A Note from Our General Manager:
World running out of time for oil alternatives
Environmental Economics Are you being Served?
Northeastern States Work on Kyoto Style Plan
Solar Electric for the Beginner
A Note from Our General Manager:
I took a solar course at the Florida Solar Energy Center (FSEC) in Cocoa, Fl recently. This is a marvelous facility. It is the largest and most active state-supported renewable energy and energy efficiency research, training, testing and certification institute in the USA. The web address is www.fsec.ucf.edu. If you have interest in learning more about solar electric and solar water opportunities, I urge you to go the site and see what they may have for you.
One of the many interesting topics we discussed during the course was how an individual homeowner's simplest means to reduce their reliance on their electric utility provider may not be by converting to solar photovoltaics but rather by making their homes more energy efficient. Correct insulation and reduced areas for air (cold-in during winter and warm-in during summer) transfer can offer major savings. We should all comb our homes looking for windows, doors, attics, basements etc that are sealed incorrectly from the outside and consider re-doubling our insulation efforts if they were inadequate in the initial construction.
Solar photovoltaics are still a bit highly priced but this is partially tied into very high demand in Europe which is offering a lot of incentives for solar electric installs. The great news is the Energy Bill (see www.fsec.ucf.edu/EPAct-05.htm) that goes into effect in 2006 does have some interesting tax incentives for solar electric and solar water installation. The largest incentive is for commercial installations. If you are planning to build a shopping mall, strip center, apartment complex, etc in 06, you should consult your tax adviser on how the Energy Bill can allow the addition of solar electric and solar water for a very tax advantaged price.
Each of the 50 states also offer varying contributions to the cost of solar electric and solar water installs. The website www.dsireusa.org is a great source to find what your state may offer. Of course California still offers the most but New Jersey has some interesting programs and there are often individual municipality programs within a state as well--give it a look!
We have solar electric and solar water consulting experts available to help you plan your projects. Simply go to our home page and follow the instructions for Custom Solar Solutions in the first column.
I finally drove a Toyota Prius--the local dealer had some new and used in stock after not having any on my last visit--he blamed the sudden inventory on Toyota now now offering the Highlander in a hybrid engine and the popularity that had caused taking buyers a bit away from the Prius. I really liked the way the Prius drove and was impressed with the bells and whistles. I cranked up the air conditioning in the middle of a central Florida summer day and it seemed to handle it well. The tonic for finding the best gas mileage involves a few variables the driver must adjust while driving but the mpg was always above 45 during my test drive in town. I see where Honda is coming out with a newer version of their Civic Hybrid soon. Both cars are in the $20k range for new and $17k range for used.
Fall tends to be light bulb season. We will send to those of you on our list a nice Fall Promotion featuring our 20,000 hour and 10,000 hour light bulbs in the next few weeks. You are welcome to encourage friends to sign up for the newsletters and promotions in the first column of our home page.
In this edition of hot topics we have a discussion, "World running out of time for oil alternatives", on the need to find alternative energy sources before lo and behold the price of refined petrol is $100/barrel which seemed unthinkable a year ago.
Another article, "Environmental Economics Are you being Served?", speaks of a more thorough accounting of the cost of raw materials from the standpoint of production to depletion and the environmental costs of each.
We have an article reporting that some northeastern US states may be trying to break with the Bush administration in it's lack of support for the Kyoto Treaty and possibly install there own pollution fundamentals. Lastly we have reprinted again "Solar Electric for Beginners" from Home Power magazine for those of you who truly realize that solar electric can be for you.
We will say that the article reprints are the ideas and opinions of the writers that are mentioned. We may or may not agree with all of what they write but we find the discussions useful.
Thanks for reading,
World running out of time for oil alternatives
Thu Aug 18, 2005
By Anna Mudeva
PETTEN, Netherlands (Reuters) - The world could run out of time to develop cleaner alternatives to oil and other fossil fuels before depletion drives prices through the roof, a leading Dutch energy researcher said on Thursday. Ton Hoff, manager of the Energy Research Center of the Netherlands, said it could take decades to make alternatives affordable to the point where they can be used widely, although high oil prices were already stimulating such research.
