What is Thermal Mass? Playing Catch and Release With Solar Power

As anyone who has lounged in a sunbeam can attest, the sun brings heat to a room. In some climates at some parts of the year, this is a good thing. In a climate that is cold, you want the heat and light of the sun to shine through your windows in the winter time. Ideally, you want the house to help store this heat and release it in the evening or on rainy days. In a climate that is uniformly warm, you want to use passive solar design to create living environments that ward off heat and light or store it for release into the outdoors in the evening. The overall aim of passive solar design is to use building design to equalize the indoor temperature throughout the day and night.

Passive heating is the use of design elements to increase the heating of a building in the wintertime. Passive heating also increases the ability of a particular building to retain heat. Passive cooling is the use of ventilation, shading, insulation and other natural cooling methods to reduce the heat in a building in the summertime. The use of thermal mass in the home can help with both of these objectives, heating the home when it requires heat and storing heat when the outside is too warm.

If you’ve been studying energy efficiency, you probably know about the role of insulation in your home. Insulation creates a fluffy blanket around your home, preventing energy from moving in and out. Thermal mass is not insulation, but it also creates an indoor environment that is a more ideal living temperature. Thermal mass is a part of the house that is used to store and radiate heat energy. Materials that are used for thermal mass include adobe, clay, mud, rammed earth, concrete, and wood. These materials can be part of walls or floors.

How does the thermal mass work? Even when the climate is cold in the winter, the sun still gives energy to the earth. In the day time, the sun shines on the thermal mass and the mass stores the energy. At night, it releases it back into the house. In warm climates, thermal mass collects heat energy and radiates it back into the outdoors as the outdoor temperature drops in the evening. Historically, homes in hot places have been fashioned from thermal mass materials such as adobe.

It is best to have the thermal mass directly exposed to the sun in order to absorb heat. The exact amount of thermal mass required to heat a building varies from place to place and from building to building. Different materials store different amounts of energy. Also, different buildings lose different amounts of energy. A general rule of thumb is that the area of thermal mass that is exposed to the sun should be about six times the area of windows that are exposed to the sun.

Using thermal mass in your home moves your home renovation or building project beyond insulation. Thermal mass creates a home that can keep itself at a comfortable temperature. Sound space age? Not really. Thermal mass is about clay, earth, water and wood.

Homes That Work With the Sun: Principles of Passive Solar Design

The sun is an exploding furnace of gas, and it is anything but passive. Designing your home for the best possible use of solar power is also a very active experience. So what is passive solar design, and why the name?

Passive solar design gets its name because it does not involve machines with moving parts. As a homeowner, the thought of no moving parts is often attractive. There’s nothing to break. However, the process of passive solar design does require a large amount of consideration. Passive solar design creates a home that collects and releases the sun’s energy at times that work for you. To design in this way, you need a deep understanding of your building site and the ways in which the building will interact with that place.

If you love the way your front yard tree provides shade for your home, you know something about passive solar design. However, to be a true designer you need to make an investment in building your knowledge of the site at the outset and make adjustments to the building and the site.

What do you need to know to begin to understand your building site and translate this into a good passive solar design?

Choosing a building site for passive solar design is more complex than it appears. You do not want to simply choose the first site with a lot of sun. To choose a good building site, you need to consider the latitude of the site. In part, the latitude determines the climate. Is this place hot in the summer and cold in the winter? Is it mild and humid all year round?

Track and understand how the sunlight changes over the course of the year or even the course of the day. You may think that the sun rises in the east and sets in the west, but where does it go in between? There’s a big difference between summer and winter sun angles. Build a home that changes with the seasons by capturing the sun’s rays when you need them. Online tools such as Sun Angle can help you calculate the altitude and declination of the sun at different times of the year. You need to know your latitude and longitude to use the program.

Walk around the site and map the ways in which major landscape features change the levels of sun, shade, and wind present on the site. Every small part of the world has its own micro-climates. Landscape features such as large trees and other buildings will change the amount of heat and light that are present on each part of the building site. Trees, walls, buildings and arbors also change the way the wind moves through the area. Be conscious of the ways in which any future buildings will change the sun, shade, wind and humidity on the site.

