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You're Doing It All Wrong: Solar Panels Should Face West, Not South
HughPickens.com writes In the U.S., a new solar project is installed every 3.2 minutes and the number of cumulative installations now stands at more than 500,000. For years, homeowners who bought solar panels were advised to mount them on the roof facing south to capture the most solar energy over the course of the day. Now Matthew L. Wald writes in the NYT that panels should be pointed west so that peak power comes in the afternoon when the electricity is more valuable. In late afternoon, homeowners are more likely to watch TV, turn on the lights or run the dishwasher. Electricity prices are also higher at that period of peak demand. "The predominance of south-facing panels may reflect a severe misalignment in energy supply and demand," say the authors of the study, Barry Fischer and Ben Harack. Pointing panels to the west means that in the hour beginning at 5 p.m., they produce 55 percent of their peak output. But point them to the south to maximize total output, and when the electric grid needs it most, they are producing only 15 percent of peak.
While some solar panel owners are paid time-of-use rates and are compensated by the utility in proportion to prices on the wholesale electric grid, many panel owners cannot take advantage of the higher value of electricity at peak hours because they are paid a flat rate, so the payment system creates an incentive for the homeowner to do the wrong thing. The California Energy Commission recently announced a bonus of up to $500 for new installations that point west. "We are hoping to squeeze more energy out of the afternoon daylight hours when electricity demand is highest," says David Hochschild, lead commissioner for the agency's renewable energy division, which will be administering the program. "By encouraging west-facing solar systems, we can better match our renewable supply with energy demand."
Obviously the panels should be motorized so that they are always facing the most optimal direction. A system that moves the panels shouldn't add that much to the cost and will probably pay for itself very quickly with the extra energy collected.
Obviously the article covers this...
Solar panels do not have to be pointed in just one direction; a homeowner can buy a device called a tracker that will pivot them, over the course of the day, like a sunflower, so they always face the sun. A tracker can raise the output of a panel by 45 percent. But adding trackers can cost hundreds or thousands of dollars, and a cheaper way to get the same number of kilowatt-hours may be simply to buy a few extra panels.
So? In the other 8 months it'll still be useful. Or split the difference and point them southwest.
Or continue trying to find ways in which you're a special little snowflake, and trying to make it so that anything that doesn't make something 100% useful for you personal makes the entire thing pointless.
I just purchased a solar panel system for our home, and I've been learning a lot about all of this stuff during the process.
The problem with the author's suggestion is that he's concerned about a problem that, by and large, we haven't quite come to yet. Solar adoption is still such a small percentage of the total number of electric consumers that the "saturation point" hasn't usually been reached yet. The entire "net metering" model for solar isn't really sustainable if you get more than a single digit percentage of homeowners in a given area going solar. I think that will hold true EVEN if you could convince all the new solar installations to use west-facing panels to time shift their power production hours.
Right now, practically everything about PV solar adoption centers around government regulations creating an "artificial" incentive for it. For example, in my home state of Maryland and a number of others, they have an SREC program in place (solar reclamation credits). How does it work? Basically, they made a rule that the state's utility companies have to obtain a certain percentage of their electricity generation via "Green" sources like wind or solar. If they fail to hit that target, they must purchase these SREC certificates in a sufficient quantity to offset it. (In reality, they're always going to pay for the SRECs rather than adopt more alternative energy generation themselves -- because for them, it's still the more cost-effective and sensible option. They don't want to spend a bunch on new infrastructure and land to place it on, just to meet those percentage targets.) For every megawatt of solar power your home solar panel setup produces, you earn an SREC which you can turn around and resell to the power company (directly, or via one of several auction web sites designed for the purpose). There's even one offering to buy 10 or 20 years' worth of your SRECs in advance, at some discounted price, giving you more "up front" cash to pay off your system's initial installation cost - should you find that the best option.
Don't forget the Federal tax credit of 30% of whatever you spent to buy the solar panel system, and states like mine who kick in another $1,000 or so. This stuff just doesn't make the same financial sense with all of these constructs removed from the equation.
The real elephant in the room that everyone's ignoring is the fact that power DISTRIBUTION is the limiting factor for the power companies. As soon as too many people start putting power from solar back onto the grid at one time, in one area? They can't really do anything with it, so it gets wasted. Yet the "net metering" rules require that pay you back for it anyway, at full retail prices. For a SHORT time, you might be able to postpone this by switching more panels to face west instead of south, but soon enough - it will become a problem again.
Honestly, I predict that what we'll see playing out is government withdrawing all of the tax breaks, followed by the value of your SRECs dropping to very little as they ease up on the requirements the utilities must meet. This will put the brakes on solar adoption, making it one of those things that only paid off for the people who got in on it early - or who have a situation where it STILL pays off (due to especially high power costs). In Hawaii or parts of California, for example, I believe the utilities sometimes bill as high as 90-some cents per kilowatt-hour used. In Maryland, by contrast? I pay closer to 11 cents.
Any time you move the panels out of close contact with the roof, you're accepting large wind loads. That means the supporting structure -- especially if it's movable -- has to be substantially sturdier.
My installer recommended against a tracker. He said a tracker system would add roughly the equivalent of an additional 2 panels' output, at a similar cost, and an increase in complexity and maintenance.
They sentenced me to twenty years of boredom
I am 56 deg north, here in Denmark.
I have 50% SW and 50% east, as that is where I had the roof for it.
Using the EU models for calculating output, the eastern panels should give me just over 80% of full production.
SW should give me 96% or so og pure sourth, and will produce further into the evening. So it is possible to do adjustments with little loss.
There are lots of payment models. Here in Denmark, I have a fixed price for the first 10 years. and a slightly lower price 10-20 years, after which it will be market price. ROI is 8 years. But since my electricity usage import/export is summarized per year, I really do not care when I produce.
The new payment model here looks at import/export every hour for some users, and other users are hit pay selling low buying high for everything the hits the grid, and for them it is advantageous to turn panels further west.
My production here in the winter is low. My 6kWp installation is expected to make 1.86 kWh/day for december.while in july I made around 48 kWh/day.
56 degrees north is another beast entirely. Here's a Sun chart for København, Denmark - http://www.gaisma.com/en/sunpa...
Winter = 8 hours of sunlight
Summer = 18 hours of sunlight
Not only is the amount of time the Sun is shining much higher during the summer, the tilt for the panel is only 58 degrees so your average roof angle would do nicely during the summer. In the winter though things change radically, the optimal tilt angle goes down to 10 degrees and the insulating factor goes way up... nearly 14x less light penetrating during December than in July. You would do well to have a 2 part system that you can move around manually - during March to Sept: first part facing WSW and the second part ESE at 34-58 degree tilt. Come September, change the configuration so both parts are facing due south at a 10 degree tilt.
Where I am (44N) it's 10h/16h, 22-70 degree tilt, and only a 5x insulating factor difference. We just set it around a 40 degree tilt (or less? can't remember exactly) to maximize winter time collection - some is lost in the summer as a result but there are more producing days in winter (due to summer storms) and we found that, since we're in a field, the reflection from the snow would actually increase production. The snow covered field effectively acts like a giant reflector so it generates even on overcast days.