4.5MW PV Generation Plant
owned and operated by
Tucson Electric Power
5KW  telecommunications system
of the Turkish National Oil Company
using SPL PV modules
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Power Analysts note that a third of the world's surface is covered by deserts with high levels of insolation and large, open spaces. If 4% of this surface were covered by solar photovoltaic systems the annual energy production would be equal to the world's energy consumption.

Principals of Solar Power Limited have worked on power generation and related industrial and economic development issues in desert areas of Oman, Yemen, Saudi Arabia, Jordan, Libya, Kyrgyzstan and Kazakhstan as well as in desert areas of the U.S., notably Nevada. In these areas, land is generally available for the installation of very large-scale solar electric power systems ("VLS_PV"), i.e. gigawatt-scale, in increments depending on local permitting and logistical requirements are met.

Solar Power Technology

Solar Electric Power

Solar energy is the energy force that sustains life on the earth for all plants, animals, and people. The earth receives this radiant energy from the sun in the form of electromagnetic waves, which the sun continually emits into space. The earth serves as a huge solar energy collector receiving large quantities of this energy which manifests itself in various forms, such as direct sunlight used through photosynthesis by plants, heated air masses causing wind, and evaporation of the oceans resulting as rain which can form rivers. This solar energy can be tapped directly as solar energy (thermal and photovoltaics), and indirectly as wind, biomass, and hydroelectric energy.

(Solar energy is a renewable resource that is inexhaustible and is locally available. It is a clean energy source that allows for local energy independence. The sun's power flow reaching the earth is typically about 1,000 Watts per square meter (W/m2), although availability varies with location and time of year. Capturing solar energy typically requires equipment with a high initial capital cost relative to conventional fossil-fueled systems, however, since there is no need for water, deliveries of fuel or ongoing maintenance, the upfront cost is the only cost during the 20-30 year lifetime of the system.

Solar Electric Power and Solar Thermal Power

Electricity can be produced from sunlight through direct heating of fluids to generate steam for large scale centralized electrical generation - solar thermal (or concentrating solar thermal) electrical generation Electricity can also be produced from sunlight through a process called "photovoltaics"("PV"). "Photo" refers to light and "voltaic" to voltage.

PV Terminology

(Solar Cell: The solar or "PV" cell is the component responsible for converting light to electricity. Some materials (e.g., silicon is the most common) produce a photovoltaic effect, whereby sunlight frees electrons striking the silicon material. The freed electrons cannot return to the positively charged sites ("holes") without flowing through an external circuit, thus generating current. Solar cells are designed to absorb as much light as possible and are interconnected in series and parallel electrical connections to produce desired voltages and currents.

PV Module: A PV module is composed of interconnected solar cells that are encapsulated between a glass cover and weatherproof backing. The modules are typically framed in aluminum frames suitable for mounting.

PV Array: PV modules are connected in series and parallel to form an array of modules, thus increasing total available power output to the needed voltage and current for a particular application.

Peak Watt (Wp): PV modules are rated by their total power output, or peak Watts. A peak Watt is the amount of power output a PV module produces at Standard Test Conditions (STC) of a module operating temperature of 25°C in full noontime sunshine (irradiance) of 1,000 Watts per square meter.

A thin silicon cell, four inches across, can produce more than one watt of direct current (DC) electrical power in full sun. Individual solar cells can be connected in series and parallel to obtain desired voltages and currents. These groups of cells are packaged into standard modules that protect the cells from the environment while providing useful voltages and currents. PV modules are extremely reliable since they are solid state and there are no moving parts. Silicon PV cells manufactured today can provide over thirty years of useful service life. Solar Power Limited provided warranties of up to 25 years on their PV product (at 80 percent of original power rating). A 50 Wp PV module in direct sunlight operating at 25°C will generate 50 Watts per hour (referred to as a Watt-hour­[Wh]).

(PV systems are made up of a variety of components, which aside from the modules, may include power conditioning units, batteries, trackers, and inverters, depending on the application. PV systems are modular by nature, thus systems can be expanded as more power is needed and components are easily repaired or replaced.

Photovoltaic Costs

New PV modules generally retail for about $1 per peak watt, depending on quantities purchased. To estimate the total cost of a solar electric 'photovoltaic' power system, one generally doubles this cost to include the batteries, inverters, and other components, known as the "Balance of System" thus a budgeted cost for a PV system in the US would be about $3 per peak watt. A typical house with a 4KWp system would be budgeted at $24K while a 10MW utility-scale solar power system would be budgeted at$50--60M.

The exact cost and installation time of a solar electric power system is typically determined by a 'Sizing Process' whereby one determines how much power is required for a specific application and when needed.

Storage of Solar Electric Power

Overview of Selected Electricity Storage Technologies
Storage Technology Advantages Deployment
Likelihood of Use in  a Solar Power System
Pumped Storage
High Capacity, Low Cost
Special Site Requirements
Peaking Gas Turbine Power Plant
High Capacity, Low Cost
Special Site Requirement, Needs Gas Fuel
Flow Batteries:
High Capacity, Independent Power and Energy Ratings
Low Energy Density
Very High Energy Density
Electric Charging is Difficult
Sodium Sulfur
High Power & Energy Density; High Efficiency
Production Cost, Safety
High Power & Energy Density; High Efficiency
High Production Cost, Requires Special Charging Circuit
Low Capital Cost
Limited Cycle Life with Deep Discharge
High Power
Low Energy Density, Site Requirements


For a detailed discussion of electricity storage technologies, including the promising Tesla Powerwall for home and utility use, consult the website of the Electricity Storage Association: www.electricitystorage.org