|Map courtesy of National Renewable Energy Laboratory.
One predicts performance of planned photovoltaic
(PV) systems with the help of the above map. PV systems make electricity. Say "solar panel" and
most people think of a PV system on a roof.
This map also works with
"solar thermal" systems used to make solar domestic hot water (SDHW) and space heat. Solar thermal systems
use "collectors" to harvest energy. We speak here of "low temperature" (max 180 - 190 degree
The map does not apply to "concentrating solar power" (CSP) systems. CSP
systems typically (but not always) utilize parabolic mirrors and high temperature (300 - 700 degrees F) liquids to make
steam to turn turbines.
CSP does not work well in Kentucky and is more
suited to the American Southwest. It requires more sustained intense sun. The ever-diminishing cost
of solar PV is presently (Fall, 2011) bringing a halt to construction of most CSP sytstems. PV has become cheaper
Also, don't forget about passive solar, especially if you are building a new home or contemplating a major remodel.
Isn't Kentucky too cloudy for solar?
LG&E and KU have in the past
distributed materials in essence saying that solar doesn't work well in Kentucky and making their point with a concentrating
solar resource map. This mis-information may have led to a misperception that Kentucky is "too cloudy
Kentucky is not too cloudy
for solar. It's just fine for large scale and small scale PV and low temperature (< 200° F)
Duke Energy operates
in Kentucky. Duke and other large utilities in places like Minnesota and Wisconsin have supported and encouraged their
customers' use of solar energy.
Xcel Energy, a large multistate
electrical utility based in Minnesota, has voluntarily set a goal of 30% renewables by 2020 in Minnesota, with solar
playing a large part in that mix.
Xcel is also a major electrical utility in Colorado. Colorado has
set a Renewable Portfolio Standard (RPS) of 30% renewables by 2020 (after previously setting 10% by 2015 and 20% by 2020 RPS
standards). Xcel customers in Colorado presently pay 0.2 cents / kWh to fund the RPS programs in Colorado.
That's only a 2% surcharge on custoimers' bills to achieve a 30% renewable energy portfolio by 2020!
In large part, Xcel has offered rebates and incentives
to customers who install small(technically "distributed generation") PV systems. So everybody pays (and benefits
by new capacity) a little. Purchasers receive some assistance with their initial up-front costs.
The Germans installed 8 gigawatts of distributed generation solar PV in 2012. Kentucky
can do the same.
Present Solar Technologies are Mature
Many are Manufactured by Well-Known Companies
and Sharp make PV panels. Rheem, Velux, Stiebel-Eltron and AO Smith make solar thermal systems and components.
Other less known but top quality names include AET, Solar Skies, FirstSolar and Caleffi.
PV and thermal systems using quality components are reliable and durable.
A PV (photovoltaic) system makes electrons
from photons and converts about 9 - 16% of the sun's energy into useful AC or DC electricity.
The wide range is due to possible variants in design and materials. 9% or so would be a thin-film PV
system. 16% or so applies to well-designed systems using regular silicon PV panels. These numbers
take into account system inefficiency losses from dust, heat, wiring, etc.
The conversion efficiency of PV
panels increases all the time. The costs are also dropping.
A January, 2011 analysis from the Argonne National Laboratory determined a production cost of 9.7 cents, 9.3 cents and 6.9 cents per kWh for
a 20 MW utility-scale PV system in Chicago, Boston and Sacramento, respectively. These numbers arise after the
effect of assumed 30% federal and 8% state tax subsidies. They are based on a 30-yr projected life.
we would be looking at 15 cents or so per kWh without the effect of subsidies.
basics of solar photovoltaics compliments of Home Power magazine.
Home Power is an excellent publication for those interested in solar energy.
broken link here. Thanks!)
A "solar thermal" system (hot water) converts
30% or so of the sun's daily energy into useful energy for space or water heating purposes.
The cost of solar thermal technology will likely not drop, nor do we see great efficiency improvements coming ahead.
Solar thermal already works really well and is cost-competitive with fossil fuels.
If you have an electric hot
water heater, a solar thermal system pays back fairly quickly (7 - 8 years with incentives, 10 to 11 without).
The payback on a gas hot water heater will take a bit longer.
Once paid back, you get hot water for 20 years or so at
very low cost!
Passive solar construction is a tremendous resource, also. The
northern Europeans have led the way in this area. Learn more at the Passive House Alliance - United States.
Louisville architect Gary Watrous designs passive houses. So does Ginger Watkins, CPHC, out of Lexington.
Here's an example of a passive house built in Berea by Habitat for Humanity and designed by Ginger Watkins.
Solar energy may not be the "do all and end
all" of our energy needs. However, it meets many needs very, very well. Systems can be designed
to perform during power failures, solar thermal and passive solar especially easily.
What solar can do, it should do.