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Interesting Technology Updates -Click on a title below

  • - A radical idea to get a high-renewable electric grid

    This is an interesting approach to optaining very high penetration of renewables such as photovoltaics and wind.  At present most large installations operate under Power Purchase Agreements (PPA) wherein the economics are based on a sell all output at predetermined prices. This contrasts with standalone systems wherein the system size Read More
  • - Breakthrough Batteries Powering the Era of Clean Electrification

    - Breakthrough Batteries Powering the Era of Clean Electrification Battery Storage Costs Drop Dramatically, Making Way to a New Era. A recent Rocky Mountain Institute (RMI) report continues to confirm that clean electrification through batteries is advancing at impressive rates. Very interesting report: Breakthrough Batteries- Powering the Era of Clean Electrification Read More
  • - Interesting Technology

    An assortment of links to interesting information   Semiconductor Nanowires Could Double the Efficiency of Silicon Solar Cells A p/n semiconductor junction is not the only way of converting sunshine into useful electrical energy.  Light consists of a flow of photons of various energy levels (colors).  See this article-Solar Cells.  Nanowires Read More
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Glossary of Terms

 

Glossary of Terms

 

Alternating Current:  Electric Current in which the direction of flow is reversed at frequent intervals, 60 cycles per second.  The type of electrical supplied by utility companies.

 

Ampere:  A measure of electric current; the flow of electrons.

 

Amorphous:  The condition of a solid in which the atoms are not arranged in an orderly pattern.

 

Atoms: The smallest particle of an element that can exist either alone or in combination.

 

Battery:  Rechargeable electric storage unit that operates on the principle of changing electrical energy into chemical energy by means of a reversible chemical reaction.

 

Break-even:  The cost of a photovoltaic system at which the cost of the electricity it produces exactly equals the price of electricity from a competing source.

 

Concentrators:  A photovoltaic module that includes an optical component such as a lens or focusing mirror to direct incident sunlight onto a solar cell or panel.

 

Direct current:  Electric current that always flows in the same direction: positive to negative. Batteries and photovoltaic cells are all DC devices.

 

Efficiency:  The percentage of available sunlight converted to electricity by a module or cell.

 

Electric current:  The volume of electricity propelled by the voltage; a flow of electrons.

 

Electrons:  An elementary particle consisting of a charge of negative electricity.

 

Greenwashing:  A policy of utilities that use disproportionately high ratios of renewable versus fossil fuel images and language, while at the same time helping to block renewable energy policies.

 

Energy:  See Watt-Hour

Grid-connected:  A house or device that receives power from a utility company.

 

Inverter:  This appliance converts independent DC-power into AC power, or regular household current.

 

Load:  The lights or appliances run by your electrical system. The amount of electrical power being consumed at any given moment.

 

Kilowatt:  A thousand watts

 

Megawatt:  One million watts, 1,000 kilowatts

 

Off-grid:  See stand-alone.

 

Peak watts:  The amount of power a photovoltaic device will produce at noon on a clear day with sun approximately overhead when the cell is faced directly toward the sun.

 

Photovoltaic:  Capable of producing a voltage when exposed to radiant energy, especially light.

 

Photovoltaic array:  A group of solar electric panels connected together.

 

Photovoltaic cell:  The basic building block in photovoltaic systems. Sometimes called “Solar Cells.”

 

Photovoltaic effect:  The conversion of sunlight absorbed by a solar cell directly into electricity.

 

Photovoltaic module:  A solar electric panel

 

Power:  See Watt

Semiconductor:  Any material that has limited capacity for conducting an electric curre.

 

Stand-alone:  An isolated photovoltaic system not connected to a utility electric grid.

Utility:  An electrical supplier serving electric power to customers (such as APS or SRP in Arizona)

 

Voltage:  A measure of the force or “push” given the electrons in an electric circuit, a measure of electric potential.

 

Voltage regulator:  An electrical device used to keep voltage at predetermined levels.

Watt:  A unit of Power, one watt is the rate at which work is done when one ampere (A) of current flows through an electrical potential difference of one volt (V). Items like light bulbs are rated in watts. Power is the rate at which energy is generated or consumed and hence is measured in units (e.g. watts) that represent energy per unit time.

