Wind vs solar

[fabricator]

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

Ahhhh, I get it now.

[hydrosun]

Almost 20 years ago Homepower magazine had an article doing the math on the benefits of a hybrid solar and wind system. the economics have changed with the lower price of solar  but the principal of higher reliability of more consistant daily input still remains.
With the lower price of solar panels I am now installing additional panels on offgrid sytems that are facing southwest or southeast to spread out the hourly input. Starts charging earlier in the morning  and later in the evening. And it helps to avoid the mid day spike that the battery bank might not be able to absorb. And like Chris Olsen putting in heating loads to use the excess electricity to store energy as heat.
Chris

[cardamon]

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.

I know nothing of you loads but it seems like you have a big system and lots of loads.  In reality would it actually work out that way most of the time?  Say you had that 35kw of solar, or that 22kw that you could have instead of all your wind, or a bit less than 22kw figuring for BOS components and charge control - whatever.......maybe its just your extremely poor solar site, the fog, etc, but in a average site, you would be getting significant input outside of that 9-3 range, and also that is a very large array so you would get quite a bit of output even on a cloudy day.  Would your battery bank really get down to 50% overnight? It just seems to me that with one of these big solar-instead-of-wind arrrays and a normal/average site one will get a a ton of output for every hour it is light even on a cloudy day......and all the hot water you could ever want in the summer

[oztules]

"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 that statement is just silly and lacks imagination.

Who fought the good fight for 12v msw inverters..... and was dead wrong.... you
Who fought the fight for 12v systems..... dead wrong again...... you
Who fought the good fight for 24v rather than 48v......who's looking for 48v inverters now??...... you.
Who champions 12v batteries instead of 2v cells    and wrong again, you just haven't worked it out yet.

You follow one blind alley after another, ignoring everyone else who might know, may have experience...... your always right .......until You end up  proveing  yourself wrong... and probably mislead neophytes up the wrong way until you recant and change direction.... again and again. Flux and Danb and Hugh to name a few and a host of others were all wrong.... Just get rid of the gear boxes, and direct drive, buy decent 2v cells,  and you will have turned the full circle.

Your ONLY off grid on a hobby farm...and  thats all.

You are not remote.
You don't look at logistics.
You dont look at supply.
You don't appreciate remote living.
Warranties mean nothing here... it has to be reliable.


You are also in a solar hole, and that makes solar in winter different for you.... I'll give you that at this point.

For the majority of folks, it will be a stupid, pointless  waste of money to go wind now..... can you see why?

And ..... size the battery bank for the design... not those 12v batts you use.... 2v cells 1500ah 48v system etc .... It's not rocket science.


In 90% of days, you need only calculate draw for night time, the solar will way way over supply the days power, and charge the bank at max C10, and probably 100-500% go unused. We design for the worst case and back off just a bit. We don't hope for the best case, then add a bit.

In the summer you could run as much air con as you could wish..... 22kw solar systems are awesome on a sunny day, and still hugely amazing on a dull day.

$22000 may buy your wind control stuff and turbines and towers......... For most folks it is  just a waste of time and money.
Only in your type of circumstance would they be more useful.

We have a windy island here, and now only about three mills supplying power for the many off gridders. Solar has taken over exactly the same as it did with pumper windmills for water, now it is solar pumps. It used to be windmills for power, now its  panels... because they work..... can you see the writing on the wall?

I would not be surprised if the Govt dropped their subsidy on remote/ off grid wind installations soon for that reason......

Have a good look at your system and how it has evolved, and then tell me who does not know what they are designing until it bites them on the bum.
You have documented history.... go back and read it and think about it before you make this statement

"And I suspect anybody who thinks that does not have an off-grid system so they don't know how it works."

22kw would be way overkill in any site and possibly yours too.. we don't have reliable figures... just what you think .

To get a big bank down to 50%  with 20kw hooked up to it will take some real effort in any normal area.... I suggest barely possible.

It's time you think this through without trying to find reasons for it to not work. Still dull days don't help you at all either.... but 22kw of solar will punch a big hole in it still.

It won't surp[rise me to find you with 10kw or more in a few years time when you realise the strength of this argument.... Imagine summer time with hundreds of KWH to burn up on whatever you can dream up.... 22kw is almost unthinkable power..

"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. "

Your just pulling my leg there.  Big arrays get power from very poor light comparatively.... when you can only get 300 watts from your little one,  you can get 2kw from a 22kw array. If you research this sensibly and without prejudice,  you will work out how to design a system that can work, instead of trying to make one that does not.

Your just not getting it, and probably nor would I if I had spent that much on a dead end.

Your hanging onto this like the 12v inverters.... no sense in it.

Any of you other folks out there that agree with Chris, get your figures for your area, and work it out yourself. Most will be way way way in front to take this path, and even if winter is a tiny bit squiffy ( hard to believe except for microclimate wisconsin), summer spring and fall will blow you away.... and BIG pure sine wave inverters are down to $760 now, (6kw with 18kw surge and 70A inverter /charger combined if you do need the genny) about 60 kilograms, need help to mount them), that you can use the summer, spring, autumn power if you want now.