"If we run out of fossil fuels -- by the time the oil price hits 100 dollars or plus, people will be screaming for alternatives, but whether they will be available at that moment of time -- that's my biggest worry," Hoff said. "That's why we need to use fossil fuels in a more efficient way to have some more time to develop these alternatives up to a level where the robustness is guaranteed and their price has come down ... This could take decades for some technologies."
Stubbornly high oil prices have renewed worldwide interest in sustainable energy sources, such as solar, wind and biomass as well as biofuels. But the world currently covers just some two percent of its energy needs with renewables as high costs and mixed policy initiatives hinder a wide-spread usage. "The high oil price makes people at least think about alternatives ... For us it's a definitely a stimulus to work even harder than before," Hoff said. LOWERING COSTS ECN, one of Europe's leading energy research institutes, is working to improve or develop new technologies to boost efficiency and lower the costs of power production from wind, solar and biomass, he said.
ECN researchers are trying to raise the energy conversion efficiency of solar panels to above 20 percent from the current 17 percent, while reducing costs.
"In 10-15 years, I expect that solar energy conversion could be in competition with electricity produced from coal," Hoff said. He believes the Netherlands has the potential to cover a large part of its power needs with solar energy.
ECN is also researching to increase the size of wind power turbines from the 3 megawatt a turbine produces now to 5 or 6 MW. This could be done by raising the height to 100 meters from 70 now and enlarging wings span to 120 meters from 90, he said.
ECN is also part of the $225 million "Global Climate and Energy Project" led by the U.S. University of Stanford and financed by General Electric, Toyota, Schlumberger and ExxonMobil.
The project aims to crack new technologies on fuel cells, which make electricity from hydrogen and emit only water vapor, energy production from biomass and separation and storage of carbon dioxide (CO2). The greenhouse CO2 gas is released when burning fossil fuels and is blamed for global warming. Under the project, ECN will develop a new type of membrane reactor, which will separate CO2 during the process of producing hydrogen from fossil fuels, Hoff said. The CO2 could later be stored by companies in depleted gas or oil fields.
Hoff and other researchers say a transition to the so-called hydrogen economy could take decades as the cost of building new hydrogen-burning cars and power plants and storing CO2 are huge.
To test hydrogen usage in real life, ECN is in talks with the northern Dutch island of Texel to install hydrogen-based facilities, which would supply electricity to homes and offices.
"The idea is to see the pitfalls, fix them ... and prepare for the future.
My hopes are that this will stimulate the usage of this type of new technology because it is extremely important to have it in real life rather than in laboratories," Hoff said.
Are you being Served?
Panama City, Panama
Environmental entries are starting to appear on the balance sheet. Perhaps soon, the best things in life will not be free.
At The Miraflores lock on the Panama Canal it is possible to watch the heartbeat of international trade in action. One by one, giant ships piled high with multicoloured containers creep through the lock's narrow confines and are disgorged neatly on the other side. If it were not for the canal, these ships would have to make a two-to-three week detour around South America. That would have a significant effect on the price of goods around much of the world. It is therefore sobering to consider that each ship requires 200m liters of fresh water to operate the locks of the canal and that, over the years, this water has been drying up.
Scientists at the Smithsonian Tropical Research Institute, in Panama, think that reforesting the canal's denuded watershed would help regulate the supply. One of them, Robert Stallard, a hydrologist and biogeochemist who also works for the
United States Geological Survey in Boulder, Colorado, has operated in the country for two decades, and knows the terrain very well. A deforested, grass-covered watershed would release far more water in total than a forested one, he admits, but that water would arrive in useless surges rather than as a useful steady stream. A forested watershed makes a lot more sense.
