Who likes free electricity? You? Me?
We all do. Solar panels harvest the suns energy and transforms it into useable energy.
There are many different types of solar panels on the market but there are 2 of which that the public can actually afford:
Monocrystiline
Polycrystalline
I'm not going to describe the two, but I will provide a link describing their benefits and advantages.
http://energyinformative.org/best-solar-panel-monocrystalline-polycrystalline-thin-film/
Batteries:
Most people use 6 volt batteries and run them in series and parallel. 12 volt or 24 volt systems are the most common set ups. 12 volt is by far the most common. And 24 volt systems are more efficient due to the higher voltage. Any battery type will work, but depends on the load your intending to put on the batteries. for example, a 12 volt 10 AH battery will not be able to start a car. Why? Because the battery was simply not made to start a car. Any type of car battery will work with a solar panel system. Its just which one is better and how much do you want to spend?
There are so many links on the internet about properly sizing your system. Going to YouTube is a great place to find many good systems and very poorly designed systems.
Charging:
When its 12 pm and the sun is directly over the panel, the batteries even if they are full, are getting charged. This cooks the batteries if the current is over 2 amps.
I would highly recommend a charge controller on any system regardless of the systems size.
Charge controllers know when the batteries need to be charged and most know when it is daytime or night time and can turn the intended load on or off depending on the time.
Solar panel size:
In this case, bigger is better. We only have so many hours of light. A 100 watt solar panel that is powering a system that draws a total of 400 watts is undersized. More batteries in this case would be better for the tinny solar panel.
Battery isolation or strapping:
Flooded lead acid batteries emit a minute amount of hydrogen (which in the perfect conditions, explode). This is the reason why almost all batteries are in the engine bay outside the car (besides it being inconvenient to place a battery else where).
If you do go with putting a battery in a confined area, ventilate the area from time to time and put the battery or batteries in a battery box in case of leakage.
If the battery is in a non confined area or area specifically made for the batteries, a battery tray or box is a good idea as well as strapping to hold the batteries down.
If installed in the exterior of a trailer a strap or straps are necessary to hold the batteries in place. A battery tray is recommended, but not required.
Wire size:
The smallest gauge that should ever be used on a system is 12 gauge. For a solar panel, stranded wire is recommended, more surface area versus solid wire and less brittle when cold.
EDIT 1: lfhoward had brought this up for his trailer build;
my system is 60 volts, so the dual gauge runs are necessary for the lighting conditions (seasons).
lets say you buy a 24 volt panel at 100w, 12 gauge would be a perfect average. a 12v 100w panel at 12 gauge would be perfect for summer but detrimental for winter.
winter has longer days, therefore more light but weaker; producing higher voltage but less amperage. smaller gauge wire carries the voltage more efficiency then (lets say) a 12 or 10 gauge run.
summer has a stronger ray, but the rays stay out for a very brief time so a perfect gauge is required. meaning not under or over.
Being tidy with your wire loom is key to preventing tangles and confusion down the road.
Fuse:
Oversize the fuse by no more then 10% of the max load. Meaning if your inverter draws 100 watts max, the fuse will blow near 110 watts. Reason being, you want a serviceable fuse blowing before the internal fuse blows on the inverter.
Just like a car, have the fuse closest to the battery and when in doubt, fuse it. Even the solar panel. No one likes being shocked!
Inverters:
There are 2 different types of inverters:
Pure sine wave;
Very clean and efficient inverter. Most of the time they are cleaner then your house electricity. They are expensive!
SEE PHOTO BELOW
Modified sine wave;
Common; cheap; inefficient. When sensitive electronics are plugged into a modified sine wave inverter, some buzzing or unnecessary flickering will be seen.
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