Solar panels have become something of a catchphrase in the green movement
this decade. They trumpet the recent advances, both scientific breakthroughs
and manufacturing triumphs. They point at the bright, glittering future
of solar power, but who are they, and what does what they say mean for
you as a consumer? To understand what the culture around solar
panels today stands for, what the people involved in the
conversation over the future of solar power are talking about, and where
the possibilities depart from reality, it’s helpful to know a
little bit about the history of solar power.
Solar power is a form of renewable energy, and that itself is a big
part of the green movement’s agenda. The green movement would
be the “they” referred to in the preceding paragraph. Going
green means living within a balance that must exist between you and
your environment, a balance that humanity has too often let fall to
the wayside in recent times. It means to minimize your impact on this
earth, and offset or even eliminate your use of nonrenewable resources.
These goals may seem lofty and unrealistic. Backers of the green movement
would counter that the unrealistic position to hold is expecting our
species to be able to go on consuming as we currently do indefinitely
with no repercussions.
The Challenge:
The primary difficulty with solar power and indeed with its cousin
wind power has been one of efficiency. There is more than enough energy
hitting the earth in the form of solar radiation to meet power needs
of our species. Estimates indicate that there is four times as much
wind energy available for our use as the species uses every year. Solar
power is even more dramatic, the sun showers the planet with more energy
every day than we use in a year. So the difficulty has never been the
availability of sun and wind, they are readily available.
The difficulty with solar panels has always been the efficiency of
power transfer. You see, it is one thing to say that the sun showers
us with several terawatts of power every day, and another thing to put
that power to work for us. The majority of modern human power use is
electric. This means we need to convert the radiant solar energy to
usable electric current. This presents a technological hurdle for us,
because for most of our history, our electric conversion has been turbine
based. Solar panels however, don’t utilize a turbine at all. Instead
sunlight striking silicon crystals creates electric potential. If those
crystals are backed by an array, this potential can be harnessed to
create a current.
History
This transfer of sunlight to electric potential has always been an
inefficient one. The scientist who first harnessed this effect, which
he dubbed photovoltaic, was only able to elicit a 1% return on the energy
he put into his solar cell. He created his cell by coating a semiconductor
(selenium) with gold. Through a century of refinement, we have painstakingly
reached solar panels that can produce a return of more than 30% of the
power they receive.
One of the reasons behind this is that any given semiconductor only
responds to a certain wavelength of light. This means a single-substance
solar panel will only ever be able to convert a portion of the sunlight
it receives to electricity; no matter how well it converts that portion.
That, in essence is where we stand today.
Manufacturing advances in the past decade have finally lowered the
cost of solar panels to the point that a 30% efficiency panel can pay
for the cost of production and installation over the first six years
of its life. This means that solar power is finally economically viable,
since panels are designed to run for at least 10 years before they start
to break down.
Where do we stand now?
Currently, solar panels are a viable alternative energy source, both
environmentally and economically. Grid-tie
systems allow you to put up solar panels, and feed excess
power back into the power grid. This isn’t an act of charity on
your part. Utilities are required to pay you for the power you put into
the system. Another advantage of staying connected to the grid is that
you won’t have to have an elaborate in-home battery system to
store energy for nights and cloudy days. You can draw on grid power
during those times, and the power will be subtracted from the amount
you put into the system.
There are also off-grid and mobile solar power options. If a home is
equipped with a battery charging
system and sufficient solar panels, it can cut ties completely with
the power grid and become self sufficient. Home
wind turbines can make a useful augmentation to solar panels
in an off grid system, since cloudy days accompany storm fronts, which
create wind. This ensures that one of your power sources is always functioning
at optimal capacity, keeping your power on. Going off-grid is an especially
appealing notion for RV
owners, because it greatly enhances the range and camping ability of
their RVs.
Local and federal rebate incentives make solar power more affordable
than ever today. The California
Solar Initiative has been a role model for other states
to follow in setting up incentive programs to promote solar power. Other
states with high solar potential and rebates or incentives include Arizona
and Florida. For more information on the viability of solar power in
your area, as well as information on local incentive programs, please
visit our free solar evaluation
page.
What does the future hold?
The future of solar power revolves around
thin film technology. Thin films have been used for centuries; one
of the first applications of them was the use of a thin layer of silver
behind glass to create a mirror. Today the most common use of thin films
is in computing, where they can be used to create extremely densely
packed circuits.
For solar panels however, thin films allow manufacturers to use much
less silicon than a crystal array requires to create a solar panel.
The resulting panel is much less efficient than comparable crystalline
silicon solar cells (which are the
traditional style); but it is much less expensive as well. It also has
applications that the traditional solar cell cannot match. Imagine having
the exterior glass of an office tower tinted, not with a mere darkening
agent, but with a microfilm layer of solar panels that turned the entire
exterior of the building into a clean electricity generating device.
The glass would still be reflective from the outside and translucent
from inside, it would just generate electricity as well. The same concept
could be used for residential building exteriors, and even vehicle paints.
Another interesting application of the thin film technique is a multi-junction
photovoltaic cell. This version of a solar panel utilizes multiple thin
films of different substances to harness a much wider range of the sun’s
light to create electricity. In fact, a recent test cited a conversion
rate of over 60% utilizing this technology. Thus thin film could both
open up new markets in solar power and increase the efficiency of solar
panels significantly. To learn more please visit our Solar
Learning Center.