My wife and I are committed to
sustainable living. I have a
separate page devoted to all the efforts we are
taking in that regard. This section of my web site documents my
experience while researching, designing and installing a grid intertied
solar power system in the summer of 2009.
I have wanted to live a solar powered life but it has always been too
expensive to consider. Over the last 10 years I have monitored the
costs of installing a system capable of powering a home and that price
has hovered around $30,000.
I am an active member of a local volunteer organization called the
Midcoast Green Collaborative. We are committed to creating a
sustainable economy in coastal Maine. In 2009 one of our efforts has
been to get legislation passed modeled on the very successful German
Feed-in Tariff law. This law levies a small
fee of a dollar or so per month on every electric rate payer's bill.
This creates a fund that the utility uses to pay a significant premium
per kWh to small scale renewable energy generators. This makes it cost
effective to finance the cost of installing solar panels (or a windmill
etc.) because the income from the sale of your electricity to the
utility covers the cost of the loan. Once the loan is paid off -
typically in 20 years you become a profitable electric micro-utility!
I testified at a hearing for this proposed legislation before the Maine
Joint Utility and Energy committee, where I presented a spreadsheet that
showed how the financing would work with a 20 year low interest loan and
a 20 year generation contract with Central Maine Power - our local
utility. I showed that a minimum payment of 50 cent per kWh would
significantly incentivize small scale solar generators on a residential
scale. For reference Ontario, Canada is paying nearly 70 cents/kWh and
Vermont just introduced a feed-in-tariff bill that would pay 30 cents.
Testifying led me to do more research on the cost and feasibility of
going solar. My first call was to my friend Naoto Inoue, the owner of
Solar Market in Maine. He had helped me to design the
solar heating system
for my workshop back in 2001, and sold me much of the equipment. He
told me of a new technology called "micro inverters" that was changing
the paradigm of solar installations. Instead of the panels being wired
together to create high voltage DC that is sent to a large single
inverter that converts the DC to the AC we use in the home, each panel
has a micro inverter mounted right behind it. The power is converted to
240 Volts AC right there at the panel. This makes the system more
efficient and more flexible. It eliminates the shading issues that can
compromise the performance of DC systems where panels are wired in
series - shading any one panel in the series will compromise the whole
string. Also one can mix and match panels of different capacity
allowing one to grow a system with a blend of panels as you can afford
them. Overall this system has a slightly better cost/performance
characteristic.
More about micro inverters on Wikipedia.
The only disadvantage of installing a grid-tied solar system like this
is that there is no battery bank. So when the utility power fails the
inverters automatically shut down to protect the line workers. So we
will still need to rely on our
Generac automatic propane backup generator (purchased from
Home Depot) during
power outages. Last winter (2009/10) we were running on propane generated power
for a total of 7 days due to 2 heavy snow storms, Maine winters can be
brutal. This cost us several hundred dollars in propane, so the
trade-off of a battery-less system can get expensive on occasion. But
in the long run it is less expensive than installing and maintaining a
battery bank.
Several other factors influenced our decision to go solar now, low
mortgage rates, recent drop in the cost of solar panels, and the
federal tax incentive that allows us to take 30% of the cost of the
system off our federal taxes. (We did not get the credit we
expected in the first year because we are self-employed
more
on that here)
Maine's electric supply has one of the highest renewable ratios in the
country, at present about 50% of the electricity delivered comes from
renewable sources.
Read more about other states renewable energy portfolio here.
So we already had a very low carbon footprint, and we have chosen to
purchase electricity from 100% renewable sources. So our electric
supply is already carbon neutral.
So my next task was to figure out how many panels I would need, and
where to put them all. Go to the
next page to see what I learned.
Also if you want to see a similarly detailed blog about a ground mounted
solar power system that also uses Enphase inverters like mine - take a
look at
Gary Reysa's site. |
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