Another problem caused by deforestation is that it allows more sediment and nutrients to flow into the canal. Sediment clogs the channel directly. Nutrients do so indirectly, by stimulating the growth of waterweeds. Both phenomena require regular, and expensive, dredging. More trees would ameliorate these difficulties, trapping sediments and nutrients as well as regulating the supply of fresh water. Planting forests around the Panama Canal would thus have the same effect as building cast reservoirs and filtration beds. Viewed this way, any scheme to reforest the canal's watershed is, in fact, an investment in infrastructure. Normally, this would be provided by the owner. But in this case the government, and Panama is in debt, has a poor credit rating and finds it expensive to borrow money. And yet investing in the canal's watershed clearly makes economic sense. Who will pay?
In the case of the Panama Canal, the answer may turn out to be John Forgach, an entrepreneur, banker and chairman of ForestRe, a forestry insurance company based in London. Mr Forgach's plan is to use the financial markets to arrange for companie dependent on the canal to pay for the reforestation. Working in collaboration with several as-yet-unnamed insurance and reinsurance companies, Mr. Forgach is trying to put together a deal in which these companies would underwrite a 25 year bond that would pay for the forest to be replanted. The companies would then ask those of their big clients who use the canl to buy the bond. Firms such a Wal-Mart, and a number of Asian carmakers, which currently insure against huge losses they would suffer if the canal were closed, would pay a reduced premium if they bought forest bonds. This is meant to be a good business deal, but it is structured in a way that brings environmental and social benefits, too. The forest will have a diverse mixture of species that the Smithsonian's scientists have demonstrated grow well (thus pleasing environmentalists), are valuable, and which local people have deemed to be useful for food and medicine. It is also a test case for Mr. Forgach. If he succeeds, he will try it elsewhere because he thinks there is an opportunity in treating the regulation of water and climate as a utility-in other words, as a service for which people will pay money. This, he says, should be a perfectly viable investment.
In From The Cold
In the case of the canal, the financial value of reforestation is clear even if who pays for it is not. But putting a cash value on what are called variously "environmental", "ecoysystem" or "ecological" services has, historically, been a fraught process.
Early attempts at such valuation resulted in impressive but unsound figures that were seized on by environmental advocates and then, when they were discredited, used by opponents to tar the whole idea. Now, though, things have improved.
First of all, science is producing abundant evidence that the natural environment provides a wide range of economic benefits beyond the obvious one of timber and fish. Ecologists now know a great deal more than they used to about how ecosystems work, which habitats deliver which services, and in what quantity those services are supplied. Last month, for example, saw the publication of the Millennium Ecosystem Assessment, the first global survey of ecological services. Its authors warn that attention will have to be paid to these services if global development goals are to be met. But the only way this can happen is if ecological services have sound, real (and realistic) values attached to them. As "Valuing Ecosystem Services", a report written recently for America's National Research Council, points out, the difficult part is providing a precise description of the links between the structures and functions of various bits of the environment, so that proper values can be calculated. What this means is that the more there is known about the ecology of, say, a forest. the better the valuation of the services it provides will be. Fortunately, according to two reports published by the World Bank at the end of 2003, significant progress has been made twoards developing techniques for valuing environmental costs and benefits. There is, says one of these reports, no longer any excuse for considering them unquantifiable.
The turning point for this way of looking at things was in 1997. In that year, the city government of New York realised that changing agricultural practices meant it would need to act to preserve the quality of the city's drinking water. One way to have done this would have been to install new water-filtration plants, but that would have cost $4 to $6 billion up front, together with annual running costs of $250m. Instead, the government is paying to preserve the rural nature of the Catskill mountains from which New York gets most of its water. It is spending $250m on buying land to prevent development and paying farmers $100m a year to minimise water pollution.
