I posted this on the Canadian forum last week and wound up with zero repies, so I'm trying it here. Hoping to get some help if anyone wants to give it a go.

Thanks.
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We have an Edmonton, Alberta, Canada client that wants to install a fairly low power - i.e. 10 KW solar panel, solar tracking installation. Although it's reasonably low powered the system would present some technical issues with battery current to the inverters. We know the cables to the inverters will be fairly large KCMil stuff but.....

However,

He wants, but we have not been involved with, a grid tie system before and would like anyone's experiences with carrying out this kind of work at these kind of power levels. Our client wants to do a grid tie system which you all know needs the POCO involved as well. So far we have their preliminary approval to tie in to their grid, providing we have all the necessary Phase/frequency requirements met along with the usual non-back feed requirements when their system quits. We have researched ad-infinitum with suppliers and distributors and of course the internet. Canadian knowledge and advice seems in short supply however.

I'm looking for thoughts/advice from anyone with prior grid tie experience that might be able to tell us the traps and pitfalls you might have experienced that go along with a solar system grid tie installation.

Thanks,

Dave., I know we did talk about a little in the chat room sometime back however.,

I will make few more addemendments what I should cover it with our conversations.,

The issue is weight of photocell if it will be mounted on the roof that roof structure that need to be check with the building engineer to make sure they can take both photocell weight plus snow load as well.

I am not sure how hot it do get in your area Dave., but if you run any conductors on roof structure watch the derateing carefully on that one due the solar system is pretty much contionus operation during daylight hours even with cloudy days it will run but at reduced capaity.

The quirk is each one is diffrent and warranty wise that part I only have limited info on them.

As far for Cananda code requrement for disconnection switch IMO for myself it should be near the solar panel for safety reason { someone told me put in interlock switch so that way it will lock out the inverter when the disconnection switch is open.}

other pitfalls it hard to say but I will let other members here to see if they can pitch in with more infomation with this set up.

Merci,Marc

Try this site

http://nmsu.edu/~tdi/Photovoltaics/PV-Energy.html

I can't say that you'll find what you need to know, but if you can't, send an e-mail to jwiles@nmsu,edu

John C. Wiles from New Mexico State University is one sharp fella on photovoltaic systems. He has written several articles for the IAEI and I was able to attend a seminar he put on at our chapter meeting.

Here are two canadian suppliers that may be of help if you have not tried them yet.

This guy is from Lumsden SK
http://www.kellnsolar.com/devSite/index.php

And this one is located here in Winnipeg:

http://www.solarengineers.com/Divisions/Residential/tabid/57/Default.aspx

The only systems I've seen in Northern California are grid tied and there is no battery system involved.
The inverter is chosen for its output voltage at a given current capacity, a range of acceptable DC input voltages and freq/phase matching is handled by the inverters internal electronics.
The inverter does nothing at night and it shuts down (even in the brightest daylight) when it loses it's sense signal from the mains during a power failure.

I think (but have no actual proof) that this is due to all of these systems being subsidized by State/POCP rebates. It wouldn't do for the end user to go and disconnect the thing they paid for half of from the grid and run it independently now would it? If I had just paid for a system and found out it wouldn't work in a 4 day power outage (like we had about this time last year) I would be upset. But I digress...


I have seen inverters for sale on-lone for off-grid use but don't know if they could be used in both grid-tied and off-grid modes or if the POCO here would allow it.


That said, the systems I have seen, including one capable of running a full 240V 200A service in bright daylight, all used a series-parallel network of panels to bring both the DC voltage and current up to levels that worked well with the inverter while not requiring huge feeders. It would stand to reason that a series- parallel network of batteries could accomplish the same thing. Might not be cost effective though.

Thanks to all for your inputs.

We started the installation, only to have it stalled a bit because the client wanted to have a solar sun tracking system go along with it. That upped the price a bunch. To me, that might not be a "bright" idea since it involves moving parts that are going to need servicing every so often to make sure it's still tracking the sun. (Good for me for the service contract, but not good when it fails unexpectedly).

The solar trackers make installation about $15,000 more for this one and it now seems that the solar panel cost is starting to diminish percentage wise compared to the system cost.

When we worked out the payback time (again) for this installation the clients wife kind of choked a bit, but they are still fairly young and in their early 40's and still want it done, so it will be paid off when they reach the age when their kids are done with their University degrees in 15 years or so.

Meanwhile, the solar panel mounts are proving to be a challenge, as is the annoyance of the City ordinances regarding fire containment for electrical storage "rooms" as it has now become. Unfortunately, there are no unambiguous guidelines from the Canadian Elaectrical Code on solar power battery on-the-grid requirements, so we are kind of winging it from what we can get from other battery room rules and hoping the City AHJ guys can be convinced that we are at least trying.

If any of you here are involved in any of this kind of stuff and the silly complications arise, I'd appreciate your input. Even more so my guys doing the actual work on the outside at minus 15 degrees Calcium (plus 258 kelvin :-)) would really like to know when this "adventure" might come to a successful completion for this customer.

