Sale of Solar Panels
The cost of electrical energy on a boat or yacht is very high. Especially if, when docked, the owner charges the batteries with an engine that does not have an external voltage regulator or a DC-DC charger installed. In this case, any equipment that generates electricity cheaper than an internal combustion engine does becomes economically profitable and quickly pays for itself.
Solar panels, or photovoltaic cells, convert free energy from sunlight into electrical energy. Considering that the price of the semiconductors from which they are made decreases every year, panels on a yacht or boat will pay for themselves within a few months or, at most, a year. That is, in the long term, it is economically profitable to install them on the boat in the greatest possible quantities, as far as the free surfaces of the yacht allow.
The Use of Solar Panels on Yachts and Their Advantages
Solar panels can be used on various types of vessels - from small yachts to large tankers and container ships, on any boat that has the ability to use environmentally friendly energy sources. This opportunity lies in the number of free spaces which solar panels can occupy, as well as on financial opportunities in order to purchase the most modern, innovative models, the types of which will be discussed in the next section.
The main areas of application of solar panels on yachts are:
- power supply for lighting and electrical equipment;
- navigation system power supply;
- power supply for air conditioning system, etc.
The main advantages of using solar panels on ships, in addition to the long-term economic benefits already mentioned:
- reduced dependence on fuel;
- increasing the efficiency of the ship's electrical power system due to the ability to use different power sources;
- increasing the autonomy of the yacht due to additional energy supply from an independent source;
- no moving parts, which reduces the number of breakdowns, maintenance requirements and the frequency of repairs;
- reducing emissions of harmful substances into the atmosphere and water bodies.
Of course, like any equipment, solar panels, especially those installed on a ship, have disadvantages. One of them is a limitation in efficiency, which depends on natural phenomena: the intensity of sunlight, the angle of incidence of the rays on the surface of the panel, ambient temperature, etc. Manufacturers are looking for and finding ways to overcome these shortcomings, which, of course, affects their cost.
High cost is another disadvantage of solar panels compared to other energy sources on ships. But as we already mentioned, long-term costs for panels and other energy sources, as well as falling prices due to market expansion, are driving solar panels higher and higher among competing technologies.
Types of Solar Panels
There are three types of silicon solar panels used on boats and yachts. In addition to silicon, other materials are used to manufacture these elements: selenium, gallium, copper, indium, polymers, telluride, organics, etc. But such panels are usually used on other objects.
It is very important to choose the right set of solar panels for a particular yacht based on type, power and placement parameters on the yacht to ensure their maximum efficiency.
Monocrystalline
In monocrystalline panels, each cell is cut from a single silicon crystal. Although some semi-flexible models also use monocrystalline cells, generally this type of panel is rigid and does not tolerate bending. Their conversion rate of light into electrical energy reaches 22%, but most often it is 16-18%.
Most monocrystalline panels have a solid, rigid back wall. Recently, double-sided models have appeared that allow light to be collected on both sides. This is convenient when there is a reflective surface under the panel, for example, a white cabin roof.
Polycrystalline
In polycrystalline solar cells, each cell is made up of several small crystals. Such panels are less efficient than monocrystalline panels, especially at low light levels, but are lighter and cheaper.
Amorphous
During the production of amorphous wafers, evaporated silicon is deposited on the substrate. Amorphous panels are the cheapest and very flexible, but they are the least efficient. They can be used as additional energy sources where it is impossible to install inflexible panels.
Each silicon cell, regardless of size, produces a voltage of about 0.6 volts when exposed to direct sunlight. The voltage of the entire battery can be approximately determined by multiplying 0.6 by the number of cells. For example, the voltage of a solar panel consisting of 30 cells is 18.0 volts.
The output current of a cell depends on its type, quality and surface area. Therefore, to obtain the same power output using amorphous and monocrystalline panels, amorphous panels will have to occupy twice the area. In addition, the power of amorphous batteries is approximately 10% less than rated for one to two years after production. In the future it will stabilize.
Prospects for the Development of Marine Solar Technologies
Thin film technologies have a very good future. They are seen as the future of photovoltaic energy, despite the fact that currently more than 90% of all solar modules produced in the world are crystalline. However, thin-film module technologies are developing very quickly, and in several directions.
