| The idea of getting something for nothing is always | | | | However, an installation of larger panels could be |
| appealing and this is the attraction of marine solar | | | | useful on a sailboat to provide power, through a |
| panels. They generate an electrical current when | | | | battery, for electronic navigation equipment. Portable |
| exposed, not just to the sun, but in any kind of daylight. | | | | panels are available which can be rigged on deck as |
| Although the current is small, it is very useful in | | | | required, but a permanent installation is much better |
| providing a trickle charge to keep the batteries fully | | | | and modern units are rugged enough for deck |
| charged when the boat is left unattended. | | | | mounting. |
| Solar panels consist of a series of photovoltaic cells | | | | Connecting boat solar panels is a simple matter. If |
| linked together and protected between rigid or | | | | there is more than one panel, take the leads from the |
| semi-rigid panels, the top panel being clear glass or | | | | panels to a junction box, and from there the twin leads |
| plastic to allow the light to reach the cells beneath. The | | | | can be taken to the charging system. The wires could |
| semi-rigid panels are better for boat use because the | | | | be connected directly to the battery or alternatively to |
| surfaces to which they have to be fastened are rarely | | | | the alternator side of the battery isolator/selector |
| flat. | | | | switch, which would allow the current to be directed to |
| A 2 sq ft panel will produce about 6 watts of power in | | | | either battery. Solar panels have a diode incorporated |
| bright sunlight - not very much, so a panel of this size is | | | | so there is no worry about current feeding back |
| only suitable for keeping a small battery topped up. | | | | through the panels from the battery. |
| Larger panels will obviously produce more power, but if | | | | Since the panels are in effect directly linked to the |
| space doesn't allow a single larger panel, the small | | | | battery, even though the isolator switch may be off, |
| panels can be linked in parallel to increase the power | | | | the leads from the panels could be a source of short |
| output. Most panels on the market today are rated at | | | | circuits unless the wiring is carried out to the highest |
| 12 volts, so if your boat has a 24 volt system, then | | | | standards. Because they are left unattended, the |
| two panels should be linked in series to obtain the | | | | portable panels could pose an unacceptable risk, |
| required voltage. In dull conditions the output will be | | | | particularly if they are connected to the battery |
| halved. | | | | terminals by spring clips. A useful safety feature would |
| One of the snags with solar power is that it produces | | | | be to fit a fuse into the supply leads to give some |
| most power when you are least likely to need it. Its | | | | protection against faults; this fuse should be as close |
| role then is primarily to keep batteries topped up. | | | | as possible to the battery on the positive side. |