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!!
Next Blog: More insights on Living Solar
Saturday, August 14, 2010
Sunday, July 25, 2010
Experience with Our Solar PV System
Our Solar Photovoltaic System Facts:
Size: 24 SunPower panels at 215 Watts each, for 5.16 kiloWatts total
Roof Orientation: South Southwest
Installation Date: January 27, 2007
Peak AC Power Output: approx 4,000 W
Peak AC Power Output for a full sun day: 33 kWh
Our Annual Power Usage:
2005: 10,278 kWh (base year for system sizing calculation)
2007: 7,738 kWh (year of system installation)
2009: 7,051 kWh
Power Production in Excess of Usage, 36 month total: 3,009 kWh
Percentage Power Production to Usage, 36 month total: 113.5%
Cost:
Total Cost Before Incentives and Credits: $39,336 ($7.62/Watt)
State Rebate Paid to Installer: $11,837
Net Out of Pocket Cost before Federal Credit: $27,499
Federal Tax Credit: $2,000 (maximum limit at that time)
Net Cost to Homeowner: $25,499
So how has our solar electric power system worked out for us? In a word, "Fine".
The installation was completed in a couple of days. The installers removed our clay roof tiles in the area where the panels would be installed, and they installed a new composition tile roof system below the position of the panels.
Things went smoothly, aside from a few misplaced bolts that we saw poking through our wood beam bedroom ceiling, and a broken window, all of which the installer quickly fixed. Our utility, SCE, replaced our old electric meter with a new digital one.
Living with a solar electric system is simplicity itself. We can ignore the system. It will produce power when the sun is shining, and our electric meter will run backwards. When it is cloudy or at night, our meter may run forwards or backwards. The system requires no maintenance or monitoring. To improve the performance of the panels, they can be cleaned with soap and water perhaps twice per year.
Issues: Pretty big ones actually. Before I go into this, I will say that everything is fine now and our installer has taken care of the problems. We are happy with our system. We and the installer learned a lot about some roofing issues from our experience, but we certainly had some worries and emotional concerns through the process.
What happened? RAIN LEAKS!! Our system was installed at the end of January, 2007. We woke up on the morning of the first rain storm to find our master bedroom ceiling leaking in 20 places! Yes, on our bed, on the carpet, everywhere that a lag bolt pierced the roof to hold the panel mounting racks, there was a leak.
We are patient, trusting people, so when the installers sent out a crew to find the leaks and fix them with mastic, we expected that to solve the problem. It didn't. They came out SEVEN times for attempted repairs before it was fixed. My poor wife Carol was so disappointed. It felt to her that we had naively agreed to turn our home over to inexperienced people and that they had broken it.
What was the problem? The original roof modification plan was poor. When they put the new composition roof in the area where the tiles were removed, they left the area that was still tiled untouched. So water ran down the tiles and onto the roof below and got underneath the composition roof tiles that they had installed, then it found its way to the lag bolts that penetrated the roof and the water leaked inside. Putting mastic into the holes from above did almost nothing. Carol had anticipated this problem from the beginning, but the company was reassuring, so we went ahead with their plan. We now know better.
When I finally got tired of letting them try the same solution, I called the president of the company. Within a few days, a supervisor came out and authorized the repair guys to remove all of the roof tiles and put on a SECOND new composition roof on top of the first one, and to place it edge to edge and top to bottom on the roof.
That finally worked. There were one or two slight leaks after that, but they were quickly solved.
The moral of the story: Make sure that the company you choose has experienced roofing experts on the staff. The electrical part of the installation is important, but our experience is that the roofing piece is more important. And if they suggest an unusual sounding installation, question it until you are completely satisfied that they know what they are doing.
Next blog entry: Things we've learned about solar.
Size: 24 SunPower panels at 215 Watts each, for 5.16 kiloWatts total
Roof Orientation: South Southwest
Installation Date: January 27, 2007
Peak AC Power Output: approx 4,000 W
Peak AC Power Output for a full sun day: 33 kWh
Our Annual Power Usage:
2005: 10,278 kWh (base year for system sizing calculation)
2007: 7,738 kWh (year of system installation)
2009: 7,051 kWh
Power Production in Excess of Usage, 36 month total: 3,009 kWh
Percentage Power Production to Usage, 36 month total: 113.5%
Cost:
Total Cost Before Incentives and Credits: $39,336 ($7.62/Watt)
State Rebate Paid to Installer: $11,837
Net Out of Pocket Cost before Federal Credit: $27,499
Federal Tax Credit: $2,000 (maximum limit at that time)
Net Cost to Homeowner: $25,499
So how has our solar electric power system worked out for us? In a word, "Fine".
The installation was completed in a couple of days. The installers removed our clay roof tiles in the area where the panels would be installed, and they installed a new composition tile roof system below the position of the panels.
Things went smoothly, aside from a few misplaced bolts that we saw poking through our wood beam bedroom ceiling, and a broken window, all of which the installer quickly fixed. Our utility, SCE, replaced our old electric meter with a new digital one.
Living with a solar electric system is simplicity itself. We can ignore the system. It will produce power when the sun is shining, and our electric meter will run backwards. When it is cloudy or at night, our meter may run forwards or backwards. The system requires no maintenance or monitoring. To improve the performance of the panels, they can be cleaned with soap and water perhaps twice per year.
Issues: Pretty big ones actually. Before I go into this, I will say that everything is fine now and our installer has taken care of the problems. We are happy with our system. We and the installer learned a lot about some roofing issues from our experience, but we certainly had some worries and emotional concerns through the process.
What happened? RAIN LEAKS!! Our system was installed at the end of January, 2007. We woke up on the morning of the first rain storm to find our master bedroom ceiling leaking in 20 places! Yes, on our bed, on the carpet, everywhere that a lag bolt pierced the roof to hold the panel mounting racks, there was a leak.
We are patient, trusting people, so when the installers sent out a crew to find the leaks and fix them with mastic, we expected that to solve the problem. It didn't. They came out SEVEN times for attempted repairs before it was fixed. My poor wife Carol was so disappointed. It felt to her that we had naively agreed to turn our home over to inexperienced people and that they had broken it.
What was the problem? The original roof modification plan was poor. When they put the new composition roof in the area where the tiles were removed, they left the area that was still tiled untouched. So water ran down the tiles and onto the roof below and got underneath the composition roof tiles that they had installed, then it found its way to the lag bolts that penetrated the roof and the water leaked inside. Putting mastic into the holes from above did almost nothing. Carol had anticipated this problem from the beginning, but the company was reassuring, so we went ahead with their plan. We now know better.
When I finally got tired of letting them try the same solution, I called the president of the company. Within a few days, a supervisor came out and authorized the repair guys to remove all of the roof tiles and put on a SECOND new composition roof on top of the first one, and to place it edge to edge and top to bottom on the roof.
That finally worked. There were one or two slight leaks after that, but they were quickly solved.
The moral of the story: Make sure that the company you choose has experienced roofing experts on the staff. The electrical part of the installation is important, but our experience is that the roofing piece is more important. And if they suggest an unusual sounding installation, question it until you are completely satisfied that they know what they are doing.
Next blog entry: Things we've learned about solar.
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