Today we finally got the mounts and solar az-el trackers working in response to the daily sun-up and sun-down times. What an amazing visit to see about 50 little step motors all working in unison! Almost like a bunch of little R2D2 guys doing their thing. At sundown tonight the panels all swung to the east at exactly the proper times to get aimed to the morning sun capture.

During the day around 13:30 - which is about solar noon here we got about 50 amps going to the batteries from the panels so I expect that should work for a grid tie system when we get that hooked up.

Thanks for all the links as well guys.

Anybody care to jump in with more experience? I appreciate anything you might have that might be anecdotal or otherwise.

Monday morning we have a meeting with the AHJ to see about battery vaults too, so that might be interesting if we have to change it.

On a large scale, solar tracking only makes sense if you are reducing the density of panel area to land area. When the sun angle is lower, the solar power incident on the land area is reduced. Trackers don't improve on that unless the panel area is nominally less than the land area. If tilted panels don't block each other somewhat, then at high noon you have gaps between the panels and no noon peak of solar power. The arrangement where tilting does have a benefit is an arrangement with less panel area and less power at noon than if the panels were at full land density.

If you have one big panel, tracking can make sense. But it is true this involves moving parts, a control mechanism (based on timing or sensing), less reliability, and greater maintenance.

The benefit of aiming the panel is lost on cloudy days. Then light comes in at all angles. This needs to be taken into consideration if you want solar power during these times. Certain multi-angle solar concentrators, such as the Winston Collector, take light from multiple angles and concentrate it. Photovoltaic cells also operator more efficiently at greater light+IR concentrations. And the multi-angle concentrators take in more light on cloudy days.

http://www.paws.dircon.co.uk/solar.htm
http://www.appropedia.org/Understanding_Solar_Concentrators

Thank you ever so much pdh. The links are very much appreciated.!!!

More coming technology:

http://www.technologyreview.com/energy/22204/

Tracking has nothing to do with clouds or weather; it increases the efficiency of the solar panels in the early morning and late afternoon when the angle of a fixed panel is poor. Pretend your eye is the sun, stick a post-it-note on a globe, and rotate it. You'll see the aspect ratio change. Then, pretend your hand is a solar tracker and I think you'll see the difference! Even with a solar tracker, you'll still see less power in the morning/evening due to greater atmospheric attentuation (lower sun angle = shining through more atmosphere), but it will be more efficient than a fixed panel. It also helps account for seasonal differences, but these are less of an issue because the cos of the angle between summer and winter is small.

Solar tracking is typically not economical for a-Si solar panels, though. Solar tracking really comes into its own when using parabolic mirrors to concentrate solar energy, as the mirrors must be perfectly aligned to focus the solar energy on the element. So, if you use a parabolic concentrator, you'd need solar tracking. Otherwise, your customers are probably better off just spending that $15k on more panels because they'll see a better return.

Also, why bother with batteries unless they're off-grid? Grid-tie, and save them a lot of cost, complexity and toxic material!

If they're doing this expecting a positive return on their investment... they're not going to see it. Unless there is a HUGE government subsidy, they're going to lose money on this, and lose big. (Even if there is a subsidy, other tax payers take the hit for them- it's still a financial dead-end.) If they want to do it for environmental reasons despite the loss, that's their call, but please make clear to them that they're not going to get any $$$ returns on their investment. Especially in Canada, wow. They may not even make a return on the energy investment of the panels that far north.

Thanks Steve for all your input.

Our client, as you state, "for environmental reasons" is their real motivation. Both he and his wife understand that there will be no return on the investment as far as the grid-tie goes, but it will give a boost to other members of their group to maybe invest a bit more dollars in research towards alternate energy production here in Alberta.

Because we are doing this contract, I think it's important for us to do it so the client can promote this stuff as much as much as he can.

As far as the battery stuff goes, there is the usual stuff going on about the supposed 2 year disposal issue for the deep cycle batteries when the batteries finally give up. (Which in my mind is a bit too short because from my research, they normally can go for 5 years without a significant deterioration.) Our client has made his own arrangements for that with some of his own business folks that he has more contacts than we do regarding battery replacement. From what he has explained to me about that, he is very aware of the requirement to replace the batteries and I checked into his disposal depot, and they are well known for doing it correctly.

In the ultimate end these folks (who are paying for it all) are trying to set an example for others, even though we know that it won't, for the time being, pay back the investment right now and maybe never but that's a decision they have made on their own.

From my point of view, we have work to do. It keeps my guys - even though it's way too cold outside right now and we have a a lot of REALLY good super neatly wired inside stuff, it keeps all of us interested in why we do what we do.

BTW

In the mean time it's minus 25 degrees Calcium and I have put a stop to the outside work for the next little while.

VRLA batteries have a very limited life. Even in UPS applications where deep cycles are exceedingly rare, 3-5 years is typical, and if you lose just one cell, you lose the entire string. Wet-cell lead acid will last longer, but they'll need to go around every month and check electrolyte levels and do other preventative maintenance. And they might not like the idea of all that acid in their basement.

