas to the bimini canvas - Panels can be attached to a piece of canvas using zippers, snaps or grommets. Sleeves can be sewn into canvas to hide and protect the wires. The canvas with the solar panels can then be attached to the bimini canvas using zippers. 3. Attach solar panels to the bimini canvas using snaps or grommets - Our flexible solar panels come with 4 or 6 sets of grommets installed. These grommets can be used to stitch the panels directly to the bimini canvas. Alternatively, these grommets can be drilled out and replaced with snaps. The mating snaps can be installed in the bimini canvas so the panels can be simply be snapped into place. 4. Attach solar panels to the bimini canvas using outdoor Velcro (hook and loop) - Stitch or glue the Velcro to the back of the panel and stitch the mating Velcro to the bimini canvas. Panels can be easily removed for storage. Note: Because the PV cells of the panels are black, they will absorb and radiate considerable heat. Some customers have inserted insulation between the panel and the canvas to reduce the radiated heat. They have used the bubble wrap encased in silver foil insulation available at most home improvement stores. It is about 5/16" thick. This was the second year we used the 160 Watt solar panel on a 35 day cruise in the North Channel area of Northern Lake Huron. The boat equipment and cruising pattern was essentially the same as last year (See prior blog entries). The solar panel performance was comparable to last year with a few minor exceptions. The data comparing the performance of the 160 Watt panel during 2013 and 2014 and the 140 Watt panel in 2012 is displayed below.
Average amp hours per day produced under various conditions: 140 Watt, poly 160 Watt, mono 160 Watt, mono 2012 2013 2014 Overall average output per day 53 amp hours 48 amp hours 48 amp hours Sunny days 69 71 69 Mostly sunny days 50 50 56 Mostly cloudy days 35 37 39 Cloudy days 32 28 20 Avg. Output on days at anchor 62 61 51 Avg. Output when engine was used 43 44 45 (We had more cloudy days at anchor this year) Min amp hrs for a day 27 28 4 Max amp hrs for a day 74 77 76 Max amps output 10.5 amps 11.5 amps 11.4 amps This data is intended to provide a general idea of what to expect from the marine solar panels under various conditions. The two primary variables are the amount of sunshine and the running of the engine (the alternator charges the batteries so the controller shuts the panels down). The test boat was running a freezer/refrigerator drawing 5 amps running 6 hours a day, LED lighting, laptop computer drawing 4 amps running 3 hours a day, radios drawing 3 amps running 8 hours a day, and instruments and autopilot when under sail and power. When at anchor on a sunny to mostly sunny day our batteries were at full charge by 2 PM so we usually had excess power. ![]() Our top-of-pole solar system addresses the need for power while at anchor and under sail. In fact, we have found the solar system usually provides us an excess of electrical power while cruising. Now we find the only additional thing we need while at anchor for an extended period is warm water for showers and cleaning dishes. Sure there is the old black bag absorb the sun's heat option but this is a bit cumbersome. Then there is the option to run the engine until it heats up the water in the water heater. Running the engine for warm water is inefficient and undesirable. Now we have what promises to be a pretty good solution; solar heated water. Because the solar panel is dark in color, it absorbs a significant amount of the sun's energy in the form of heat. This is dissipated through the back and front of the panel by air currents. By attaching a heat collector/exchanger to the back of the panel, properly insulating it and circulating water through the heat exchanger we are able to collect that excess heat and store it in the water heater tank or in a separate holding tank. While still in the test stages, we have completed proof of concept and can make the heat exchangers available to DIY mariners who are interested in setting up such a system. We plan on offering a complete water heating system retro fit kit within the next year. Initial tests indicate that with our 140 and 160 watt systems we can heat 3 gallons of water from 60 to 110 degrees F in less that a half hour on a sunny day with the ambient temperature of 65 degrees F. Our top-of-pole system is about to be a 3 in 1 assembly; solar panel mount, outboard motor crane and solar water heating system. Call us if you are interested in participating in our test program. ![]() When our supplier told me they had a new high output marine solar panel that was flexible I was skeptical. The specifications seemed just