Wind vs solar

[cardamon]

Ok so now that solar modules are under a buck a watt, what does this mean for wind?  Granted most people who participate on this site do wind because they have one or more of the following: the time, the know how, the tools, and find it fun, but say from a purely economic standpoint can an argument be made that wind is worth it?  I currently have 500 watts solar and 1kw wind and next summer I am thinking of adding a KW or two of solar for domestic space and water heating.  I havent played with any numbers yet, but even with my killer wind site and poor winter sun-hours here in central NY, I think a pallet of modules may be the way to go.  I love playing with wind as much as the next guy but I have a million projects and have to work for a living.  Just wondering if others have has this dilemma and what you concluded...

[Frank S]

 All I can say would be that one sort of goes with the other wind no matter how you look at it has the potential to be able to work 24/7 whereas solar is limited to a few hours per day. Without solar wind  simply cannot be depended on to produce all of the time and without wind your storage has no chance of being supplemented at night. and neither are worth having installed if you are off grid without a good engine driven standby generator

[Mary B]

I currently have solar but am thinking of adding a couple hundred watts of wind. Winter is coming on so less sun but generally a lot more wind.

[SparWeb]

I'll only go into solar PV big-time if I can mount them on trackers.
It's gotta move or do something, man.

But dollar for dollar, PV is the way to go.  Everything in wind power is more expensive.  Even if you make the PV cells and the wind turbine yourself, a ground-mount pole costs a lot less than a tower.
The sun comes up every day.  The wind doesn't blow every day (don't I know).

[oztules]

Solar under $1/w means wind is not an option worth economically persuing..... and I'm on a windy place.
If your really going off grid it is not cheap..... but very much better than it was.

I built 4kw (in this system) of solar. I use about 13kwh/day inc elec hot water and stove/oven etc etc. No gas appliances at all.
In the last 300 days (inc all of winter and autumn and part spring) only 25 days fell below the 13kw. If I double the solar for another 4000, only very very few days will fall below the 13kwh mark.  Next 4kw will be here within the week. All ground mount, as trackers are just expensive toys... buy more panels, and stay fixed.

So buy as much solar as you can, a half decent battery bank, and every night but a few will see you with full batteries, and mostly about 20kwh to 40 kwh spare to throw away if you have 8kw at 40 degrees south in the windy ocean.

Windmills are expensive, and poor producers. (over here it is an exception, there's a 1.3kw AWP that most days gets above 24kwh, but great site..... and he is even going to buy more solar and toss the mill as it is 7 years old now, and not worth the maintenance/upgrade.

A really good robust, way over powered off grid system is now available for less then 15 grand ( 8 for panels, 4-5 for  batteries and the rest for 18000watt surge 6000watt cont pure sine inverter / charger (less than 800 dollars (weighs over 100lbs)) and charge controlers.

This is big news really from a few years ago when $30000-$50000 was normal, and a mill was necessary because you could not afford to waste solar money.

Note, to do this we need to be very wasteful, ie face 3kw to the east, three to the north, and 2 to the west. That way your likely to recharge the o/night deficit (5-8 kwh) before lunch most days..... we can just waste the rest............. at that price who cares.

There is no point facing them all north (southern hemisphere) or all south (northern hemisphere), as few banks can use that sort of withering power.... spread it throughout the day.

I have 2x 4 meter mills, but don't use them anymore.... sad really, but the power is just not required95% of the time.... not worth the real estate.

I set one up recently for a neighbour for less than 5000, as he already had the batteries, and only needed 2kw solar to cover. He has not used the genny for the last 6 months (through winter as well).... but he does not burn power up like I do either. His battery does not drop below 48v. It's 400 ah, and does not get enough excercise I reckon.



..................oztules

[ChrisOlson]

I'll only go into solar PV big-time if I can mount them on trackers.
It's gotta move or do something, man.

LOL!  I think that could be incorporated into a sig somehow   

The sun comes up every day.  The wind doesn't blow every day (don't I know).

The sun might come up every day.  But it don't make power every day.  If you are grid-tied, or have grid power, then I'd say wind power is a waste of time.  But if you are off-grid, wind power is worth it's weight in gold.  If you live off-grid and only have solar, and then get a week of cloudy, overcast conditions where the solar don't make even 10% of its rated capacity you're going to be running the generator.  A single wind turbine many times can't carry your loads or charge the bank, but it can get you thru to the next good solar day and minimize the amount of time the generator runs.

Off-grid gen power typically costs upwards of a buck/kWh.  You can pay for a $10,000 wind turbine that produces 2,000 kWh/year within five years in an off-grid situation, just by saving that much fuel in the generator, and not having to replace the generator because it's wore out after producing 10 MW of power.

That same wind turbine with grid power is useless because you can buy 10 MW of grid power for $1,500.

So it all depends on how you look at it.  After being in this off-grid business for close to a decade my wind turbines are like my guns - they can take 'em when they pry my cold dead fingers from around 'em.  And for us, wind power produces roughly 80% of all our power in the winter months (~25 kWh/day home).  Solar produces roughly 80% of our needs in the summer.  We have 3.5 kW of installed solar capacity, and that 3.5 kW of solar can't even come close to what a single 2.5 kW wind turbine can do in the winter.  And we got three of those turbines.

