High Voltage vs Low Voltage with Classic 150

[ChrisOlson]

I've been playing with my panels, trying to decide what's best, and wonder what the solar experts think?

I put a re-configurator switch (technical term) in the combiner so I don't have to mess with high voltage wiring that could leave me quiverin' like a bowl full of jelly.

If I flip the switch to Low Voltage the panels operate at about 80-90 Vmp.  If I flip it to High Voltage the panels operate at about 105-120 Vmp.  At solar noon I switched it back and forth and measured the power output to the battery bank.  Can't tell one bit of difference in output.  However, the Classic seems to run hotter (the cooling fan runs more) on high voltage than it does on lower voltage.  I'm guessing any gains in the wiring run at the higher voltage are eaten up in the Classic having to step higher voltage power down to bank voltage, so it's a wash.

What would be the advantage (if any) of leaving them in High Voltage Configuration on cloudy days and early morning/late afternoon?  I did notice one thing - I got one wind turbine tower that casts a shadow across the array from about 9:30 to 11:00 this time of year (in summer it doesn't do that).  On High Voltage the controller doesn't complain about PV Shading.  On Low Voltage it it does.

The wind is blowing good today so the controller doesn't get to do much now in Absorb.  But when the wind picks up the controller floats the panels up to 128 with only a couple amps coming in like this to limit their output.  And it says the Voc is 137


If the wind turbines go into Full Crank then it stops putting out power altogether and shows 136



In really cold weather I suppose that could be an issue and cause the controller to lock the panels out in HyperVOC.

And now here's what happens once it drops into Float in high voltage config - the controller absorbed the bank for the minimum 100 minutes and then dropped into float right away.  The green float light is on on the side of the display, and the red light is on inside the controller, which means AUX 1 is active and the system is heating water at 2 kW load for the rest of the day:



When the wind isn't working it's fine.  But when the wind turbines go to Full Spin the controller still cuts the panels back to just about zero and the panel voltage floats up to Voc:



I think this will work OK for now.  But I wonder what problems this could cause in really cold weather (like 20 below F)?
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Chris

[gww]

Chris
Im the guy you took three days exsplaining your hot water dump system to before I even had a clue.  Thank you.  If your dump has kicked in through the aux on the classic,  why would the panels ever cut back even if the wind kicked in unless the dump is not big enough?  Is everything;  wind and solar going though one classic?
gww

[ChrisOlson]

No, all power does not go thru one Classic.  The Classics on the wind turbines are set at higher charging voltages than the solar one is.  That allows the solar one to control the water heaters and properly regulate charging of the bank while the wind turbines continue to run in Bulk MPPT charge state at maximum available power.

I'll try to explain this by charge state for each controller:

Solar Bulk MPPT
Everything is running at maximum available power to get the bank up to absorb voltage.

Solar Absorb
Wind turbines continue to run in Bulk MPPT because their charge state voltage set points are 0.2 volts higher than the solar.  The solar controller attempts to maintain absorb voltage at 30.0 volts by throttling the panels back if the wind puts out too much power, and even engaging the water heating load momentarily if cutting the panels back doesn't work.  Absorb goes on for minimum one hour, 20 minutes and maximum 3 hours, 30 minutes.  After the minimum timer has expired the controller looks at amps required to maintain the absorb voltage, and if it's less than 24 amps it drops into float.

Solar Float
The solar controller can no longer maintain voltage by throttling the panels back so it turns on the AUX1 and starts heating water.  The wind turbines are still running in Bulk MPPT, putting out full available power.  This goes on indefinitely until the loads finally drop the bank to rebulk voltage and let the solar controller go back to Bulk MPPT charge mode.

Wind Absorb
If the water heaters get up to temp and shut off, the first thing that happens is that the solar Classic shuts down the panels completely.  Then the bank voltage starts to rise.  When that happens the Classics on the wind turbines are still in Bulk MPPT because they never reached their Absorb voltage set points.  So the bank shoots right up to 30.2 volts (absorb for the wind turbines).  When the wind Classics see that 30.2 volts they unload the turbines to whatever it takes to maintain that voltage for 30 minutes.  During that 30 minutes the turbines are running balls out and the voltage clippers kick in to limit turbine speed to 450 rpm.

Wind Float
When the bank drops back into float (as far as the turbine Classics are concerned), the AUX1 in the wind Classics are set to come on only in float.  The AUX 1 engages the clippers really hard and pretty much shuts the turbines down - they kind of still turn a bit, but they turn really slow and remain shut down until the bank drops to rebulk voltage.  They don't all drop out at the same time.  Due to slight differences in how each one measures voltage, sometimes only one or two will get all the way to float and that puts all the loads on the remaining one that never got done with absorb so it drops back into Bulk MPPT because it can't maintain absorb voltage all by itself.