to good to be true. So I ordered some to test. Well, I was pleasantly surprised. These panels are very well constructed and they have a power generation comparable to our hard panels. These panels can be flexed to 30 degrees so can conform to most boat curved surfaces. The 100+ watt panels have an electrical box on the front (not shown in the picture) which contains two blocking diodes. The 50 watt panel has one blocking diode. The base material is very sturdy and strong. Each panel has grommets for attaching the panel. I have tested the output of these panels under various weather conditions and their susceptibility to shading. Below is a quick comparison of output of our three mid-range panels laying flat at mid day on a mostly sunny day measured with a meter: Flexible 100 watt Rigid 105 watt Rigid 100 watt Monocrystalline Monocrystalline Polycrystalline Short Circuit Current (Isc) 5.48 amps 5.50 amps 5.26 amps Open Circuit Voltage (Voc) 19.2 volts 19.7 volts 20.5 volts Computed Power (not rated power) 105 watts 108 watts 108 watts Additional information is available on our solar panel page. ![]() In an earlier blog entry dated 8/10/2011 I documented the performance of our 130 watt mono-crystalline solar panel on a 22 day cruise in the upper Great Lakes. In an August 2012 blog entry I documented the performance of our 140 watt poly-crystalline solar panel. This year I documented the performance of our 160 watt mono-crystalline solar panel on the same boat under similar conditions. The only variables were the weather and the running of the engine when moving from anchorage to anchorage (wind was on our nose quite often this summer). The number of days of each cruise varied so I an presenting average performance based on four weather conditions; sunny, mostly sunny, mostly cloudy and cloudy. Test conditions:
Test Results: Definition: amp hour – amps produced or consumed in one hour Average amp hours per day produced under various conditions: 130 Watt, mono 140 Watt, poly 160 Watt, mono Overall average output per day 54 amp hours 53 amp hours 48 amp hours Note: 160W had only 5 sunny days, 140W had 10 sunny days and 130W had 8 sunny days Sunny days 71 69 71 Mostly sunny days 51 50 50 Mostly cloudy days 46 35 37 Cloudy days 24 32 28 Avg. Output on days at anchor 62 62 61 Avg. Output when engine was used 35 43 44 (difference partially because 130W was often disconnected often when engine was used. Not so for 140W and 160W) Min amp hrs for a day 16 27 28 Max amps output 10.5 amps 10.5 amps 11.5 amps Interpreting the Results: Each solar panel performed about as expected. The average daily output was less for the 160 watt panel but it had half as many sunny days and comparable mostly sunny days. The 130 watt mono panel provided a slightly higher average output on sunny days and the 140 watt poly panel provided a higher average output on cloudy days. The max output of the 160 watt panel was an amp higher that the others. My sense was that the poly-crystalline panel was less sensitive to shading from the rigging but this is difficult to document. On sunny days, both solar panels often performed above their sticker rating of 130, 140 and 160 watts by as much as 50 watts (9.5 amps at 21 volts is 189 watts) . I believe this is due to the high quality of silicone crystals used. Observations: All three solar panels generally met our power needs for the duration of the cruises. We occasionally ran a small deficit of amp hours during an extended anchorage when cloudy but never needed to use the engine alternator to charge the battery banks except when motoring from place to place. On days when the engine was used we often had an excess of power generation from the 75 amp alternator and the solar panel. Choosing the right type of solar panel: Based on the performance data, each solar panel will perform adequately under most conditions. The 130 watt and 160 watt mono-crystalline solar panels are an excellent choice for boats in mostly sunny areas with little possibility of shading from the rigging. The 140 watt poly-crystalline solar panel is an excellent choice for areas with more partly cloudy and cloudy days and on boats where there is some shading from the rigging. In an earlier blog entry dated 8/10/2011 I documented the performance of our 130 watt mono-crystalline solar panel on a 22 day cruise in the upper Great Lakes. This year I documented the performance of our 140 watt poly-crystalline solar panel on the same boat under similar conditions. The only variables were the weather and the running of the engine when moving from anchorage to anchorage (wind was on our nose quite often this summer). Also this panel performance was documented over a longer period of 34 days.
