Residential Solar Power Blog » Solar Thermal

RiverCentre Brings Clean Solar Thermal to St. Paul

Jeanne — Tue, 22 Mar 2011 16:40:29 +0000

The St. Paul, Minnesota RiverCentre project is the first solar thermal project to connect to an established city network of hot-water heating pipes in North America.

The connection, to District Energy St. Paul’s downtown loop, which heats 80 percent of St. Paul city buildings, will hopefully became a solar focal point, attracting the attention of other cities and towns across America to help solar energy reach grid parity, when it becomes as cheap and abundant as coal-fired energy.

Funded by $1 million from the U.S. Department of Energy (DOE), the 1-megawatt installation is comprised of 144 commercial-grade solar collectors that cover an area equivalent to about 1.25 acres.

These collectors look like the type of solar panels that generate electricity but instead contain an antifreeze-type solution which will provide hot water for RiverCentre’s restrooms and kitchens, and heat for the 162,000-square-foot convention center during Minnesota’s notoriously cold winter days.

The size of the system precludes it being used on all but the largest buildings, but when used it can not only provide clean, renewable hot water and heat for indoor spaces, but flow over into established systems like that built by District Energy in 1983 to respond to the energy crisis of the mid- to late-1970s. Any leftover energy will flow into District Energy’s hot-water-heating loop.

The solar thermal system is sized to provide up to five percent of the district’s hot water needs in the summer, or one percent of yearly demand, and will offset enough natural-gas heating to prevent 484 metric tons of carbon dioxide a year, which is equivalent to 12,403 trees planted and nurtured for a decade.

It’s also a nice money-saver. According to RiverCentre spokeswoman Kathy O’Connor, the center spent $385,000 last year to heat its water and building space. Even one percent of that is some pretty hefty pocket change.

Photo Credit: mtellin via Flickr CC

Massachusetts to Launch $1,000 Solar Thermal Rebates

Kayla — Fri, 04 Feb 2011 15:04:41 +0000

In an effort to make clean energy more affordable in the home, Massachusetts is launching a pilot rebate program this month for solar thermal hot water panels.

The program, headed by the Massachusetts Clean Energy Center, would award $1,000, on average, for a two-panel system. For a typical household of 4-5 residents, the panels would cost about $8,000-$10,000.

But residents could even save as much as half of the purchase price through other state and federal rebates, including the 30% federal renewable energy tax credit.

While the rebate will cover a significant number of customers, there are certain restrictions. Those hoping to cash in must be a customer of NSTAR, National Grid, Unitil, or Western Massachusetts Electric Company.

For those that are not customers of these companies, they must reside in the towns of Ashburnham, Templeton, Holden, Holyoke, or Russell.

The program is funded with $1 million from the MassCEC’s Renewable Energy Trust.

Photo Credit: Alan via Flickr CC

Massachusetts Fires up Solar Hot Water Rebates

Jeanne — Mon, 10 Jan 2011 22:46:48 +0000

Massachusetts may seem like an unlikely state for solar power. When you look at its solar insolation value of only 4.0 kilowatt-hours (compared to California’s 6.0 and Florida’s 5.0), the New England state seems lacking in sunshine.

In spite of that, Massachusetts has shown a definite fondness for solar energy ever since passage of the Green Communities Act of 2007 – a move that put it in the running for a slot among the top ten best states for solar (where it won #5 in 2008, #10 in 2009, and #5 again in 2010).

Now, to put a little shine on that well-deserved reputation, Massachusetts is offering a rebate program for residential installations of solar hot water. Beginning in February of this year, the Massachusetts Clean Energy Center will accept applications for a pilot program designed to test the waters (pun intended).

The application process is described as “non-competitive” (you have to meet standards, but not jump through 10,000 hoops), and the rebates begin at $12.50 per square foot of collector, or an average of $1,000. Each system (or its components) manufactured within the state also qualifies for an additional $200, which means that a solar hot water system can reportedly be had for less than half the cost when combined with other federal, state, and utility incentives.