Li-Ion battery has made HUGE progress in the last few years, and may be worth considering. They've developed techniques to stretch the life out of the batteries, too. If I recall, the Chevy Volt only charges it's Li battery from 40-80% capacity, never fully charging it or discharging it. And Chevy is expecting it to last 10 years under normal daily use.

*All* these batteries need to be air conditioned, too. VRLA battery life is cut in half for every 15 degrees above 77F, and others are similar.

Of course, if your client is up on solar as much as it sounds, they probably know *exactly* what they want and all the pros and cons of it and just need you to put their plans into action

An update on this installation.

We are now finished (even though the outside temps were around minus 3 bazillion knots below kelvins) with the panels.

As things progressed our client wanted 3 more 93 watt panels and sun trackers installed to increase the capacity even more. It took us two extra days to get that done.

We also installed 10 more lead-acids to handle the charging from the panels. When the whole installation was complete, the whole house was supplied with more than adequate energy to run for at least 2 days without any direct sun. The meter on the outside of the house was running backwards at a rapid rate during the day yesterday when I saw it.

As Steve said, the next move to upgrade the system is likely a move to Li-Ion batteries, or what ever new technology that might show up for energy storage, but so far the system will have to live "on it's own" for the time being.

If we have to do something like this again? I don't know, but we learned a lot about how to get it done, from the AHJ's "opinions" to land zoning issues with the City to the technical aspects. It was a fun "once only" project for now, but I get the feeling that it's going to come up more often these days here in Alberta.

BTW Steve, we put in a couple of 4 inch diameter pipes along with a variable speed coaxial fan in the ducting, running from the outside and over the battery bank and then back outside again with a shroud that contained the air movement over the batteries to keep them as cool as we could. So far, even with minus 30 outside the batteries stayed at a nice cool plus 10C so that seems to be working O.K. Summertime might present some issues when it gets to PLUS 30 however.

We'll be back to deal with that this July, I think. I just hope the batteries don't overheat when the air conditioning system is pulling 30 amps in the house. The system will shut down if the batteries get above 50 degrees C so I'm hoping it's not going to be an issue.

Whether it's worth it or not? My opinion is that the price is just way beyond what the average HO is willing to go for. Our client just spent a little bit over $45,000 to get this all done up. Kudos to them and a brave decision for a proof of concept for them and their friends. I applaud them for their guts at spending funds that will likely never be fully recovered.

What's sad is they'd spend all this money to put this system in Alberta, when, environmentally, they'd have been far better off to have paid to put a grid-tie-only system on the house of a low income family in the arizona desert, which would have provided a MUCH larger offset than the grid power they'd consume in their own house. Probably have gotten 3-4x more energy for their dollar. Would have been even better to have invested in an energy company making an even more efficient commercial-sized solar farm.

Oh well, it's their money.

Why do you think that the money would be better spent in Arizona? Both Arizona and Alberta would get roughly the same amount of daylight during the course of the year.

I'm not a meteorologist, but if I remember my high school science correctly, the equator gets 12 hours of daylight and 12 hours of darkness everyday of the year. The north pole gets 24 hours of daylight during the summer and 24 hours of darkness during the winter. The South pole gets 24 hours of daylight during the winter and 24 hours of darkness during the summer. But all 3 average the same amount of daylight during the course of the year. The same is true for all areas in between the poles and the equator.

Or have I forgotten a key lesson from 30 years ago?

Bruce

You missed the part about the attenuation of light in the atmosphere. That is why it is 114f in Phoenix on a day when it might be in the 80s there. There also are not many cloudy days in Phoenix and snow will never cover your collectors.

Exactly. There's temperature derating of a couple percent, too (cold aSi panels are less efficient), but cloud cover, atmospheric attenuation, condensation/frost and snow account for most of it. Sufficed to say, a panel in Arizona will make far more energy over it's life than that identical panel in Alberta.

Let's put this "air resistance" issue in perspective.

Assume you start to get a sunburn at sea level in 60 minutes.
In Reno - about 1 mile elevation - you will burn in 30 minutes.
At Lake Tahoe - about 1-1/2 mile elevation - you will burn in 20 minutes.

The same applies for latitude. If a certain panel generates
100 watts at the equator, at 45 degrees latitude it will produce about 70 watts. At the Arctic circle, it will produce perhaps 50 watts ... all because the sunlight has to pass through more air to reach the panels.

Hey Reno, it has been a while for me here. Although the atmosphere thickness does defuse daylight more at northern latitudes, the loss is minimal enough where it does not have any real bearing on the size needed. Panels are deliberatly under rated on their outputs because the panels will degrade over time and many panels come with a 20 year power output warranty. My panels up here when oritentated right exceed there rated wattage when they come out of their box. The only time the output is really affected like at the Artic Circle is in the winter time which the sun is at its lowest and is under the horizion hence zero day light.

It would effect the total isolation hours you would get up here but then again so does everything else so the "loss" per say due to atmosphere thickness is minimal since the atmosphere is the thickest at sunrise and sunset and your array is typically not optimally oriented at that time of the day.

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.