Author Topic: Blasphemy..... Solar power.  (Read 67883 times)

LowGear

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Re: Blasphemy..... Solar power.
« Reply #150 on: March 17, 2017, 04:28:34 PM »
What angle do you set your panels?
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BruceM

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Re: Blasphemy..... Solar power.
« Reply #151 on: March 17, 2017, 06:07:13 PM »
Panel angle depends on your latitude, and you would normally optimize panel angle for the sun angle at your month with the greatest heating degree days.
Close counts.  If you are using polycarbonate glazing, you should also be trying to minimize stagnation time through the summer.

Casey, you are further north than I thought at 21 degrees of latitude.  If your goal is water heating alone,  your optimum panel angle varies between 45 degrees in on 1 January, to 27 degrees (from flat) at the end of June. 

For those farther north, you have to consider that winter optimum angle is steeper than the noon angle; take a look at your mid morning to mid afternoon optimum angles too.  Vertical isn't bad for winter gain in the mainland US, and can easily be in shade during most of the day in summer.

You can play around yourself using the calculator here:
https://www.esrl.noaa.gov/gmd/grad/solcalc/azel.html

LowGear

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Re: Blasphemy..... Solar power.
« Reply #152 on: March 18, 2017, 05:03:14 PM »
Easy site.  Seattle is at 47.5 degrees latitude.  Then I tried this site.  http://aa.usno.navy.mil/data/docs/AltAz.php which reports that the Sun is about 65 degrees to the surface of the earth at the Summer solstice.

The 65 degrees to the surface is what I find interesting.  This tells me that the optimal angle of the collectors would be 25 degrees as the complement for 90 degrees or perpendicular to the Sun.  Of course this is optimal for one day and starts to decay as the days accumulate before or after solstice.  On equinox the Sun is about 43 degrees so 47 degrees would provide the perpendicular relationship to the Sun.  I've decided to not worry about collection very much during the Fall and Winter months of the year.  Hence optimal collection angle for the Spring and Summer, without adjusting the angle, would be about 35 - 36 degrees.  http://learnframing.com/angle-calculator-slope-degrees/  suggests a 9/12 slope to achieve this attitude.

I feel like I'm missing something?

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BruceM

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Re: Blasphemy..... Solar power.
« Reply #153 on: March 18, 2017, 07:35:19 PM »
I think you got it well sorted out for your intended use.  Think about the middle angle for the  morning to afternoon for all the months.  Check the boundary months as well.  For winter, more vertical helps full day collection, for summer, more horizontal.  Close counts.

buickanddeere

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Re: Blasphemy..... Solar power.
« Reply #154 on: March 19, 2017, 06:37:24 PM »
  I kept track of the output of two sets of 10Kw grid tied systems on my road. One is a tracker and the other is fixed. approx 44.5 degree latitude.  Almost exactly  the tracker made 18,000Kw hr per year and the fixed 12,000Kw hr.

BruceM

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Re: Blasphemy..... Solar power.
« Reply #155 on: March 19, 2017, 08:36:49 PM »
That seems about right, B&D.  Now that PV panels are pretty cheap no one in the right mind would do a PV tracker except as a fun hobby project.  The cost of the tracer exceeds the cost of adding more fixed panels, which then don't have any ongoing maintenance cost.   

In the winter in the northern hemisphere off grid homes need energy the most,  tracking is pointless, since the total useful range in azimuth is so small.




LowGear

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Re: Blasphemy..... Solar power.
« Reply #156 on: March 20, 2017, 08:51:23 AM »
Wow.  A 10 KW system that tracks.  That's around 40 panels isn't it?  Can you get any photos?

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buickanddeere

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Re: Blasphemy..... Solar power.
« Reply #157 on: March 20, 2017, 03:36:49 PM »
Wow.  A 10 KW system that tracks.  That's around 40 panels isn't it?  Can you get any photos?

Casey

I suppose, dozens of the buggers around here getting paid 80.2 cents per Kwh while hydro electric can generate at 5 cents but is spilling water past the turbines due to production surplus. Makes Ontario  power the most expensive in North America .
  I'll post a few images one of these days .

LowGear

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Re: Blasphemy..... Solar power.
« Reply #158 on: March 20, 2017, 04:46:48 PM »
Well if I were one of the buggers I'd call myself a very luck bugger.  They have a similar program here in Washington state, USA but it's coming to an end in 2020. 

Don't you worry big oil will raise her pretty head pretty soon.  Too bad they're sloshing water rather than reducing fossil fuel consumption.

I'm still hoping to see a 10 KW array that moves.