The rebates make sense from both a resource standpoint (heating water is 11 percent of a household’s energy use) and a financial one (a typical homeowner spends about $500 per year to operate a 75-gallon hot water tank), and a typical passive solar water heating system, looking much like a series of solar photovoltaic panels, can provide up to three-fourths of a home’s total hot water needs.

Photo Credit: Wonderlane via Flickr CC

BrightSource Solar, The Little Engine That Did

Jeanne — Mon, 27 Dec 2010 23:55:57 +0000

Earth2tech recently listed BrightSource Energy as numero uno on a list of ”Top 10 Cleantech IPOs Picks for 2011.”

I don’t know much about its IPO potential. I don’t follow stocks and think that, in terms of the Dow and NASDAQ at least, the game may be rigged. But I’d have to agree that BrightSource, as a contender in the solar power industry, outshines its competitors lately. In fact, I would call BrightSource “The Little Engine That Could.” (Remember that from your childhood? “I think I can, I think I can”).

Starting out as Luz International, Ltd., reportedly the first company on the planet to build commercially viable solar thermal projects, that company’s team merged with a “world-class” finance and project development team to complete the array of skills needed to transform Luz into BrightSource.

The new company is backed by the likes of Google, Morgan Stanley and several oil companies, and in February was the recipient of a $1.4 billion loan guarantee from the U.S. Department of Energy. That’s certainly a good financial neighborhood from which to launch a public offering.

BrightSource’s proprietary LPT 550 system uses power tower and heliostat mirror technology to deliver megawatts of solar thermal energy to the grid – or will, as soon as the three units (I and II, 100 megawatts, or MW, each; III, 165 MW) of the Ivanpah Project are complete.

Notice I didn’t call them phases, because according to the California Energy Commission, the regulatory agency, the “three plants would be developed in concert,” sharing infrastructure like an administration/operations building, a maintenance building, and a substation – all on 5.3 square miles.

How much is 365 MW of energy? Enough to power 365,000 households, or a city the size of Boston (based on primarily two-person households)!

Of course, BrightSource had to compromise to get approval. This meant moving the project’s perimeter to avoid an area of rare plants, agreeing to cut Phase III by 23 percent, and reducinmg the number of Unit III towers from five to one to help protect the endangered desert tortoise, which will be relocated.

An Ex-Airline Employee’s Brilliant Solar-Thermal Combo System

Kayla — Fri, 12 Nov 2010 01:19:01 +0000

Bob Doyle of Blairco Solar entered the solar thermal market a little late in the game—nearly 27 years into his career in the airline industry. But after installing a hydronic heating system in his parents’ house and seeing the benefits first-hand, namely the system’s efficiency and cleanliness, Doyle was hooked and ready to start his own business.

Save money on your heating bills this winter, get free solar estimates today!

Doyle has since joined Blairco as the head of their solar division in the unlikely town of Camas, Oregon, about 20 minutes from Portland. While the location may not seem ideal for harvesting sunlight, Doyle swears that the western side of the Cascade Mountains generates 25 percent more sun than Germany.

After working for a few years in the industry, Doyle’s reputation has made him one of the go-to guys for homeowners in the area. One such homeowner recently called on his expertise when their pool heating bills got a little too steep to handle. Doyle convinced them to branch out from the traditional pool heating system into a solar thermal combination system.

Such a combo system has a plethora of advantages: it is operational year-round, qualifies for the 30-percent federal tax credit (and another $1,000 from the local utility company), and can greatly reduce a home’s energy expenses when the bulk of that is being carried by water.

For this particular job, Doyle installed six Schuco Slim V Plus solar panels, two 115-gallon Schuco Solar electric back-up storage tanks, a solar pump station, five temperature sensors, two pumps, and a motorized valve pass-through, among other technologies.

So how much did the solar-thermal combination system save the homeowners? They estimate that over just a few months they’ve saved a whopping $1,000 in pool heating costs alone, and they plan on recouping the $20,000 installation cost in no time.

It’s after completing projects like this one that Bob Doyle remembers why he entered the renewable energy market—and why he plans on never looking back.

Towers to Generate Solar Power in the Dark?