Test conditions:
Test Results: Definition: amp hour – amps produced or consumed in one hour Average amp hours per day produced under various conditions: 130 Watt, mono 140 Watt, poly Overall average output per day 54 amp hours 53 amp hours Sunny days 71 69 Mostly sunny days 51 50 Mostly cloudy days 46 35 Cloudy days 24 32 Output on days at anchor 62 62 Output when engine was used 35 43 (difference because 130W was disconnected often when engine was used. Not so this year for 140W) Min amp hrs for a day 16 27 Max amps output 10.5 amps 10.5 amps Interpreting the Results: Both solar panels performed as expected. Their average daily output was about equal. The 130 Watt mono panel provided a slightly higher average output on sunny days and the 140 Watt poly panel provided a higher average output on cloudy days. My sense was that the poly-crystalline panel was less sensitive to shading from the rigging but this is difficult to document. On sunny days, both solar panels often performed above their sticker rating of 130 and 140 watts by as much as 50 watts (9.5 amps at 21 volts is 189 watts) . I believe this is due to the high quality of silicone crystals used. Observations: Both the 130 watt solar panel and the 140 watt solar panel generally met our power needs for the duration of the cruises. We occasionally ran a small deficit of amp hours during an extended anchorage when cloudy but never used the engine alternator to charge the battery banks except when motoring from place to place. On days when the engine was used we often had an excess of power generation from the 75 amp alternator and the solar panel. Choosing the right type of solar panel: Based on the performance data, both solar panels will perform adequately under most conditions. The 130 watt mono-crystalline solar panel is an excellent choice for boats in mostly sunny areas with little possibility of shading from the rigging. The 140 watt poly-crystalline solar panel is an excellent choice for areas with more partly cloudy and cloudy days and on boats where there is some shading from the rigging. ![]() I mounted our new 140 watt polycrystalline solar panel and tracked its performance for four days in northern Lake Huron, Michigan. Fortunately, I experienced different weather conditions each day so there is some data to compare the 140 watt panel to the 130 watt monocrystalline panel. The panel was tilted at a 30 degree angle and rotated three times during the day; morning, noon and late afternoon. The panel was partially shaded by the back stay during the late morning. This seemed to degrade panel performance by about 1 amp. When pointed toward the sun during a clear sky period, the panel produced between 8 and 9.6 amps, considerably higher than its rated output. The controller recorded a max output of 10.6 amps. This is very impressive and shows the Class A silicone wafers are clearly worth the added cost over Class B wafers. Power consumption was from refrigerator/freezer, computer, lights (LEDs) and radio. The house battery bank was negative 28 amp hours after four days. Had the sunny day been the last day, the battery bank would have been fully charged. Below is the data: Amp Hours Weather Day 1 80 AH Sunny all day Day 2 62 AH Hazy, partly cloudy all day Day 3 31 AH Cloudy, overcast, rain until 5 PM Day 4 56 AH Hazy, partly cloudy, no clear sky all day Preliminary conclusions: The 140 watt polycrystalline panel performance is comparable to our 130 watt monocrystalline panel. The panel performed above its rated output by 1-2 amps. Performance during cloudy and hazy periods was very good. The 140 watt panel appeared to have less sensitive to shading than the 130 watt panel. Relative solar panel size: the 140 watt panel is smaller than the 130 watt panel by only 3 square inches. The performance of our 130 watt solar panel is documented in an earlier blog entry below. I will publish additional data as it becomes available. We haven't been just sitting around waiting to the water to soften up here in the Midwest. We've been working on enhancing our products and finding the latest and greatest technology.
Our 90 watt solar panel had been such a popular high performer that we went back to our supplier to see if they could provide us with a higher wattage panel for our top-of-pole mounting system. We specified a solar panel that was Class A-9 quality polycrystalline with an efficiency of 16.5% efficiency or higher, sealed and robust for the rigors of marine use, a nearly square shape for our top-of-pole application, and at a cost our customers could afford. They met our request and came up with a 140 watt polycrystalline high performance panel that measures roughly 39 X 39.5 inches and uses the same design and construction technology as our 90 watt panel. We have them on order with an expected delivery date of early May. We anticipate that the 140 watt panel will perform about as well as our popular 130 watt monocrystalline panel in full sun and outperform our 130 on a cloudy day or when partially shaded. This will make the panel ideal for northern climates where those sunny days just don't happen every day. We plan on publishing a complete analysis by mid to late June. Also stay tuned for our introduction of several new LED lights. Only recently has LED technology advanced to the point of offering brightness and reliability that meets or exceeds that of traditional bulbs and at an affordable price. Cruising mariners know that cabin lighting can consume a significant amount of electrical energy. Fortunately, cabin lighting is simple and relatively inexpensive to modify to achieve energy savings; simply change the bulb.
Advantages of LED lamps include:
At other places on this blog and on our web site we talk about how to determine the size of solar panel (how many watts) you will need to meet you power consumption requirements. Once you know your panel size requirement there are some things to consider in selecting a solar panel.