Suffice it to say we'd be living pretty damn meager here with just solar panels.
--
Chris

[oztules]

"And for us, wind power produces roughly 80% of all our power in the winter months (~25 kWh/day home).  Solar produces roughly 80% of our needs in the summer.  We have 3.5 kW of installed solar capacity, and that 3.5 kW of solar can't even come close to what a single 2.5 kW wind turbine can do in the winter.  And we got three of those turbines.

Suffice it to say we'd be living pretty damn meager here with just solar panels."

On those figures, 20 kw of solar will probably cover you even in winter  for your situation. Thats only 20,000 bucks.

The cost of your mills/towers/guys/buckles/concrete etc, and expensive control systems would pale into insignificance.

The $10000 mill for 2mwh per year, looks pretty silly against $10000 solar.... an easy  14mwh 40 deg south.

Dull overcast days can make good power with a decent sized system.

It needs to be foggy all day or very dark to even get mine down to 3-7kwh / day (with 4kw installed).... get some lighter sky and your back to 11-16kwh, some sun poking through for an hour or two, and your up at 15-21kwh...... a sunny day in winter gets you 25kwh, in summer probably only 28kwh. If you had 5 times that capacity, you'd struggle to get less than you needed on most days. Most times the batteries would be full up at dusk.

Have an honest look at your solar logs, and do the math. Even 30 kw if needed is still cheaper and more stable than your current system.

It is not a crime to not use your available power, and with solar you just ignore it. 30kw would net over 200 kwh/sunny day (irrigate perhaps with the overflow).... but so what, youll still get at least 25kwh in all but the darkest  darkest darkest days....... and no moving parts, no maintenance, no real fancy control required, and probably an unused genny.

Your system as it currently stands is very expensive, and still uses over 800 hours of generator time.....not my idea of ideal.

If you have a big system, and batts to go, you cannot lose with lots of solar. Actually in big lots, probably can get down to 70c/watt for certified panels.... can get 62c/w for container loads here, probably better there.



...............oztules

Edit: " summer probably only 28kwh. ".... why so low??? the panels are set for winter..about 45 degrees. In summer, the sun wont hit then till about 9.30 and loses them at about 4pm. If the angle were changed for 15 degrees in summer the results would be wildly different. They would see another 6 hours probably then.....


In winter they soak it up from sunrise to sunset, as the sun rises and sets north of east and west respectively in winter, and south of east and west in the summer. (opposite for you folks up in the northern hemisphere)

[Frank S]

If I remember correctly Chris's Pv set up has several settings that he changes for the seasons

[ChrisOlson]

I change the tilt for the different seasons.  They're almost vertical in the winter and at about 30 degree tilt in summer.

We depend on the "noreasters" that roar off Lake Superior from the winter solstice to March 1.  The days are very short - the sun comes up in the SE, makes a little arc across the southern sky and sets again in the SW.  There are 1.2 hours of available sunshine here per day from December to March.  The turbines will produce 50-60 kWh/day with zero maintenance all thru the winter, and many days we only run one or two turbines.

Those wind turbines will flat out stomp 20 kW of solar capacity into the ground and spit on it from the winter solstice to the first of March, with no problem.

We run our generator about 400 hours/year - mostly for peak load management.  I have our system set up that way because using the generator for peak load is way cheaper than buying more batteries to run the heavy loads.

Here we are - only the 3rd of November, and our 3.5 kW of solar produced only 2.0 kWh today.  There's still enough light so the panels are at 45 volts, but not enough to make any power:


The turbines produced 21.5 kWh.  And they're still running, floating the bank at well over it's float set point of 27.0 volts at 6:00 PM as I write this.  Depend ONLY on solar for off-grid power?  No freakin' way.  Not here.  We'd be hammering the batteries pretty bad right now - or running the generator.  And I RARELY run the generator to charge batteries - and that's because I got wind power.

YMMV - take it for it's worth.  But my experience is that anybody who says you can live off-grid in northern latitudes above 45 degrees with JUST solar power, without running the generator alot, or living pretty meager, has never actually tried it in an area where you would have ZERO incoming power for 18 hours a day.
--
Chris

[SparWeb]

I think I can see the truth in the different points of view of CO and OZ, but they are comparing "apples to oranges."  They live in very different environments.  It's obvious to me that one person can live somewhere that requires a balance of wind and solar to make a go of off-grid (or even grid-tied) living, while someone else living in a different place can do well or better with just solar alone.

[ChrisOlson]

Spar - there are many folks who don't comprehend living in a place where it's dark and dense overcast for weeks at a time in the winter.

But the upside is that in the summer we get longer days than the southern folks, and more perfect solar conditions because it's cooler here so the panels work better.

There are plenty of online tools where you can calculate your solar days for your location where you live.  These can help you decide how much money to spend on solar, and how much must spent on other power sources, if you are living off-grid.