Alan of the Jungle wakopol I think from memory did just this in the Daintree area in Aust. Runs the aircon 24/7 10kw solar, no mills........oh and he uses 2v cells and was a big power station operator. He knows what power generation is. Thats a Florida type area, so less solar than I would need for the same thing.... maybe 50% more for here.



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

[birdhouse]

oz-
first off, i have a ton of respect for you.  you have gone out of you way to explain things to me that have made my offgrid life much easier and more productive.  not to mention you being such an innovative turbine guy...  (inventor of chainsaw blade carving)  so my hat is continually off to you! 

chris has always fought the norm with off grid living.  i remember the times he thought there was nothing wrong with 12v MSW for a large system.  those arguements are obviously long gone.  now he's 24v, and thinking about 48v.  he complains about solar on a regular basis even though *guessing* it is his prime provider in the summer. 

based on this discussion, and the prices of panels, i can see how doubling the PV is worth the minimal cost(compared to a 10k tower)yet i don't doubt the power in the wind for times when the panels are covered in snow. 

this is close to home as the panels at my place are also routinely covered in snow.  it's these times that my turbine really shines!  yet at the same time, if i had even 1200w or panels, i'd be way less worried about the whole thing (600w now). 

i really hope all can be constuctive here and not turn this into a he said/she said arguement.   

adam

[oztules]

Fair commentary on the he said she said bit Adam.

Chris I apologise unreservedly if I have over personalised it, but you are very good at machine fabrication, good with words and I'm sure a lot of folks follow your every word.
I fervently dont agree with what works for you at the moment, is necessarily good for most other folks, thats why my strong stand.

I don't know everything, and I strive to fill in the gaps. I love windmills and will be putting mine back up when I can find a use for them..... not sure what that will be.... maybe just running a dummy load for looks perhaps. I certainly won't need the power.

Adam,
It is no secret I don't have snow on my panels... only 1/2 inch of frost in winter, but it's gone in minutes after the panels catch the light and start working... interesting watching the water run off them, and the frost slide off.

I suspect poking some power through the panels will do the same for you too. Mine are 45 degrees tilt all year.just enough power for winter, and don't need more in summer so they are fixed.

The next 4.5kw will be idle curiosity ..... interesting to see what I can use them for really, apart from filling in the gaps in the few days in winter the original bank can't do.

The eerie part is, over here is when we get the really crummy days in winter, they are dark and still, so the mills would be no help then either. If it is blowing, the cloud action seems to be enough to get around 8-13 kwh of solar out of that bank. The 2kwh days I have see this year were foggy and still all day..... lifes not always fair.


I've said enough for a while.



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

[DamonHD]

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.

Except as it happens my roof is about full and there is no other space on my property.

If I covered every square metre of space ignoring all planning rules, etc, it would not cover our (very modest) midwinter consumption on the darkest days.

But then wind would not work for us either as we are in a dip surrounded by houses and trees...

Rgds

Damon

[bob golding]

i dont think there is anything new here ,just the price of solar has come down to a price where it is more sensible to upgrade to more panels. i have been waiting for this to happen for years. at the price i am paying for damaged panels at the moment will be the price everyone will be paying in a couple of years, as things are going. then solar will really be the way to go. no trackers no mppt needed, costs more than the panels so the limiting factor will be the area you have to put them. the only time you wil need mppt or trackers is where you are limited by space like Damon.

[DamonHD]

I already do MPPT (and the most space-efficient PV available to me, Sanyo/Panasonic HIT); no trackers though!

Yes, I do think that for many many people "just buy more panels" and don't worry about trackers will be the right thing to do (though I advocate MPPT for various reasons, especially when batteries are low).  "Overproducing" is safe with PV, especially if you have the local grid to dump any excess into and maybe get paid for it.  Managing overproduction with wind is harder.

Rgds

Damon

[bob g]

my direction has turned away from  wind for the following reasons

1. i ended up in town, although i could do wind power, i doubt i ever will for anything other than idle curiosity

2. i have amassed about 4.5kwatts of panels, and have excellent access for good sun. (central kansas)

3. i am on the grid

having said all that, i would like to add the following

i think my panels would likely supply all my needed power for most of the year, and i could use the grid as a backup supply or for peaking.

i have a fairly highly developed trigeneration system, wherein i can produce 10kwe  for approx $4.10 at the current price of diesel and factoring in depreciation and service on the generator.  that works out to about .41cents per kwatt hour of electricity alone.

if i harvest the waste heat and put it to use, the cost of produced electricity drops to about 1/3 this cost or about .14cents per kwatt/hr
which is pretty close to my utility cost per kwatt hour, but strangely less than what they end up charging me after all the add on charges are included.

the neat thing is the sun shines less in the winter months, at which time i have most use for the waste heat from the trigenerator.

bottom line is this, even if i were to get rid of the electric company, i could do just fine living offgrid in an area of on grid houses.

the question then becomes this

why spend the money to do this, when you are grid connected?

my answer

things like hurricanes, we don't have to deal with, but
we may see a time when the power is not dependable or the price may be more than i am willing to tolerate from the utility company.
and it just seems reasonable to cover ones arse and be prepared.

and it is sorta fun isn't it?

bob g

[ghurd]

the price of solar has come down to a price where it is more sensible to upgrade to more panels. i have been waiting for this to happen for years. at the price i am paying for damaged panels at the moment will be the price everyone will be paying in a couple of years, as things are going. then solar will really be the way to go. no trackers no mppt needed, costs more than the panels so the limiting factor will be the area you have to put them.

