Until recently, the main obstacle to widespread residential solar installations on a large scale has been the cost of the systems. Overcoming the challenges of high capital investments, coupled with long payback periods, has been helped along by government subsidies provide to manufacturer , developers, investors, and end-users, for installing solar power photovoltaic systems.
However, in the last few years, the convergence of several dynamics has made PV systems economically feasible as viable electricity-generation and water heating solutions.
Higher electricity cost of conventional power plants
Worldwide concern with global warming and other environmental issues
Political uncertainty in the oil-producing countries
More reliable and efficient photovoltaic systems
Easier assimilation of PV systems with traditional plants
Advancements in these areas have driven down the cost of solar panels by 50 percent since 2008. In 2010, installed prices dropped 20 percent.
Although rooftop installations have been slow to take hold in the civilian residential communities of the U.S., the military leads the charge to make solar-power plants on the rooftop of military housing a reality for many of its families.
Island Palm Communities
Several years ago, motivated to reduce the military's reliance on fossil fuel, the U.S. Department of Defense (DOD) collaborated with a private developer to build seven solar-powered residential communities on Oahu -- Hawaii's largest island. Annually, the island receives an average 271 days of sunshine.
Originally called the Army Hawaii Family Housing (AHFH), groundbreaking took place for the development inJuly 2005. The master-planned community covers 1,702 acres, and will ultimately result in 7,894 residences -- 5,388 new construction and 2,506 renovated homes. The project covers seven development sites on the island.
The system requires connection of the homes to grid and from solar modules. The solar panel systems install on the roof of the garage units. The modules fit inside the standing seam metal roof panels and laminate to the roof sections.
The PV technology consists of triple-junction panels covered with damage-resistant plastic panels to replace glass. Instead of allocating power to individual homes, the systems tie into the grid. The plant operators distribute the solar-generated electricity to meet the electrical needs of the entire community. The first families started moving into the units in June 2006. Late last year, officials renamed the developments the “Island Palm Communities.”
The cost of the project, which has a projected completion date in 2015, is $2.3 billion (USD). The solar powered system connects to a smart meter and routed to a micro-grid, which powers homes, maintenance offices, and 11 community centers. The total power generation capacity -- six megawatts, should provide up to 30 percent of the community's power needs.
In addition, the island depends on ship to deliver fuel, which makes its residential utility cost more than twice as high than the U.S. mainland average. In 2010, residential costs exceed $0.25 per kilowatt-hour. At the start of the project, the AHFH burned oil for 93 percent of its electrical needs. The development expects to save up to 18,000 barrels of oil annually.
SolarStrong
The U.S. Department of Defense (DOD) has formed a partnership with SolarCity, which will double the number of photovoltaic installations in the U.S. Over the next five years, the initiative involves the installation of PV systems on 160,000 rooftops of military housing units, and other buildings, located across 33 states.
Ultimately, the SolarStrong will cost about $1 billion and generates 371 megawatts of residential solar power capacity. Department of Energy Secretary Steven Chu labels SolarStrong “the largest domestic residential rooftop solar project in history.”
In early September, SolarCity received a “conditional” loan guarantee, from the U.S. Department of Energy, for 80 percent of $344 million loan, just days after the well-publicized solar panel manufacturer Solyndra filed for bankruptcy protection.
SolarCity's founder and CEO Lyndon Rive tout the “risk-free” attribute of the project for banks as well as the government. SolarCity funds the solar modules with it own money. The company receives reimbursement after completing the installation. According to Rive, the loan guarantee enables the company to spread resources across the U.S. creating jobs and economic opportunities, especially to military veterans and communities.
However, the Congressional investigation into the Solyndra bankruptcy heaped additional paperwork requirements on the firm. Subsequently, SolarCity was unable to meet the extra documentation request and gain final approval before the program expired on September 30, 2011.
SolarCity has a proven “solar services provider” business model, which means it designs, owns, operates, installs, and maintains the installations. The company claims to be the first “single source” solar firm to provide one-stop service for residential, commercial, and governmental customers. It sells the solar-generated electricity to the customer. Usually, customers receive electricity at a lower price per kilowatt-hour than local retail electricity rates.
Early this year, the U.S. Air Force base signed an agreement with SolarCity to install solar panels on 600 rooftops in the Hickam Communities located in Honolulu, Hawaii. The modules will generate four megawatts and provide 5.6 million kilowatt-hours of electricity - enough to power 2000 homes. SolarCity has a 20-year purchase power agreement.
Five years ago, SolarCity had just two employees. The company now employs over 600 workers across 24 operations centers in 11 states and Washington, D.C.
Largest Solar-Thermal Project in U.S.
In the United States, about 18 percent of energy usage in residential buildings goes towards heating water. Solar-thermal water heating systems provide as much as 80 percent of a home's needs. It eliminates fuel costs and reduces operation and maintenance expenses typically associated with convention water heating systems.
A solar-thermal project at Camp LeJune has the distinction of being the largest solar-thermal powered- residential development in the continental United States. It involves the installation of 2,200 solar hot water systems. Phase one of the project consists of the installation of 900 systems.
Fifty percent of the solar thermal systems go on the rooftop of newly constructed homes. Existing housing units will receive the other half. Phase one will generate 2.5 million kilowatt-hours annually. Each system, which requires one 10-by-4 foot solar module installed on the rooftop, has the capability of producing 45 to 50 gallons of hot water per day.
Along with privatizing a substantial portion of its housing, the United States Department of Defense is aggressively moving towards its goal of generating 25 percent of it energy usage from renewable energy sources by 2025.
From the look of things, solar photovoltaic systems will play a large role helping to meet that objective. The DOD partnership with private developers will create some of the largest solar-powered communities in the world.