![]() ![]() ![]() ![]() Our Sun emits about 1045 photons per second.important to understand solar sails rely on photons What does geothermal translate to in Greek? Geothermal is Greek for "earth heat". For light only a tiny amount of momentum is transferred per photon, but stars emit a lot of photons. When light bounces off a surface, it gives it a tiny push. Light does not have mass, but it does have momentum. Solar sails as a propulsion method in space are moved how? A solar sail is a large sheet of reflective material acting like the sail on a sailboat, except it relies on light for propulsion rather than wind. Degradation of the solar panels comes close to making this solar energy system uneconomical and unrealistic. Panels require high-strength shielding to protect against space debris and their huge surface areas can make them vulnerable to incoming space junk. What is one of the big threats to putting solar panels in space? Protection against projectiles in space is a big concern. In what band of the electromagnetic spectrum would we beam solar energy to Earth from satellites? Orbital solar power collection involves placing several large satellites into geosynchronous Earth orbit.Very large, nanotech-based surfaces on each satellite's solar array (typically 1 to 3 km in size) capture the sunlight energy, which is then beamed down to Earth via microwaves or lasers. What is a heliostat? Power-tower systems are solar thermal power plants that use a field of heliostats - flat Sun-tracking mirrors - to focus sunlight on an absorber at the top of a central tower. A parabolic trough concentrator focuses sunlight to a line rather than a point. The most effective solar concentrator shape is what? The most effective concentrator is a parabolic concentrator, which reflects parallel rays to a common point of focus. They're therefore simple, inexpensive, and self-contained, and are widely used. Such thermosiphon systems avoid the need for a pump. What is a thermosiphon? If a storage tank is located above the collector, the density-driven flow is in the right direction to collect energy rather than lose it. ![]() You can get a blackout if the system goes down longer than the battery charge and there is no backup power source. A stand-alone PV system of this type offers independence from the utility companies. How do you align a solar panel angel for your living location? 45 degrees? Facing south in Northern Hemisphere Why do you need power storage batteries with a solar power system? The use of batteries allows the system to produce usable power even if there is not enough light for the PV cells to operate. You can misalign a solar panel up to what degree and have no effect on power generation? A misalignment of up to 15° makes almost no difference. Solar collector on roof Besides furnaces, what home system uses the most energy to run? Water heating Why are solar panels placed broadside to incident sunlight? A solar panel produces the most power when it is broadside to incident sunlight, so the Sun's rays shine straight down on the surface. What are the two most popular types of home active solar power systems? Domestic water heating Active systems are more compact than passive solar designs and allow for more flexible placement of components. Why are active solar power devices more efficient than passive solar systems? Active solar heating systems use pumps and fans to move heated fluid from solar thermal collectors to an energy-storage medium, and from there to wherever heat is needed within a building. Radiation from the back of the wall provides additional heat transfer into the house. Air confined between the wall and glass warms and rises, resulting in natural convection that circulates warmed air throughout the house and returns cold air to be heated at the wall. What is a Trombe Wall? where sunlight passes through glass and strikes a massive vertical wall serving as both absorber and thermal mass. R characterizes a specific thickness of a material. The higher the R-value, the greater the insulating power.R value measures a materials resistance to the flow of heat. What is an R-value? R value is the material's resistance to the flow of heat. ![]()
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