It's kind of hard to explain, really, unless you've worked with a Classic controller.  But that's what it does.

You have to get the notion out of your head that the water heating load is a "dump load".  It's not - it does not control voltage whatsoever.  The controllers are fully capable of controlling charging voltages without it.  It's main purpose is to keep the system at full power once the bank is charged up, and use that power to heat water.
--
Chris

[gww]

Chris
What does VOC stand for?  I understand the hot water is a usefull way to use made power when you have more then you need for battery charging and loads. I am impressed with the depth of your explinations.  I didn't, even with all that, understand your problem.  Is it that the panels are shutting down due to too much power or is it that the voltage is going to the edge of the classics capabilities?   "Or"  is it that I am still so green I don't understand RE language at all?  I probly can't help but I always learn from you.  I'm like the guy at the bar that leaves when it's my turn to buy.  In my defence I have no money.
Thanks
gww

PS
It probly would make no sence to make the solar the higher of the two and put the hot water on the turbine controller as the wind is prolbly less reliable and would it also use the clipper if configured this way?  I guess you have to lose the power to be able to keep the batteries fully charged.  Just food for thought.  There is supposedly a monitoring system that will work with the outback system that uses a computer program to track trends over long periods of time and then schedules loads "hot water" so that there is barly enough to still fully charge you batteries.  Probly works better to keep you from selling in a crappy grid tie set up unlike your off grid.  Sort of like a cruse control that learns the terrain.  Have you heard or even see a use for a generic program like this?  I hope after all you posted that it is the cold weather raising voltage that worries you.  Not cause your worried but because maby I understood.

[ChrisOlson]

Basically, with the panels in high voltage I'm worried that in really cold weather they'll go over 150 volts.  That won't hurt the controller but it will cause it to go into HyperVOC where it stops putting out power until the panels drop below 150 Voc again.  This means we come home and find out the panels were dead all day and didn't do anything.  The AUX is still active in the controller when it goes over 150 volts, though (up to like 167 Voc, or something like that).

Voc is Voltage, open circuit.

Using the clippers to heat water doesn't work.  I tried that already.  I mean, it works, but it's not the best way to dump 8 kWh into the heaters every day because it keeps warming the elements up, then cooling them, warming them up, etc..  To heat water efficiently those elements need to come on and stay on at their rated power, otherwise they get scale on them from running too cold.  Plus the clippers are three phase, which requires three elements (or three phase elements).

It works better with the solar controlling the water heating and let the turbines do whatever they do because the solar is more stable and doesn't wildly vary from trickle charge to wire melt in the blink of an eye.
--
Chris

[gww]

Chris
Too bad you can't put a simple timer to make the switch on your high voltage to low voltage connections.  Then you could let the voltge drop in the middle of the day when it really wouldn't change your output.  When under load does the voltage drop?  If it does maby the shading from your turbines will be a natural timer and would bring the voltage down even if they were high for a short period.  Once under load again the voltage might be controlled?
Thanks
gww

[ChrisOlson]

I don't really want to switch it back and forth.  Today we got a cloudy overcast day with drizzle now and then.  The high voltage configuration is working better with the cloudy conditions by 30-40 watts.

I'm not sure how the controller looks at Voc.  It does a performance sweep whenever the output changes by more than 10% and the panels momentarily go Voc when it does that.  In really cold weather I don't know if the loaded Vmp voltage is used by the controller to determine if it's over volts.  I think if Voc is over 150 it will lock out in HyperVOC, regardless of what the loaded voltage is.  Guess I'll have to wait and see.
--
Chris

[gww]

Chris
136.6 volts is mighty close to 150.  If there is any head room in the classic, you might survive.  Plus 10% is 150.25 volts.  It should be interesting and I hope next spring you will update your results.
Good luck
gww

PS  Its a good thing you got that new generator incase it goes badly.

[boB]

Chris
136.6 volts is mighty close to 150.  If there is any head room in the classic, you might survive.  Plus 10% is 150.25 volts.  It should be interesting and I hope next spring you will update your results.
Good luck
gww

PS  Its a good thing you got that new generator incase it goes badly.