Many of the valuation studies done since then have involved water, probably because it is so obviously a valuable ecological service. Forests and swamps (or "wetlands", to give the latter their politically correct modern moniker) filter and purify water, and act as reservoirs to capture rain and melting snow. When such areas become degraded, it may be necessary to make expensive investments in treatment plants, dams and other flood-control measures. Several other American cities, following in New York's footsteps, have calculated that every dollar invested in environmental protection would save anywhere from $7.50 to $200 on the cost of what would otherwise have to be spent on filtration and water-treatment facilities. Nor is it only rich countries that benefit. In 2003, Muthurajawela wetland sanctuary, just north of Colombo in Sri Lanka, was calculated by the Water Conservation Union to be providing services worth $8m a year or $260,000 per square kilometre. These services include the cleaning of sewage and waste water from industry, as well as flood attenuation and the support of downstream fisheries. At the same time, the waste water processing capacity of a swamp in Uganda was calculated to be even more valuable than this, at least per unit area. Its 5.5 square kilometres provided a service worth $2m.
When valuation has been done, payment can follow. In Cape Town, South Africa, for example, it proved cheaper to restore the town's watershed to its native vegetation than to divert water from elsewhere, or to create reservoirs. And there are a wide range of other cities and towns in the poor world that use ecological payments to protect their water supplies- from Quito in Ecuador with 1.2m people to Yamabal in El Salvador with only 3,800. More complex benefits can be paid for in more complex ways. A scheme in Costa Rica, which costs $57m a year, is paid for partly by hydroelectric-power producers, who receive services such as stream-flow regulation, sediment retention and erosion control, partly by private consumers of water, who use it for irrigation, and partly by the country's government, in order to supply towns with water and maintain the area's scenic beauty for recreation and ecotourism. Meanwhile in Columbia and France, these are schemes financed entirely by the private sector. Large agricultural producers in the Cauca Valley pay fees for watershed management projects, such as erosion control and reforestation. And Perrier-Vittel, a bottler of mineral water, has found it necessary to reforest parts of heavily farmed watersheds and also to pay farmers to switch to modern facilities and organic farming in order to preserve the quality of some of its products. Valuing ecosystems services can also point to places where inaction is best. After fires in Croatia had damaged man forests, a study was done to see if restoration was worthwhile given their value to the tourist industry. Examination of 11 sites revealed that the net benefits varied significantly. Some sites were not worthy candidates and were dropped.
As scientific understanding of ecological services improves, new financial opportunities emerge. For example, the importance of insect pollination to the crops such as coffee, almonds, and apples, has only recently come appreciated. Last year, a study in Costa Rica found that on one farm alone the natural pollination of coffee by insects was worth $60,000. Coffee yields were 20% higher on plots that lay within a kilometre of natural forest.
Simply having this kind of information could change the way that coffee farmers view areas such as forest and wild grasslands on or near their property. Looked at another way, it might encourage owners of forests that help to pollinate a neighbor's crops to demand payment. Indeed, a version of this sort of blackmail already happens on an international scale. Elliot Morley, Britain's minister for the environment, says that developing countries sometimes say to him, "give us the money or the forest gets it."
We will list the balance of this article in our next Hot Topics.
Northeastern States Work on Kyoto Style Plan
August 24, 2005
NEW YORK (Reuters) - Nine northeastern U.S. states are working on a plan to cap and then reduce the level of greenhouse gas emissions from power plants, the first U.S. deal of its kind and one which would see the region breaking with President George W. Bush who refused to sign the Kyoto Protocol. The move comes as California, Washington and Oregon are considering a similar pact -- a dynamic environmentalists say could pressure the federal government to adopt a national law. Bush refused to sign the Kyoto Protocol, the greenhouse gas reduction plan already adopted by over 150 countries.
Under the plan being worked on, New York, New Jersey, Connecticut, Delaware, Maine, Massachusetts, New Hampshire, Rhode Island and Vermont would cap carbon dioxide emissions at 150 million tons a year – roughly equal to the average emissions in the highest three years between 2000 and 2004. Starting in 2015, the cap would be lowered, and emissions would be cut by 10 percent in 2020.
Each state legislature would have to approve the caps, said Dennis Schain, a spokesman for Connecticut's Department of Environmental Protection. "This is a process that would be an agreement among states and to really implement it and have a firm commitment, the states will each have to approve legislation and regulations to meet these conditions," he told Reuters. The draft is being circulated among industries, power companies and environmental groups for feedback, he said. The group hopes to reach a final agreement in September. Phil Cherry, policy director at Delaware's Department of Natural Resources, also confirmed details of the pact.