I expect the price to go back up.
China has been dumping solar.

"The Commerce Department issued a final confirmation of its May finding that Chinese producers and exporters had been selling solar cells into the United States at artificially low prices, and put the anti-dumping duties at between 18 percent and 250 percent."

From
http://www.solardaily.com/reports/US_confirms_heavy_duties_on_Chinese_solar_cells_999.html

After they bankrupt all the US etc manufacturers, then they have us where they want us... again.
G-

[DamonHD]

There may be a bit of a bounce, but I think that the trend is still very firmly downwards...

Rgds

Damon

[fabricator]

There may be a bit of a bounce, but I think that the trend is still very firmly downwards...

Rgds

Damon

I believe that is true, because Chinese producers are not a monolith, they are much the same as producers here, in competition with each other.
On the other hand prices in the US are bound to go up as the stock of dumped Chinese panels is depleted, but US manufacturers are going to have to meet certain price points or demand for panels will just fall off, so they are between a rock and a hard place, that is the place where innovation happens.

[ChrisOlson]

In short reply to all the above, we had a 12 volt MSW system here for 7 years and got by fine with it.  When we decided to go bigger so we could live more comfortable, we went with 24 volt.  Is there a problem with that?  12 volt MSW systems are cheaper to set up and they are automatically discounted as being "useless" for off-grid.  But I'll tell you what - I've seen some damn big boats and RV's that run totally on 12 volt are nicer than most people's homes.

So keep things in perspective, please (oz).

I advocate using BOTH wind and solar for off-grid power.  Not just one or the other.  It doesn't always boil down to cost/watt and 12 volt is no good because if you don't have 24 or 48 you're nothing but a pipsqueak.  It boils down to reliability and how much do you want to run your generator?

Here's the quiz for the day.  It's a timed quiz and you got 30 seconds - it's multiple choice.  Failure to get a score of 100 will leave you with a house with no lights (or running the generator).  Ready?  Go:

1.) Wind vs Solar - which one do you think is producing the power for this off-grid home for the month of November 2012?

       a.)

       b.)

--
Chrs

[wiredup]

both

[Eric L]

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.

This has been my approach too with a grid-supported system. I limit my charge-controllers' output amps to avoid over-charging my relatively small battery bank. It seems crazy at first, but with panel prices so low, as long as you have fairly decent year-round sun conditions, it makes sense to move towards using the array to get a maximum consistent daily harvest, rather than trying to maximize harvest and storing the extra power in a larger battery bank. Or in other words, the larger array size starts doing more of the work that the batteries would have done back in the "bad old days" when the panel-to-battery price ratio was skewed much more toward the panels.

Here is how I implemented my grid-supported system using this idea:
http://www.wind-sun.com/ForumVB/showthread.php?14524-Could-cheap-panels-alter-the-panel-battery-ratio&p=117259#post117259

Since making the linked post, I've  significantly increased my daily production to around 12 KWh/day, thanks in part to Chris' post on hot water heating with a Classic. In fact, it's working well enough that I'm planning to expand my array size to 5.5 KW even though my battery bank will stay at 17.5 KWh (and charge rate rarely exceeds C/8). I'm now pretty confident I can consistently use that surplus most days.

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.

Besides sunelec that Cardamom mentioned, there are others selling name-brand panels well under $1/watt. Solar Blvd is one such (not the only one); they were recently selling new Sharps under .90, e.g. Right now they have .75/watt for MEMC panels at the pallet size + $300 pallet freight; that's 2800 watts at .86 delivered (can't speak to the quality, but it's probably o.k.). Incidentally, I've found these places give some of their best deals via. their email list. I subscribe using a "junk" email address to avoid cluttering my regular one.

I built DIY superstrut ground-mounts at about .30/watt. .30/watt X 2800 watt (using that MEMC pallet as an example) = $840. Add in a delivered price of $2400for the 2.8 KW of panel, a Midnite Classic lite at $500 delivered (it's possible -- shop around) + $200 (estimate) for a combiner box, breakers, and wire (and your free labor) = $3940.

$3940/2800 watts = $1.41/watt, and that's with everything shipped, in the ground, and ready to start charging your battery bank.

That's using real-world numbers. For the diy-er, it's going to be a very, very tough price to beat right now unless, like Chris, you have terrible sun conditions.

[clockmanFRA]

For us in Rural Normandy, now that PV prices are down, it has to be PV on Our New design of trackers.

For years i had been building Hugh Piggots design 12 footers wind turbines, at about a 1000GBP for roughly 1Kw.
Including material costs for our trackers, PV is now just below 1000GBP.

Just starting an enlarged Tracker design for 2kw worth of panels, good quality PV panels are costing me 1184GBP.

But will still put up another 2 wind turbines.

If you can do both, then do so.