Where do you go first thing in the morning? The kitchen? The living room? If the sun is not too harsh, use it to warm living spaces in the morning and sleeping spaces in the evening. Orient the house on an east-west axis so that you can use the sun to your advantage. Strategically control shade and micro-climates to create the climate you want in each room. Use outdoor and indoor blinds and arbors to make certain rooms shadier at certain times of the day.

By using passive solar design, you can construct or renovate a home so that it requires fewer machines to heat and cool the air. For your budget and for your repair bills, that can only be a good thing.

Solar to Go: Small Folding Solar Panels

It’s nearly summer, and it’s almost time to plan vacations. Rambling folks need power too, and those outlets can be hard to find on the road. Going off the beaten path, into less-serviced campgrounds? You’ll need your own power. If you’re going on an extended trip but you need to stay connected to the outside world through phone and email, a folding solar panel might be just what you’re looking for.
Merchants need power too. From solar displays that power tables at a summer festival to solar panels that power the equipment in a roadside vending stall, folding solar panels allow merchants to tap into solar energy as a ready power source. Sometimes there’s no outlet to be found, nowhere to plug into the power grid. At other times, it’s easier to get a good location if you’re not restricted to where your power sources are placed. Using solar also brands your business as a sustainable business.

When you are investigating small scale solar for travel or business on the road, consider the following questions:
How much power do you need? Determine whether you can scale back your appliances or convert to more energy-efficient appliances. You can also change the way you use the appliances to use them in a more efficient manner.  Do you need solar power for your small electronic devices? Small, folding solar panels are the solution for summer time adventures. These panels come on a flexible backing and are a good way to do business on the road. They are ideal charging devices for laptops, cell phones, and other everyday devices. You can also small solar panels to recharge batteries to suit a more diverse array of power needs.

Do you need to store the solar panel when it is not in use? If you need to store the panel, you may want a smaller or a folding solar panel.
How do you install the solar panel? If you need a panel that you can bring to events, it should have its own independent structure and require little if any mounting. A solar panel system for an RV would be better mounted on the RV so you can get up and travel without worrying about reinstalling your power system.
Does the solar panel tilt to ensure maximum light? When you install solar panels on a house, you install them with maximum light in mind. However, an RV or a mobile display or vending unit will move, and it is important to consider how you will collect solar power when you are stuck on a prescribed site. Solar panels that have legs to tilt allow you to harvest the most energy.  
Is it possible to add additional panels to the system? Your energy needs can change over time. Ideally, look for a system that allows you to add solar panels if your needs increase. This helps you have an integrated power system.
Small scale solar panels are ideal for summer time. Summer is the season when you head out into the world to events and on vacations, but you want to pack light. It’s also the season of sunshine, the perfect time to use a solar panel for your power needs.

Hot, Hot, Hot! Connecting Solar Hot Water to a Tankless Water Heater

We like it hot. Our showers, that is. So we stand in the glorious fountain of water that comes out of our shower, enjoying the hot cascade and using up the contents in the hot water tank in the process. Ah, the enjoyment. Oh, the guilt of using hot water.

But what if you didn’t have a hot water tank? What if warm water flowed freely from the tap? What if some of this water was heated by the sun?

What is Tankless or On-Demand Hot Water?
In North America, most homes are built with a hot water tank. This tank stores water in a large cistern and keeps it at a constant warm temperature. However, those who are watching their gas or electric bills creep or leap upward may wonder about the efficiency of the hot water heater. It doesn’t make a lot of sense to heat water over and over, day in and day out, while we only use it a few times a day.

A tankless or on-demand water heater is a device that heats water when you need it. It does not store hot water all day. This makes it far more energy-efficient than a traditional hot water tank.

Tankless hot water heaters do have their drawbacks. Those with hot water tanks worry about the long shower or the shower that occurs after running another appliance that uses hot water. It is possible to run out of the stash of hot water. Those with tankless hot water heaters do not need to worry about running out of hot water. However, all of the appliances that are on a single system need to share the hot water, so it is possible to try and do too many activities with hot water at the same time. By installing an additional tankless or on-demand water heater, you can solve this problem.

