In the July/August 2006 issue of Beaver Journal, we featured “Taming the Sun,” an informative story about the installation, operation and maintenance of your RV solar panels. That story generated numerous requests from readers for more information. With a list of specific questions in hand, we once again consulted the experts:
Q What is the optimum amount of solar panels to install on an RV?
A If you are only interested in keeping up with the parasitic load, one or two solar panels should do the trick. For RVers who find themselves away from hookups for three to five days, three to four panels are recommended.
Q Can I start small and add more panels later?
A This will depend on the wattage rating of the solar controller. Some controllers are rated only for one panel, but others are designed to enlarge the system. Before you add more panels to a current system, first check the wattage of the solar controller. If you are installing a new system and think additional panels will be added in the future, start with a controller that allows for expansion.
Q Is it possible to add solar panels of various sizes to the same system?
A You can add different wattage solar panels together as long as they all contain the same operating voltage. Different voltages confuse the controller and prevent the system from delivering maximum power.
Q Should I add only enough panels to take care of the parasitic load and let the generator take care of the rest?
A This depends on your personal preference and camping style. The generator will most certainly handle all your electrical loads while away from shore power, but take into consideration that every solar panel you add will cut back on the need to operate the generator.
Q Will the solar controller provide the electrical system with excess energy after the batteries are charged?
A The HPV-30D is designed to directly run DC loads after the batteries are fully charged, as long as the sun is shining.
Q Is a generator with the auto start option more cost effective than additional solar panels?
A It is recommended to have both. Additional solar panels will maintain the batteries at a higher state of charge. This puts the auto generator program in a reserve mode, which saves you the cost of fuel and maintenance. More solar panels can also extend the life of batteries by keeping the battery state of charge over 50 percent.
Q The Aladdin system can show as much as 16 or more volts produced by the panels, but how much is actually being used to charge the batteries?
A The voltage you see on the Aladdin is the voltage going to the controller. The controller converts energy to a safe charge voltage before it reaches the batteries.
Q How do I test a solar panel to confirm that it is working?
A Disconnect the positive and negative wires located on the roof near the panel. Using a meter at the output terminals the panel should register well above 12 volts DC when not hooked to a power draw.
Q What is Pulse Width Modulation (PWM)?
A A method of charging that tapers off as the battery approaches full charge. This process provides the highest state of charge to the batteries with the least amount of water loss.
Q Should solar panels be connected in series or parallel?
A The solar panels should be wired in parallel to produce optimum charging amperage.
Q Can I replace a small panel with a large panel and still use the same wiring?
A This depends on the size of the wire. Wire diameter (American Wire Gauge) and the length of run will limit how much current a wire is capable of handling. First, do your homework and be sure all the components of the system are capable to handle the upgrade. Then calculate the wattage of the solar panel system to determine wire size.
Q How far can I run the wires from the controller to the batteries?
A It is recommended to locate the controller within fifteen feet of the batteries, but not so close as to expose the controller to hydrogen gas emitted by the battery bank. Also keep in mind that the farther from the batteries the controller is located, the larger the wire diameter required.
Q Is there a process to repair broken glass on a solar panel?
A The solar panel is a layer of glass laminated together with a series of specially crafted materials. If the glass is broken, the underlying materials may still be functioning, although at a reduced rate. A milky white spot on a broken panel usually indicates water penetration and signals that the solar panel is no longer functioning. When the glass is shattered, all the laminate materials are likely damaged and it is usually best to replace the panel. |