Dan — Thu, 07 Jan 2010 00:51:44 +0000

Solar power towers are the new trend in thermal power plants. Instead of rows of curved mirrors focusing sunlight onto miles of black tubing, power towers use Heliostat (sun-tracking) mirrors to focus light on a central tower. As first conceived, that “power tower” would contain water that when heated, creates steam to spin a turbine and generate electricity. Two new solar power towers set to be built by SolarReserve will make one major improvement: instead of using water in the tower, they use molten salts.

The advantage of molten salt is its high heat capacity, allowing it to get much hotter during the day and retain much of that heat throughout the night. The result is a clever form of solar energy storage that could help transform solar into a base-load, on-demand power source. SolarReserve is introducing the concept to the desert Southwest. A 100-megawatt plant will be built in Nevada under a power purchase agreement (PPA) with NV Energy. A second, 150-MW power tower will come as part of a deal with Pacific Gas & Electric (PG&E).

The Nevada plant, dubbed the Crescent Dunes Solar Energy Project, will have at its center a 538-foot-tall concrete tower topped with a collector containing millions of gallons of molten salt. That liquefied salt, an eco-friendly mixture of sodium and potassium nitrate, is heated to more than 1,000 degrees during the day. Crescent Dunes will have up to 12 hours of storage capacity, allowing near round-the-clock draw. The California project will have seven hours.

Power towers are still in their early stages. Some already exist around the world, including a few molten salt towers in use in Spain, but those are at best 20 MW in size. The ability to successfully store solar electricity created by these power plants could effectively double the usefulness of solar thermal power. According the National Renewable Energy Laboratory, electricity from power towers could sell for 5.47 cents per kilowatt-hour by 2020.

Many solar thermal plants in US deserts are mired in controversy due to environmental fears surrounding damages to landscape and habitat. Compared to conventional solar thermal power plants, power towers demand a smaller footprint. Their ability to store electricity allows them to create even more electricity with less space. Scarce water supplies may be an issue. Some power towers are air-cooled rather than water-cooled to preserve precious local resources.

Photo & Source: New York Times

Brothers, Cornell Grads Invent Solar Tube Collectors

Dan — Fri, 04 Dec 2009 22:19:10 +0000

In 2005, Matt and Adam Farrell, Cornell graduates and owners of Ithaca, New York-based Silicon Solar, made the transition into solar thermal water heating. In doing so, the brothers invented their own version of evacuated tube solar collectors and have now landed at least one major solar water heating project.

The brothers will be installing a solar water heating system at the Wallkill Correctional Facility in the Hudson Valley. Silicon Solar’s collectors consist of heating tubes made from two layers of borosilicate glass separated by a vacuum. An anti-freeze solution runs through the collectors, where it is heated by the sun. From the collectors, the fluid is sent to the hot water system, where it transfers its heat to the water supply.

The move into solar thermal systems is another step in the Farrell brothers’ goal of making solar power an affordable prospect for any home or family. Their evacuated tube collectors are made in Bainbridge with company headquarters in Ithaca. Adam Farrell localized Silicon Solar’s ambitious solar thermal goals with the bold proclamation, “We want to make Ithaca the solar thermal capital of America.”

Silicon Solar is best known for integrated solar products; solar fountains, solar lighting and portable solar electric kits.

Source: Elmira Star Gazette

All About Solar Water Heating Systems

Dan — Tue, 18 Aug 2009 18:56:58 +0000

Solar water heaters are the most inexpensive and cost-effective way to go solar. These solar thermal systems may be used in any climate to great effect. While initially more expensive than conventional water heaters, solar hot water systems take advantage of free solar energy to save money over time. Federal, state and local incentives and rebates also cut down on those initial costs by at least 30 percent.

Types of solar water heaters

There are two general types of domestic solar hot water systems. Active systems have electronic controls and circulating pumps to move water throughout the system. Passive systems do not have any mechanical components and use convection, gravity or other natural forces to draw hot water through the system.

There are two types of active systems as well: indirect and direct flow systems. Direct systems circulate water through the collectors (described below) and into the home in a continuous cycle. Indirect systems utilize a medium, or heat transfer fluid, which runs through the collectors, absorbs solar heat, and then passes through a heat exchanger (typically within close proximity to the storage tank to prevent heat loss as the heated water travels), where that heat is transferred to the water supply.

