HW#6
Due, Friday,
February 15, 2002
Recommended Answers in Red
1. Solar PV: “Is the glass half empty or half full?”
Case A: One might spend about $10,000 on a solar PV system rated at about 1 kw-electric and find that it would produce not much more electrical power on average than that required to operate a 100 watt light bulb. This doesn’t appear to be a case of money well spent.
The result
is about right for a solar PV system installed in Seattle (with battery storage
backup).
1000 watts
(rated peak) x 0.12 (average capacity for the year) = 120 watts average
electrical power produced. The $10,000 solar
PV system would do little more than continuously run a 100 watt light bulb.
Case B: On the other hand, a solar PV system of $10,000 and 1 kw-electric might, over its lifetime, be able to generate electricity at a cost almost as low as 10 ˘/kwh. This might be a prudent investment.
We cannot
get down to the 10˘/kwh number unless we reduce the system cost to $6500 and set
up the system in a very sunny place, such as the deserts of Arizona or
California. We might be able to reach
the $6500 cost if we drop the battery backup (and just install a grid-tied
system), and we shop around for the best price on panels and inverter and avoid
system frills.
Then:
$6500 x
100˘/$ =
9.9˘/kwh
1 kw x
0.25 (capacity) x 8760hrs/yr x 30yrs
Your task: Explain (confirm) the numbers for cases A and B, and the assumptions and conditions used. Are both cases right? Are both cases wrong? Or is one case right and the other wrong? Explain the apparent paradox presented by these two cases.
2. Solar energy offers environmental benefits compared to other methods of generating electricity. However, all electricity generating technologies, including solar, have environmental impacts. Please do a bit of looking into the environmental impacts of solar thermal electric and solar PV. Then write up your findings in about 2 or 3 pages of double spaced type.