Solar Electricity
pv_cells_on_roof.jpgphotovoltaic_pic.gif
a. Goal
To use solar energy to provide electrical power to the village. Because solar energy is a renewable resource, this could potentially allow the village to be self-sustaining and reduce its negative effects on the environment. The village is also intended to highlight technology, and solar power does this in two ways. First, it highlights the advances being made in solar power today. Second, it provides the power to run other technological appliances.
b. Benefits of the specific technology to the community
  • Solar power provides a conversion directly to electricity, which allows for the use of mainstream appliances.
  • Solar cells and photovoltaics are popular right now, and many people will want to see them and learn about how they work.
  • Compared to many other power-producing methods, solar power is fairly efficient.
  • Solar cells tend to last for decades (even if more powerful versions come along), so they are unlikely to break and become useless.
c. Local Availability
d. Regulatory or Industry Standards for Implementation of Technology
In the US, most companies producing photovoltaics require that the cells be installed by their workers. However, in some cases this does not apply.
i. International Standards
ii. Local code enforcement

e. Description of Product (s) or Process (es) and its Functionality (Succinct but Detailed Enough)
f. Design parameters
i. Sizing
ii. Materials needed for Fabrication/ Construction of Technology
1. Various Options

iii.Other resources Needed for Implementation/ Use
  1. Construction Equipment
  2. Labor: Some of the installation would be mechanical (placing and securing the panels), and much would be wiring the system together. This would most likely require some form of technical advice from someone who works with electrical systems. There should be minimal labor after installation.
  3. Technical Consultation: Consultation will be necessary for proper installation. If a PSU student participates in one of the hands-on solar activities here they could be of use, as would be an electrician.
  4. Transportation Requirements: Solar cells and batteries are large and heavy. If there places nearby that sell such equipment at reasonable prices, this would be preferable to shipping overseas.
  5. Energy Requirements: On a typical day we can expect 6 peak hours of sunlight with cells at one angle. During the rainy season it is possible that we will get only 2 hours! We can manipulate some of this using multi-angled arrays, but we must know how much sun we will get during rainy season. If we were to use batteries, they would most likely be capable of running lights and other small appliances for about 24hours without solar intake, but they would not be able to run something like a clothes dryer or a stove.
  6. Space: The amount of space needed depends on the type of solar cell. In general, we should hope to have south facing, sloping rooflines to accommodate the cells as much as possible.
  7. Spare Parts
  8. Time for Construction
iv. Technical Skills Required to Operate or Utilize
  1. Training Requirements: A basic knowledge of electrical engineering is needed for the installation and basic maintenance. This would include knowing polarities, how to connect to batteries or to the grid, etc. A basic practical knowledge is essential here rather than an advanced theoretical one.
g. Associated Costs
According to Andy Lau, silicon solar cells will cost approximately $5/watt peak. The advantage to more expensive cells is that they are smaller for the same output, so we could get more out of the space. In general, we must know how much energy we intend to use to estimate cost. We will also need to purchase converters, which vary in price. Converters that intertie to the grid will be more expensive than standalone converters because they must regulate the frequency and current more carefully, but this provides security. Batteries are also necessary and have an added cost. Depending on the professionals at the nearby university or site, we may need to hire an electrician to install the system.
i. Capital
ii. Operations & Maintenance

In general, the cells themselves should not need maintenance for many, many years. The batteries would need replacing before then, and some electrical work would need to be done. The members of the site would need to know how to perform simple tasks (dealing with breakers? simple wiring?) but a local electrical expert would be best for any of the other problems. They do not need to be experts in solar electricity- just electricity.




OTHER INFO:
  • Monocrystalline Silicon 15-18% eff, expensive compared to poly
  • Polycrystalline Silicon 12-14% eff, series of cells, inexpensive
  • String Ribbon/ Thin-Layer Silicon Panels- similar to polycrystalline, slowly draw thin strip of silicon from molten form, then assembled together, eliminates need for sawing into wafers
  • Amorphous/Thin-film Silicon- 5-6% eff, can be applied directly to materials since crystal structure is not an issue, less fragile than crystalline. quick/easy to manufacture. can be flexible
  • Group III-V- 25% eff, GaAs ex, high cost but high efficiencies. a LOT of research for space and new apps
  • Building Integrated PV Systems- semi-translucent layer amorphous Si into glass for window panes, or shingle sized panels for roofing. low efficiency (amorphous Si) but produces more than a regular window or roof
  • Concentrators- added optical lenses to increase the intensity of light hitting panels. can reduce space needs. depend on DIRECT light, while other PVs require direct or diffuse. more difficult to install.
  • High Efficiency Multi-junction- each layer receptive to different frequencies of light. GaAs and amorphous Si commonly used. typically 3 or 4 junctions

http://www.mtpc.org/cleanenergy/solar_info/types.htm

From Andy Lau:
in general, panels will cost about $5/watt peak. Everything in production (realistically) is Si, and the type doesn't matter. Higher quality will just mean less space taken up. We can hope for about 6 hours of peak per day, but in the rainy season (depending on how rainy) we may get only 2 hours.

CAN WE ACCESS THE GRID? converters which connect to the grid will be more expensive in order to regulate current/frequency etc. But this is security.

Batteries- for one of the solar D houses (1000 square feet roughly), requires 4 120lb batteries which would run things like lights for 24hours, but not appliances like a stove or clothes dryer

AIR CONDITIONING?

solar cookers- some places have taboos about cooking in public (don't want others to see what they cook)
these are very very slow

batch solar water heater (for washing). only need about 160ish degrees for purification and pasteurization

installation- requires electrical knowledge but not specific.

batteries usually die before the PV cells do.


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