SOU Sustainability Council
Data updated on current utility consumption.
This is a graph that has our last 3 years of usage
as well as the current year comparison to last year.
The Hannon Library Solar Array
In August of 2000 several Northwest power concerns worked together to commission three significant photovoltaic arrays in Ashland. One of these is atop the University's Hannon Library, and is shown in the rooftop photo below. Photovoltaic arrays are solar cells, packaged into panels, which convert solar photo-energy (sunlight) directly into commercial grade electricity.
The Hannon Array consists of 24 solar panels connected together to send its output direct current electricity through a power conversion device (inverter) that feeds directly into the City of Ashland's 3-phase power grid, at 220 volts AC. This system has been faithfully producing its peak 5 kw since installation, except during the months required to relocate the array when the SOU Library system moved into the Hannon Bldg.
The original purpose of this project was to distribute, introduce, showcase, and test larger-scale solar PV technology around the Northwest. Ashland was able to find appropriate locations and commit to the terms of the purchase, which was eventually accomplished by selling the output power back to the utility (PPL) through the grid. The other two arrays in Ashland are atop the roofs of the police station and an Oregon Shakespeare Festival building.
The chart and graph below give the average monthly energy output in kw-hrs of the Hannon Array, from Aug. 2000 to July 2007. The accompanying variations partially reflect some downtime as well as natural solar fluctuations. This array was disconnected during the move to the new Hannon building, which is not reflected in the data. A kilowatt-hour (kw-hr) is the energy used by, say, a 1000 watt lamp in one hour. Or the energy needed to operate a 60 watt light for about 17 hours.
Average Hannon Array Output
|
Month |
Energy (kw-hr) |
|
Jan |
362 ± 89 |
|
Feb |
520 ± 148 |
|
Mar |
745 ± 94 |
|
April |
812 ± 133 |
|
May |
1070 ± 72 |
|
June |
1106 ± 56 |
|
July |
1097 ± 76 |
|
Aug |
981 ± 149 |
|
Sept |
951 ± 36 |
|
Oct |
773 ± 77 |
|
Nov |
353 ± 77 |
|
Dec |
279 ± 28 |
System Cost and Financing …..
[Coming Soon]
The Photovoltaic (PV) Process.
The photovoltaic process is the production of electricity directly from the conversion of the energy carried by light, or solar rays, in this case. Imagine particles of light (they are called photons) from the Sun streaming onto a flat surface consisting of nearly pure silicon wafers. Each photon carries energy, and it can be harvested. Your skin does this, collecting the energy in the form of heat. Silicon wafers can do this, but they can convert some of the energy into electricity instead. PV cells are very simple, with no moving parts, no sound, no emissions, and with nothing to wear out or require maintenance. Solar electric panels consist of silicon wafers connected together and packaged into light, thin units of a few sq. ft., and weatherized to extreme conditions.
Commercial panels generally carry a 25 year warranty, and they come in all sizes and power outputs. The Hannon APC solar panels provide 285 watts output each, and are approximately 4 ft. by 6 ft. The Hannon Array consists of 24 such panels, with a total direct current output of 6450 watts. When this is converted to grid quality 3-phase AC power it has dropped nominally to 5000 watts power. The power ratings of PV systems are given for full or maximum sunlight.
PV Efficiency
The standard single crystal silicon wafers used for PV cells have an efficiency rating of about 12 to14%. This had not changed much since the process was first developed for power 50 years ago, and may not change. Is 12% efficiency a good thing? Well, when the source it converts to electricity is limitless, absolutely clean, free, and well-distributed around the world, 12% is a very nice number! [Compare it to the 1-3 % efficiency of the photosynthesis process which is used to obtain bio-fuels. This is even more meaningful when the very significant overhead needed to convert bio-fuels into usable forms of energy is considered. PV is directly usable, and can fed right into power lines.]
Solar Electric Potential
Perhaps an easy way to gain a sense of the potential of solar electricity is to consider some scale statistics. Try this: if 1% of Arizona was covered with PV panels, they would have a combined power equivalent of 100 of the largest nuclear power plants (which approximately equals the total US nuclear output). To use this data to imagine large-scale solutions, consider 1 acre out of 100 covered with solar electric panels.
Of course, we cannot cover 1% of Arizona with PV panels (can we?). But there are vast, unused solar-rich areas available in the US. There are millions of rooftops. There are millions of acres of ranch and farm land quite useful for combined grazing and solar production.
The Cost of Solar
The cost comparisons made between solar electricity and other means of producing it are usually superficial and inadequate. The high upfront cost of solar arrays is generally calculated against the existing, developed costs of fossil fuels and nuclear thermal plants. There are four intrinsic flaws in this. First, a true comparison can only be made if the 100 years of development costs and mining subsidies of fossil fuels and 50 years of nuclear development are included. Another omission made is the costs of health care and waste disposal of the conventional fuels systems. These are very high whereas solar has none at all. A third omission is the rising costs and scarcity of conventional fuels. A fourth omission is the cost of geo-political forces so often connected to unbelievably expensive wars and military positioning, while solar electricity invites no war.
The Future of SOU Solar Energy
Southern Oregon University is currently examining possibilities for incrementing its solar collection in significant units. Undoubtedly, the Hannon Library installation would be augmented first –and there appears to be quite a large potential for doing this. One can imagine similar systems atop other SOU buildings.
Now, a very important point must be made. One does not use relatively expensive PV systems to produce heat, which is a 'lower grade' form of energy. Instead, where heat is desired, it is economically and physically advantageous to extract solar heat directly. SOU is simultaneously working to determine how it might best use direct solar gain systems to offset its conventional heating (and cooling) needs. In the very long range, a few SOU planners envision a completely solar university!
Prof. Tom Marvin, Physics Dept., Emeritus
marvin@sou.edu