What is Solar Water Heating?
The solar water heater is a device that uses the sun’s energy to heat water. The sun is remarkable at heating water, especially when it is assisted by materials that collect heat, such as black cloth. Solar hot water systems are generally placed on the roof of the home to heat water for a pool or for in-home use. Using the sun is a very energy-efficient way to heat your water, but it doesn’t always produce the quantities of warm water you would like, especially on a gray sort of day.

Like the traditional home water system, solar systems have a water tank. However, solar hot water storage tanks are far more energy-efficient than the traditional gas or electric hot water tank. Solar hot water tanks get warm through direct or indirect means. A direct solar system moves hot water from the collectors to the storage tank. An indirect system circulates hot fluids from the collectors to a heat exchanger, which heats the hot water in the storage tank. 

Combining Tankless and Solar Hot Water Systems
It is possible to combine these two energy-efficient technologies to reap the benefits of the instant hot water of tankless and the extremely efficient nature of solar hot water heating.

The tankless hot water heater goes on when water is below the temperature that you’ve set as your desired hot water temperature. Use a controlling mixing valve to combine the solar-heated water with the tankless system. When the water is at the correct temperature, the tankless element will not go on. When the water is too cold, the tankless heater will go on and heat it up to the desired temperature.

To combine your solar and tankless systems, you must have hot water systems that are compatible. If you currently have a tankless or solar system, work with a water heating contractor to determine whether the systems will be compatible.

Energy Efficiency, Water Conservation and Tankless and Solar Systems
One word of warning: for those who love to love hot water, the energy efficiency of a tankless system may not be up for the challenge. A tankless system used alone or on a gray day will still use energy, especially if your showers are long.

Water conservation is still a concern for those who are looking into tankless and solar hot water heaters. Making water messy and sending it down the drain to be cleaned means that you still have an ecological impact and send waste-water to be treated, unless you treat the water yourself in a greywater marsh.

Climb aboard the solar and tankless hot water train, and you’ll find a better way to heat your water: two better ways, in fact! While you’ll still need to remain conscious about the amount of time you spend in your shower, you’ll be spending some quality time with water that has been heated by sunshine instead of lurking in your basement all day, and that’s a wise choice for energy efficiency.

Outdoor Temperature and the Efficiency of Home Solar Panels

The weather outside is hot: really hot. You sit inside, pleased because all of this sunshine must be good for your solar panels. You expect great returns on your energy investment, so you’re surprised when the efficiency of the panels seems to be dropping. Surprise! In extremely hot temperatures, photovoltaic solar panels actually become less efficient.

Around the home, you may use thermal solar panels for heat energy. These common solar panels are used to collect heat and warm up hot water. Place them on a hot roof and they work wonderfully. However, photovoltaic solar panels do not use heat to make energy. These solar panels use the light that falls on your home and turn it into energy to power appliances. When you are researching, installing, and using solar panels around the home, it is important to understand that these different solar systems work in very different ways. Heat is what is required for solar hot water systems. These systems work well on warm days. Light is required for photovoltaic solar systems. These solar systems work well when it is sunny, but it does not need to be warm. In fact, a cold, clear day is ideal for solar energy.

Why is this the case? Temperature changes the efficiency of photovoltaic solar panels. The efficiency of a solar cell is expressed as a wattpeak (WP). On the package for your solar equipment, you will generally find the efficiency in wattpeaks. This number gives the efficiency of the cell under laboratory conditions. The laboratory temperature used for peak efficiency is 77 degrees Fahrenheit.

A photovoltaic solar panel is designed to collect visible light. However, it is also very dark. Dark colors absorb heat. When the air temperature is a nice, stable 77 degrees, all is well with the solar panels. However, as temperatures climb to 100 degrees and beyond, the energy output of the solar panels decreases. To reduce the effects of heat on solar panels, avoid placing solar panels on a metal roof. Allow for some air flow around a solar panel to provide ventilation. Also, consider what use the solar energy will go to. If you live in a desert climate and plan to use solar panels to power an air conditioner in the heat of summer, this is possible, but the panels will certainly not be at their most efficient.

