EnerygLover » Solar

Why No Modular Solar Systems?

eneryglover — Wed, 02 Sep 2009 23:41:35 +0000

In the early days, 1950’s of air conditioning, contractors purchased a compressor, slab coils, a water pump, a redwood cooling tower and a mess of pipe and electrical components. The compressor was installed in the garage, the slab coils were fitted on top the furnace to form an A coil and the water tower and pump were installed in the alley.

Today all these components are packaged into units that can be installed in hours.

Solar manufacturers would be wise to build modules that are as close to plug and play as possible. Many residents motivated to get off the grid without economic justification would purchase a module to run the lights this year and another for the dishwasher and clothes washer next year.

The price of rooftop solar panels has fallen drastically, but for some homeowners, the upfront costs remain prohibitive. One way to move more modules would be to put smaller arrays on homes. If financial constraints are a consideration, why make us save for years to put dozens of panels on our home when you could put just one or two now?

Package a solar panel, micro inverter, storage battery with the hardware. Size the units to handle 400, 600, 800 or 1000 watts and match the system to a dedicated lighting circuit or appliance

Thermal Solar Hot Water System

eneryglover — Fri, 14 Aug 2009 17:46:28 +0000

Everyone uses hot water to bathe, shower, wash our hands, wash our dishes and wash our clothes. Many of us use hot water to heat our homes. few of us are addicted to soaking in a hot tub or swimming in a heated pool. The uses and demand for hot water are significant. Why not make all you want and pay nothing for the energy.

Thermal solar hot water has been around long enough to become a mechanically mature technology. We built my fist experimental solar collector in the mid 70’s. We installed a commercial system in the late 70’s. (Government funded) Unfortunely most of these solar systems were taken out of service due to their requirement for regular maintenance and repair.

Solar thermal systems are now available that are very reliable and require only minimum maintenance. They are simple enough that almost anyone could build, install and operate a system. If low up-front costs are important, start stockpiling your materials. If time availability is the issue or you are just not handy, call one or the installers listed at the end of this article.

Several books and e-books are available for the DIYer.Click Here!.

Infrared radiation (IR) are produced when short wave radiation (light) hits the absorber plate, which is then trapped inside the collector. Water, in the absorber tubes collect the trapped heat and transfer it to a heat storage tank. Heat storage allows a solar thermal system to produce electricity at night and on overcast days.

Several types of Solar thermal systems are available but we recommend you keep it simple and use flat plate collectors. Flat plate collectors are the simplest and most common type. Copper pipes wind back and forth through the flat plate collector, which is painted black to absorb heat and covered with glass, or “glazing,” to prevent heat from escaping. Often the pipes are painted black and bonded to the material of the flat plate collector to maximize heat absorption.

Solar Basics, Thermal Hot Water

eneryglover — Fri, 14 Aug 2009 17:45:07 +0000

Most energy sources are the indirect result of solar energy conversion processes. Wood burned gives back, in the form of heat, solar energy absorbed by the tree as it grew. Coal, oil and gas are also created from converted solar energy. If you remember from science class, energy isn’t ever destroyed, it’s just converted to another form. In our case, solar radiation energy converted to heat energy. A good comparison, one square meter of a dark surface exposed to sunlight will absorb about one horsepower of (746 watts) of energy.

Visable light that our eyes can see is only about 25% of the energy in solar radiation. Much of the solar energy is absorbed by the ozone and atmosphere so only 45% will reach the earths surface.

Passive and Active Solar Energy Systems

There are two types of solar systems, passive and active. Passive solar systems depend on the solar radiation striking directly on the surface or area to be heated. A good example of passive solar is a greenhouse. In a typical greenhouse the energy flows through the glass into the area where the plants grow. Passive solar energy collectors usually require no pumps or blowers to distribute the energy collected.

A house with south facing windows designed to allow sun in winter months would be considered a passive system.

In an active solar system the energy is absorbed into a collector, stored and then redistributed as needed by mechanical means.

An active solar energy system will have the following parts.

Collector for solar radiation.
Method of moving the heat from the collector to storage and point of use.
Method of storage.

Collectors

Collectors trap solar radiation. The color black is produced when all visible radiation is trapped, so the most efficient collector will appear to be black because it has absorbed all the light. Collector surfaces should be finished with a high temperature black finish or one of the engineered selective finishes. The finish should not be shiney , reflective or smooth. The maximum temperature a black object can reach in full sunlight is 253F. If a glass is placed over the black collector temperatures of 625F are possible.

Glass is the most widely used cover for collectors. If the frame is metal care must be taken sealing the glass to the frame since the materials expand and contract at different rates. The glass will break if not allowed to expand at its own rate. Some manufacturers place their collectors in vacumn sealed glass tubes.

Installed Angle of Collectors

The surface of the collector is normally perpendicular to the rays of the sun. Since the angle of the sun changes an average is usually used. In midwinter the sun angle is 66.55 degrees minus the site latitude. The angle in summer is 113.45 degrees. If the collector is used to heat a building and since winter requires the most heat an angle of 45 to 55 degrees to horizontal would be used in the mid-section of the United States. Hot water only would be installed 35 to 45 degrees to horizontal. Collectors should face south or up to 30 degrees east or west from due south.

Storage

The heat from the collector is normally stored in a preheat tank about half the size of the powered hot water heater. The preheated water is fed into the powerd heater for any final heating from 105 to 120 degrees

Solar Electric PV

eneryglover — Fri, 14 Aug 2009 17:43:32 +0000

Solar radiant energy can be converted directly to electricity. This is accomplished using photovoltaic (PV) cells. Solar cells have the advantage over other electricity generating equipment of being virtually maintenance free. They have been used in unmanned remote stations including space stations. Although PV sells are expensive for the electricity produce, there are many advantages over fueled engines and fuel powered cells.

Solar cells operate similar to batteries. Each cell produces a +-volt depending on the material of construction. The cells are assembled in modules of usable voltage such as 12 volts. Except for the simplest systems, solar electric systems usually require batteries for storage and an inverter to convert the electricity to alternating current (AC) and the required electrical voltage, amperage and frequency. Direct current (DC) motors and devices may be substituted to eliminate the additional cost of inverter systems.

Another disadvantage of solar electric (PV) is, if the sun isn’t shining or it is overcast, there is little or no electricity generated. Expensive battery storage or another power source is required to operate electric powered devices during this time. A low cost, high capacity method of storing electricity would revolutionize solar PV and the adaptation of other electrical innovations such as electric cars.