Watt-hours:  A unit of Energy, defined as power over a time interval.  One watt of power for one hour is one Watt-Hour.  Often used with the prefixes Mega and Kilo for 1-million and 1-thousand.

How Not to Treat Batteries - Maintaining Battery Electrolyte Levels

battery

 

During normal operation, water is lost from a flooded lead-acid battery as a result of evaporation and electrolysis into hydrogen and oxygen, which escape into the atmosphere. One Faraday of overcharge will result in a loss of about 18 g of water per cell. Evaporation is a relatively small part of the loss except in very hot, dry climates. With a fully charged battery, electrolysis consumes water at a rate of 0.336 cm^3 per cell per ampere-hour of overcharge. A 5000-Ah battery overcharged 10% can thus lose 16.8 cm^3, or about 0.3%, of its water each cycle. It is important that the electrolyte be maintained at the proper level in the battery. The electrolyte not only serves as the ionic conductor, but also is a major factor in the transfer of heat from the plates. If the electrolyte is below the plate level, then an area of the plate is not electrochemically active; this causes a concentration of heat in other parts of the battery and “Sulfation” of the dry portion of the plates which may not be reversible. Periodic checking of water consumption can also serve as a rough check on charging efficiency and may warn when adjustment of the charger is required.

 

Since replacing water can be a major significant maintenance cost, water loss can be effectively reduced by controlling the amount of overcharge and by using hydrogen and oxygen recombining devices in each cell where possible. Note that these devices can overheat and cause battery damage if the battery is charged at a high rate. Read specifications carefully, the expensive “Caps” may need to be replaced before the end of battery life. Addition of water is best accomplished after recharge and before an equalization charge. Water is added only at the end of the charge to reach the high level line. Electrolyte expands as the battery is charged significantly increasing in volume. Therefore overfilling must be avoided because the resultant overflow of acid electrolyte will cause tray corrosion, ground paths, and loss of cell capacity. Gassing during overcharge will stir the water into the acid uniformly. In freezing weather, water should not be added without mixing as it may freeze before gassing occurs. Only distilled water should be added to batteries. Although demineralized or tap water may be approved for some batteries, the low cost of distilled water makes it the best choice. Automatic watering devices and reliability testing can reduce maintenance labor costs further. Although distilled water is no longer specified by most battery manufacturers, good quality water, low in minerals and heavy metal ions such as iron, will help prolong battery life.

How Not to- Battery Connections

meltdownPhoto shows the situation after a battery discharge 
test at 300 amps was terminated on a 1530 AH IBE battery string when one post melted.

During the discharge test all cell voltages are logged. The sum of the cell voltages was 2.73 
volts lower than the 48-volt string voltage. This is an average of 118 mv per inter-cell 
connection, 5-10 mv is the normal range in a properly connected battery bank.

Lesson learned: Bolts are not for current carrying. 
Bolts are to hold lugs, etc. in tight contact with electrical terminals.

 

 

How Not to Install PV - Orientation & Shadowing

Orientation and shading issues

 

These are photovoltaic powered restrooms. The view is to the Northeast at about noon in February. The photovoltaic module provides power for operating a vent fan for a composting toilet. Unfortunately, the photovoltaic module on the right restroom is facing West and as a result gets very little sunshine. In addition, the shadow cast by the vent pipe is shading the module and further reducing the output.

About

  • Welcome to the Arizona Solar Center

     This is your source for solar and renewable energy information in Arizona. Explore various technologies, including photovoltaics, solar water heating, solar architecture, solar cooking and wind power. Keep up to date on the latest industry news. Follow relevant lectures, expositions and tours. Whether you are a homeowner looking to become more energy efficient, a student learning the science behind the technologies or an industry professional, you will find valuable information here.
  • About The Arizona Solar Center

    About The Arizona Solar Center Arizona Solar Center Mission- The mission of the Arizona Solar Center is to enhance the utilization of renewable energy, educate Arizona's residents on solar technology developments, support commerce and industry in the development of solar and other sustainable technologies and coordinate these efforts throughout the state of Arizona. About the Arizona Solar Center- The Arizona Solar Center (AzSC) provides a broad-based understanding of solar energy, especially as it pertains to Arizona. Registered Read More
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