There is actually a slight amount of headroom, but not much.  I think it will work up to 150.9 volts and stop
at 151.0 volts input....  I think.

boB

[ChrisOlson]

The way I read the manual, if it goes over 150 it will go bank nominal above that in HyperVOC (shutting down the panels) but the AUX will still be active up to 174 volts?
--
Chris

[boB]

The way I read the manual, if it goes over 150 it will go bank nominal above that in HyperVOC (shutting down the panels) but the AUX will still be active up to 174 volts?
--
Chris

Well, neglecting the decimal part, the next higher voltage above 150 is 151 so that's what is meant there.

The Aux1 and Aux2 high voltage settings are good for HyperVoc voltage (150) plus 60 volts except for
Aux2 Clipper function, where it is good up to HyperVoc (150V).

boB

[ChrisOlson]

OK.  I think I understand that.  So it won't hurt the controller if the panels would go a few volts over 150 - they'll just stop working.  Right?

I guess I'd like to continue using the higher voltage configuration if I can.  I see a most definite improvement in less than ideal solar conditions, and seems pretty much a wash in good solar conditions.  The less than ideal conditions, of course, is when the most energy production is good.  It's not much, but it's some.  Flipping it back and forth and comparing several output readings from about 10:00 to 3:00 it seems to consistently produce 30-40 watts more.
--
Chris

[boB]

OK.  I think I understand that.  So it won't hurt the controller if the panels would go a few volts over 150 - they'll just stop working.  Right?

Right.  Correct-imundo.  Affirmative.  QSL

boB

[ChrisOlson]

Right.  Correct-imundo.  Affirmative.  QSL

 
--
Chris

[gww]

Chris
 Here is something that I thought might interest you.  Near the end it gives a few interesting possible suloutions to your possible issue.  http://www.outbackpower.com/forum/viewtopic.php?f=9&t=346&p=4341&hilit=gvfx3648#p4341
I would exsplain it but I don't know how but I am sure you will reconize how to handle it.
good luck
gww

[dave ames]

OK.  I think I understand that.  So it won't hurt the controller if the panels would go a few volts over 150 - they'll just stop working.  Right?

Right.  Correct-imundo.  Affirmative.  QSL

boB

Agreed, Don't think we can get your array cold enough to exceed your hypervolt limit of 174 VOC. 150+24

Looks like we don't have to get that cold to go into lockdown though..only about 25*f..using a voc of 137, the string calculator shows we have to get colder than -60*f to break it. (go over 174voc)

I'm curious if anyone has managed to take one of these classics out yet?

I only got to play with one (classic 150 on solar) for a few hours and was impressed (not my system).

Your out front with these controllers Chris, solar and wind! I'm always following along with your great projects. Thanks for All your sharing.

Cheers, Dave
.... ..  .... ..

[ChrisOlson]

Looks like we don't have to get that cold to go into lockdown though..only about 25*f..using a voc of 137

Dave, what are the calculations to figure out the Voc with change in temp?  You're saying that at 25° F I might hit 150 open?
--
Chris

[gww]

CHris
If they were sharp panels the link I posted above says at -5 degrees ferinhight you would have to times the voltage by 1.25%.  137v x 1.25 = 171.25
gww

[ChrisOlson]

Actually they're 250 watt Helios 6T250's, made in Milwaukee, Wisconsin:
http://www.heliossolarworks.com/Portals/132436/docs/6t.pdf

It says in the specs that they have 37.4 volts @ 77°F cell temp.  So with four in series that's 149.6 volts.  I'm probably pushing my luck with four in series and I should drop back to three   

One of the RE outfits 40 miles from us handles these Helios panels and every time they get a pallet in they call me up and go, "Hey Chris we got a good deal on a pallet of panels - want a couple?"  Sure.  Why not.  So I've kept collecting them in pairs and now I got 12 of 'em.  When I had 10 I was running two in series and paralleling the 5 pairs in the combiner.  When I got 12 I went to three in series.  And then I got the wild idea recently about going 4 in series.  This latest wild idea was probably not a good one.
--
Chris

[dave ames]

Looks like we don't have to get that cold to go into lockdown though..only about 25*f..using a voc of 137

Dave, what are the calculations to figure out the Voc with change in temp?  You're saying that at 25° F I might hit 150 open?
--
Chris

It's cool to see what your array would do, think your right though, that four is pushing it a bit.

Could do the pencil and paper calcs with the *c to *f conversions and the heilo data of 0.32%/Degree *C change in VOC.

Or cheat and use the midnite calculator:
http://www.midnitesolar.com/sizingTool/

Note that they use 0.33 as a standard..Be fun to input all your data and see what pops up...The sizing tool is down at the moment but maybe later?

Geepers those are big panels, don't think I could wrestle those around by myself!

Great fun!
Cheers, Dave

[ChrisOlson]

Geepers those are big panels, don't think I could wrestle those around by myself!

