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home > solar power
Installing a grid intertied
solar electric power system


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Overview System
sizing
Financing Panel
Siting
Hardware Grounding Rail
Installation
Inverter
Installation
Panel
Installation
Real-time
Stats
More
details
 
OVERVIEW
Workshop with solar panels and collectors
Image updated March 10, 2013 after adding 2 panels on right (south wall)
Home Power issue 136 coverHome Power articl first page
I wrote an article for Home Power magazine
(issue 136, April/May 2010)
that summarizes the project, click here to get a copy,
or click here to visit the Home Power web site.

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 a local big box hardware store) during power outages.  In recent years we have lost power for an average of 5 days each year 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 (2009), 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). 
Note that prices of solar panels have plummeted since I did this installation!

Maine's electric supply has one of the highest renewable ratios in the country, at present about 30% of the electricity delivered comes from renewable sources.  Read more about other states renewable energy portfolio here.

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.  Also there are many updates about my system on my blog.

Live web cam (updates every 60 seconds)


Project timeline
DATE Progress
June 6, 2009 Signed loan for project financing (home mortgage re-financing)
June 18, 2009 Picked up 11 solar panels and the rack mount rails.
June 25, 2009 Re-roofing the building
June 26, 2009 Installed interior load panel for the 240 Volt power from the inverters
June 30, 2009 Picked up 10 more solar panels
July 26, 2009 Installed mounting rails for solar panels
August 1, 2009 Installed grounding wire for the rails, and roof junction boxes
August 14, 2009 Installed the first 12 (of 21) inverters
August 28, 2009 Installed the first 12 solar panels
September 3, 2009 Installed 9 more inverters
September 4, 2009 Installed the last 9 solar panels
September 16, 2009 More details and real time performance statistics
March 3, 2010 Article I wrote about the project published in Home Power Magazine
August 18, 2010 Installed 2 more 175 Watt panels (now have 23 panels installed)
June 29, 2011 Installed 2 more 175 Watt panels (now have 25 panels installed)
July 29, 2011 Installed 1 180 Watt panel (now have 26 panels installed)
June, 2012 Installed 3 230W panels (now have 29 panels all using M190 inverters for 5.2 kW total)
March, 2013 Installed 2 245W panels on south wall with Enphase M215 inverters (now at around 5.8kW total)

 I highly recommend subscribing to Home Power Magazine

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Home Power magazine is the Hands-on Journal of Home-Made Power. If you are interested in: making your own electricity from renewable energy, alternative vehicles, or finding out the latest in related technologies and life-styles, then this publication can keep you up to date.

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