With solar panels you can clean them off in the morning in the hopes that you'll get a few watt-hours out of them.  Then you get basically nothing all day.  Wake up the next morning and they're covered by another dusting of snow.  If you don't clean it off it crystallizes on there and forms a ice coating that is virtually impossible to remove without heat.  You do this for several weeks, and finally give up on them because they don't make enough power to justify the time and work it takes to keep them working on the remote chance that you'll get one day that the sun will break thru for a couple hours.

We can't put them on ground mounts here because the snow will bury them.  So they have to be on a roof mount.  And that makes it hard to get to them to clean them.  In just a few weeks this is what it looks like out our back door, day after day after day:



By the middle of January:



Come on up, oz - I'll show you how cold it gets here and how many thousands of lbs of snow 20 kW worth of installed solar capacity can hold.
--
Chris

[oztules]

No Sparweb, were comparing apples to apples. .... I'll explain as bluntly as I can.

Eg. In Chris's location with panels at 45 degrees all year, a 4kw array derated to 3kw of output (his controller is compromised see below) will produce an average of 7.5kwh per day in the depths of November  December.

The average output per sq meter in his area is about 2.3kwh/kw installed in November December.
In his area, there is greater than 5kwh/kw installed from May until August......

If he only had 16kw installed and used a decent controller regime, he would get in excess of 30kwh on average even in December.
If he had 30 kw (probably $27000 worth now days) he would have average of  over 50kw each day in December..... well over 1.5mwh per month even in nov dec.

Chris's mppt  picture,....... either his controller is set low, doesn't work properly, is not Mppt or he is just kidding.
If it is mppt, the max power point is not open circuit x no current..... unless it is turned off..... which I suspect it has for most of the day.

If you measure one thing and don't realise it to be another, then the results are dead wrong.

He notes 20kwh from the mills, so the solar has probably not contributed because the batteries did not take it/allow it/ set too low )under the mills), not because the solar had none to give. The real figure for solar into a batt bank with a decent mppt would be probably much much higher..... maybe 3-4 times higher, unless it was dark and I mean dark all day.

44.87° N      91.48° W 273 m above sea level in Wisconsin USA gets the figures I quoted from, not Chris's "experience"
From here:   http://rredc.nrel.gov/solar/calculators/PVWATTS/version1/US/code/pvwattsv1.cgi   for Eau_Claire.

The results in Green bay are slightly better, Lacrosse is slightly better and Milwaukee is better still.

I suspect the Govt over there knows, or Chris puts his panels in the shade, or he has not told the full story.

I stand fully by my previous comments, as they are backed up by the government  over there, and funnily enough, seem eerily similar to what is seen over here at 45 south. I'm only 40 south myself, but the figures are on the net for all to see, and do their own calculations.

I'm not making it up, I'm not comparing apples to oranges, just simple facts making simple systems.

It's possible that Chris is living under a mountain shadow, but his figures do not work out..... most probably because the Mills are distorting the picture very markedly, and he will only see what is happening on a still winters day, where all the power from the panels will go to the batteries. If the wind comes up, guess which one is easily turned down,so the mills can stay loaded.

I think Chris is comparing apples to oranges in this case.

Now once you get much north of the great lakes, it is more problematic, but at 45 north, it is doable for modest money (off grid is expensive no matter what you do, but much cheaper now than even a year ago.)...... and solar lasts a long long time with no upkeep..... all the money should go into solar. ( I suspect in Chris's case he could get another 60 kw for what he has spent so far   

"YMMV - take it for it's worth.  But my experience is that anybody who says you can live off-grid in northern latitudes above 45 degrees with JUST solar power, without running the generator alot, or living pretty meager, has never actually tried it in an area where you would have ZERO incoming power for 18 hours a day."

Well you must live in a dark hole. The rest if your state gets enough sun for an average of 30kwh/day  from a 16 kw array in Nov Dec.
Your experience does not reflect what is possible, only what you have thus far achieved with your systems as they currently stand.

The sun comes up every day, and when it's feeble you need a lot of square meters, and under $1/watt that is now doable by anyone.



..................oztules

[oztules]

Chris, Just read your post after I was typing.

I think if you drive current through the array, it will de-ice. The cells are just diodes, and if you make them conduct like diodes, they lose 1/2 volt /cell x the current, and this wattage  could be used to de-ice the glass itself.

I will look into this to see if this is commonly used/damaging.
I do not suffer that ignominious weather  at this time, but I suspect plenty do, and there will be an easy fix for it I would presume.

...............oztules

[ChrisOlson]

Chris's mppt  picture,....... either his controller is set low, doesn't work properly, is not Mppt or he is just kidding.
If it is mppt, the max power point is not open circuit x no current..... unless it is turned off..... which I suspect it has for most of the day.

We live in the North Woods:
http://en.wikipedia.org/wiki/Laurentian_Mixed_Forest_Province

in the shadow of the largest body of fresh water on earth, over 100 miles north of Eau Claire:
http://law2.umkc.edu/faculty/projects/ftrials/superior/superiorfacts.html

The government fails to point out that in order for solar panels to work the energy has to be able to get thru dense cloud cover caused by evaporation off that big lake in the winter time.  So they only do the studies down south in civilization from Eau Claire on down.