Every time I got another pair of panels I built another roof mount rack for them.  So each pair is on its own rack on the shop roof.  To get them up there I leaned the panels against the shop wall, then backed my pickup up to the shop wall.  My wife and I stood on the tailgate (the truck is a Dodge Cummins 4 x 4 so it's pretty high off the ground).  Then we grab a panel and hoist it up and slide it up into the rack.  My wife is 5' 11" so she has no problem reaching it.  Then my wife holds it there while I jump out and climb up on the shop roof with a ladder.  She positions the panel so the bolt holes line up and I slip one bolt in to hold it on one of the top holes, then finish putting the rest of the bolts in to bolt it down.

Where there's a will, there's a way.   

This is a couple of those Helios panels on the Standard Ground Mount System:



I never weighed one, but I suppose they're 50 lbs each.  Over a year ago I bought two Schott Solar 250's and those were polycrystalline panels.  Now these suckers were heavy!  Shown on the Standard Picnic Table Mount:



When I started buying Helios panels this past year I ended up trading the Schott's in on a couple Helios 6T250's so all the panels would be matched because the Vmp was slightly different between them.  I also used to have 10 Sharp 123 watt 12 volt (17 Vmp) panels and I traded those in on new Helios 6T250's.  The place where I got all the Helios panels gave me a really good trade-in price on my used panels.  But they work better with the Classic if they're all matched.
--
Chris

[gww]

Chris
I love that you always post pictures.  What is that between you panels in your first picture?   Hot water or hot air solar heater?
Thanks
gww

[ChrisOlson]

That's a solar hot air panel.  Works really good too.
--
Chris

[boB]

You have snow there ALREADY

Or, maybe it's just that global warming ??

Gee...  I'm gonna have to try moving south for the winter !

boB

[ChrisOlson]

You have snow there ALREADY

No, that was from early last winter or early this spring - don't remember which.

Typically, though, solar panels in Wisconsin are a device that was invented to collect snow at the proper angle so they effectively reflect all the sun's energy down to the Bahama's.
--
Chris

[Frank S]

Typically, though, solar panels in Wisconsin are a device that was invented to collect snow at the proper angle so they effectively reflect all the sun's energy down to the Bahama's.
--
Chris

all the more reason to book a 4 month stay in fernandezbayvillage that way you would bet some benefit from your array in the winter time

[ChrisOlson]

We go to Sweden instead, where most of the country is above the Arctic Circle   

We get really poor solar conditions from about mid-December thru the middle of February.  Mostly due to lake effect from the largest body of fresh water on earth.  If that lake freezes over (which has only happened a couple times in my lifetime) then we get clear perfect solar conditions.  But usually Lake Superior is nothing but a big weather modifier otherwise.  That lake is bigger than the state of South Carolina and it has more water in it than all the rest of the Great Lakes combined, several times over.

Even in the summer, if the wind is from the south we get hot weather.  But if it turns to the north it can get downright frigid here in the middle of July.  The water in that lake never gets above 46 degrees at the surface out on the big water, and the temp at 660 foot depth is a constant 39 degrees year 'round.  Some of the shallow bays can warm up to 60 degrees in the summer up around Wisconsin Point and the Apostle Islands.  But otherwise that lake is just plain big, cold and deep.  And it causes drastic weather patterns around here sometimes - it's not unusual with our winter time nor-easters to not see the sun for 6 weeks at at time in the dead of winter.  And temps can drop to 40 below once you get 30-50 miles inland from the lake because it has the effect of sucking every last bit of heat out of the air to evaporate water off the surface.

We love to fish Lake Superior but no sailor with any experience will go out on that lake in October and November.  There has been over 350 shipwrecks on Superior since 1890 and over 1,000 sailors have lost their lives.  The most famous was probably the Edmund Fitzgerald, which broke up in 51 foot seas and went down with all hands 17 miles from Whitefish Bay on Nov 10, 1975.  The Fitz left Superior, Wisconsin on Nov 9 in clear beautiful weather with 13,600 tons of iron ore.  The next day a storm suddenly popped up with 100 mph winds and all that was left of the biggest boat on Lake Superior was for Gordon Lightfoot to write a song about it.
--
Chris

[birdhouse]

i went to school at NMU in marquette. 

i know what you're talking about.  i've seen 35' waves at the shore when there was barely a storm brewing. 

lake superior is a beast that will never be conquered...  she merely lets boats pass unharmed when she isn't looking.

adam 

[ChrisOlson]

When Superior claims one she never gives up her dead either.  If you go down on Superior there is a 99.9999% chance your body will never be found, based on history and the number of people that have died on that lake.

