Solar energy is a hot topic in the news these days. But if you’re not already familiar with the terms, it can be confusing. What's the difference between active and passive solar energy systems? And which one is better?
Active solar technology uses electrical or fuel-driven mechanical equipment to perform some of its functions. For example, some solar swimming pool heating systems use electric pumps to move the heated water from the coils in the solar panels into the pool. Large off grid solar electrical systems that provide 100% of the electricity to buildings usually use diesel or gas-powered generators as part of their backup systems.
Some solar electric systems use motors to allow their photovoltaic arrays to track the sun's movement throughout the day in order to maximize the amount of sunlight they capture. Grid-tied solar electrical systems are also considered to be active systems because they rely on the electric company as a backup source.
Passive solar technology does not use additional mechanical or electrical devices to deliver heat or electrical energy. There are no additional fuel or utility costs, and no added environmental impacts. For this reason, many people think that passive solar technology is superior to active solar technology.
The most common passive solar application is solar water heating. A truly passive solar hot water system can provide enough hot water for washing and bathing. It usually consists of a collector tank located on a south or west-facing wall or on the roof, and a plumbing system that delivers the water using gravity. These types of systems are most successful in moderate climates where temperatures don't get cold enough to cool the water in the storage tank.
It's also possible to combine passive and solar energy systems to get the benefits of both. Any of the active systems that use electric motors can also use solar cells to create the electricity. For example the motors that move photovoltaic arrays can easily be powered by solar cells. And solar cells can also power the electric pumps that move the water in solar swimming pool heaters, and in water heating systems used in buildings.
Some active solar electric systems, like off grid systems, need external generators. They are part of the system to provide backup energy during long periods of cloudy days when there is no direct sun. Solar cells won't work under those conditions. But it's still possible to stay green by using bio-diesel fuel to power the generator.
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Saturday, April 11, 2009
Friday, April 10, 2009
Off-Grid Solar Electric System Explained
If you have ever dreamed of being completely energy independent, then your ultimate goal is to live "off grid". Most people who live off grid are located in remote areas where electric utility service is not even available. But more and more people are considering it as a personal lifestyle choice.
There are two main factors involved in living off-grid. First, you'll need to become very aware of when and how you use electricity. You won't have to live without it, but you won't want to waste it, either.
Second, you'll want to become familiar with how your solar power system works, and what kind of maintenance is required. It would be best if you become an expert on your particular system, so you can troubleshoot anything unexpected that arises. Becoming an expert is not that hard to do since there is so much information on solar energy available now. But it will require time and commitment on your part.
A basic off-grid system is made up of 9 components.
First, the photovoltaic array and mounting rack. Wikipedia describes the array as “a linked collection of photovoltaic modules, which are in turn made of multiple interconnected solar cells”. The mounting rack allows you to attach them the roof and point them toward the sun.
Second, the array DC disconnect. This is basically a breaker between the array and the rest of the system. It allows you to disconnect from the system in order to troubleshoot problems with the array.
Third, the charge controller keeps the batteries from overcharging.
Fourth, the battery bank stores excess electricity. You will usually need enough batteries for 2-3 days worth of stored electricity in case of a cloudy period.
Fifth, the system meter is like your car's dashboard. It reports how the various components in your system are doing,
Sixth, is the main DC disconnect. This is a breaker between the storage batteries and the inverter.
Seventh, is the inverter. This is the component that transforms the DC (direct current) electricity, which is generated by the array and stored in the batteries, into the AC (alternating current) electricity that can be used by your household appliances.
Eighth, the AC breaker panel. This is the same kind of breaker panel that the electric company uses to connect your house wiring to its electrical source.
Ninth, your backup generator. This is in case you have a stretch of cloudy days that outlast the electricity stored in the batteries. You can use traditional fossil fuels, but you’ll probably want to use biodiesel to maintain your green lifestyle.
Now that you’ve seen the components of the photovoltaic system, you can see why it's not that complicated to become your own expert. Each component is relatively simple. The only moving parts are in the backup generator, and you hopefully won't be using that very much.
There are two main factors involved in living off-grid. First, you'll need to become very aware of when and how you use electricity. You won't have to live without it, but you won't want to waste it, either.
Second, you'll want to become familiar with how your solar power system works, and what kind of maintenance is required. It would be best if you become an expert on your particular system, so you can troubleshoot anything unexpected that arises. Becoming an expert is not that hard to do since there is so much information on solar energy available now. But it will require time and commitment on your part.
A basic off-grid system is made up of 9 components.
First, the photovoltaic array and mounting rack. Wikipedia describes the array as “a linked collection of photovoltaic modules, which are in turn made of multiple interconnected solar cells”. The mounting rack allows you to attach them the roof and point them toward the sun.
Second, the array DC disconnect. This is basically a breaker between the array and the rest of the system. It allows you to disconnect from the system in order to troubleshoot problems with the array.
Third, the charge controller keeps the batteries from overcharging.
Fourth, the battery bank stores excess electricity. You will usually need enough batteries for 2-3 days worth of stored electricity in case of a cloudy period.
Fifth, the system meter is like your car's dashboard. It reports how the various components in your system are doing,
Sixth, is the main DC disconnect. This is a breaker between the storage batteries and the inverter.
Seventh, is the inverter. This is the component that transforms the DC (direct current) electricity, which is generated by the array and stored in the batteries, into the AC (alternating current) electricity that can be used by your household appliances.
Eighth, the AC breaker panel. This is the same kind of breaker panel that the electric company uses to connect your house wiring to its electrical source.
Ninth, your backup generator. This is in case you have a stretch of cloudy days that outlast the electricity stored in the batteries. You can use traditional fossil fuels, but you’ll probably want to use biodiesel to maintain your green lifestyle.
Now that you’ve seen the components of the photovoltaic system, you can see why it's not that complicated to become your own expert. Each component is relatively simple. The only moving parts are in the backup generator, and you hopefully won't be using that very much.
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