Oddly enough, photovoltaic solar panels work extremely well in light, cold environments. Actually, all electronics work best in the cold, because cold materials are good conductors of electricity. Cold locations such as Colorado and Scandinavia have been very successful using solar power on a large scale. If it’s hot where you live, you can certainly use solar panels to generate energy. However, be gentle with the solar panels and give them good ventilation to improve their efficiency. In the peak of the summer heat, reduce your use of household appliances and lights since the panels will not be operating at peak efficiency.

Solar Kits for Kids

While it is winter and the sun has yet to make an appearance for more than a few minutes, it is coming. At least I hope that it is. While we wait for the sun to shine, teachers and parents can plan for summer and for children’s birthdays by thinking about toys that teach creativity and sustainability. What are these sustainable toys? They’re solar kits for kids.

Many adults hear about solar and keep it on the fringes of their ideas of what is possible. Solar power is something to place in vast arrays in the desert, or maybe it sits on the roofs of those who are very motivated to make a difference. It’s not at the front of everyone’s mind as an option for power and warm water, and that’s where solar kits come in.

What solar toy kits are out there? One perennial favorite is the solar-powered race car. There are any number of companies that create solar-powered vehicle kits, a good alternative to a battery-operated car. There are also solar boat, dog, and robot kits available. One of the most intriguing solar cars is actually powered by hydrogen: the H2Go Radio Controlled Hydrogen Powered Car fills up with water. It then uses solar energy to split the water into hydrogen and oxygen gas, and the car can run for up to an hour.

For those more into crafts than building, Sundance Solar has toys like UV-sensitive photo paper, an alternative way to create and process your photos. They also have very groovy sun-sensitive beads.

For teachers, Sundance’s Solarlab Learning Kit is good for teaching children about the basics of electricity and electrical circuits. Sundance also has small solar panels available so that children can build their own solar kits. The 6 in 1 robot kit is also a good choice for the classroom, since children can build any number of different movable solar projects with the pieces in the kit.

If you can’t find a solar kit that is suitable, purchase a solar-powered battery recharger for parents of small children. This uses the sun’s energy to do something that parents need to do anyway, whether it’s recharging batteries for a flashlight or a singing, dancing toy. Their wallets will thank you, and so will the landfills and toxic waste collectors, for being rid of the toxins from disposable batteries.

For teens, there are a number of gadgets that are powered by or can be recharged with solar energy. How about a solar charger for a phone? These are widely available. How about a laptop for teens to use, powered by a flexible solar panel like a SolarRoll? Or how about a SoulRa, a dock for an iPod that is powered by solar energy? If teens have gadgets, you might as well take the load off home power and invest in solar chargers at the outset.

To many of those in urban areas, energy comes from the wires above the house or buried below. We’re disconnected from our sources of energy, whether they are sustainable solar, hydro, or coal. When we no longer have to burn fuel to stay warm or use candles to keep the darkness at bay in the winter, we lose a connection between us and the relative sustainability of our power sources.

Giving a child a solar kit or a toy that is powered by solar energy brings this technology to the foreground. It becomes a normal way to collect energy, and that’s important if this technology is to be popular one instead of technology for a niche market.

Image courtesy of dynamic at Stock Exchange.

Fun in the Sun: Powering Your RV with Solar

Living in Portland, Oregon, the sun is not something we take for granted seeing how we average only 144 sunny days a year. When the sun does decide to shine down and grace us with its presence, we get out there and soak it up (with appropriate SPF of course.)

So I’m sure you can imagine the lack of sympathy I have for my friend, a pilot who lives in the Portland area, who due to the economy was recently transferred and is now based out of Los Angeles where they have on average 291 sunny days a year.  Even though he’s living in an RV in the LAX parking lot 3 weeks out of every month, I’m pretty sure I’d trade places with him, at least for a little while.

On his last visit home, we got to talking about life in the RV and the sudden demise of its generator. With a family at home in Portland and a second “household” (RV-hold?) in L.A. to support, he’s been looking into the most cost efficient way to power the RV appliances and miscellaneous gadgets like his computer and cell phone. He asked what I thought about going solar. Given there’s no shortage of sun in Los Angeles, especially on an airport tarmac, it seems like a no-brainer. I told him I thought it was a great idea, and here’s why.