The Ojibwe call Superior "Gichigami" - translated to English, "big water".

My wife and I were going to buy this yacht this spring.  It's a Chris Craft Roamer, originally built in Holland, Michigan













It was moored at the marina on Madeline Island all summer but they got it out of the water now.  They didn't want much money for it because it's a steel hull and it needs some plates replaced.  And it's got 6-71 Detroit diesels and nobody would touch it with a 10 foot pole with those old Detroits in the engine room.  We sailed it from Madeline to Superior to try it out and we liked the boat.  But we have to have a marine surveyor come down from Thunder Bay and x-ray the hull to find out how bad it is.  Plus they get more for a slip at the marina for one summer than the boat costs.  So we didn't buy it.
--
Chris

[Frank S]

Chris' technically Lake Superior may be the largest single body of FRESH water on the American continent but Lake Huron & lake Michigan could be classed as a single lake since they are at the same elevation separated only by a narrow straight not by a river.That would give them a larger surface area but not volume.
 However if we were to consider the largest FRESH water lake by volume lake Baikal in Siberia with a total volume of fresh water roughly equivalent to all 5 of the Great lakes combined.  between the 5 great lakes & lake Baikal you are looking at nearly 44% of all of the fresh water on the planet. 23% in Baikal alone depending on who's estimates you look at it could be only 40% Lake Superior contains nearly as much or possibly more fresh water as all of the (FRESH) water contained in the total Global Glacier content not all Sea Ice is fresh
 When   Etienne Brule discovered lake Superior between 1615 & 1618 he must have wondered what the heck? I wonder what he thought after paddling up the St Mary's when he arrived at Lake Superior. Can you imagine traveling by canoe around Lake Huron Erie or Ontario  possibly later  lake Michigan  but to adventure up the St Mary's  which in places is wide enough to be considered a small lake by itself only to end up at a body of water which would  stretch for miles in every direction, he must have thought he had found an Ocean except for the fact that it is fresh water.

[ChrisOlson]

When Etienne Brule discovered lake Superior between 1615 & 1618 he must have wondered what the heck? I wonder what he thought after paddling up the St Mary's when he arrived at Lake Superior

Brule only "discovered" Superior as far as the white man is concerned.  The native people who lived here thousands of years before the white man ever came knew more back then than the white man knows today about this area and Superior.  I've played in her waters since I was a kid, and it's one of those deals where you develop a respect for her power very early or she will become your grave.
--
Chris

[Mary B]

I got to swim in the center of superior one summer, my  brother in law tacked without warning and dumped my sister and myself over. We were both wearing life jackets so it was just a matter of freeze and wait for him to come around. Brrrrr

[ChrisOlson]

Turns out my voltage decision turned into a mute point today.  I went and bought two more of those Helios 250 panels.  Got a "good deal".  So now I got 14 of 'em.  So now I have to wire them in series pairs and drop the input voltage to about 55-60.  The Classic can't handle all 3,500 watts on a 24 volt system.  But I'm going to put all 14 of 'em on one Classic anyway.

On a perfect day I'll never get full power because the Classic will only put out 94 amps for a little while - until it gets hot and derates to whatever.  But I don't need full power anyway.  What I need is more power on the average day when the panels only run at about 75% of their rated output.  And on cloudy days when they run at less than that even.

I should be able to push that Classic right to its limit on the average day with 14 panels.  I'll find out how good that controller is yet   

I went right to work and got the new roof rack partially built for them tonight.  I never took a photo of one of these things before when I built the other ones.  The rack is only long enough for where the bolt holes are on the panel frames - the panels hang over the top and bottom of the rack by about a foot on each end.  The two pieces on the floor bolt to the rafters in the shop and the the whole thing can be tilted because it pivots on the bottom.  The bottom of the panels hang over the eave of the roof so I can get the snow off in the winter without it piling up on the roof.  The back stands that are adjustable for tilt angle aren't on yet in the photo.



I have mounted them in pairs because to tilt them for the seasons I have to climb up on the shop roof and lay on my back under each rack, take the bolts out on the back legs, adjust the panels to where I want them, and put the bolts back in.  Trying to handle more than two panels at once is too heavy.  It's a good thing I only change their angle twice a year.  I lay them down parallel with the roof in the summer (about 30 degrees).  And tilt them up almost vertical in the winter (75 degrees).

The rack is totally made of 1-1/2" x 3/16" angle, and when they're parallel with the roof in the summer they're up off the roof 9-1/2".
--
Chris