My controller is working fine.  It had been clicking back and from from Resting to Bulk MPPT for the last half hour when I snapped that photo of it.  The panels are wired for ~90 Vmp.  When the controller tried to get something from them the input voltage would drop to bank voltage and the controller would get .1 to .2 amps for a little bit.  Then it drops to zero so the controller clicks back out and goes back to Resting.  It monitors the input voltage and if changes or improves it tries it again.  But if the panels can't produce any more power than it take to run the controller, it disconnects and goes back to Resting.

It just happened to be in Resting when I snapped that photo.

The Classic controller has a "de-ice" mode in it (haven't studied the manual on it) where it backfeeds power into the panels to heat them up to de-ice them.  This will be my first winter with the Classic 150 on solar so I haven't tried it yet.

most probably because the Mills are distorting the picture very markedly, and he will only see what is happening on a still winters day, where all the power from the panels will go to the batteries. If the wind comes up, guess which one is easily turned down,so the mills can stay loaded.

I would like to add, oz, that my mills are on Classics and they are set so they work together with the solar.  The wind turbines will properly bulk, absorb and float the bank, at the same voltage set points as the solar.  I use an ingenious feature in the solar Classic called "Waste Not Hi" mode that uses excess power from either solar or wind, or both if its available, to heat water with 240VAC power.

The inverter will start the generator if our bank has not been above 27.0 volts within the last 24 hours.  Today the turbines kept the bank at around 28 volts - it never did make it to absorb.  But that's enough to keep the generator from running until tomorrow and we'll see if we get enough power to get the thing up to absorb so we can heat some water here.

We have not had enough incoming power all week to heat any water - our pre-heater is down to cold water and the main water heater is down to 130 degrees.  If it gets down below 125 degrees then the top element (2 kW) comes on with the stat setting and pulls power off the bank to keep us in at least 25 gallons of water at 125 degrees.  So I'm hoping either we get really good wind, or sun, or both tomorrow.  If we can get the bank up to absorb then the Classic fires that heater up with a SSR on it's AUX 2 output with PWM and uses anything the bank don't need to heat water.

So our system is not as hick stupid as you think it is.  But we DO depend on those wind turbines because experience has shown me they're much more cost effective than solar panels for winter time power.
--
Chris

[oztules]

"So our system is not as hick stupid as you think it is.  But we DO depend on those wind turbines because experience has shown me they're much more cost effective than solar panels for winter time power."

Maybe when solar was 3 bucks a watt, but not now. I'm not buyin it.... Even in Michigan on the lake at 46.47 deg north,

Station Identification
City:   Sault-Ste. Marie
State:   Michigan 
Latitude:   46.47° N
Longitude:        84.37° W
Elevation:   221 m
PV System Specifications
DC Rating:   4.0 kW
DC to AC Derate Factor:   0.770
AC Rating:   3.1 kW
Array Type:   Fixed Tilt 
Array Tilt:   46.5°
Array Azimuth:   180.0°
Energy Specifications
Cost of Electricity:        8.3 ¢/kWh
      
Results

Month    Solar Radiation
(kWh/m 2/day)    AC Energy
(kWh)    Energy Value
($)
1     2.81         287       23.82   
2     4.05         375       31.13   
3     5.45         541       44.90   
4     4.97         453       37.60   
5     5.54         494       41.00   
6     5.48         462       38.35   
7     5.43         473       39.26   
8     5.25         455       37.77   
9     4.15         362       30.05   
10     3.27         296       24.57   
11     2.32         208       17.26   
12     2.27         227       18.84   
Year     4.25         4634       384.62 
 
Note: even in November when I assume the temp differential is greatest from the water to the air aiding evaporation, they still get 6 to 7 kwh/day average ..... so 16kw will still yield average 26kwh/day.... at de-rated value.... more like a real 32kwh input to your mppt.

Further north and west gets us to Houghton 47.17 deg, on the lake

Station Identification
City:   Houghton
State:   Michigan 
Latitude:   47.17° N
Longitude:        88.50° W
Elevation:   329 m
PV System Specifications
DC Rating:   4.0 kW
DC to AC Derate Factor:   0.770
AC Rating:   3.1 kW
Array Type:   Fixed Tilt 
Array Tilt:   44.4°
Array Azimuth:   180.0°
Energy Specifications
Cost of Electricity:        8.3 ¢/kWh
      
Results

Month    Solar Radiation
(kWh/m 2/day)    AC Energy
(kWh)    Energy Value
($)
1     2.56         258       21.41   
2     3.70         337       27.97   
3     4.68         462       38.35   
4     5.72         514       42.66   
5     5.25         471       39.09   
6     5.56         468       38.84   
7     5.58         479       39.76   
8     5.38         464       38.51   
9     4.48         384       31.87   
10     3.20         294       24.40   
11     2.09         187       15.52   
12     2.11         209       17.35   
Year     4.19         4527       375.74   

Now we have 187x 1.3 (un-de-rate for AC)/30 or still over 8kwh/4kw array, or 32kwh for a 16kwh array.