First of all, solar panels are quiet, unlike a generator. Nothing can ruin the peacefulness and tranquility of the great outdoors quite the roar of a generator coming to life as campers start their morning coffee. In the case of my friend who’s living at an airport, I’m not sure the noise factor is as relevant, but if you’re using your RV in a campground, your neighbors will thank you.

In addition, solar panels require little to no maintenance (the occasional removal of bird “bombs” aside) and because there’s no gasoline, diesel or kerosene used as there would be with a generator, there’s no pollution or emissions generated, so mother nature will thank you, too! 

Some people may argue that solar panels are too expensive and noise and pollution benefits aren’t worth the additional cost.  However, today’s solar panels are really cost competitive. If you’re in doubt, consider this: a gas powered generator can run anywhere from $1500 – $3000 (or more depending on the size of your RV and energy needs).

For roughly the same price you can purchase an RV solar kit which comes with everything you need to get started including the panel, charge controller, inverter, roof mounts, and cables. And if you find you have greater energy needs, additional solar panels can easily be added.

Probably the biggest incentive for people considering a switch to solar is the substantial long term cost savings on fuel. Those having already made the switch estimate they save around $500 a year by not buying gas for their generator. So all things considered, assuming an equal life span of 5 years for both a generator and solar panels, you could see a total savings of nearly $2500 by installing solar panels on your RV. If you’re in the market to upgrade or replace your RV’s generator, consider going solar; by going green you can save green, too!

RV Solar Kits

New Solar Cell Material Has Theoretical Efficiency of Over 60%

Conventional solar cells based on silicon semiconductors, can only absorb visible photons with a particular amount of energy, which is then transfered to the trapped electrons. Unfortunately, these conventional systems cannot use visible photons that contain more or less than a certain amount of energy, making then quite inefficient.

However some advances were made in 1997 by another Spanish scientist, who found a way to increase that usable spectrum of visible photons. He found a way to collect the lower energy photons and store them until another lower energy photon was absorbed and then combine them to make the electron jump. Even though these advances were quite significant, the theoretical efficiency of silicon based solar cell have still remained under 40%.

That is, until now…

A couple of scientist in Madrid, Spain have invented a new type of solar cell which not only collects visible light, but captures the energy of non-visible infrared light. These scientist have devised a way to create an intermediate energy level for collecting visible and non-visible low level energy photons, by adding vanadium and titanium to the semi-conductors. Instead of collecting two low level photons and combining them to make them jump to the full energy level, the titanium and vanadium actually alters the electronics of the semi-conductors allowing them to absorb and jump on intermediate energy levels. This new advancement according to the team will give these new solar cells a theoretical efficiency of 63%.

via NewSientist

Solar Industries First 1GW Production Tool

Nanosolar is a thin film photovoltaic manufacturer who is making major strides in the solar industry. The most notable stride is the fact that Nanosolar is the first manufacturer to figure out how to make solar panels at less than $1 per kW. This news broke many months back and Nanosolar has been all over the green blogsphere, so we did not write about it at the time even though it was probably the larges solar breakthrough we will ever see.

Since then, Nanosolar has been producing their thin-film photovoltaics on a very large scale and have only been providing panels for 2-10MW municipal solar power plants. Much to dismay of die hard solar enthusiast(like me) eager to get their hands on these $0.96 per kW solar panels, Nanosolar has not begun selling their panels on the free market. Nanosolar wants to make the biggest environmental impact they can, and by only selling to large municipalities at first, they will do just that. Even though it hurts, it is whats best for the solar industry and for the environment.

Along with these major stride in pricing, Nanosolar just put into production the solar industries first 1GW thin-film photovoltaic production tool. The tool shown in the video above is printing thin-film solar panels at 100 feet-per-minute and is capable (in theory) of ramping up to over 2,000 feet-per-minute. The photovoltaic printer cost Nanosolar $1.65 Million. Now considering that the current high-vacuum process that other manufacturers are using will generally produce 10-30MW per year and cost almost ten times as much as Nanosolar’s printer, I’d say Nanosolar is about to dominate the solar industry and give coal a run for its money.