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The more I think about it, the more I like the idea of ground mounting solar panels.

The two major benefits of ground mounting are optimal tilt / adjustable tilt and ease ofĀ maintenance. The only drawbacks I can see are space and cost.

Personally, ground installation wins hands down becuase I could do most of the work. (This negates the cost issue.) Here is a great link to someone who did just that. His total cost was $6500 for a 2150 Watt array, Installed! I too would go the route of wooden frame. I think a solar pergola would be great!

In case you did not know, I live in Indiana. Not really the sunshine state but we do alright. I was surfing the web and landed on a local COOP page. Hoosier Electric. They have a few solar sites in central Indiana. One is only 15 miles away. (I will have to visit this sometime soon).

Franklin, IN has a 3kW solar installation.

Dubois County, IN has the same 3kW solar installation.

I have been looking at the historical data from the site. Man, do the numbers look good. To get us on the same page, here are two “as perfect” (very sunny days) at two very different times.

Solar output on December 22nd

Solar output on December 22nd

Victory Solar output on June 29th

Solar output on June 29th

Total output for December 22nd was 18.86kW

Total output for June 29th was 20.83kW

The difference is only 2kW yet the total number of hours the sun is above the horizon being 6 hours longer for June! Don’t forget the more direct path thru the atmosphere too.

So what is going on. We know that temperature is a big factor. Also, with that, these panels are pole mounted. No heat trapping roof to slow down the air cooling of the panels. Even still there is something else. These panels are special. Sanyo Bifacial Solar Panels! They convert light into electricity from both sides of the panel! This means if there is snow on the ground the reflected light up into the panels will be converted. Now I am not thinking about putting panels on my roof but instead placing them on my south facing hill. With some white stone underneath I may be able to make this work! I will have to see if I can get some more data. I know the company that installed both locations. šŸ™‚

What is the “edge-of-cloud effect” and how can it cause a solar array issues?

What is it? Well, just as the cloud begins to cover the sun or when the sun is emerging from behind a cloud, there is a sudden burst of energy that produces more power than normal. This is caused by light refraction. Refraction can concentrate the sunlight while the edge of the shadow passes by. The result is a boost in module voltage output. On a day with bright blue skies and fair weather cumulus clouds, the effect is quite noticeable.

So how can you account for this increase in output. Common practice is to add 20% to 25% to the amperage rating of the solar controller. But many controllers today are the MPPT type. They track the arrays Maximum Power Point on its IV curve. As the edge of clouds start causing over-irradiatance. The MPP voltage starts to rise, so too, does the current. The MPPT controller then adjusts the voltage up to correct for this effect.

Take for example a Sunny Boy 5000 Watt grid-tie inverter. The lower the voltage of the array the better the efficiency. Of course the design of an array depends on the solar panels but you should never design around the highest voltage under standard conditions. In this case 480 VDC. Me, I would design around 350VDC to 400VDC under normal operating conditions. This would allow for the MPP to move around where it wants to.

Basically, solar controller can handle brief overages of current, but not voltage. The edge-of-cloud effect is only going to be a problem when it is very cold outside and passing clouds. You can use this sizing tool for SMA Sunny Boy Products. Also, solar panels have a Voc (open circuit) and a Vmp (max power). for a 12VDC panel Vmp may actually be 17VDC and Voc around 21VDC. Since the edge-of-cloud effect normally occurs when the inverter or controller is running you already have some extra wiggle room.

(I guess you could have a rolling black during the day and have your grid-tie inverter shut-off. But then you would also have to have record cold temperatures. But then it would be winter and you would have less transmitted light because it has to travel though more atmosphere at an oblique angle. Plus you would have to have perfectly clean panels. As you can see, not likely to happen any time soon.)

For every watt of renewable energy capacity, you have to have a backup. That backup is almost always going to be a fossil fuel. Not that is don’t want renewable energy. I just understand that we will continue to have to use fossil fuel for a long time to come. I was at an state environmental meeting a few years back. The one thing I remember about that meeting was a question posed by one of the guest speakers for the day. He asked, “What is going to be the fuel that drives our energy needs fifty years from now?” His answer, “Coal.” Maybe he is right? I don’t know? But, coal will be with us for a long time. Like it or not. Personally, I hope that every house has a solar array and a highly efficient battery system. That way no one will even need a power company. The power company will be the people that come out to do regular maintenance and repairs. If we still have a grid it will be to support your local neighborhoods power consumption during times of high usage in that neighborhood. I was reading that after the Chevy Volt battery has lived a good life inside the car that GM thinks it would be a great edition to a solar system as the primary storage of excess generation. 25kW hours could go along way in a power outage. (Sadly for some, it would not last more then half a day.)