Scientists believe carbon dioxide and other greenhouse gases cause global warming that is affecting coastal areas, icebergs and wildlife. Around 40 percent of U.S. carbon dioxide emissions come from fossil fuel power plants.
The United States is the world's largest emitter of carbon dioxide. The Bush administration wants cuts to be voluntary and resists mandatory measures it says would hurt economic growth. Many international leaders have criticized Bush's refusal to sign Kyoto, which is meant as a first step toward braking a rise in global temperatures from a build-up of gases from fossil fuels emitted by power plants, factories and cars.
In the absence of national control on emissions, Schain said: "This seems to be the appropriate course of action." The so-called Regional Greenhouse Gas Initiative would explore a market-driven cap-and-trade system where businesses must trim emissions under set limits or buy credits from companies that have complied with the limits.
Environmentalists praised the proposed plan.
"It moves the United States further toward doing something about the problem," said Kert Davies of Greenpeace in Washington, D.C. "That eventually allows us back into the global solving of this problem."
The deal was brokered by New York Republican Gov. George Pataki, who is weighing a White House run in 2008. Pataki spokesman Andrew Rush said no final deal had been reached but, "We've made a lot of progress and we look forward to reaching a final agreement." Political experts note such a plan brings Pataki national attention. "This is another clear signal that George Pataki is positioning himself on the national stage to run for president," said political strategist Hank Sheinkopf.
A regional emissions control program would likely cause higher energy prices for power company customers in the Northeast, but Delaware's Cherry said the states had not yet decided on a method to combat rising costs.
Solar Electric for the Beginner
from Home Power online March 05
Perhaps what the home-scale renewable energy (RE) world needs most are ways to introduce people to RE technologies and the gizmos that make it possible. After all, even the best ideas aren't embraced until they are explained in simple terms. So whether you are the rookie who wants to understand how solar-electric systems work, or that better describes your spouse, friend, or prospective customer, this article explains the guts and bolts of the three most common options in solarelectric systems: grid-intertied, grid-intertied with battery backup, and off-grid (stand-alone). Understanding the basic components of an RE system and how they function is not an overwhelming task. Here are some brief descriptions of the common equipment used in grid-intertied and off-grid solar-electric systems. Systems vary-not all equipment is necessary for every system type. In the diagrams, the numbers in red correspond to the components needed.
Also known as on-grid, grid-tied, or utilityinteractive (UI), grid-intertied solar-electric systems generate solar electricity and route it to the electric utility grid, offsetting a home's or business's electrical consumption and, in some instances, even turning the electric meter backwards. Living with a grid-connected solar-electric system is no different than living with grid power, except that some or all of the electricity you use comes from the sun. In many states, the utility credits a homeowner's account for excess solar electricity produced. This amount can then be applied to other months when thesystem produces less or in months when electrical consumption is greater. This arrangement is called net metering or net billing. The specific terms of net metering laws and regulations vary from state to state and utility to utility. Consult your local electricity provider or state regulatory agency for their guidelines.
PV panels are a solar-electric system's defining component, where sunlight is used to make direct current (DC) electricity. Behind a PV panel's shimmering facade, wafers of semiconductor material work their magic, using light (photons) to generate electricity- what's known as the photovoltaic effect. Other components in your system enable the electricity from your solar-electric panels to safely power your electric loads like lights, computers, and refrigerators. PV panels are assigned a rating in watts based on the maximum power they can produce under ideal sun and temperature conditions. You can use the rated output to help determine how many panels you'll need to meet your electrical needs. Multiple modules combined together are called an array. Although rigid panels are the most common form of solar electricity collector, PV technology also has been integrated into roofing shingles and tiles, and even peeland-stick laminates (for metal standing-seam roofs). PV modules are very durable and longlasting-most carry 25-year warranties. They can withstand severe weather, including extreme heat, cold, and hail stones. 2 Array Mounting Rack AKA: mounts, racks Mounting racks provide a secure platform on which to anchor your PV panels, keeping them fixed in place and oriented correctly. Panels can be mounted using one of three approaches: 1) on a rooftop; 2) atop a steel pole set in concrete; or 3) at ground level. The specific pieces, parts, and materials of your mounting device will vary considerably depending on which mounting method you choose. Usually, arrays in urban or suburban areas are mounted on a home's south-facing roof, parallel to the roof's slope. This approach is sometimes considered most aesthetically pleasing, and may be required by local regulators or homeowner's associations.