Here's a tounge in cheek vid the Mrs had to make, original company titles removed, of her sporty endevours around our place.!

http://www.youtube.com/watch?v=Opf836APBcw
 

 

 

[ChrisOlson]

Chris I apologise unreservedly if I have over personalised it, but you are very good at machine fabrication, good with words and I'm sure a lot of folks follow your every word.
I fervently dont agree with what works for you at the moment, is necessarily good for most other folks, thats why my strong stand.

I installed a new inverter today, and was wanting to get on that project this morning although I wanted to directly reply to this, oz.

I just present things as I see it.  You mentioned us going from 12 volt MSW to 24 volt, for instance.  Like I "saw the light" and I was "dead wrong".  I didn't "see no light" and I was not wrong.  There is absolutely nothing wrong with 12V MSW systems for off-grid power.  I know some folks who have had 12V MSW off-grid for 19 years with a Trace DR inverter.  The truth is, MSW works perfectly fine for most things for off-grid folks.

The reason we decided to switch our system is because we wanted to get some more stuff that makes our lives more comfortable.  The stuff we wanted to get (like my wife's induction 240 volt range) requires pure sine wave 240 volt power.  It's got electronics and digital clock and whatnot.  That's why we did it - so we can have that stuff.  It does not mean 12V MSW is "bad" or "wrong".

Same thing with the reasons why we installed a new 48 volt inverter today.  There's nothing wrong with the 24 volt system.  Just that running dual inverters with a balancing transformer is a power hog.  I could not get a big enough single inverter in 24 volt to run our loads.  So we put in a 48 volt one, which has more capacity and can do it with one unit.

It's twice as efficient at 300-1,000 watt load as the stacked setup, and consumes less battery power to run the same loads.  The stacked setup was twice as efficient at 6 kVA as the single 48V inverter is.  But 98% of the time is spent with the inverter at 300-1,000 watts, and very little time at 6 kVA.  So that's why we did it.  Again, I didn't "see no light" that 48 volt is somehow inherently "superior" to 12 or 24.

So people sometimes assume the wrong things because they don't have all the information.  And that's all I'm doing with this wind vs solar deal is passing on information.  There are many places other than just here where solar just plain does not work in the winter time.  And just because it does work where you live, doesn't mean it works for everybody.  And nor does it mean I can do something totally stupid like throw 20 kW of solar power at the problem just to not run wind turbines.

The facts are, those wind turbines are about as dead reliable when it comes to power as it gets.  They run at night when solar doesn't work.  They produce so much power in a blizzard that we can't even run them all when the solar panels are buried under snow and no solar energy can get thru.  I get the distinct impression you've never seen a place where the overcast is so heavy day after day that solar panels produce virtually zero power.  I say virtually because our 3.5 kW array DID product 2 amp-hours today.  That's enough power to run a 100 watt light bulb for one hour.  It snowed and rain/snow mix all day.  The panels are covered with a sheet of ice as I write this.

And you act like it's just me?  Nope.  I know many, many people who live in the upper midwest and Canada - that all live off-grid - that are in same boat.  If folks live someplace where solar power works year 'round - then great.  But most I know need a balance of systems to prevent running the generator.  So telling somebody that they should just throw more money at solar power and totally forget wind power, without knowing their situation, is bad advice.

That's all.
--
Chris

[birdhouse]

There are many places other than just here where solar just plain does not work in the winter time.  And just because it does work where you live, doesn't mean it works for everybody.

my offgrid place is not quite as cold as yours, but still, there are weeks in a row where my panels are covered in snow...  usually with an ice layer beneath the snow.  i've been ther with three to four foot of snow on the ground.

during these times my turbine keeps it all together, and i'd be stuck without it! 

now here's an interesting thought, as i have more or less equal solar to wind ratio.  if a person found themselves in my same position, which is rare... 

would you rather double your wind output or your solar output? 

my answer would without a doubt be double my WIND output!

in the summer my solar alone does more than enough, though in the winter it does a pretty skimpy job.  double the wind power would easily keep my batteries topped off daily, though double the solar would not even come close to that mark when it's nasty out. 

conclusion:  i think that if you never get snow/ice, run pure solar.  if you rarely get snow/ice, solar is the best bet (obviously with a small turbine).  though if you regularly get snow/ice, wind is the better bet(obviously with a small solar array).  if your in the artic circle, run pure wind, and if your in the middle, do both to equal extent, and after all that, if you have extra money, buy more panels, and better/more CC's.   

can we all agree on that?

adam

adam

[ChrisOlson]

now here's an interesting thought, as i have more or less equal solar to wind ratio.  if a person found themselves in my same position, which is rare... 

would you rather double your wind output or your solar output? 

my answer would without a doubt be double my WIND output!

I would increase the wind output.  To my way of thinking solar capacity comes up against a wall where you got too much for your battery bank size so it can't be used on a good day.  And then you got the poor days.  We got 2 amp-hours from our 3.5 kW array today.  It was so dark here all day that people were driving with their headlights on because you couldn't see a car if it was a 1/4 mile away without the lights.  So doubling the solar capacity to 7 kW to get 4 amp-hours doesn't make sense.

