Alternative Energy Product Manufacturers: West Marine

West Marine’s View of Solar Power in the Boat Owners World

“Replacing Fossil Fuels with Photovoltaic Solar Power

Solar panels, or photovoltaic panels, produce electricity when exposed to the sun. This electricity is used to charge batteries, which can power DC loads, or panels can be connected to inverters to produce AC power. Silicon, the primary material in quartz sand, is refined, purified (by an expensive process), sliced into thin wafers and “doped” with the addition of chemicals. This process alters the wafer so that, when exposed to light photons, one side produces a surplus of electrons and the other side has a deficit. A voltage difference between the two sides of just under 1/2 volt is created. Acting like an “electron pump,” solar cells create electrical current, the quantity determined by the size and efficiency of the cell and the amount of light. Solar modules are created by connecting cells in parallel to increase amperage and in series to increase voltage. Typical solar modules have 30 or 36 cells (generating between 14 and 18V DC).

Types of panels most commonly used in boating applications contain either multicrystalline or amorphous silicon cells. Multicrystalline (c-Si) panels are the most powerful. When sized correctly and matched to appropriate batteries, these are the panels to use for running large DC loads such as lights, a TV, radio or VCR. Amorphous silicon (a-Si) panels are only about 50% as efficient as multicrystalline panels. However they are more efficient in low or diffused light conditions and are less subject to voltage drops when they heat up. These are the panels most often used for low amperage charging and battery maintenance. They don’t generally have enough output for serious energy replenishment, but can be used to “float” or trickle charge a battery.

We are happy to once again have a source for flexible solar panels with two new Sunsei Flex panels from ICP. These multicrystalline panels are constructed from copper, indium, gallium and selenium (CuInGaSe2), a new semiconductor material. Unlike silicon panels, these thin film panels feature multiple layers deposited on a metal surface (with more of the p-n junctions—in a “heterojunction” system—than c-Si panels). Thin film panels, either the amorphous silicon type used in the rigid Sunsei battery trickle chargers, or the CIGS flexible panels represented by the Sunsei Flex panels, offer lower manufacturing costs than c-Si panels like the bigger Sunsei panels (45% of their cost comes from making the raw silicon crystal structure).

Fastest growing energy source

Solar generating capacity grew by 39% worldwide in 2005, with huge increases in Germany, the world’s leading solar economy—a solar market eight times as large as the US. Global solar production (totaling 1,460 Megawatts) breaks down as follows; with Germany possessing 57% of PV capacity, Japan 20%, the US 7%, the rest of Europe 6%, and 10% for the rest of the world. Some big solar projects are in the planning or building stages. Last fall, internet search engine firm Google announced a 1.6 Megawatt project, with 9,212 solar panels (enough to light 1,200 homes) to be installed this year on roofs and carports at Googles Mountain View, CA. headquarters. This gargantuan array is projected to pay for itself in five to ten years. West Marine has embraced photovoltaic technology, with our own sizable 57,600KW array on the roof of our Santa Cruz, CA, store (with 480 panels of 120W each, connected to 24 inverters, rated at 2,100W each, producing enough electricity to meet 70% of the store’s electrical needs). During the first 20 days of operation in May 2004, this system saved the equivalent of 10 barrels of crude oil, and reduced C02 greenhouse gas emissions by 1.5 tons. More information about this project can be found at www.westmarinesolar.com.

Solar power is clean, silent, safe energy, but is not always the perfect solution. Many boat owners are disappointed when they learn the real-life energy economics; the size of the panels needed, the effect of partial shading, temperature, and the hours of available sunlight. What is the real world performance you can expect? A look at some of the limits of photovoltaic systems is helpful for getting a clearer picture.First, the amount of time a panel spends in full sun averages 4 or 5 hours per day in most of the continental U.S. Full sun means enough light so you see fairly sharp-edged shadows, and most locations get no more than 80 to 85% of full sun (defined as 1000 watts of energy per square meter). Shadows covering even a tiny fraction of the panel have a dramatic impact on power output. All the individual cells are arrayed in series, and shaded cells show a large voltage drop which acts as a barrier to useful power production. Shading a single cell on a panel can cut its output by 20% or more. Shading two or more cells effectively turns off the panel until the shadow is removed. This defect is corrected somewhat by the use of bypass diodes across each cell, which allow the module to produce power even when partially shaded.Temperature also changes the efficiency of a solar panel. The colder the temperature at the panel surface, the higher the output. Performance on a clear, cold winter morning can be 30 to 40% over rated specs.

As a general rule panels that produce less than 1.5% of a battery’s rated capacity in amp hours do not require regulation. This means that a 1.5 amp panel is the largest you should use without a regulator on a 100-amp-hour battery. Regulators should generally be used any time you have two or more large panels connected to your batteries. One caveat to the general rule applies to cruising boats that run an “energy deficit”. That is, when your boat removes more energy from the batteries than the panels replace. In this case, regulation might not be required. If you think you might fall into this category, it would be helpful to develop an “electrical budget” for your boat. You will find a helpful guide to this in the Advisor section at westmarine.com. Frequent checks of your system voltage can alert you to possible over-voltage situations. Remember, a simple On/Off switch can remedy this problem by taking the panels off-line.

A clear and understandable standard
Until recently, almost all solar panels were rated in watts of output, while battery banks, chargers and alternators are rated using amps of current. Unless you are familiar with Ohm’s Law (Watts = Volts x Amps) and can use this formula backward and forward, watts are not a useful method of determining power output. Therefore, our selection of solar panels are rated by their amperage. The model numbers of the Sunsei panels indicate their output (in milli-amps), so the SE-400, for example, is a 400mA charger. It is much easier to estimate what to do with 400mA than with a 6-watt panel.

Our Technical Sales staff at 1-800-BOATING are often asked to help size a solar system, and they find that boaters usually underestimate their electrical needs. Make a list of the appliances on your boat, get the amperage (Amps = Watts ÷ Voltage) and estimate the operating hours to get weekly amp hours for each device. You can then create an estimate of your “electrical budget” and size your system correctly.Beware of cheap panels and inflated numbers Not all solar panels give the output that they advertise. Humboldt University in Berlin compared ICP Solar panels side by side with amorphous-silicon modules made by a Chinese manufacturer and marketed under various brands in North America. Humboldt’s results, released in 2006, showed that ICP’s panels delivered over twice the output of the competitive modules at stable power despite having similar ratings. After months of testing, ICP Solar’s modules delivered stable ratings of 14.2 watts vs. label of 14 watts. Modules manufactured by the Chinese competitor delivered just over 6 watts despite carrying a “15 watt” label. These results confirm findings of other earlier studies carried out in England.

Conclusion
The rapid increase in oil prices has made photovoltaic solar energy an increasingly realistic alternative for producing electrical power. Replacing a gas or diesel generator with a clean and properly sized solar module, which has no moving parts and requires no fuel or maintenance, is a great investment in making boating both cleaner and more affordable.”

Filed under: Green Products

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