In areas with a lot of space, pole- or ground-mounted arrays are another choice. Mounting racks may incorporate other features, such as seasonal adjustability. The sun is higher in the sky during the summer and lower in the winter. Adjustable mounting racks enable you to set the angle of your PV panels seasonally, keeping them aimed more directly at the sun. Adjusting the tilt angle increases the system's annual energy production by a few percent. The tilt of roofmounted arrays is rarely changed-adjusting the angle is inconvenient and sometimes dangerous, due to the array's location. Changing the tilt angle of pole- or ground-mounted arrays can be done quickly and safely. Pole-mounted PV arrays also can incorporate tracking devices that allow the array to automatically follow the sun across the sky from east to west each day.
Tracked PV arrays can increase the system's daily energy output by 25 to 40 percent. The DC disconnect is used to safely interrupt the flow of electricity from the PV array. It's an essential component when system maintenance or troubleshooting is required. The disconnect enclosure houses an electrical switch rated for use in DC circuits. It also may integrate either circuit breakers or fuses, if needed. A charge controller's primary function is to protect your battery bank from overcharging. It does this by monitoring the battery bank-when the bank is fully charged, the controller interrupts the flow of electricity from the PV panels. Batteries are expensive and pretty particular about how they like to be treated. To maximize their life span, you'll definitely want to avoid overcharging or undercharging them. Most modern charge controllers incorporate maximum power point tracking (MPPT), which optimizes the PV array's output, increasing the energy it produces. Some batterybased charge controllers also include a low-voltage disconnect that prevents over discharging, which can perma nently damage the battery bank.
Without a battery bank or generator backup for your gridintertied system, when a blackout occurs, your household will be in the dark, too. To keep some or all of your electric needs (or "loads") like lights, a refrigerator, a well pump, or computer running even when utility power outages occur, many homeowners choose to install a grid-intertied system with battery backup. Incorporating batteries into the system requires more components, is more expensive, and lowers the system's overall efficiency. But for many homeowners who regularly experience utility outages or have critical electrical loads, having a backup energy source is priceless. Your PV panels will produce electricity whenever the sun shines on them. If your system is off-grid, you'll need a battery bank-a group of batteries wired together-to store energy so you can have electricity at night or on cloudy days. For off-grid systems, battery banks are typically sized to keep household electricity running for one to three cloudy days. Gridintertied systems also can include battery banks to provide emergency backup power during blackouts-perfect for keeping critical electric loads operating until grid power is restored. Although similar to ordinary car batteries, the batteries used in solar-electric systems are specialized for the type of charging and discharging they'll need to endure. Lead-acid batteries are the most common battery used in solar-electric systems. Flooded leadacid batteries are usually the least expensive, but require adding distilled water occasionally to replenish water lost during the normal charging process. Sealed absorbent glass mat (AGM) batteries are maintenance free and designed for grid-tied systems where the batteries are typically kept at a full state of charge. Gel-cell batteries can be a good choice to use in unheated spaces due to their freeze-resistant qualities. System meters measure and display several different aspects of your solar-electric system's performance and status, tracking how full your battery bank is; how much electricity your solar panels are producing or have produced; and how much electricity is in use.