But, conservation is still king. Do more with less. (I always hated to here that in a work environment.)We don’t have a need for a new high tech power plant if people would just start using less. In Indiana, my electric bill is usually around $100 for 1000kW hours. That same 1000kW hours in New York or California may cost well over $300. Not that anyone wants to pay more for anything but I think it would be nice if people would stop and look at their consumption. My TED unit has helped with that quite a bit.If the power company wants to help people reduce there bill so they don’t have to build another expensive plant then they need to inform their customers about their usage in real time. Not once a month.

Before I think about a solar system, I know that conservation is king. I would hope that yours is too. Paying good money for a high quality energy efficent appliance will save you more money than throwing more solar panels on your roof.

Cool your house with ice generated at night! That is right. Mostly right anyway.Ā  Ice Energy has a produce that “makes” ice at night and uses the stored energy during the heat of the day. So for all you people out there that have TOU rate plans, this could save you money. (I am thinking of California!)

Basically, you have a regular AC unit that runs at night to make the ice inside the unit. When the thermostat calls for cold air, the ice is then melted providing the building with up to 30 ton-hours of cooling. (360,000 BTUs) I will use my house as an example. The other day it was 90 degrees outside. My air condition ran most of the day. Lets say 12 hours. I have a 2.5 ton unit. That would be about 2.5 x 12 hours = 30 ton hours. (convenient) If I was in California and had TOU (Time of Use) like most do, I may have paid $0.40 a kWhr. (3kW x 12hours x $0.40 = $14.40 a day) With the Ice Bear 30 that I run at night… (3.5kW x 10hours x $0.10 = $3.50 a night) That is a savings of $9 a day. A few things to note. One the regular AC unit is running in the heat of the day this will cause it to use more energy. On the flip side the Ice Bear is running in the cool of the night. This will cause it to use less energy. Even though the Ice Bear has a 4.3 ton compressor. It could use less energy because of the temperature difference between night ad day. In this example the AC would have never run out of ice until the end of the day. Everything is good. But if the ice did run out then the Ice Bear would have turned on it compressor and started to cool the building. Thus never leaving you without air conditioning.

On a similar train of thought. Think if you had a solar system installed. You would be selling power at peak rates and then buying it back during the cheapest times, middle of the night. This Ice Bear system could actually allow you to install a smaller solar system because of the rate differences. By the way, most power companies love it when you shift your load to an off peak time. Why? because they have excess capacity at night and not enough in the middle of the day. That is what TOU is all about. They want you to change how and when you use electricity. By making it cost more when they can’t generate enough.

Again, this technology is not for me. I have a flat rate structure. I also want a heat pump. This would mean I would have an Ice Bear and a heat pump and that would not make financial sense at all. It will work with heat pump. All they do is place a dedicated heat exchanger in the air handlers air stream. Everything works the same but you can run the heat pump in heating mode.

So, for some of you out there this can save you some serious money! Especially, if you already have solar on your roof.

Duke Energy just lowered the price for purchasing “Green Power”. It used to cost almost twice as much. So, I just enrolled for 500kW hours. It cost me about $10. I will admit, I do feel somewhat better. I would feel much better if I could just make my own power, but this is a step in the right direction.

Why 500kW hours? This has been my target consumption for the start of my energy reduction plan. I keep this target even after installing the hot water heat pump that runs on electricity. Hopefully, my goal is not too far out of reach.

If I have a backup style grid-tie solar system will my inverter start my Air Conditioner? Maybe, just depends on the Air Conditioners LRA rating and the inverter starting capacity. LRA means Locked Rotor Amperage. This is the inrush current that any motorĀ  has when it first starts up. The motor in this case is the compressor.

Here is an example that may e similar to many installations. (This would be what I am thinking of doing in my house anyway.)

Inverter would be a Xantrex XW 6048. It has a LRA surge rating of 52.5 amps. My current air conditioner, I think, is a 2.5 ton AC unit. Since I don’t know the LRA rating I used a new Goodman SEER 13 unit. This unit has a LRA rating of 49 amps.

