Solar Panels: You Should Need To Know

Solar panels

With very little land surface could cover all the needs of power on earth and is a matter of time that we see more and more industrial parks PV installations. Solar panels are composed of cells connected together in parallel to sum the current generated by each. When exposed to light, a solar cell produces electricity. Depending on the intensity of sunlight, it occurs more or less electricity and obviously full sunlight are preferable to shade, although stray light is also generated some energy. We must remember that the effectiveness of the panels significantly decreases when the cell temperature increases, and it is for this reason that the bottom of the panels is open and airy so it will not overheat due to sun exposure. Each cell of about 10 cm side is able to generate 1.5 watts, and a typical panel a square meter delivers about 100 watts.

An interesting place to place the panel. When not intended to charge batteries, it remains without disturbing the vertical position of the image. But you can also lift and adjust the tilt angle hovering over the side as if it were a table.

How much energy the sun sends us?

The maximum irradiation corresponds to areas where orange received over 2,250 kWatt / m2 year.

The sun constantly emits huge amounts of energy; a fraction of it reaches the earth. The amount of solar energy received in one day is more than enough to meet global demand for a whole year. However, not all the energy from the sun can be used effectively.

The intensity of the sunlight that reaches our planet varies by time of day and year, place and weather conditions. The total energy registered is called “radiation” and indicates the intensity of said light. The radiation time is expressed in Watts / m² per day.

In order to simplify the calculations, solar energy is expressed in equivalent hours of full sunlight. Full sunlight registers a power of about 1000 watts / m. This is approximately the amount of solar energy recorded during a sunny summer day, with clear skies, in an area of one square meter, placed perpendicular to the sun.

Radiation varies with the time of day. However, you can also vary considerably from place to place, especially in mountainous regions. Radiation ranges from an average of 1,000 kWh / m² per year, in the northern European countries (such as Germany), and 2,000 to 2,500 kWh / m² per year, in desert areas. These variations are due to weather conditions and the difference between the relative position of the sun in the sky (solar elevation), which depends on the latitude of each place.

In the prepared cruise ships and transoceanic crossings, it is very common to find installations of solar panels. In this case, the panel is mounted on the stand that protects part of the tub.

Silicon is nothing more than the fine sand of the beach, which melts to eg make glass or melts very very pure and allowed to crystallize as it cools, serves to make cylinders of silicon that are cut into thin slices a tenth of a millimeter, then modify them with other compounds and achieve manufacturing a solar cell. Thus monocrystalline crystals are obtained after a complex and high-tech operation. To cut costs can cool the silicon and treated with dopants and crystallize in a polycrystalline structure which will subsequently be cut into slices ready to make solar cells. Polycrystalline is, therefore, more economical, pays 5% less but the panels are somewhat flexible. The third technique consists in vaporizing gaseous silicon on a substrate to obtain a lightweight flexible cells but with an even lower yield.

For 12 volts are serially connected cells 36, but with increasing temperature will decrease the voltage delivered by the panel. 10 degrees warmer, we will lose 0.7 volts. We must be very careful with the shadows cast on the panel, because if for example, 25% of the panel stay in the shade, the power output will be greatly reduced to one-fifth. In short, the panels must operate fully lit, and be placed on sites that can be targeted to the sun. The can be mounted directly above the deck, on an arc or on a support placed on the transom. In the multihull, there is plenty of surfaces and find a suitable place is much simpler.

Flat mounting on the deck. The club often creates shadows to fall precipitously performance panel. When some cells are in shade panel these act as a high resistance to rest panel so the current delivered descends in a much higher percentage than would correspond to the shadowed area.

Tilt angle

The sun in winter (1) rises much less than in summer (2). Therefore we must also adjust the azimuth angle of the panel.

The sun moves in the sky from east to west. Solar panels reach their maximum effectiveness when they are facing the sun, at a perpendicular angle with it at noon. Usually, the solar panels are placed on a roof or structure and have a fixed position; they can not follow the path of the sun in the sky, and on a boat … to talk more. Therefore, there will be oriented towards the sun with an optimal angle (90 degrees) throughout the day.

Because of the Earth’s motion around the sun, seasonal variations also exist. In winter, the sun does not reach the same angle as in summer. Ideally, in summer the solar panels should be placed in aslightly more horizontal position to maximize sunlight. However, the same panels will not be, then, in theoptimal position for the winter sun. In order to achieve a better average yield, solar panels must be installed in a fixed, predetermined angle somewhere between the optimum angles for summer and for winter. Each latitude has an optimum tilt angle. The panels should be placed in a horizontal position only in areas close to Ecuador.

A great solution. The panel will receive no shade and regardless of the direction of navigation, adjust the panel orientation to get the best irradiation projected on cells.

When connecting solar panels, we must place a diode to isolate the current supplied Battery Park. If we set up a regular diode it is unnecessary unless we put several solar panels in parallel, in which case it is necessary to prevent the current delivered by a panel can be absorbed by other working less efficiently or is in the shade. The power cord used must have an adequate section and at least use a section of 2.5 mm. With installations of several panels in parallel, we must increase the cable section about 4 millimeters.

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