Increasing our wind capacity is basically what I've done over time.  I kept building smaller 3-4 meter class turbines and strapping more of them up instead of building bigger ones that are less efficient.  It's still a game of swept area with wind power.  Three 11.5 foot turbines have a swept area of 312 ft².  That's the same as a single 20 foot diameter turbine.  However, my high performance MPPT turbines run at 32% overall efficiency, provide three separate power inputs to the battery bank instead of one huge one, provide redundancy in the event there's a problem with one, require way less cost in towers and foundations (even considering three towers) than a 20 foot machine takes, and they walk all over a single 20 footer for power output day in and day out.  I can easily get 60+ kWh from those turbines on a good day.  And on any average day when we get 12 mph wind they make ~20 kWh.

On the most perfect solar day we can get, I can get 5.3 kWh/kW of installed solar capacity.  I would need 4 kW of installed solar, and perfect solar conditions 365 days a year, to match what I get from those wind turbines day in and day out.
--
Chris

[oztules]

Sorry about the weather.... but it is the weather after all.

Back to square 1

This is as close as I can get to you... your govt is pretty slack with their data sites, even on this island there are at least 4 insolation sites available as data to the public

So this is not for you persay, but an indication of whats around in your local area  (your states are so small over there).

So saying that solar is no good at your latitude is incorrect for most of you. Look at this carefully.
We'll use Eau Claire again.

"City:    ","EAU CLAIRE            "
"State:   ","WI"
"WBAN No: ", 14991
"Lat(N):  ", 44.87
"Long(W): ", 91.48
"Elev(m): ",   273
"Pres(mb):",   983
"Stn Type:","Secondary"
"SOLAR RADIATION FOR FLAT-PLATE COLLECTORS FACING SOUTH AT A FIXED-TILT (kWh/m2/day), Percentage Uncertainty = 9"
"Tilt(deg)","       ","Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec","Year"
"0        ","Average", 1.7, 2.7, 3.7, 4.6, 5.6, 6.1, 6.1, 5.2, 3.9, 2.7, 1.6, 1.4, 3.8
"         ","Minimum", 1.4, 2.2, 3.0, 4.2, 4.8, 5.1, 5.4, 4.7, 3.1, 2.2, 1.3, 1.1, 3.5
"         ","Maximum", 2.0, 3.0, 4.5, 5.2, 6.4, 7.1, 6.6, 6.0, 4.6, 3.1, 1.9, 1.7, 4.1
"Lat - 15 ","Average", 2.9, 4.0, 4.7, 5.1, 5.7, 6.0, 6.1, 5.6, 4.7, 3.7, 2.4, 2.3, 4.4
"         ","Minimum", 2.0, 2.8, 3.5, 4.5, 4.8, 4.9, 5.3, 5.0, 3.4, 2.8, 1.6, 1.7, 4.0
"         ","Maximum", 3.6, 4.8, 6.0, 5.9, 6.6, 7.0, 6.7, 6.6, 5.8, 4.5, 3.1, 3.1, 4.8
"Lat      ","Average", 3.3, 4.4, 4.9, 5.0, 5.3, 5.5, 5.6, 5.4, 4.7, 3.9, 2.7, 2.6, 4.4
"         ","Minimum", 2.2, 2.9, 3.5, 4.4, 4.5, 4.5, 4.9, 4.8, 3.3, 2.9, 1.6, 1.8, 3.9
"         ","Maximum", 4.2, 5.4, 6.4, 5.8, 6.2, 6.4, 6.2, 6.3, 5.8, 4.8, 3.4, 3.6, 4.8
"Lat + 15 ","Average", 3.6, 4.6, 4.8, 4.6, 4.7, 4.7, 4.9, 4.8, 4.5, 3.9, 2.8, 2.8, 4.2
"         ","Minimum", 2.3, 3.0, 3.4, 4.0, 4.0, 3.9, 4.3, 4.3, 3.1, 2.8, 1.6, 1.9, 3.7
"         ","Maximum", 4.6, 5.8, 6.5, 5.4, 5.4, 5.5, 5.4, 5.7, 5.6, 4.9, 3.6, 3.9, 4.5
"90       ","Average", 3.5, 4.3, 4.1, 3.3, 2.9, 2.8, 2.9, 3.2, 3.3, 3.3, 2.5, 2.7, 3.2
"         ","Minimum", 2.2, 2.8, 2.8, 2.8, 2.5, 2.4, 2.6, 2.8, 2.3, 2.4, 1.4, 1.8, 2.8
"         ","Maximum", 4.5, 5.4, 5.7, 3.8, 3.3, 3.1, 3.1, 3.7, 4.2, 4.2, 3.3, 3.9, 3.4
This tells me that an average day with panels tilted permanently for latitude will deliver in the dead of winter an average of  2.6kwh/sqm/day
Thats average... what about the minimums.

The minimum average is measured at 1.6 somewhere in November, 1.8 in December. and a maximum in several good months of 6.4kwh/sqm/day

These are flat plate collectors that measure what they see.... not what we see.... What does it mean anyway?