So, your system is maybe not as good as you think, or your panels are covered with snow, or whatever or you live down a hole, but your situation is abnormal, and should not be used as a yard stick to design another system anywhere else is all I can surmise.

You DON'T need direct sunlight when you have a bigger system.

Your not the only one with water close by. 

I have the pacific ocean on one side (cold east) and a huge body of water to the west  Bass Strait)  which is some of the roughest water in the world, most dangerous water in the world, and which is shallow enough to heat up in summer, compared to the east coast sea which is close to the continental shelf      we get the same good ole cloud effects too..... but strangely that does not mean no power.

In winter I still get an average 12kwh/day....most of them cloudy, on the 4kw array, next year I will have 8.5kw, and a minimum of 25kwh/day.... I only need 13kwh/day.... power to burn big time.

The cost of wind power and all it's associated support system is not even comparable to solar now. It is no contest..... Before you needed it in the mix, or go broke buying enough solar to do what you can today. If your near the Arctic circle,then I'm all for windmills.... but +50 down to -50 degrees, solar will win the cost effective stakes.

When your experience was doing the figures, I can only assume solar was not sub $1/watt ..... but it is now, and I know your committed to your course.... until you work out whats really better.... like 12v msw to 24v sinewave etc. Personally I think 48v for your size requirements, but you don't, and it still works. You like batteries, I like cells, I think I'm right, and  you think that your the engineer so your right........

I have experience too, and on a remote island in the roaring forties, solar still wins easily...... and we can get 24kwh from a single mill very regularly...... we got wind! There are a lot of off grid systems here.


...................oztules

[ChrisOlson]

oz, you keep looking at places that aren't affected by that lake.  Sault Ste Marie, as an example has clear weather in the winter.  They are in same situation as Thunder Bay on the North Shore where there's superb solar conditions in the winter.

The only time we get good solar conditions here in the winter is when the lake freezes over, and that has only historically happened twice since 1900.  Our prevailing wind is NW-NE out of Canada in the winter.  When a high pressure area moves in from the west the clockwise circulation pulls cold air down out of Canada, over the lake, where it is warmed and pulls moisture out of the lake.  Then the air moves over land (northern Wisconsin) cools to the dew point and keeps us under constant thick overcast (or snow).

When a low pressure area moves in the counterclockwise rotation of the low pulls air from the warmer south.  That warmer air meets the cold air over Lake Superior and Canada and causes the warm air to rise over the cold air.  The southern air rarely contains enough moisture to cause cloudiness so we get warmer weather and some sun.  The low moves eastward and now we're on the back side of it and it acts just like an approaching high - again pulling moisture off the lake and putting it right over us.

It's called a microclimate.  From the Twin Ports to the Michigan border and south to US 8 thru Rhinelander, we live in it.  People come here to study it:
I am very excited to be at Northland College, a school where quality of teaching is valued as much as meaningful research experiences for students and faculty. Having grown up in southern Minnesota, I was always fascinated by weather especially severe storms (summer and winter). However, in graduate school, my interests changed focus to the impact of regional scale phenomena on the large scale climate. The microclimates in northern Wisconsin are a perfect setting for my research as well as any weather enthusiasts, with varying landscapes inducing wild fluctuations in weather over small distances.
http://www.northland.edu/m-faculty-profiles.htm?id=322

You just can't seem to get it thru your head that the sun does not freaking shine here for six weeks at a time in the winter and we have dense overcast so that solar panels produce virtually zero power.

The microclimate here is so pronounced that we were not affected by the drought that wiped out crops in almost the entire rest of the US.  It rained here all freaking summer and we brought in all-time record crops out of the field this year.  Down south by Eau Claire they had total disaster and drought, along with the rest of the US.

So, sorry to bust your solar bubble.  But solar panels up here in the winter time are only useful to collect snow at the proper angle to reflect what little solar energy we get down to the Bahamas.
--
Chris

[Frank S]

Someone once said that in theory calculations and practice should yield the same results, in practice it doesn't

[ChrisOlson]

"In theory, there is no difference between theory and practice.  But in practice there is"
-- Yogi Berra

oz, you're welcome to come visit us in the middle of January.  But I'm warnin' ya - bring a shovel.  Because if you expect us to give you something to eat, I expect some help getting in my shop door:



--
Chris

[oztules]

Thanks for that explanation Chris, that clears up the situation for you.

All the more reason for folks to balance your input into this thread unless they live in your immediate area.
You effectively live in  a solar hole in winter.  An unusual area from the looks of it.

For the majority of the folks, my reasons stand.... for you they  dont.

Best of luck with your microclimate......... -4 is the lowest temp I have seen here.... frost but no snow

It would seem the rest of Wisconsin gets reasonable solar insolation, and for them the cheap cost of solar is a no brainer.

It also brings with it an immense amount of spare power if you way overdo the solar..... and it's dirt cheap to do now.