Operating your solar-electric system without metering is like running your car without any gauges- although possible to do, it's always better to know how much fuel is in the tank. In battery-based systems, a disconnect between the batteries and inverter is required. This disconnect is typically a large, DC-rated breaker mounted in a sheetmetal enclosure. This breaker allows the inverter to be quickly disconnected from the batteries for service, and protects the inverter-to-battery wiring against electrical fires. Inverters transform the DC electricity produced by your PV modules into the alternating current (AC) electricity commonly used in most homes for powering lights, appliances, and other gadgets. Grid-tied inverters synchronize the electricity they produce with the grid's "utilitygrade" AC electricity, allowing the system to feed solar-made electricity to the utility grid. Most grid-tie inverters are designed to operate without batteries, but battery-based models also are available. Battery-based inverters for off-grid or grid-tie use often include a battery charger, which is capable of charging a battery bank from either the grid or a backup generator during cloudy weather. Most grid-intertie inverters can be installed outdoors (ideally, in the shade). Most off-grid inverters are not weatherproof and should be mounted indoors, close to the battery bank. Although they are most common in remote locations without utility grid service, off-grid solar-electric systems can work anywhere. These systems operate independently from the grid to provide all of a household's electricity.
That means no electric bills and no blackouts-at least none caused by grid failures. People choose to live off-grid for a variety of reasons, including the prohibitive cost of bringing utility lines to remote homesites, the appeal of an independent lifestyle, or the general reliability a solar-electric system provides. Those who choose to live off-grid often need to make adjustments to when and how they use electricity, so they can live within the limitations of the system's design. This doesn't necessarily imply doing without, but rather is a shift to a more conscientious use of electricity. The AC breaker panel is the point at which all of a home's electrical wiring meets with the "provider" of the electricity, whether that's the grid or a solar-electric system. This wall-mounted panel or box is usually installed in a utility room, basement, garage, or on the exterior of the building. It contains a number of labeled circuit breakers that route electricity to the various rooms throughout a house. These breakers allow electricity to be disconnected for servicing, and also protect the building's wiring against electrical fires. Just like the electrical circuits in your home or office, an inverter's electrical output needs to be routed through an AC circuit breaker. This breaker is usually mounted inside the building's mains panel, which enables the inverter to be disconnected from either the grid or from electrical loads if servicing is necessary, and also safeguards the circuit's electrical wiring. Additionally, utilities usually require an AC disconnect between the inverter and the grid that is for their use. These are usually located near the utility KWH meter. Most homes with a grid-tied solarelectric system will have AC electricity both coming from and going to the electric utility grid. A bidirectional KWH meter can simultaneously keep track of how much electricity flows in each of the two directions-just the information you need to monitor how much electricity you're using and how much your solar-electric system is producing.
The utility company often provides intertie-capable meters at no cost. Off-grid solar-electric systems can be sized to provide electricity during cloudy periods when the sun doesn't shine. But sizing a system to cover a worst-case scenario, like several cloudy weeks during the winter, can result in a very large, expensive system that will rarely get used to its capacity.
To spare your pocketbook, size the system moderately, but include a backup generator to get through those occasional sunless stretches. Engine generators can be fueled with biodiesel, petroleum diesel, gasoline, or propane, depending on the design. These generators produce AC electricity that a battery charger (either standalone or incorporated into an inverter) converts to DC energy, which is stored in batteries. Like most internal combustion engines, generators tend to be loud and stinky, but a welldesigned solar-electric system will require running them only 50 to 200 hours a year.
As you can see, the anatomy of a photovoltaic system isn't that complicated. All of the parts have a purpose, and once you understand the individual tasks that each part performs, the whole thing makes a bit more sense. Now you're ready to look at the system articles and schematics in Home Power without your eyes glazing over, and you'll have a clearer understanding of what is going on in the articles. To solidify your understanding, your next task should be to examine a solar-electric system in person. The National Tour of Solar Homes each fall is one way to see a variety of systems. Also, many renewable energy fairs and workshops feature tours of solar homes.in the Happenings calendar in each Home Power issue to find out where you can learn more about RE systems and meet the people who are using renewable energy in your area.