Photo Credit: r_neches

Water heater components

A solar water heater consists of two main components: the collector and the storage tank (add pumps and controls for active systems). There are three types of solar thermal collectors in residential use. The most popular of these is the flat plate collector, which are large, flat and contain a metal absorber plate that collects and transfers solar heat to water flowing through tubes attached to the absorber.

Evacuated tube collectors are more sophisticated, expensive and more efficient than flat plate collectors. They are therefore better suited for mild climates, such as those found in the northern half of the United States. Evacuated tubes consist of metal absorbers encased in parallel glass tubes. A header pipe runs across the upper side of the tubes. A transfer fluid (typically an anti-freeze solution) runs through the tubes, collects the absorbed solar heat, and carries back to a heat exchanger where that heat is transferred to the water supply. There are several different designs for evacuated tube solar water heaters, which you may explore .

Integral-collector storage (ICS) systems are used for passive water heating applications. In this instance, the storage tank itself is the collector. These systems consist of a tank, painted black, encased within a glass or plastic glazing. Solar radiation is collected through the glazing and absorbed by the tank. Convection, the tendency of warmer fluids to rise, works within the tank, pushing the warmer water to the top, where it is drawn for use within the home.

Thermosyphon systems are similar to integral collector storage systems. They are also called batch solar water heaters because they have a batch collector on the roof, which holds water within a tank that is itself within a box with glazing on one side. The water is sent, using only the pressure of the home water supply, into the collector where it’s heated. Convection causes the warm water to rise. It’s drawn from the batch collector and flows down into a storage tank within the house to be used for hot water. Such systems can work in colder climates but must have a drain valve so that the water can be drained from the collector in anticipation of a freeze.

Storage tanks for solar water heaters are usually heavily insulated to prevent heat loss as the water waits to be used in the home. Most of the time, they’re placed within the home, often right next to the pre-existing conventional water heater, which is used as a back-up on cloudy days. Storage tanks should be sized to properly fit your family’s daily water usage. This helps to prevent too much standing water inside the tank.

The problem with freezing

Photo Credit: Jimmy_Joe

Direct systems, which circulate water directly through the collectors, are best suited for warm climates where there is little chance of freezing temperatures. Frozen water within the solar collectors will severely damage the system, often irreparably. For that reason, indirect systems are popular in northern climes, where anti-freeze solutions (propylene or ethylene glycol) are used and the water supply does not leave the storage tank.

Cost of a solar water heater

Solar water heaters cost a lot up-front compared to conventional electric or gas systems. Prices range from $6,000 to $9,000 installed. Although in warmer climates, where less parts and freeze-prevention are required, initial costs can fall dramatically. Passive, ICS systems are the cheapest and often built by the homeowners themselves.

There are two main factors that make solar water heaters economically feasible. One is government incentives (sometimes local utility incentives as well). The federal government will pay for 30 percent of the system. Many states also have their own tax incentives for solar water heaters, usually comparable to the federal program. Many states exempt parts and materials from sales and use taxes, as well as property taxes on any increase in home value as a result of the installed solar system.

The second factor lies within the solar water heater itself. As expensive as it may be up front to install, from then on you are drawing on free solar energy to heat your water. Water heating is second only to space heating and cooling in the amount of money spent each year by the average American family. Which means that savings on utility bills will pay for the system over time. Payback periods for solar water heaters are often less than 10 years, while the system will last much much longer than that. Talk to a solar installer here to find out more specific information for your situation.

System maintenance

Solar water heaters require very little maintenance. Active systems of course may be prone to electrical failures from the pump or controls. Passive systems, with their lack of moving parts, are virtually maintenance free. In systems using a transfer fluid, that fluid will need to be changed every five years or so.

For more specific information and to find out which solar water heater is best suited to your home and climate, talk to a professional solar water heater installer today.

Does the Water in Solar Thermal Systems Need to Be Replaced?

Dan — Fri, 05 Jun 2009 16:57:52 +0000

Photo credit: Snap

Along with photovoltaics, solar thermal hot water heaters are growing more fashionable and marketable every year. Solar hot water heaters are more expensive than conventional models, although energy savings over time and increasing federal and state financial incentives narrow that gap considerably. After your new solar water heater is installed there is typically very little maintenance required — a big selling point for manufacturers and installers.

