Photovoltaics (Solar Panels)

Solar Panels or Photovoltaics have the ability to harness the suns immense energy and convert it into electricity. This is most commonly achieved by using cells manufactured using one of several types of silicon. These cells are arranged in panels which are then in turn arranged together in groups referred to as strings or arrays. These arrays are placed together to gain the optimal balance between space and sizing for a desired output. The largest photovoltaic plant in the world can generate up to 60 megawatts of electricity, or enough to electricity to supply the demand of 40,000 homes. Yet the smallest systems power your standard hand held calculator. The possibilities are truly endless.

Many have found that solar panels can be the ideal option for providing power to homes or businesses. A system can be sized to provide all of your electrical requirements or desired portion. Generating your own energy can also provide the security of knowing you will not be without power when the grid goes down, and it is less wasteful and harmful to the environment than using energy from the utility company. An additional benefit is once the initial investment is paid back your electricity is produced at no cost. Many people chose to add solar panels as a statement rather than an investment. Whatever your interest may be photovoltaics may be your solution. So what are some things to consider when pondering using photovoltaics? Let’s look at the installation of a system on a residence to get an idea of the process.
First, there are several options regarding the type of system you may choose to install. The three main types are grid-tied (connected to your local utility), independent or a grid-tie with battery backup.
Grid-tied systems make up the majority of installations. These systems feed energy to the home first, and whatever the house doesn’t use goes back into the electrical grid. When the panels are not producing energy the home is powered by electricity from the utility company. For this system to work, the utility company that supplies the house must provide net metering. Net metering means that the power meter for the house literally runs backwards when it’s being supplied by the solar panels. This allows the owner of the house to save on the monthly power bill. This type of system also uses the least equipment, so it results in the quickest payoff of your investment.
An independent system is completely local with no connection to the grid. This type of system requires storage of the energy generated by the panels for use when the sun is not shining. This is usually done using batteries. Batteries are an expensive addition to the system, so candidates for an independent system are usually those that are in mountainous or remote areas that are far away from utility lines. The high cost of connecting such homes to grid power makes the cost of batteries very reasonable in comparison.
Lastly, it’s possible to have a grid-connected system that also has battery storage to provide electricity in the event of a power outage. Such a system would be a luxury for most home-owners and would not be worth the extra cost financially speaking, but for some the added security of knowing you will never be without power is worth it.
The next decision to make is to choose the optimal panel and desired mounting location. Panels that double as roof tiles are available for a truly integrated look, but the more economical option for retrofit applications would be separate panels that you can mount on the roof or at a remote location a little ways away from the house. For a sloped rooftop installation you will want to use the portion of the roof that faces south for the best efficiency from the panels (if you’re in the northern hemisphere that is). The optimum angle for the solar panels varies with the latitude of the location, but oftentimes it would require additional mounting hardware to achieve this angle. In some cases the best option is to mount the panels directly on the roof. Many sloped roofs are close enough to the optimum angle that not much efficiency is lost by mounting the panels at the same angle. If the roof is flat, however, it is better to use frames that provide for the optimum angle of tilt. For the best efficiency and most power output a solar tracking mount can adjust the panel to the optimum angle of tilt and rotation (for a dual-axis tracker) or just the best angle of tilt (single-axis tracker). Remote installations can use either a fixed mount or a tracker as well.
With the type of system and type of panel chosen it’s time to move on to the other required equipment. The electrical current that a PV panel generates is DC (direct current). Most modern household appliances and electrical accessories are designed to run on AC (alternating current) power. To switch the power from DC to AC an inverter is needed. Depending on the system, other components include batteries, AC and DC switches, a charge controller, and various other miscellaneous parts.
Although photovoltaics can seem rather expensive to purchase and install, incentives are available that can help to subsidize the initial costs resulting in reasonably short payoffs in many cases. Most installations will require a knowledgeable engineer to perform a site analysis, feasibility study, and design of the system as well as a licensed electrician to install the system. An improper installation can cut your panels ability to produce electricity. The shadow of an exhaust pipe can lower your output by as much as 50% on a roof mounted system. Energy-1 can provide all of the above and answer any other questions you may have about photovoltaics or any other renewable energy solution for your home or business.
Photovoltaics can be a great way to provide your house with electricity, but what about heating and cooling? Check back in a week or so for the basics of geothermal heating and cooling.

