Solar

When someone puts a “solar power system” on their home, what does that mean? There are two types of power that can be derived from the sun, electric and thermal. Electricity is generated from sunlight with photovoltaic panels, those black colored panels you see on rooftops. Thermal energy, or simply heat, is captured by solar thermal panels. They are boxes with a glass top that trap the suns' heat and transfer it to water-filled pipes. The orientation and design of a house can take advantage of the sun as well, using passive solar design.

Photovoltaic Panels

Photovoltaic panels, also called solar panels or PV, convert light from the sun directly into electricity. The manufacture of photovoltaic cells has expanded dramatically in recent years. Solar cells produce direct current electricity from light, which can be used to power equipment or to recharge a battery. You see practical applications everyday, pocket calaculators, traffic control and roadside phones. Today the majority of photovoltaic modules are used for grid connected power generation. In this case an inverter is required to convert the DC to AC.

A panel is created from individual solar cells, which are protected from the environment by a glass sheet. When more power is required than a single panel, panels are electrically connected together to form arrays.

Solar Hot Water

Solar heating systems are generally composed of solar thermal collectors, a fluid system to move the heat from the collector to its point of usage, and a reservoir or tank for heat storage and subsequent use. The systems may be used to heat domestic hot water, swimming pool water, or for space heating. The heat can also be used for industrial applications or as an energy input for other uses such as cooling equipment. In many climates, a solar heating system can provide a very high percentage (50 to 75%) of domestic hot water energy.

Residential solar thermal installations can be subdivided into two kinds of systems: compact and pumped systems. Both typically include an auxiliary energy source (electric heating element or connection to a central heating system) that is activated when the water in the tank falls below a minimum temperature setting such as 50 ° C. In this system you'll always have hot water available along with your lower energy bills.

Thermal Gain and Passive Solar

Passive solar technologies convert sunlight into usable heat, cause air-movement for ventilation or cooling, or store heat for future use, without the assistance of other energy sources. Passive solar systems have little to no operating costs, often have low maintenance costs, and emit no greenhouse gases in operation.

The first thing to understand about passive solar is that it doesn't have anything to do with solar panels, photovoltaic cells, or any other technology. The whole idea is to build and locate your home in such a way as to harness a maximum amount of the sun's energy in the winter, while blocking the sun's rays from heating your home in the summer. You need to understand how the Sun moves where you live.

There are three main elements that make a passive solar home different from a conventional home: South-facing windows; a ledge of a certain length and angle above those windows; and a mass-wall.

During the winter months the ledge above the windows is short enough and placed at such an angle as to allow the winter sun to shine in and fill the mass wall (or thermal wall) with heat during the day.  This heat will begin to  radiate from this thermal wall as the house cools at night. And the cycle begins again as the sun comes up the next morning.

As summer comes around the path of the sun is at a higher angle allowing the ledge to block the sun from directly shining onto the thermal mass creating a heat build up. The mass wall stays shaded and cool as does the house.  Tile and stone flooring can also be used to supplement thermal mass in both exterior and interior spaces.  Insulation is an important factor in absorbing or reflecting the sun's heat. Passive solar and thermal gain are building concepts that people around the world understood thousands of years ago – you work with the earth; not against it.

Any of these solar energy systems will reduce your home's energy bills, saving you a significant amount of money over the course of your home's life. These types of energy also reduce electric peak loads (when electric utilities have a hard time meeting demand in the afternoon) as well as reduce carbon emissions.