|Solar Powered Tree House|
This splendid example of a tree house was built on the land my parents Purchased in Evergreen Colorado. As gracious as they where my parents purchased the land and then returned to Chicago for another 2 years before they finally decided to develop the land. during those 2 years the tree house acted as my "summer home" up in the mountains.
Only trouble was, the tree house had no utilities what-so-ever. and in theory you could get snowed in fairly quickly if you where staying the night during the fall season. I wanted to at least have enough power to run a CB radio. I quickly decided that the tree house would be great testing grounds to start working with solar power.
While a heavily forested area of Colorado may not be one of the best locations in the world to rely on solar power, it is far from the worst. The back side of the Tree house roof faced a small opening in the trees that allowed for a few hours of direct sunlight every day, and quite a few hours of indirect sunlight as well. It also helped that at higher elevations and being away from city smog meant clearer skies and even more sunlight!
Solar power is fairly easy. You have four main components. A solar panel (PV) A battery, the charge regulator, and if you want 110vac you'll need a power converter. For simplicity sake a 12v solar power setup was chosen for the tree house as there are many accessories for 12v power sources already built to work within cars, and 12v batteries are usually easy to find.
Photovoltaic cells (PV's) convert the energy in sunlight into electricity. When sunlight hits a PV cell, electrons are dislodged, creating an electrical current. The brighter or more direct the sunlight the more current the cell can produce up to its limits. The electricity produced through a PV is in DC (Direct current) just like a battery. Pretty much anything you can power via a battery you can power with a PV of the appropriate size. The problem is a PV itself has no ability to store energy only produce it. So if you had direct sunlight you might be able to run a radio from the cell but as soon as the sun went behind a cloud your radio would go dead. Due to this limitation most solar powered devices do not draw there power directly from the cell rather they pull energy from a battery that has been charged by the cell.
A lead-acid battery is a chemical storage device that uses a reversible chemical reaction to store energy. It uses a combination of lead plates or grids and an electrolyte consisting of a diluted sulphuric acid to convert electrical energy into potential chemical energy and back again.
Deep Cycle batteries have thick lead plates that make them tolerate deep discharges. They cannot dispense charge as quickly as a starter battery (car battery). The thicker the lead plates, the longer the life span, all things being equal. Battery weight is a simple indicator for the thickness of the lead plates used in a battery. The heavier a battery for a given group size, the thicker the plates, and the better the battery will tolerate deep discharges. Some "Marine" batteries are sold as dual-purpose batteries for starter and deep cycle applications. However, the thin plates required for starting purposes inherently compromise deep-cycle performance. Thus, such batteries should not be cycled deeply and should be avoided for deep-cycle applications unless space/weight constraints dictate otherwise.
The Amp-hour (Ah) Capacity of a battery is the amount of usable energy it can store at a nominal voltage. The Ah will define how long your solar power rig can supply current and how long it will need of full sunlight to be fully charged again. The Higher Ah you have the larger capacity. Many solar power rigs are comprised of multiple batteries in parallel to increase Ah.
A charge regulator protect batteries from over- and dis-charging. Solar PV charge controllers take the uncertain voltage from a solar panel and condition it to safely charge lead acid batteries. Some even use pulse width modulation (PWM), and a 3 stage charging method, bulk, absorption, and float (maintenance) charge. They also protect the panels from the batteries after the sun goes down. To get the longest life out of your expensive PV cells and batteries solar charge regulators are necessary to protect your PV investment.
Power Converters change the 12v DC power from your batteries into 110v AC current to run standard wall socket type devices. If at all possible you want to stay away from excessive 110v usage in a small solar rig like the one I built. Sure you can get 110v from it but its going to drain your batteries quickly. You are far better off using 12v devices. Since my main goal was to install lighting, radio, and CB it was easy enough for me to use a 12v car stereo and CB and only do the outdoor flood lamps in 110v. for that I chose a small 300Watt converter so I would not be tempted to use more 110voltage than was needed. The indoor lighting was done using an array of High powered LED's off the 12v circuit (wish I would have banked on that idea before everyone started selling them)