Yes, the inverter would start the Air Conditioner. Or would it. Remember there are two other fans in a split system. A condenser fan and a blower fan. Both of these have a LRA ratings also. So in the end the chance of starting the entire system is low. Especially since you will have other power users running while the Air Conditioner is trying to turn on.

So I can’t run the entireĀ  house AC unit on the inverter. But can I run a small window unit. Yes, if the unit is 120V this inverter will not have a problem with it. That is because the inverter has a surge rating of 110 amps @ 120V. The house air conditioner was @ 240V.

If you wanted to run a window unit with an off the shelf inverter take the amperage while running and multiple by 7 to estimate the LRA draw. So if the running amps is 5. Then the estimated LRA would be 35 amps. Take the 35 amps x 120V = 4200 Watts. This would be the minimum size surge rating inverter you should buy.

Inverter-Driven Rotary Air Conditioners.

The nice thing about this type of air conditioner is the running amperage is very close to the Locked Rotor Amperage. The inverter in the AC unit starts the compressor out slowly and then ramps up to the desired speed. This means that if your windows unit or your central unit has this newer technology many more DC toACĀ  inverters will do the job. The Xantrex XW line of inverter should have no issues getting it done. (FWIW – when I upgrade my AC I would like to go with an inverter type heat pump.)

I don’t pretend to be an expert (just someone who cares and wants to learn) but this ongoing debate in the U.S. to choose a better regulatory framework for solar power has really piqued my interest – mostly because there already seems to be a market-proven way to go about this in Europe. But as usual, if America’s not the first to come up with the idea- anything else is considered spurious.

Come on, America’s ego – stop making excuses and get to work!

A tariff by definition is a table of fixed charges. ‘Net metering’ is used to describe the current U.S. policy on paying consumers who tie in to the grid with their renewable energy sources, but because net metering guarantees the power company profits from your generated power and you just get a ‘zeroed’ meter, generating your own power still seems out of reach for most Americans.

In Germany (and Spain, and Greece, and France, and Italy) they’ve developed a model where you, the consumer, gets paid more than three times what the power is actually worth and you get paid for every single kilowatt hour you generate – not just the excess left over after your personal Kwh-usage is deducted. These are your incentive to generate your own power – you will get a paycheck from the power company at the end of every month for the power you’ve sold them. You will generate your own power and power to spare for others to use. The system supports itself.

It’s called distributive generation.

We’ve thrown a lot of money in this country at far less conscientious, non-market proven, rich-get-richer schemes…

The Drake Landing Solar Community located in Okotoks, Alberta has 800 solar panels located throughout the community. It is also the first implementation in North America of seasonal solar thermal energy storage. This means that it collects solar thermal energy during the summer for wintertime use!

Web site: DLSC
Note the Project Status and Highlights listed on the main page. šŸ™‚

Two recent articles shed further light on the advantages of setting up or beginning to plan to set up your own system for generating solar power.

From LaserSolarWorld comes the news of two grad students in England heralding the impending affordability of solar panels. Sooner, rather than later, these two claim solar power will actually be less expensive than conventional power by the year 2014.

“Both researchers believe that it is time for consumers to think seriously about installing solar panels. Sean believes that the most common argument against using them is the initial capital outlay needed. “The average system today in 2008 costs approximately Ā£3,000 including grants, with a payback time of just six years, and this period will reduce significantly over the coming decade,” he says. (As of July 2, 2008, Ā£3,000 = $5977.50.)”

If you’re geeky and interested like me, follow the link to read the entire article:Photovoltaic cheaper than solar by 2014. There’s talk of amorphous silicon – less expensive, less toxic, and more efficient ways to build solar panel cells, and exactly how these two plan to make it happen.

In related news this article illustrates how a couple of U.S. ‘think green’ tanks believe the cost of solar will match that of fossil fuels by 2015. The study …

“… predicts that the cost of energy produced from solar photovoltaic cells will decline from today’s average of $6 per peak watt to an average of just $1.5 in 2025. This, together with the advantages of solar energy (zero carbon-based emissions, energy delivered at source, zero fuel costs), should make solar a “ubiquitous” energy source in the future …”

This June 2008 study was compiled by compiled by clean-tech research and publishing firm Clean Edge and green-economy non-profit Co-op America and can be read in its entirety here.

I find it very encouraging that timelines on this matter are beginning to converge and further, that regular people are beginning to understand the urgency and need to pay close attention to this kind of science. The sooner people tune in and realize our comfy way of life is partly to blame for the current woes of the world, the sooner we can all join together and make a positive difference.