How does Solar Energy work ?

The Sun

How does solar energy work?

The Sun (the closest star) to planet earth a mear 149.60 million kilometers (92.96 million miles) away, is a giant energy emiting power house. It is estimated that the suns power output is about 386 billion, billion megaWatts. The conditions at the Suns core is extreme, with a temperature estimated at 15.6 million Kelvin and the pressure of 250 billion atmospheres! The surface temperature of the Sun, (called the photosphere), is at a temperature of about 5800 K. In addition to heat and light, the Sun also emits a low density stream of charged particles, (mostly electrons and protons), known as the solar wind, which propagates throughout the solar system at about 450 km/sec. This causes dramatic effects on the Earth ranging from power line surges to radio interference to the beautiful aurora borealis.

Aurora Borealis

The Sun's magnetic field is very strong (by our earthly standards) and complex. The sun powers photosynthesis in green plants, which is the process that alows all plants to live and grow and is ultimately the source of all food and fossil fuel. Effectively fossils fuels are a deminishing deposit of energy that was ultimately produced in part by the suns energy. Even wind and waves finds its source from the effects of the sun heating the earth.

The Sun solar energy

Mans attemps to harness the Sun

The question how does Solar Energy work, can be answered in many ways but let me start by assuming (that since it has been asked), the one asking the question is wanting to harness it's energy for home use? If the answer to that is yes then let me answer from a home user perspective. If your interest is more concerned with understanding solar energy from the perspective of large scale commercial power generation I will look at this further down the page.

For house hold use the 4 main usefull ways one can harness the energy from the sun is in the following ways:

Solar Water Heaters

These are devices that use the light and infra-red rays to heat water for domestic cleaning and bathing.

Question: So how does a solar water heater work?

Answer: A solar water heater is a relatively simple device that is really just a large heat exchanger. In the same way that water is heated, in a garden hose pipe, lying in direct sun light, the same principle is applied in the most efficient way possible to heat water buy circulating it through dark pipes, or vacume flask type pipes (solar collector) that effectively transfer the suns heat into the water that is circulated. There are various types some that use other anti-freeze type liquids that are circulated and heated, which then transfer the heat to the water in a secondary circuit. This heated water is then stored in an insulated vessel similar to a household geyser.

Direct Solar Cookers

These are devices that heat up, to cook food through concentrating the suns energy.

Solar Cookers allow one to cook for the cost of the cooker, with no electrical or fuel costs. These kind of cookers can bake, boil or steams any kind of food with the power of the Sun. A solar cooker cooks very much like your home oven however the downside is that it limits cooking to the middle of the day when the sun is at it's strongest. Temperatures can reach to 360° to 400° F on sunny days, and even on cloudy days one can cook but the time needed is much longer. The process is totally safe, as long as one uses oven gloves to handle the hot pots. There is no fire danger and it is very hard to burn anything since the heat is evenly dispersed. These cookers are versatile, easy-to-use, and portable.

DIY Solar Cooker

The Solar Cooking Wiki has free plans for making a very cheap and effective card board solar cooker, that works and is portable. I made one like the plan showed within a few hours and was able to boil a small pot of water, within 2 hours. (at midday in winter)

DIY solar cooker

Have a look at the Solar Cooking Wiki for more details on solar cookers and to print out the full size Cookit design and make one yourself. Materials needed, include: Cardboard, Glue, Aluminum foil a black pot and heat resistant oven bag.

For a details plan of the Cookit Solar Cooker

For an overview of the Cookit Solar Cooker have a look at the following link.

Solar PV arrays

PV stands for Photo Voltaics and are devices that convert solar energy into electrical energy.

Question: How does a PV solar panel or array work?

Answer: Traditional PV solar panels use crystalline silicon as a semiconductor (similar to computer Circuit chips) and sunlight to make electricity. When sun light strikes the PV cell, a certain portion of it is absorbed within the semiconductor material. This has the effect that the energy of the absorbed light is transferred into the semiconductor. The energy "knocks" electrons loose, allowing them to flow freely. The silicon material uses a relatively narrow band of light frequencies that are effective in this material.PV cells also all have one or more electric fields that act to force electrons freed, by light absorption to flow in a certain direction. This flow of electrons is low current, and by placing metal contacts on the top and bottom of the PV cell, the current is drawn off. The electricity made is a constant DC voltage and with low current. Due to the pretty low power output of an indivdual PV cell, solar panels are made up of a number of individual cells put together into Solar panels of varying power outputs.

Solar Panel Array

Question: How do the thin film or the newer PV materials compare to the older crystal type PV's?

Answer: In the last few years there has been a huge amount of money invested in finding new and more efficient types of PV materials. The push for "green" energy has caused a rapidgrouth in the PV market. There are 3 main types (a-Si, CdTe and CIGS)of thin film materials. Researchers are looking for higher power output efficiencies at lower manufacturing costs. These materials can be mass produced at lower costs on glass or often on flexible plastic surfaces. Other considerations are toxins used in the manufacturing process and the energy used in the manfactureing process. The Thin film PV materials researchers, are making huge strides, and on large scale projects the costs have dropped to the same level as fossil fuel power plans on a cost per Watt comparison.

Gadgets that include PV elements

These include flash lights, cell phone chargers, garden lights, calculators etc. to charge or power items without using mains power.

Green entrepreneurs are relising that it is hip to go green and solar. You can find so many cool solar gadgets on the market these days. From SolarBulbs to Solar Lampshades, and Solar Doghouses to Solar Dollhouses - the options are endless! You can even get a car solar battery charger!

There are many solar gadgets that are on the market, that can help one kill your traditional battery consuming ways. Solar gadgets will literally free you to enjoy your life, without worrying about environmental impact of enviromentally polluting batteries and wondering when and where you can recharge your devices.