A short introduction to Solar Photovoltaic energy generation
Animation explaining how solar panels (dye sensitized) make electricity from the sunlight
by Andrew Michler, 07/27/1
Although net-zero projects have been creating a lot of buzz lately in the field of green building, the Sonnenschiff solar city in Freiburg, Germany is very much net positive. The self-sustaining city accomplishes this feat through smart solar design and lots and lots of photovoltaic panels pointed in the right direction. It seems like a simple strategy -- but designers often incorporate solar installations as an afterthought, or worse, as a label.
Designed by Rolf Disch, the Sonnenschiff (Solar Ship) and Solarsiedlung (Solar Village) emphasize power production from the start by smartly incorporating a series of large rooftop solar arrays that double as sun shades. The buildings are also built to Passivhaus standards, which allows the project to produce four times the amount of energy it consumes!
The project started out as a vision for an entire community — the medium-density project balances size, accessibility, green space, and solar exposure. In all, 52 homes make up a neighborhood anchored to Sonnenschiff, a mixed-use residential and commercial building that emphasizes livability with a minimal footprint. Advanced technologies like phase-change materials and vacuum insulation significantly boost the thermal performance of the building’s wall system.
The homes are designed to the Passivhaus standard and have great access to passive solar heating and daylight. Each home features a very simple shed roof with deep overhangs that allows winter sun in while shading the building from the summer sun. The penthouses on top of the Sonnenschiff have access to rooftop gardens that make full use of the site’s solar resources. The rooftops feature rainwater recycling systems that irrigate the gardens and while supplying the toilets with greywater. The buildings also make use of wood chip boilers for heat in the winter, further decreasing their environmental footprint.
The project’s simple envelope design is brightened by a colorful and dynamic façade. Gardens and paths cross through the development as well, linking the inhabitants. Offices and stores expand the livability of the community while contributing a sense of communal purpose.
let windows generate electricity
By Deborah Netburn
July 24, 201212:50 p.m.
In the future, solar panels will no longer be restricted to the roof. You'll be able to put them on your windows too.
Scientists at UCLA have invented a thin, transparent solar cell that can turn the energy of the sun into electricity, while still allowing visible light to stream through it.
"If you take a piece of glass and compare it to our solar cell, it is difficult to tell the difference," said study leader Yang Yang, a professor at UCLA and director of the Nano Renewable Energy Center at California NanoSystems Institute (CNSI).
The transparent solar cell is made out of a plastic that absorbs invisible infared light while letting most visible light pass through.
Additionally, even the metal that carries the charge out of the cell is transparent. In collaboration with Paul S. Weiss, director of CNSI, Yang was able to install a silver nano wire that served as the conductive metal that is essentially invisible.
The result? A solar panel that is 70% transparent to the human eye.
There is a catch, of course: Transparent solar cells are not nearly as efficient as opaque ones. Yang said that by solving the visibility problem, 30% of a cell's energy-absorbing capability had to be sacrificed.The good news is that the process is very economical, and the material can be fabricated as a liquid that can be sprayed on a surface, much in the same way that car factories spray paint onto automobiles.
Yang said he had already received calls from people ready to buy the transparent solar cells, but he does not expect the product to be ready for commercial use for at least five years.
"I don't have the patience to wait much longer," he said. "I'd like to say in five years we'll have something on a small scale, and then in 10 years it will be popular."
Solar photovoltaics is growing rapidly, albeit from a small base, to a total global capacity of 69 GW at the end of 2011.
The total power output of the world’s PV capacity run over a calendar year is equal to some 80 billion kWh of electricity.
This is sufficient to cover the annual power supply needs of over 20 million households in the world.
Solar photovoltaics is now, after hydro and wind power, the third most important renewable energy source in terms of globally installed capacity.
More than 100 countries use solar PV. Installations may be ground-mounted (and sometimes integrated with farming and grazing) or built into the roof or walls of a building (either building-integrated photovoltaicsor simply rooftop).
Driven by advances in technology and increases in manufacturing scale and sophistication, the cost of photovoltaics has declined steadily since the first solar cells were manufactured and the levelised cost of electricity (LCOE) from PV is competitive with conventional electricity sources in an expanding list of geographic regions.
With current technology, photovoltaics recoup the energy needed to manufacture them in 1 to 4 years.
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