ECN Forum Forums General Topics of the Trade General Discussion Area Solar panel installation

Of the sunlight that hits the earth:
19% is absorbed by the atmosphere
8% is reflected by the atmposphere back into space

On the equator, you're losing 27% of that energy to atmospheric losses. If you're at, say, Edmonton at 51 degreees north, the angle of inclination means that light has to shine through 1.6x as much atmosphere, so you end up losing not 27%, but somewhere around 43%. And that's not even taking clouds into account yet; if it's a cloudy day, your solar panel output goes to practically nothing. Plus, there's thermal derating for the cold which takes a few percent, too. Semiconductors simply work way better when they're hot (don't confuse this with the properties of the metal interconnects which dominate for microchips and work better cold) There are very very few cloudy days in the desert. There are quite a few cloudy days in Alberta, though, and that has a HUGE impact, way beyond simple atmospheric losses. A panel placed properly in the california or arizona deserts will produce over twice the annual power as one placed in Edmonton and even more than that when compared to New England and Seattle. Poor Seattle, one of the "greenest" places on earth, but also one of the worst places in the world to put in a solar panel...

But hey, at least Edmonton is better off than Toronto!



Another map:
http://1.bp.blogspot.com/_cwrSE63jF...SuXMFZmM/s1600-h/us_solar_energy_map.jpg

That seems to duplicate what I am seeing in my ERDA Pacific Regional Solar Heating Handbook (Mar 1976 during the other "energy crisis"). It gets worse in winter. I can copy the chart for about 2 dozen western US cities if you like. It gives total solar radiation for each month. It does not talk about Canada but the trend is clear.
We were hearing about that "cheap PV array" that was only a year or two away then too. Still waiting.
I would love to have a solar PV array but I still can't get the numbers to work. I am too poor to have a $30,000 solar energy hobby. At my age, even if these things performed better than they advertise, I would never live long enough to get my money back.

That is is the big problem with solar. In many places the numbers do not add up. For example, I am on hydro power so I pay $0.09 per kilowatt. Since I am in the middle of a rain forest, I have to deal with clouds, trees, mountains, just to say I am a pround owner of a solar panal, I am looking at an 80 year payback just for the cost of the panels. Just like business, location, location, location is the key.

Right across the Wrangell Narrows from me, the folks over there do not have hydro power just portable power (geneartor) so they have to transport fuel and such which adds up. I am in the process coverting and upgrading several govt sites up here to solar. Beteeen location, the logistics of getting stuff there and these sites are only used in the summer months makes the number works.

Steve,

Thanks for putting that map/chart up on the website here.

I showed that exact one to our client and he very nicely asked what the difference was between a 3.0 in Edmonton and a 5.0 in Phoenix when it came to generation of energy. I couldn't really give a good answer except to tell him that the capture area needed to be a lot bigger. We then sat down and figured out what might be needed and that's why we added the 2 more 93 watt panels and the associated sun trackers. When we added it all up, it meant that we could get just as much energy with 2 more panels here as it might take with 2 panels less in Arizona. We also realized sun trackers were probably NOT needed in Arizona, but as he said, "That's part of doing business north of the 49th parallel".

So far, even in March and some crappy weather/cloudy/snowy days the meter is still running backwards during the daytime and averages up until about 2:30 AM on a previous overcast days. It seems to pick up immediately at sun-up on clear days so far. If it has been clear all day, the system maintains the charge until the next morning, so clear days in late February/early March are good. I don't know how this will work out next November and over the winter when the sun is way below the horizon on the darkest days until about 08:30 and sets about 16:00. We'll just have to see what happens.

I really appreciate the thoughts of all of you too. Your opinions on all the issues are much valued to me.

My only issue now is that I still need to run a regular business but our client is now out actively persuing more folks to convert to solar power and is actively recruiting to have us do the installations.

I'm not too sure I want the extra business.!

some informative stuff here....

i've a question about the alternate energy #'s amortization in regards to the debut of the grid tie inverters now available.

do they make the scenario more viable and economically correct ?

~S~

I'd like to keep this discussion going...

Specifically, is offering sales and installations for renewable energy equipment (both solar and wind) a viable direction for an electrical contracting company to pursue?

How many people on this forum actually deal with this equipment with their companies?
Of those that do sell and/or install and/or service renewable energy equipment, are you creating a nice niche market for yourself, or has the market not developed yet to the point that a business could concentrate on renewable energy?

Thanks... Bruce

Any confidence I might have had in solar vendors, or even the very idea, was shaken at the LEED seminar I attended last weekend.

Why? Well, the first 'shake'was the assertion that greedy electrical contractors, in collusion with solar equipment makers, were suppressing effective technology.

The second 'shake' was the assertion of a rapid (1-3 year) payback on solar and wind systems. I'm sorry, but the systems I've examined so far will never pay off, unless they magically are without any maintenance issues in the next few years. (Naturally, all bets are off if you take today's installed cost, and assume an immediate, and massive, increase in both subsidies and power costs).

Finally, a large amount of time was spent panning Nevada's net metering law. That the localPoCo will let you go to zero, but will not pay for any surplus, was seen as a major flaw. California was held as a good example ... yet, even there, you are severely limited in what you can sell back (unless you want to be regulated as a public utility yourself). In any event, the issue is moot, as I haven't seen any systems that were able to produce electricity significantly above what the home uses; most systems can -maybe- handle off-peak loads.

My conclusion: there will be a surge of "alternative power" legislation, rebates, etc. in the near future ... geared towards rewarding equipment makers and those who ALREADY have such systems. Everyone else is shark bait.

I want to apologize upfront if this has been answered already, I did not read through all the posts.

The chart indicates average isolation hours you can expect per day all year from a solar array providing the array is properly oriented through the seasons and there is no obstructions from trees, buildings, mountains, power poles, (etc). It also does not take in consideration for the systems inefficiencies like PWM charge controllers

In other words, lets say you have a 1000 watt array and you were going to put it into an area that that was marked with a 4, you could expect 4000 watt-hours per day from your array if you adjusted it per season (4 isolation hours x 1000 watts = 4000 watts.

These types of charts are based on annual averages typically 10 years. It makes the complicated calculations of power output a little easier. They take in considerations for cloud cover, early morning and late evening limited outputs and such. These charts are a good reference to get you pointed in the right direction. To get a real good answer, you need to do a whole lot of home work to find out what you would get specifically at each solar site. Most home systems typically end up with only a few panels and such because they can not afford a full blown system to meet their needs. The chart can be used to approximately show your customer about how much energy they will get out of the solar array over time.

Just a short note here about payback.

Our client knew before he started doing the installation that there would probably never be an endpoint for payback.

I must admire him however for his dedication to the environment. He does a bunch of other stuff regarding that as well but composting and recycling go along with all this as well. I'm not into that kind of "green" stuff very much but when someone has that kind of motivation I must admire the guy and his dedication. I know he is about to be recognized by some of the press here soon so maybe it will help his business attract more customers of a like mind.

On a side note, we've been swamped with requests to do some more solar installations. So far, I've said no more because we are just now finally catching up with 3 months of work due to the recession. Maybe once we get to a 2 week backlog we can do another few of them.