Things we've learned about Solar

Hi again.  I'm back to blogging after some busy weeks and some fun-filled travel to the Puget Sound area.

Living with a solar PV system is simplicity itself.  You have it installed, set up a Net Metering Agreement with your utility and forget about it.  The system wakes up each morning and puts itself to bed each evening and you don't have to pay any attention to it.  Your electric meter will run backwards on sunny days and forwards at night, and it may even stand still on cloudy days.  When it runs backwards (which is GREAT FUN to watch at first), power is going to the electrical grid for other people and businesses to use.  This is great for your power company and your region, because you are making extra power at times when most people are using it to run their business or their air conditioner, etc., the so-called "peak hours".

The Net Metering Agreement is a good idea if your solar PV system is large enough that you'll make more power than you use during some months.  Basically, the power company monitors your meter each month.  For months when you make more power than you use, they bank those kilowatt hours (kWh) for you.  For months when you use more than you make, they take those kWh out of your bank.  At the end of 12 months, the power company calculates whether you owe them money or whether they owe you money.  You get only one bill or one check each year, except for a monthly bill of maybe $5 for their costs to deliver power to you and monitor your meter.

Living up to the promises: The Solar PV installer companies try to estimate for you how much power your system will make.  This is dependent on several factors, and they have computer programs and experts that make the estimates for you.  The factors are: The number of solar panels you install; The power output (in watts) of each panel; The compass orientation (N, S, E, W) of the roof or other surface where you are installing the panels; The degrees of angle that your roof is from horizontal; any Shading caused by trees or structures during any part of the day; the Latitude and Longitude of your home (which allows them to predict the "insolation" or the amount of sunlight to expect to hit your roof); and Whether or not your system has motors to allow the panels to track the sun during the day (very rarely done because of expense and complexity).

As for compass orientation, the best direction is South for those of us living in North America.  This places the panels facing toward the sun for the largest part of the day.  The next best alternative is West, followed by East, and North, as I am fond of quoting Monty Python is "RIGHT OUT" (meaning if you only have a north facing roof tilt, don't waste your money, such a system won't be cost effective.).  Our main roof faces slightly West of South.  If you don't have a South or West facing roof or if you have major shading of the roof area, you are probably NOT a candidate for solar PV unless you have a large area of ground where you can place a slanted structure for the panels.

Our installer predicted that our system would produce 8,724 kWh of electrical power per year.  Our usage for the previous 12 months was 10,278 kWh, so we would produce almost 85% of our power needs from our system.  In fact, after the first 12 months of use, the system had produced 8,666 kWh.  So the company was very close in their estimate.  Exact predictions are impossible because nobody can predict weather patterns in exact detail.  We learned quickly that cloudy days can make a huge difference.  A rainy, gloomy day can reduce your output to almost nothing for a full day.

Have we gotten Greener?:  Well yes we have.  In 2005 and before, we paid only average attention to our electrical use, turning off lights when we remembered to.  During 2006, we got "the message".  We saw the film "An Inconvenient Truth", and that really got us thinking.  No matter that Bruce Willis showed up on David Letterman that month and joked that he was making a movie called "An Unappealing Hunch", we decided to see what we could do to reduce our energy usage.

By replacing almost all of our light bulbs with compact fluorescent designs, replacing our Christmas lights with LED lights, switching computer CRT screens and TVs to LCD screens, and being more careful with leaving lights on when not needed, we have steadily reduced our usage so that instead of the 10,278 kWh that we used in 2005, we used only 7,051 kWh in 2009.  That is more than a 31% reduction.

As a result, our solar PV system has regularly made at least 1,000 kWh MORE than we have used each year.

What are we going to do with that extra power?  Well, right now, we are selling it back to our power company.  In the first years that we had solar, California didn't require the utility companies to pay us for the extra power that we made and sent to them.  So: THEY DIDN'T PAY US A DIME.  Is there anyone else left out there who still thinks that we don't need government telling companies what to do?  Now there is a law requiring the power companies to pay us for the extra power we make.  So next year sometime, we'll get a check.  It may only be $100 or a bit more, but it's something, and they really do owe it to us.  After all, we are now a power generation station!!

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