When my extra 4.5kw goes up, on a sunny day in summer I can reasonable expect 40-55kw day after day in the summer. No idea what to do with it at this point, if anything..... but you can bet even in the winter, the batts will be fully charged and regularly equalised, and there will still be a surplus of over 10kwh/day most days.
Winter will bring about 25kwh on average..... really bad days will be in the 4-10kwh range...... but they have to be very dark for that, and rain all day non-stop. This is unusual to last for more than a day or so, then the higher cloud lets the panels do much better.....  only need 13kwh/day

For the cost of Jamies AWP system alone, he could have put up 16kw of solar NOW, but back then, 1.2kw of solar  cost  over $10,000, so he just could not do much more, and back then it was the right decision...... but just those two items was over $26000 back then.... imagine 26kw solar for the same money....... darn near run a small village in this insolation.

Times have changed, and mills are now (for most of us anyway) fun curiosities. A buck a watt or less for most of us means forget the wind.... no question, and no maintenance for the next 30 years or more.

Frank. Solid theory does yield the proper result, sketchy theory ( anything to do with weather and predictions from models) will be wayward, as it is based only on models and past history, neither of which predict the future.... no matter what #$$# they try to tell us.

If Chris has insolation history of his area, it will go a long way to describing the averages of the past, but will never predict the future reliably...... but what else to go on?
Weather is too complex for mankind, even with all the super computers, and satellite help..... when they need to average 26 weather models to work out tomorrows weather, you know they really don't have a clue either....... but they try anyway... we demand it.

Economists... same thing.

"Someone once said that in theory calculations and practice should yield the same results, in practice it doesn't " says a lot about the theory ..... still a work in progress,...........but there are plenty of  formulas that do work time and again, and when the practice does not match, you know you've missed something in either or both.

The insolation predictions for my area were wrong. This year they are apparently 20% less than average, but my power yield was greater than expected for the flat panel insolation figures..... 45degree panels was the big difference in winter I guess, and the summer....... beats me???.

.................oztules

[Frank S]

"(Frank. Solid theory does yield the proper result, sketchy theory ( anything to do with weather and predictions from models) will be wayward, as it is based only on models and past history, neither of which predict the future.... no matter what #$$# they try to tell us.)"
 Yep; but in order for there to ever have been a solid theory the equation started from 2 or more known's based on someone's prior practice to arrive at the un-known, and even then after the calculation has been pun into practiced application  there is still the random factor of"X" which will rear it's ugly head from time to time. I tell all of my young engineers it is perfectly fine to optimize something to the NNTH degree but to build it somewhere nearer to the center of both extremes taking into account cost, performance,& longevity. then what ever you do will outlast and out perform your wildest expectancy The cost of going just a little over board will have been long forgotten when their less than perfectly optimized widget is still performing years after the others have been replaced many times

[ghurd]

It depends on what the system is supposed to do.

Look at the insolation maps for north east Ohio.  It is off the bottom of the scale.
Solar works here when it is properly planned out.  I put in a system with 2 Sundanzers (a fridge and a freezer), laptop, large portable DVD player (no real TV), cordless tools, home lighting, cell phones, etc.  The solar cost, even counting panels, the battery bank and the sundanzers, still cost less than a decent tower.  Works fine in less sun than you get.

I have a feeling the controllers are smart enough to stop the solar when the wind is howling, and that would skew the data.
Granted, if the batteries are low then there was not enough sun and wind.

Chris, your batteries are a little different if I recall... but I wouldn't bother starting the genny until they were lower than that.  I don't have any concern at all until 'regular' FLAs get down to 12.2 / 24.4V.  All the 'real' systems I do are solar, and they go down to 12.6~12.7 at sundown anyway, so not sure I would as concerned as you about keeping them at that high of a voltage.
I like to have a full tank of gas in my car, but I don't stop and fill it up twice a day, if you know what I'm saying.

I work in the snow belt.  Usually, after a brushing off of the major snow, the panel ice melts and evaporates itself off even when badly overcast.  I posted a pic of a couple small panels showing the ice a long time ago, with ice sickles hanging down from the frames. In a light snow, when its still bright out, often the snow melts and evaporates as it lands on the panel.  Not sure why you have more trouble than here, unless it is just enough colder to have it 'stick' longer.

The water temps may be a bit of an issue if they stay that low for long.  Legionnaires disease was a hot topic here several years ago when people were turning the tank temps down to save money.
G-

[ChrisOlson]

All the more reason for folks to balance your input into this thread unless they live in your immediate area.
You effectively live in  a solar hole in winter.  An unusual area from the looks of it.

No, it's not really unusual.  There are hundreds of off-grid installations in the Wisconsin North Woods - year 'round cabins, seasonal cabins and homes.  Most of them (including us) can get grid power if they wanted to pay for it.  And it would be cheaper to get grid power than staying off-grid.

But many refuse to pay the utility companies here to run wires because they don't trust it.  Somebody out hunting will shoot the insulators off the power lines because they're pissed that they ran wires and poles thru their woods.  Many years ago they tried to run a huge transmission line from down south someplace to the Twin Ports and they finally gave up on it.