HOW SOLAR THERMAL PANELS WORK

Solar Thermal

Over the coming weeks I’ll be discussing a number of renewable energy technologies that can be applied to your home or business in order to save on energy costs and reduce the carbon footprint of your building. The topic for next two weeks will be solar power. When most people think of solar power they think of photovoltaic panels that turn energy from the sun directly into electricity. We’ll be going over that next week. What we’re looking at today is solar thermal energy.
What is Solar Thermal Energy?
Solar thermal energy refers to the process of using the sun’s energy to heat something up. The heat can be used to provide hot water for residential or commercial use, space heating using radiant floors or panels, or converted to electrical power via a turbine. The focus of this entry will be solar thermal for hot water and space heating because these topics are of the most interest to a building owner looking to incorporate some renewable energy.
What goes into a solar hot water system?
A solar hot water system uses a solar collector that heats a fluid which is either used directly (if the fluid is water) or is used in a heat exchanger to heat water. Water can generally only be used in warm climates where freezing is not a worry. In these situations a flat plate collector is used. The flat plate collector is basically an insulated box with a clear glass or plastic top that has a dark colored copper or aluminum absorber plate connected to a series of pipes that water flows through. The sun heats up the absorber plate which heats up the water pipes and the water itself, while the box prevents heat from escaping to the environment. A flat plate system with water as the fluid can be used to heat a pool or to provide domestic hot water for the home.
In cooler climates a solar thermal system can still be very effective, but a different fluid is needed to prevent freezing. Generally a mixture of glycol and water is used. This fluid can be used in flat plate collectors, or evacuated tube collectors. Evacuated tube collectors have one larger tube with a smaller tube inside of it in which there is a fluid. The space between the tubes is vacuum-sealed to provide near-perfect insulation, so the radiant energy heats the fluid and the heat cannot escape. The heated fluid rises to a manifold at the top of the tubes through which the glycol mixture is being pumped. The heat from the fluid inside the tubes is transferred to the glycol mixture. The glycol then goes through another heat exchanger that heats pure water.
The water that is heated can be used directly for domestic or commercial use, or it can be used to heat your home using radiant floor heating, radiant panels, or a forced air system. Regardless of the use, a system usually incorporates a pump, one or more heat exchangers, and a tank to store hot water. Specification of the components and layout of the system should be performed by a qualified Mechanical, Electrical, and Plumbing Engineer.

Images courtesy of the U.S. DOE: http://www1.eere.energy.gov/solar/sh_basics_collectors.html
How long will it take to pay for itself?
Generally solar thermal collectors are cheaper to buy and install than photovoltaic panels, but a detailed technical and economical analysis is needed to determine how long it will take for energy savings to exceed installation costs. Some things to take into account are:
· The solar resources available which depends on latitude, local climate, cloud cover, and shading.
· The efficiency of the solar collector which depends on the collector itself, the fluid to be used, orientation, and placement.
· Cost of equipment purchase and installation.
· Incentives that may be available through federal, state, and local governments as well as utility companies.

Energy 1 is a company that can provide a feasibility study that takes all of this into account and provides you with the information you need to know like savings on your monthly energy costs, payback period, installation costs, etc. They can also provide feasibility studies for photovoltaics, wind energy, micro-hydro, cogeneration, and geothermal energy.
If you aren’t concerned with detailed economic analysis and would like to “jump right in” you should still be aware of the incentives available to offset the cost of your project. Energy 1 can give you a comprehensive break down on Federal, State and Local tax grants and incentives. In most cases this can give a residential application a payback in less than 7 years.

How can I get a Solar Hot Water system for my building?
Need a hand installing your system? For an easy no-headache installation Energy 1 can do a feasibility study, provide the design, install the system, and provide routine maintenance on your installed system. Or call (406) 587-2917.