Panel Type - There are many articles written on the two types of solar panels; monocrystalline and polycrystalline. Monocrystalline panels are made up of single crystal silicon wafers. Polycrystalline panels are made up of silicon that has a multiple crystalline structure. There are pros and cons to each type of panel. Monocrystalline panels have a higher output per square inch in direct sun but are very sensitive to shading and output will degrade faster on cloudy days. Polycrystalline panels are not as sensitive to being shaded and output will not degrade as much on cloudy days. At CMP we offer both a polycrystalline and a monocrystalline panel. Panel Crystal Quality - Because we have a confined space on our boats, we need to have the maximum output per square inch from our solar panels. The quality of the silicon crystals used to make the panel is a key factor in determining the panel output. Crystals are passed under a fixed light and graded as to their output (1-10). Grades are grouped into classes. Class A crystals are grades 8-10, Class B crystals are grades 4-7 and so on. Crystal quality follows a bell curve; there are many more Class B crystals than Class A. We at CMP specify only the best Class A crystals for use in our panels. Less expensive Class B and C panels are often used on land based solar farms where space is not an issue. 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. Choosing the right panel for your needs will require study and/or discussion with panel experts. The following is the result of testing the CMP130 watt monocrystalline solar panel with the top-of-pole mount and dual output controller cruising for 3 weeks in the North Channel of northern Lake Huron. The panel mounting system is shown on our Gallery of Installations; the Ericson 38. (Well, somebody has to do it. :-) )
Test conditions:
Date Amp Conditions of the day Hours 7-7 46 At dock, shore power on 7-8 39 Motored 4 hours, partly cloudy 7-9 17 Motored all day, cloudy tried solenoid 7-10 26 Cloudy, motored 1 hour, sun 5-6 hours 7-11 55 Mostly sunny, travel day – under sail 7-12 64 Mostly sunny, at anchor 7-13 79 Mostly sunny, at anchor, reset meter when rewired batteries 7-14 70 Mostly sunny, at anchor, panel not turned for part of the day 7-15 49 Cloudy morning, sunny afternoon, motored for 2 hours with solenoid on 7-16 51 Mostly sunny, motored 2 hours with solenoid on, topped off batteries 7-17 34 Mostly cloudy, at anchor all day 7-18 47 Mostly cloudy, motored 2 hours 7-19 20 Hazy, cloudy, motored 2 hours 7-20 71 Sunny, at anchor 7-21 80 Sunny, at anchor 7-22 67 Mostly sunny, ran engine 1.5 hrs, topped off batteries 7-23 39 Mostly cloudy, at anchor 7-24 73 Mostly sunny, at anchor 7-25 68 Mostly sunny, at anchor 7-26 16 Hazy, cloudy, motored 4 hours, topped off batteries 7-27 26 Cloudy, hazy, motored 9 hours, batteries charged 7-28 42 Mostly sunny, motored 2 hours with panel connected, batteries charged Analysis: Definition: amp hour – amps produced or consumed in one hour Average amp hours per day produced under various conditions: Overall (22 days) 54 amp hours Sunny days at anchor 71 Cloudy days at anchor 37 All days at anchor 62 Days engine was used 35 Max amp hrs for a day 80 Min amp hrs for a day 16 Max amps output 10.5 amps Conclusion: The 130 watt panel generally met our power needs for the duration of the cruise. We occasionally ran a small deficit of amp hours during an extended anchorage but never used the engine alternator to charge the battery banks except when motoring from place to place. On days when the engine was used we often had an excess of power generation from the 75 amp alternator and the 130 watt solar panel. The solar panel is very sensitive to cloudy days and to shadows. The panel output on sunny days exceeded it rating. This is the nature of mono-crystalline solar panels. Several fellow mariners have reported their engine Tachs sometimes give sporadic readings with the needle bouncing around. I recently had a similar experience on my boat and did some research. Most high output alternators with smart regulators and many solar panel controllers charge batteries using a technology called Pulse Width Modulation (PWM). The Tach uses PWM to determine the alternator (and thus the engine) RPM. The two PWM sources may, at times, create an interference. Thus the sporadic readings on the Tach.
The solution to this is disconnect the solar panel when the alternator is running so the controller doesn't function. This can be easily done by putting a switch in the positive wire leading from the solar panel to the controller. Alternatively, you could put in relay (closed when no powered) on this wire and wire it so the relay is open when the engine is running and closed when it is not. There is another very good reason to put a switch in the panel to controller wire. The smart regulator reads the battery charge condition and sets the output of the alternator accordingly. If the solar panel is producing power, the regulator will see the net of the battery charge plus the panel output and thus may prematurely put the alternator in float mode. this will result in getting limited performance out of that big expensive alternator. The Kyocera KC85T is a solar panel we have recommended for pole mounting on boats with moderate power requirements. It has been very popular with our customers. Unfortunately, Kyocera no longer manufacturers this panel. To serve our customers, we are having a similar panel manufactured to our specification. This panel is the same dimensions as the KC85T, is rated at 90 watts, and is a polycrystalline Class A marine grade solar panel. This panel has a 10 year manufacturer warranty and a 10 year warranty from CMP. Out tests indicate that this panel is an excellent performer. It is now in stock and can be ordered through our web site with or without our custom top-of-pole mounting system.