People set up on hills over a mile away with Barrett 50's and 460 Weatherby's and whatever they had that would Reach Out and Touch Someone from great distances.  They were shooting the insulators off those high voltage transmission lines faster than workers could bolt 'em back on.  They brought in cops and helicopters and thought they were going to catch the perpetrator.  Except it turned out to be they were fighting an army that HATES wires strung their pristine woods.  And the people that live here know the land like the back of their hand while the law enforcement types were like bumbling idiots.  They never caught a single one and the insulators kept getting shot off every single day.  They finally halted construction when workers were replacing one and somebody shot an insulator off right next to the worker.

They left and never came back.  They abandoned the whole thing and to this day only managed to ever get the one high voltage transmission line that runs along US53 up to the Twin Ports.

So then they got a new plan in 2007 and built the Taconite Ridge Wind Farm for Twin Ports power - that's right wind turbines - not solar panels.  2.5 MW turbines - 10 of 'em.  We don't care.  We like our wind turbines because we live in an area where they work, and each one only takes up a small footprint and requires only a portion of the maintenance that it takes to make solar panels work.
http://www.mnpower.com/video/taconite_ridge_1_video.wmv
--
Chris

[ChrisOlson]

Chris, your batteries are a little different if I recall... but I wouldn't bother starting the genny until they were lower than that.  I don't have any concern at all until 'regular' FLAs get down to 12.2 / 24.4V.

Glen, our auto gen starter has four timers-
24 hr is set at 27.0
2 hr is set at 23.5
15 minute is set at 23.0
30 second is set at 22.0

If the system voltage drops below those settings for the time for each one, it starts the generator and bulks and absorbs the bank.

The 2 hour timer looks low, but it's not.  Our system is always under load at about 1 kW average.  If you take all the loads off after it's been down below 23.5 for two hours the bank will recover back to about 24.2 at rest and it's at 50% SOC.  So that's there in the event that it happens, and the inverter goes, "OK, we got no incoming power - it's time to take care of the problem".

The reason I have that 24 hour set at 27.0 is because there are many times that we'll go for a week (just like this last week) where the bank makes it above that every day, but never makes absorb.  The bank gets cycled from about 60% to 80% day after day.  If our loads exceed incoming the bank gradually keeps getting discharged until there comes a day when it don't make it above 27.0.  This is actually good because it's a lot more efficient when you're not wasting power absorbing batteries every day.  More of the incoming goes to loads instead of being wasted in heat charging batteries.  But when it goes on for long enough, there comes a time when the generator should start and boil the bank for a couple hours.  And that's what it does.

We had a "bad" week this past week and it made it above 27.0 every day, but never to absorb.  The generator probably would've started today and "fixed" it.  But the weather cooperated and we got nice breeze PLUS perfectly clear skies today.  As I write this the bank is already above 27.0 and it'll be absorbing by noon.

Our generator RARELY runs for battery charging.  Mostly only for peak loads.  But without those wind turbines this last week we would've burned generator gas for charging.

I don't believe in throwing more of one power source at the problem.  I believe in harvesting multiple sources for off-grid power because each has its pros and cons.  Wind power can work 24 hours a day.  Solar can't.  Wind power running all night can take the "edge" off what it requires to get the bank to absorb the next day.  Where if you only had solar you'd have charge at over C/10 to get it there on a big bank in the hours of solar time you got for it to work in.

There's more to it than just saying "solar is cheaper so forget wind power".  And I suspect anybody who thinks that does not have an off-grid system so they don't know how it works.  Batteries aren't built to handle huge charging amps over only a short time each day that solar works.  They like to be bulk charged at no more than C/10.  So anybody designing an off-grid system has take that into account for the hours of daylight you have at certain times of the year.
--
Chris

[bob golding]

interesting. i have installed 750 watts of solar to supplement my 500 watts of wind turbine. i dont have any figures at the moment as i have given up on those cheap watt hour meters,after 2 of them fried. so my only way of checking is the lights on my charge controller and my meter.so far i have only had to run the genny once after 3 days of fog. fog is normal here on the coast. i have had 2 panels up for most of the summer. i am feeding them straight into the batteries so losing a fair bit in efficiency,but as the panels where very cheap and i can get more of them at £50 each i am not going to bother with a MPPT controller. i like the KISS principle. i am getting around 6 to 8 amps into the batteries at the moment. with the wind as well i am definatley better of than with a bigger turbine. i am going to keep adding to the solar as money permits. i am running the genny on 75% veg oil and 25% gasoline with a splash of vegiboost to up the octane a bit.

[fabricator]

Oz, you are operating under one misconception, we cannot get good panels here in the US yet for under a buck, every once in a great while you will see good name panels for under a buck bit not very often, panel builders here are folding left and right.

[Mary B]

Even here in SW MN winter sun can be rare. I don't care what someones study says, I have lived here my entire life and winter is gray and depressing. Few Sunny days are usually accompanied by -20 temps. Last week I think I saw the panels hit 400 watts once, rest of the time max I could get from my 1.1kw of panels was about 200 watts. Enough to keep the batteries floated for the ham gear.