Very little, however, does not mean zero maintenance — just very rare maintenance. For active systems, pumps and other electrical components may need repair or replacement, but usually not for at least 10 years (quality solar thermal systems come with at least a 10-year warranty).

Yet another good maintenance question comes in regard to the water or fluid flowing through the system and/or solar thermal collectors.

Water

The water in solar thermal systems rarely needs to be replaced, even for systems with a storage tank. According to the federal government, the average person uses 15-20 gallons of water per day. That is why the average family of four’s water tank will be about 80 gallons in size. Remember that reducing your water usage will save even more money and reduce the size of your system, saving on initial costs as well.

Because the system is sized to provide enough water for daily use, the water within the system is not allowed to grow stagnant — the only real reason why the water would need to be replaced. Speak with your solar thermal installer about any further considerations that may arise based on your location, lifestyle, and type of system.

Transfer Fluid

For indirect, closed-loop systems — most common in climates with periods of freezing temperatures — an anti-freeze or propylene glycol solution is run through the collectors. This fluid will not freeze, thus making the solar water heater usable year round. The heat collected by the anti-freeze solution is transferred to usable water in a storage container by a heat exchanger. The transfer fluid will have to be replaced every 3-5 years on average and should be tested at regular intervals.

Solar Thermal Technology to Tap Auto Industry

Dan — Tue, 14 Apr 2009 17:01:56 +0000

Photo Credit: borman818

The solar auto industry brings to mind sleek, futuristic cars humming silently down smooth highways, gleaming in the midday sun. Yet that idyllic picture of a green auto industry may have some viable competition. One struggling solar startup thinks it has discovered a cost-effective way to bring grid-independent solar thermal power to millions, all while boosting a desperate auto industry.

Infinia, a rather unique startup, has found a way to mix 21st Century ideals with 19th Century technology. Their innovation begins with a Stirling engine, one that runs on hot and cold air. So long as one end of the engine remains hotter than the other, the Stirling, which alternately compresses and expands a quantity of air or gas, will keep on pumping. It is so adaptable to today’s needs because the heat source does not matter.

That’s where Infinia’s design comes in. They’ve mounted the Stirling at the center of a large concentrating solar collector – a large satellite dish in appearance. This solar-powered Stirling uses solar heat to keep the engine pumping out electricity during the day. It folds up like a flower at night to conserve heat and is backed up by a small bio-fuel generator.

Photo Credit: infiniacorp.com

While Infinia has launched several failed Stirling-based technologies since 1985 when the company was formed, their latest innovation is their most positive. So far CEO J.D. Sitton has already garnered $70 million in funding and their first client: the U.S. Army.

Infinia’s solar generators claim 24% efficiency in converting solar energy into electricity, a number that stands reasonably higher than current averages for solar photovoltaic cells. A good deal of their potential also lies in off-the-grid possibilities in rural areas and for homeowners. Because Infinia could use current auto technology with little upgrade, they believe they can cut costs considerably and deliver cheap, clean power to their customers. Infinia’s goal is to produce 100,000 Infinia Solar Systems in 2010 at a price of $15,000 each.

For such goals to be reached, Infinia will need some large scale manufacturing capacity. Fortunately, their Stirling-based design is relatively simple and easy to mass produce, especially for the auto industry, which already has the technology and equipment to do the job.

Photo Credit: infiniacorp.com

Auto suppliers are already equipped with more than enough capacity and skill to support Infinia’s needs. First of all, automobiles run on internal combustion engines, which are more complicated than Stirling engines, so adaptability for auto suppliers is not an issue. Not only that, many auto suppliers are currently in desperate need of work due to unprecedented decline in the American auto industry. According to CNN, the auto industry used less than 60% of its manufacturing capacity in 2008. That creates a potentially symbiotic and lucrative relationship for both Infinia and the auto industry

So far the dish collector and engine — the two most important pieces of the Infinia system — are currently being manufactured by Autoliv and Cosma, two prominent auto suppliers.