I recently mounted the 90 watt panel on my boat in the Great Lakes to see how it compared to ym KC85T. The results were impressive. The 90 watt panel produced 5.5 to 6 watts consistently on sunny days (rare this Spring) and achieved a max output of 7.3 amps. It will easily produce 35 amp hours a day. We also now offer a 130 watt solar panel which has the same dimensions as our 120 watt panel. It is ideal for pole mounting because it only weighs 24 pounds and is shorter and wider than standard panels of similar power. If you have a need for smaller panels on your boat, check out Atom Voyages. James offers a top-of-pole mounting system that is ideal for panels in the 50 to 65 watt range. The amount of power needed while cruising depends on many factors including the energy used by appliances and lighting, the output of the engine alternator, the climate and the length of time away from shore power. These and other factors will determine the amount of solar power and thus size of the solar panel(s) you may need. Working with Ed Foster of foster-wills.com, we have developed a worksheet to assist you in inventorying your on board power generation and consumption and estimating you solar power requirement. Print out our Solar Power Calculation Worksheet and use it as a guide to figuring out your power generation requirement. From this you can get an idea of what your solar panel options might be. Hope it helps!
We are often asked about the impact of wind resistance on solar panels mounted on a pole when the boat is under sail or when it is blowing a “hooley” out there in heavy seas. This is a valid concern. Anytime you put something in the way of the wind on a boat there are bound to be consequences.
It is important to note that none of our customers to date have reported a problem with wind resistance nor have we had a problem on our test boats. Fortunately, an adjustable pole mounted solar panel offers numerous options to address wind resistance. Some of our customers have reported that they tilt their panel to a horizontal position in a blow to minimize wind resistance. Other customers have replaced the single nut and bolt that attaches the panel to the pole with a locking pin or lynch pin. In a blow, they simply pull the pin, unplug the panel and stow it down below. Other customers just leave the panel alone and don’t worry about it. The panel is usually tilted at a 30 to 45 degree angle to achieve optimum sun angle. This alone reduces wind resistance by over 50% relative to a panel in a vertical position perpendicular to the wind (not sure why a panel would ever be in a vertical position however). Also, it is important to consider that the boat is moving smoothly with the waves thus enabling a relatively even airflow over the panel. In addition, the panel can be rotated so achieve some potentially beneficial results. With the top of the panel tilted into the wind, the unit will tend to put a downward force on the stern. With the panel bottom into the wind, it will tend to put a lifting force on the stern. What is the weak point in the system in a heavy wind? Looking at the system as a unit, it is apparent that the pole, the tilt mechanism and the braces attaching the panel to the tilt mechanism are plenty strong. The brackets attaching the pole to the stern rail are plenty strong. Our tests have proven this to be a fact. The only remaining point of potential failure then is the stern rails. We have seen boats with very strong well anchored stern rails and boats with rather dubious stern rail anchoring systems. Each boat owner must assess the strength of the stern rails and determine their ability to support the stresses of a pole mounted solar system. It could be that lateral braces connecting the pole to the deck or to the bimini frame are necessary. The size of the panel is directly proportional to the amount of potential wind resistance. We recommend mounting a panel no larger than our 120-130 watt panel which measures approximately 49 X 32 inches on a boat with strong well designed stern rails. The Kyocera 85 watt panel measuring approximately 40 X 26 inches is ideal for our smaller panel system. See other blog entries for an analysis of the performance of this panel. Originally designed for the harsh marine environment, our top-of-pole solar panel mounting systems are now being used for land based applications. The adjustable tilt mechanism has proven to be ideal for land based installations because the panel can be easily adjusted for change in sun angle throughout the year. Customers with large arrays can use two tilt mechanisms mounted on two poles and achieve the strength necessary to withstand sever weather conditions.
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AuthorThomas Trimmer has been cruising with his Ericson 38 sailboat on the Great Lakes for over 20 years. He has pioneered the use of solar energy for wilderness cruising. He is continually designing and building equipment to simplify and enhance the cruising experience. Archives
June 2025
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