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We speak of solar systems in terms of their
rated peak power output. For example, a
system of five 200-watt panels has a rated
peak output of 1,000 watts. Using the rated
power, we estimate the total electricity
production of the system based on the sun and
shade conditions for your location. (Sun
hours per day x Rated power x System
efficiency x 365 = kWh per year)
In central Massachusetts, in unshaded
conditions, a 1,000-watt solar electric
system with the panels facing polar south and
mounted at 45 degrees will generate about
1,200 kWh in a typical year and offset 0.7
tons of carbon dioxide per year. The panels
will cover 65 to 85 square feet and cost
around $8,000 to $10,000** installed.
Now imagine that a homeowner uses 10,000 kWh
per year and wants to offset half of that
power consumption, 5,000 kWh per year, with a
solar electric system. To do that, they would
need a system just over four times larger
than the 1,000-watt system used in the
example above. Here is the math: 5,000 kWh
per year / 1,200 kWh per year = 4.2, 4.2 x
1,000 = 4,200 watt system.
Therefore, a system big enough to generate
5,000 kilowatt-hours per year would need to
be about 4,200 watts. It will offset about
2.5 tons of carbon dioxide, cover 275 to 360
square feet, and cost $34,000 to $42,000**
installed.
Ouch! For most of us, those are big numbers.
**Grants and Tax credits not included in the cost estimates. In Massachusetts up to $3,000 in state and federal personal income tax credits are available and, if you are an NStar, National Grid, or Unitil (or any other publicly traded utility) customer, about 20 to 30% of the system cost can be deferred via state grants. If you are a business, the tax benefits include accelerated depreciation and a 30% investment tax credit. |
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While solar electric systems are expensive in
the short term, they are quite reliable, can
be expected to last well beyond the 25 year
warranty provided by most panel
manufacturers, and they will eventually pay
for themselves by offsetting electricity you
buy from the power company.
So how do you make the cost of the solar
electric system smaller? Use less
electricity. This turns out to be both
economically sensible and environmentally smart.
If, for example, you cut your usage from
10,000 to 5,000 kWh per year, your home's
carbon footprint (the amount of carbon
dioxide your home is responsible for putting
into the atmosphere) goes down by about 2.5
tons per year.
Also, by cutting your usage in half, to 5,000
kWh per year and putting in a 2,100-watt
solar system, you can realize three savings.
Your electric bill goes down by $800 a year
because you have reduced your usage, it goes
down another $400 per year because your solar
system is making half of your electricity,
and your only need to put up a a 2,100 watt
solar system at half the cost of a 4,200 watt
system.
A Request: I've heard from a number of
readers that they have started to reduce
their electricity usage. I'd like to hear
more. What have you done so far? What is
working? What's not working? Email me at
mark at this domain. I'll collect your
results and share them in future newsletters.
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Did you know that a solar electric panel's
performance goes down as the panel heats up?
How ironic, the very phenomenon that make a
solar panel work, also makes it work less
effectively once the sunlight is converted to
heat.
That is where Renewable Energy
Technologies, LLC comes in. RET has
invented a solar panel cooler that doubles as
a solar hot water maker. Yes, the Supplemental
Solar Energy Collector (SSEC) attaches to
the back of a solar electric panel, keeps the
panel cool, and on average, improves the
performance of the solar electric panel by
10% or more.
Secondly, the "waste heat" collected by the
SSEC is used to preheat domestic hot water
and reduce your water heating bill. For the
roof space of a solar electric system, you
get both a solar electricity and some solar
heated water.
The addition of SSEC panels to a traditional
solar electric system will increase the
electricity production and improve overall
system payback. If you are interested in a
hybrid solar
electric/solar hot water system. Please call.
We've just completed an installation with
prototype SSEC panels and found it no more
difficult than a solar electric or solar hot
water system.
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On January 23, the Massachusetts Technology
Collaborative will launch Commonwealth
Solar. Commonwealth Solar is new name for
the solar grant portion of the Renewable
Energy Trust.
With this announcement we
expect changes in the grant amounts and
process for solar systems for both homes and
businesses. Stay tuned for more information.
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Turn off the lights, wear a sweater, keep a blanket on the couch, unplug unnecessary appliances, add insulation, take shorter showers, walk instead of drive, group your errands, inflate your tires, grow your own food, eat locally-produced food, recycle, use your most efficient vehicle, get a hybrid vehicle, wash your clothes in cold water, use a clothesline instead of the dryer, print with narrower margins, buy less, use both sides of the page, compost, put computer gear on a power strip and turn it off at night, install a renewable energy system...
Thanks for Reading the Energy Miser,
 Mark Durrenberger
New England Breeze, LLC
email:
phone:
978-567-WIND (9463)
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