[cardamon]

I believe you can get good panels for under a buck a watt.   Sunelec.com has sovellos for .89 cents.  As far as I know these are reputed to be a good module.

 This is a very good discussion.  So I think we all can agree on several things.  1. Chris is in a hole and  his insolation schedule is extremely poor. 2.  It depends on what you are doing with your power.  IF are are charging batts, than as Chris said, you may not be able do utilize that solar power if you have a small batt bank.  For  me thats not really an issue because I am looking for more input for heating not charging.  3.  Of course it depends on what you spend on a wind system - are you buying it off the shelf or building it?  I built my wind system for about $6k and that a 1kw on a 90 foot tower 1500 feet from the house.  I think that is pretty damn good, but thats 4.5kw of solar and that makes a lot even at 2 sun hours/day in the winter.  Chris how much do you have in your wind system(s) if you dont mind sharing?

 Here are some real rough figures for what I have gotten out of the wind the last 58 hours.  I have diverted about 4.2kwh/day for the last 2.5 days and it has been nice and windy.  I dont currently have a way to measure total production, but the batteries were pretty much full at the start of these figures and I havent been home all weekend, so lets say the fridge and a bit of absorbtion on the batts is a wash with it being windier than average.  Hell lets just say I produced 5kwh/day.  That 4.5kw of solar would make 7kwh on the average during the winter.  Now it sucks that Im off grid so in the summer its mostly a waste, but maybe i can put in an air conditioner......

As oztules said, you dont have to have sun to get energy from PV.  If I did that 4.5kw of PV, thats still, what,  around 500 watts all day on a gray day?  That luxurious to me!

[fabricator]

That's why they had to come up with a new name for cabin fever up here, SAD (Seasonal Affective Disorder) for places that don't see the sun for a month at a time, when the sun comes up it just gets a little lighter shade of gray, when it's like that the snow is gray the sky is gray and psychiatrists do a land office business.

[DamonHD]

Even here in London (UK) I expect to generate only just about 1kWh/d midwinter from my 5kWp+ of PV.

See some pretty pictures of sample outputs here:

http://www.earth.org.uk/WW-PV-roof/EVAnalysis201210/

though not that the system has been upgraded twice.

Some days reaching 100W at any time would be good.

Rgds

Damon

[ChrisOlson]

Chris how much do you have in your wind system(s) if you dont mind sharing?

It's not something that I've kept track of over time because I keep designing new turbines and testing them.  I have never gone to big turbines but instead have kept building machines in the 3-4 meter class, and put up more than one.  I know I have roughly $10,000 in my latest tower.  But that is an inflated price because I spent the money on getting engineering certs done on it for the simple reason that build and sell off-grid turbines to folks, and certified wind towers are hard to come by.  So I built my own and got a stamp on it.  And that costs money.

If I had to venture a rough guess as to what it would cost for somebody to just buy and install the 7.5 kW of wind capacity that I currently have, I would say about $22,000.
--
Chris

[fabricator]

Even here in London (UK) I expect to generate only just about 1kWh/d midwinter from my 5kWp+ of PV.

See some pretty pictures of sample outputs here:

http://www.earth.org.uk/WW-PV-roof/EVAnalysis201210/

though not that the system has been upgraded twice.

Some days reaching 100W at any time would be good.

Rgds
Damon

So if I understand what OZ is saying if you were to put in ten times the capacity you have now you would be making 10kWh/d a day in the winter and you could be pretty profligate in your power use in winter and have power to throw away in the summer.

[ChrisOlson]

So if I understand what OZ is saying if you were to put in ten times the capacity you have now you would be making 10kWh/d a day in the winter and you could be pretty profligate in your power use in winter and have power to throw away in the summer.

That's the gist of it in theory.  But here's in practice.

We got 3.5 kW of solar.  So let's increase that 35 kW (10x more).  35 kW of solar @ 75% efficiency puts out 875 amps @ 30 volts.  Got that?

Our bank is 2400 ah.  It can handle max 240 amps charging rate during bulk.  If it's at 50% SOC in the morning that means it needs 1,200 amp-hours.  1200 amp-hours from 9:00 am to 3:00 pm in the winter is 200 amps, alright.  But solar just starts working at 9:00 am, reaches its peak at solar noon, and is putting out nothing again by 3:00 pm.

So what I am I supposed to do?  Push 875 amps into the bank at solar noon to make up for the low amperage on each side of it?  No thanks.  My wind turbines charge 24 hours a day and prevent this problem, and they treat the bank nicely.  I won't use a power source that only comes in 6 hours out of the day, starts out at a trickle, melts the bank to a crisp, then trickles off again while the bank is sitting there still smoldering.
--
Chris

[bob golding]

sorry should have added my panels are rated at 250 watts. the reason i got them cheap is due them having broken glass on the front. short circuit current is 6 amps so not too shabby. should ideally be 8 amps, but doubt anyone gets that that. i am paying 25p a watt. £50 a panel