Well, for a 6x6 cell we make about 4w, so we need 44 cells per sq meter or 156watts/sq meter of cells@1000w/sq meter light
For a kilowatt of solar we need 1000/156 or  6.4 sq meters. so the minimum measured for this La Crosse area is 1.6x6.4 X efficiency or 10.24Xefficiency (probably 16% nowdays) so 10.4x.16=1.634.... so we can say that 1.6kwh/sqm/day is almost the same as 1.6kwh/kw installed.... Thats the first time I have ever bothered to calculate this ... I think it's right?

I'm guessing the minimum is the average minimum,there will be worse days, but very few, thats what the genny is for if there is a string of them....  but even at the minimum average 1.6kwh/kw installed is ok for me for a 10kw array, year round in La Crosse... I only need 13kwh, and with a 50 kwh bank, should make it to the next not minimum day.

No Chris it is not you, but it is more average for up north than your solar dark spot, and folks can look at their own area instead of blindly building mills that are not going to be the best financial decision, or more likely the best power decision for them.

"To my way of thinking solar capacity comes up against a wall where you got too much for your battery bank size so it can't be used on a good day"

What are you talking about here.....a 10kw setup in summer will probably deliver in excess of 60 kwh.... so what........ throw it away and only use what you need to fill the batts. Is this different to your 60kwh coming from the mills on a good day?? Whats the difference?

"We got 2 amp-hours from our 3.5 kW array today.  It was so dark here all day that people were driving with their headlights on because you couldn't see a car if it was a 1/4 mile away without the lights.  So doubling the solar capacity to 7 kW to get 4 amp-hours doesn't make sense.
" 48 watt hours from a 3.5kw array.... is that with the midnight removing the snow?... and does it work... curious thats all.

It is near an hour before sunset officially here now, the panels are still doing 90 watts, and it has been a dark day all day, so it's getting quite dark now.... but not head light time though..... but still, 8/8 cloud cover at this time of day is very very dull.

So, I think you have established that your in a solar hole in winter....you should  keep your turbines. But for most south of 47degrees, the figures seem to look pretty  good, and way way way cheaper than turbines. They are set and forget..


"The reason we decided to switch our system is because we wanted to get some more stuff that makes our lives more comfortable.  The stuff we wanted to get (like my wife's induction 240 volt range) requires pure sine wave 240 volt power.  It's got electronics and digital clock and whatnot.  That's why we did it - so we can have that stuff.  It does not mean 12V MSW is "bad" or "wrong".

Same thing with the reasons why we installed a new 48 volt inverter today.  There's nothing wrong with the 24 volt system.  Just that running dual inverters with a balancing transformer is a power hog.  I could not get a big enough single inverter in 24 volt to run our loads.  So we put in a 48 volt one, which has more capacity and can do it with one unit."

Your quite right, there is nothing wrong with 12, 24 or msw, but as you have found, there is more flexibility with the 48v unit, and half the price I suspect.
Thats why if folks are going to design a house style off-grid system, they cant skimp, and all those before us have realised as have you, 48v offers advantages..... so we should start with advantages.

There are plenty of folks here with 12 and 24v systems, but they tend to live like hobbits, as theve never had sufficient solar, or even game enough to use wind for that matter, and tend to do all the heavy lifting with their gennies... as I believe you did at one time too... I recall the 3am starting problems you had, and 800 hrs per year was your lower goal at that time.

It is not that the lower voltages and msw don't work, they do, just not as "griddish". If I want to turn on the 60ton brake press, or run the center lathe, or milling machine,  I don't want to start a genny, I don't want to feel in my mind the 1800 amps @ 12v trying to start it, or the 900 amps at 24v. The 48v 18000w surge would be problematic with lower voltages. I think you may have found the same thing. You can deal easier with 500A surges, but thats as high as I wish to see.
You have seen fit to make the move, and  you won't regret it.

I want people to do their own research with the figures available, not what folks remember the weather being like. Look realistically at their skills, look realistically at their needs, and design it from the start accordingly, or if they are currently off grid or just playing part off grid and want more power, they likely know already what solar does where they are, and can figure the costs of turbines and all the associated hardware (turbine is the cheapest part), against the cost of solar.... but the previous cost of solar meant we did not design for 2 or even  5 times what we needed... it was insane then, but not now

With all renewable things ... solar hot water, power (wind or solar) it is intermittent and needs a storage of some kind. For power thats batteries.
12v batteries certainly work, and most will cut their teeth on them, but if they need a good reliable power pack, then the fork lift guys got there first, and settled on 2v cells. All the people I know that had 6 or 12v batteries, and eventually went the 2v cell way, would never go back. Maybe there is good reason for that?

Most folks south of you should at least  get the sun that  Lacrosse gets, in which case solar will probably win in the dollar per watt, the reliability stakes, and even the power on most days. Even the average minimum would do to scrape by... 1.6kwh.kw is pretty low, but still in the game as it is the minimum average for winter, not the average for winter which is 2.6, very do-able with 10kw for most folks. (even we have electric stove/oven and electric hot water...... we don't have the -40 degrees, but use wood extensively in winter.



