Practically all you ever hear about is solar panels… are they really so much more effective then other methods, such as using energy from the sun to power a steam-powered turbine enclosed in a system with a vacuum so that the water evaporates at a much lower temperature to power a turbine?
More Pages:
- Solar Power: Solar Power Cost Effective Calculation? (7/27/2011)
- Solar Energy: Is It The Heat That Gives Energy To Solar Panels Or A Something Else? (7/16/2011)
- Solar Products: Can Solar Panels To Heat Pool Be Used For Other Household Purposes? (6/17/2011)
- Solar Lights: How Do I Use The Power I Get From A Solar Panel Or Wind Turbine? (7/5/2011)
- Solar Power: What Is The Most Efficient Way Of Powering Your Home? Do You Use Solar Power, Wind Turbine, Coal? (6/4/2011)
{ 4 comments… read them below or add one }
No
It entirely depends on the application, power requirements and investment costs.
Steam plants (of any kind) are very expensive pieces of infrastructure and require much capital to build and many long years to return the investment. Solar steam has the added problem of storage of heat for use when the sun is not shining. But a Solar steam plant can create more effective power generation than passive photovoltaic panels at large scales, but not small scales.
If you needed a small amount of power at a remote location with no transmission lines, then photovoltaic is the only game in town from solar power perspective. (not to mention wind).
Using the most energy efficient technology is not always the right answer. One could never afford to build a steam solar plant for a remote dwelling. But photovoltaic may do just fine. In any event the cheapest, most reliable option (but far from the most energy efficient) is to hook up to the local power grid.
No. Solar panels are just more versatile. Solar panels can be put almost anywhere while a turbine system requires a significant amount of dedicated space. Also, solar panels have no moving parts, so there’s less maintenance.
I guess in the household situation solar panels are more attractive, as they are simpler. Solar absorption systems are of course used for hot water, and are roughly equivalent to what the average household rooftop systems might be – a few kilowatts of capacity. Solar absorption systems are more of a utility thing, because of the size, the need to track the sun etc.
Looking at the Stirling Energy Systems sun catcher for an example, this uses an 11m dish to produce about 25kW. The heat engine is a 4 cylinder stirling cycle engine, presumably because it doesn’t need a large condenser like a rankine cycle turbine, and can use hydrogen gas as the working fluid, and run at a variety of temperatures.
The capture area of the dish is pi*r^2 = 95m^2 for 95kW energy from the sun, so efficiency is around 25kW/95kW = 26%, which is better than most PV systems. Additionally it can use this for more hours per day, as it tracks the sun (maybe 30% more energy per day for given watts capacity), but it can be argued that it does not work well in overcast conditions, as it needs a spot source (the sun) to focus on the collector. Thermal absorption systems can store energy as heat too, using molten salts technology.
Another 50MW thermal absorption facility operates in Spain to provide electricity over night as well using molten salt storage. These systems are still evolving, but clearly are capable of reasonable operations in suitable conditions.
Another concentrator system using solar PV is interesting. This system with dish like tracking mirror arrays produces about 35kW each dish with efficiency said to be up to 40% using a small solar PV receiver (0.23m^2 = about 1/2 meter square) with about 500 times concentration. This receiver produces ~400V @ 92A, per dish, and is said to be lower cost than a same rated flat panel system. These have 135.5m^2 of mirrors but the dish diameter is 13.7m so capture area is really 147m^2, giving 147kW/35kW = 23.8% efficiency with SOC. Typical peak production at Windorah Qld Australia (Ergon Energy) is 26kW because the site has other than SOC (Standard Operating Conditions = 1000W/m^2 and 25C). The location is inland near the tropic of Capricorn so I expect this is due to ambient temperature, as the voltage is lower, though they are liquid cooled. These are said to use 35% efficient solar PV receivers. This same company can also provide base load PV solar using a hydrogen system.