Are Companies Like SolarCity Wasting Taxpayer Money?
Not all forms of energy are equal; electrical energy is more precious, and costs much more than heat or mechanical energy. Companies such as SolarCity are wasting taxpayers’ money by increasing the grid’s entropy, and from a physics point of view, solar thermal makes more sense, and ultimately, it’s only these incentives that make SolarCity an economic reality.
To properly talk about the question of what’s best to put on your roof, a few terms need to be defined.
Exergy is the amount of energy available to be used in a system. A cup of boiling water can only release energy into its environment until it is in equilibrium with its surroundings.
Entropy is the amount of disorder caused by making useful work. Turbine engineers can look at where entropy is created in an effort to reduce losses such as frictional loss and thermal loss; electrochemical losses can also be determined using entropy.
In the case of rooftop solar, radiative heat energy is turned either into electricity using photovoltaic panels, or the heat is collected for other purposes using solar heating panels. Solar heating can generally be used for three purposes: heating your water at home, heating your home, or cooling your home. Cooling your home using heat is done using absorption coolers using various thermodynamic processes, and can drastically reduce electricity use for air conditioning in warmer climates. Passive measures can also reduce heating costs by up to 50 percent, which in turn will further lower A/C costs.
From an efficiency standpoint, solar thermal collectors can collect up to 74 percent of the solar energy beaming onto them – this by itself means that the building underneath will require less heat. Combine that with better insulated windows, doors, and walls, and your heating and cooling costs – and energy use – will plummet.
U.S. companies hold the claim that heating your house can be done with only a hair dryer, and cooled with dehumidification. Commercial solar panels can collect up to 22 percent of the energy landing on them. There are considerable system losses and entropy production from turning solar radiation into electricity, and then back into heat. – READ MORE