It has been dark here for the last four days. Havent seen a shaft of sunshine. The mist is hanging on the mountains (and they are small anyway 350meters or so), it rains tiny rain drops a lot of the time, for no real rain..... that kind of weather pattern..... its crap really.

There was a bit of breeze this morning, but lasted only for an hour.... in this instance, a mill is no good either... it's been pretty still... so much for roaring forties. The mill up on the hill (Jamies seems to make it's own wind, and is still producing something) so site matters.... but he's going solar only too soon.

My solar still managed to put out  13, 12, 8, and 8kwh for the days (1,2,3,4) between 3 and 2 kwh/kw

So the sun didn't come out, the wind didn't blow, and if I had the second array up now, I'd still get my 13kwh/day easily. It is supposed to be getting towards summer here...

What did we learn..... every day is different, we can prove whatever we want with examples.... so thats moot really.

We can only look at the figures from the respective agencies and make our decision.

"And nor does it mean I can do something totally stupid like throw 20 kW of solar power at the problem just to not run wind turbines."

Until I can get some real figures from your area, I'll take your word for it, but from here, most other folks would do better with the 20kw, and rarely ever use it, rather than buying an expensive turbine, and finding out the hard way that wind don't blow all the time, but every day gives us light (except your area apparently)

Over here, Maatsuyker Island Lighthouse is one of the poor solar places, windy, and only about 1kwh/kw solar in winter. It has 279 days of rain per year , is the southernmost point in Tasmania. Wind would be the ticket.... except it would probably be a maintenance nightmare. They got wind big time.... but the lighthouse is solar. Runs for 16 hrs in the winter at over 1kw.... so 16kwh on the long winter nights.... still just solar. Some clown designed it to work in hostile low solar end of the earth type places... and probably a govt employee too.

I think there is enough here for folks to see both sides of the coin now....... but don't think everyone has buckets of money like you  to spend continually upgrading, only to ditch it and upgrade again, because you didn't design it for comfortable trouble free living in the first place.
And yes I still admire your tenacity and your design with your mills, I just wouldn't emulate them.... I'd copy the high voltage (500v+) ferrite AWP.... don't seem to need mppt then to get 2kw continuous from 3.6 meter mills..... and they can't burn out either. There is always another way I guess for everything.

For those watching this, please do your own research, and try to future proof it at the start, unless funds are very limited, but then perhaps you will be going solar anyway. Mills, towers and controllers for them are not cheap add ons... even Chris would probably agree on just that one point.



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

[bob g]

oz, chris and others:

been following this thread with some interest, when it dawned on my the deciding factor, all things being approx equal these days.

that being i don't like heights at all, i don't like standing on roofs, and i don't like climbing up to where i can stand on one, this means i don't like climbing towers, and i damn sure don't want to go climb one in the dead of winter when the wind is howling.

actually i refuse to climb a tower on a nice day, and would rather face a firing squad rather than doing so in the winter!  i think my odds of survival are better with the firing squad! 

i guess i am glad i live in a fairly sunny area, and have sufficient panels to put up on the roof to cover my needs....

awe dang,   there we go again, mentioning the roof!

bob g\
ps. can i lay my panels on the ground? 

[bob golding]

oz, chris and others:

bob g\
ps. can i lay my panels on the ground? 

mine are on the ground. think it depends on  how safe you think they are. i am in a large field in the middle of nowhere so theft is not a high risk, plus all my panels have broken glass so no resale value. they will work just as well as long as they don't get shadows.

[fabricator]

Bob, who the heck climbs towers? Tilt towers are pretty much the norm for almost any wind installation these days, so not wanting to climb a tower is a complete non issue.

[ChrisOlson]

This is as close as I can get to you... your govt is pretty slack with their data sites, even on this island there are at least 4 insolation sites available as data to the public

Actually, our government is pretty slack between the ears.  Some of us want to overthrow the government, as is our constitutional right.  But with the present state of affairs, we're just biding our time because now we're thinking it will collapse under it's own weight all by itself.
--
Chris

[oztules]

"bob g\
ps. can i lay my panels on the ground?  "

Bob, I know it was probably only a quip, but if you look at the flat plate radiation figures, the flat on the ground actually produces more power in the summer than latitude or latitude-15 does....... not so smart for winter though.

Your generator system is way cheaper than Grid power on the mainland at peak shoulder and "special days"...... they can gazette up to 7 days  per year where they expect super peaks... and can charge over a dollar/kwh..... it won't get better now they have smart meters over there (mandated gouging ).

As we are really talking of only using the genny for "peak power".... when the sun didn't work as advertised for a long period........ it's cheaper than grid connect power on the mainland  by a mile..... fancy that........ well done!



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

[oztules]

There is one other interesting aspect to this.

A fellow is coming here today to talk to me about grid tie inverters, and their use with off grid "grids"

If I read him correctly, he tells me we can run the big inverter from batts, make the local grid, and then hook the grid tie inverter into that same grid.
I believe he was referring to sunny boy power inverters and grid tie inverters.

It intrigued my, as if your power inverter has a battery charger incorporated (mine has a 70 amp inverter charger built in), then apparently when the solar grid tie inverter starts to overpower the house inverter, the "H" bridge output stage works backwards, and the grid tie inverter supplies the house and feeds back into tha batteries via the home inverter's charger.