The very first thin-film module technology to become commercially available was amorphous silicon film. The first generation with single-junction solar cells had a short service life and an efficiency of 4-5%. The second generation also had single-junction elements, but their service life was almost equal to the service life of crystalline elements, and the efficiency was 6-8%.
The third generation includes the most modern multi-junction thin-film elements, which make it possible to achieve even greater efficiency (up to 12%) with a long service life, even in marine operating conditions.
These technologies are not yet used for yachts – for now we have flexible solar plates based on silicon monocrystals, such as Mono PERC Shingled Flexible, presented in the topRik marketplace in various capacities.
This solar panel is made of highly efficient monocrystalline cells, guaranteeing exceptional performance even in low light conditions. The lightweight design makes it easy to transport and install anywhere in any facility due to maximum flexibility.
How to Choose Solar Panels for a Specific Yacht
Solar batteries are tested under standard conditions. The resulting characteristics indicate the solar cell specification. But it should be borne in mind that even under standard testing conditions, the output power at the battery charging voltage is always 20-25% less than the nominal one. This is because the panel voltage at maximum power depends on the number of cells and their temperature. It is always higher than the recommended charging voltage, but decreases when connected to the battery.
There are other losses that must be taken into account when choosing and before installing solar panels on a yacht or boat. On land, the panels are mounted on supports located at an angle to the horizontal. In this case, the maximum amount of sun rays reaches the surface. But if you install the panels on a boat or yacht in this way, after each turn they will lose the sun. To avoid this, panels on boats are almost always installed horizontally in a fixed location. However, even in the tropics, solar noon (the time when the sun is directly overhead) lasts only a few hours a day. The rest of the time, the sunrays fall on the panel at smaller angles and the amount of energy they transmit is noticeably reduced.
Bypass Diodes
The actual power of the panel is reduced even further if a cloud obscures the sun or if a shadow from rigging, sails or a mast falls on the surface of the battery. Even partial shading of one cell in a series-connected circuit significantly reduces the output current.
Sharp shadows affect power output more than shadows with soft edges. If the cells do not have bypass diodes installed, then a sharp shadow on one cell will reduce the output current of the entire panel in proportion to the shaded area (for example, 50% shading of just one cell will reduce the output of the entire panel by 50%). A cell in the shadow consumes current from its neighbors and overheats.
Bypass diodes reduce problems from shading. They isolate a cell in the shadow and stop the development of “hot spots”. However, each cell removed from the common circuit reduces the voltage of the entire panel. Since the output voltage of the panel decreases due to heating, a situation may arise when it is below the level suitable for charging the battery. In this case, the benefit of bypass diodes disappears.
What Are Peak Solar Hours?
Even in sunny climates, the energy actually generated by the panel during the day rarely exceeds 4-5 hours of operation at maximum power. Often this value is even less. It is better to base calculations on the assumption that daily electricity generation corresponds to 3-4 hours of battery operation at rated power.
This method of comparing the actual energy generated by a solar battery with the maximum is called peak sun hours - Peak Solar Hours (PSH). There are websites that calculate PSH for different parts of the world and for different periods of the year. However, almost all of them assume that the solar panels are installed at an angle to the horizon and that no shadow falls on them. In this case, PSH is significantly overestimated. Since a realistic estimate of PSH is 3, the number obtained from the online calculator must be reduced by at least 30%.
Solar Panel Voltage
To charge the battery, the voltage of the solar panel, like any other charger, must be higher than the voltage of the battery. Moreover, the difference should exist even when the battery voltage rises to 14.0 volts.
It would seem that these conditions are easily met, but this is far from the case. Much depends on the degree of heating of the panel surface - black silicon. If the panel temperature exceeds 25°C, its output voltage will begin to decrease from its rated voltage depending on the temperature increase. Therefore, it is important to correctly calculate the number of panel cells for each specific boat.
This is not a complete list of points that should be considered when choosing a set of solar panels for a yacht power plant. Only experienced specialists can help with this.
If you have questions about choosing solar panels for your yacht, ask them to the experts of the topRik marketplace. All consultations are provided for free, even without registration on the website.