The  house inverter controls the grid tie inverter by changing the base frequency  a fraction, and the grid tie one then governs it's output to the house grid by lifting the V/A curve to use higher voltage, and less current to slow the charge etc ..

Very interesting for those off grid, with loads of solar panels. You'l never need to load shed to the genny for big loads if the daylight is even only fair.

Hopefully he can fill in the spaces, and I may do a topic on it. Someone else here must know about this local grid behaviour.... it's neat.



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

[fabricator]

I believe the Xantrex XW series and the new Radian and probably the new Magnums have that capability, they call it mini grid or local grid or something like that.

[ChrisOlson]

A fellow is coming here today to talk to me about grid tie inverters, and their use with off grid "grids"

If I read him correctly, he tells me we can run the big inverter from batts, make the local grid, and then hook the grid tie inverter into that same grid.

In theory it can be done with any battery based inverter system providing the stable "grid" and grid-tie inverter.  The problem is in how grid-tie inverters "see" the grid as an unlimited hole to dump power into.  I tried it at one point with a Jacobs turbine and it was a disaster.
--
Chris

[oztules]

Sorry Chris,

I didn't explain it very well perhaps.
The home grid CONTROLS the grid tie inverters.
It means no midnight controller, no mppt units..... solar panels hooked up for 300v.. etc.

The grid tie does all  the mppt, AND limits the power to the home grid so that it/they supply the home power AND through the home inverters charger.....charge the batteries at the same time.

The home grid inverter does nothing but control the base frequency  most of the daylight hours (if you have an obscene amount of solar that is)

The grid ties are controlled by the home inverter which governs their output by communication the power required by the grid inverters by shifting the frequency slightly....
Eg, 60 hz........ go for broke and use all you can from the panels to run loads and charge the bank if possible.

Then the home inverter finishes charging, and so shifts the freq to 60.5hz for example, and the grid tie unit/s respond by lifting the voltage point on the panels V/A curve and limit the power to the home grid to maybe just powering the  house, but batteries are full so this turns off the  charger.

Shift to  61 hz, and the grid tie basically sits back doing very little as it shifts the voltage up the VA curve even further. to maybe even idle ........viola.... a fully controlled power station just by the two/three units, no other stuff required, including running the very large loads in the daytime, without using the batteries if you have an indecently big solar array.

Does that make sense now?
The grid tie units can't overpower the home grid, as it just shifts frequency and makes them change their outputs to suit.

If it really works as described..... thats darn nifty to put it mildly.

Hopefully I will know more today, but it means lots and lots of solar will be even easier to utilise properly..... a good thing for the batts too.



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

[ChrisOlson]

The problem I had with it is that the grid tie inverter for the Jacobs thought the inverter was the grid and it tried to back feed the power into the inverter like it would the grid.  The off-grid inverter didn't like that it and it shut down with an error, same as if you'd hook a generator up to the inverter's output and try to backfeed it.

Then the grid tie inverter saw that the "grid" went down so it disconnected and free-wheeled up against the governor, and all the power went out.

I even tried using the inverter's output to sync with the grid-tie inverter and feed the inverter's AC1 grid input with the turbine in pass-thru.  That didn't work either because the grid tie inverter couldn't stay sync'd without having the grid to sink power into, so the inverter would spit it off and the turbine would just run up against the governor again.

I fiddled with it for better than six months trying to get the two to work with one another, and finally gave up up on it.  I tried some of Rob Becker's ideas on how to get it to work that we discussed in a different thread, and even thought about trying an Aurora inverter on it.  But in the end, even assuming it could work, it appeared to be a finicky unstable system any time you start relying on inverters that are sync'ing sine waves without direct communications between them.
--
Chris

[oztules]

"That didn't work either because the grid tie inverter couldn't stay sync'd without having the grid to sink power into, so the inverter would spit it off"


Thats the key to this working. If you can't control the mppt of the grid tie unit, it cant work simply/sensibly.

Thats why the grid frequency shifting telling the tie inverters whats going on is key to this.

Once we (they) can have their mppt points controlled by the load (via hz from home unit), it is all simple stuff, until then finicky is too kind of a  word to use.

It cannot work usefully without control from the home unit... If both units cannot be programmed to play nice, it cannot work, no matter how low impedance the home unit may be, because it's impedance will rise with input from the grid unit, until it over powers the orchestra's conductor... and then it will turn off because of freq shift or volt over.... probably freq shift first.

If we are in control from the load end .. of the input power (VA curve), we can win all the way to the bank.


........oztules

[ChrisOlson]

oz, that was the problem for me - I couldn't find two inverters that would discuss the situation and decide what to do.  They both wanted to do their independent thing and that most times was going in opposite directions.

They make inverters that do this - stack Xantrex units with a ISC-S stacking cable, for instance, and they "talk" and each put out sine waves 180 degrees from each other.  Or use the parallel cable and they will "talk" and both put out sine waves exactly in sync with one another.  But at the time I tried it, there was no "stacking" or communications cable that could be connected between a grid tie and off-grid inverter to make them "talk".
--
Chris