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buickanddeere

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Re: Blasphemy..... Solar power.
« Reply #159 on: March 21, 2017, 07:06:52 PM »
Burning natural gas for 17cents instead or using hydro electric for 5-6 cents

mike90045

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Re: Blasphemy..... Solar power.
« Reply #160 on: March 22, 2017, 11:15:45 AM »
Panel angle depends on your latitude, and you would normally optimize panel angle for the sun angle at your month with the greatest heating degree days.
Close counts.  If you are using polycarbonate glazing, you should also be trying to minimize stagnation time through the summer........

For my PV array, I set it for the optimum winter angle, to reduce the generator run time and enhance self-cleaning via rain, summer, worse angle, but much better weather and more hours to recharge the batteries.
 
For my rooftop water heater, I was stuck with the angle of the roof, good for summer, nearly useless in winter, it reflects instead of harvests.  But in winter the Masonry Heater has a hydronic coil and preheats my water in a 80 gal tank in a 2nd floor closet.

glort

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Re: Blasphemy..... Solar power.
« Reply #161 on: October 22, 2017, 02:02:41 AM »

Thought I'd do an update and keep all the info in one place.

Here's the abridged version for my mate Casey whom I know is a very busy man and has limited reading time.
Solar: It good!

Now, for those that have made their Coffee and have a few more moments of reading time....

I have now moved to the new place and made some more advancements on my solar learning and adventures.
I bought another 20 250 w used panels (5Kw) for $800 or $40 ea. Guy selling them seemed a bit dodgy but had 100's of them. Obviously has a deal with a solar installer and buying their old panels from upgrades.
Brought them home, tested them and they all work at spec or as close as I can measure.

I have set them up on the back lawn to test them and frankly, see if I was going to get worthwhile power out of them before going any further.  Suffice to say I'm well pleased. I have 10 leaning up against some scaffolding I set up which amazingly, worked to angle them within a couple of degrees of ideal when I set them up for winter tilt and again when I did them for summer the other day. Can't believe I got that lucky! The others with a couple of extra's I picked up elsewhere are lying flat on the grass. 

At first I had a bit of trouble really getting any grunt out the things. I have the inverters plugged in to a long extension cable and going into a power point. The new place has 3 phase with 1 Digital meter and 2 analogue spinny meters.  The old meters do run both ways, the digital meter which also controls the hot water only runs one way, forward whether you are pulling or pushing power.
I found a Phase with the old meters supplied the shed, septic pump and the lighting circuit.  I had trouble keeping the line voltage under 265V at which point the inverters would trip out to overload.  I tried splitting the arrays and had the same problems and thought it was the phase voltage going high.
I tried powering through the lighting circuit but that was a failure as I later realised would only be wired for 1.5mm cable not the 2.5mm for the power circuits.

The best part of farting round with this stuff is what you learn and one of the real eye openers for me was understanding properly about voltage drop and resistance in wiring.  I knew about voltage drop but I didn't consider what I call now voltage compression.  Drop is when you are pulling power and the voltage at the load end is lower than the supply end. It works in reverse too. When trying to push power down a lead, the voltage at the end you are trying to push down can be a LOT higher than the point to which you are trying to push it.
And this was my problem. 
I could get away with it up to about 2 Kw but after that the phase voltage went up a little but enough to make the inverters see over 265V at their end even though the actual phase voltage was only 249-250.

The most I was able to pump back into the meter was 11 KwH day.  Still, that did make some progress on that phase knocking over 150 KWH off it plus supplying the power we used on that phase over a month.

I lived with the realisation that was all I was going to be able to do in the test setup for a couple of weeks and then a sparky mate came round and I got him to shift the circuits around on the different phases.  Everyone says about the loads being balanced but mine were all heavily biased to the digital meter.  The other thing is that I had FAR more load capacity on the other house but it was single phase. So much less potential load here but split on 3 phases as nearly all homes in the area only being an average of 20 yo are.
I cured that and took everything I could off the  digital metered phase and put it on the other 2. Only things I can't shift  are the off peak hot water and one leg of the 3 Phase AC.  Everything else now is on the spinny meters which DO run in reverse... quite nicely I might add!

With the circuits ( the much fewer there are than the other place) carefully split, I can now for the mean time, plug into both and the difference has been dramatic. I can now run the 2 arrays into seperate circuits which keeps the inverters happy. As now there is also some more load on those phases such as fridges, computers and TV which combined have a constant load not to mention the septic aeration and water pumps, the phase voltage is also lower.

So far my best day, a few days back was 26Kwh for the day.
That was a nice sunny day from dawn to dusk but I have been surprised by the many days we have had with more overcast or partial cloud hours than clear sky.  I did 16KWh for 3 days on the trot when we were expecting rain which surprised me given teh light difference.

The temporary setup I have atm is one bank of 10 panels on a 2Kw inverter and another array of 12 panels on a 3Kw inverter.  I picked up 3 near new 260W panels as well but broke one of the 250's playing ball with the dog. 
The bank of 10 panels is on the scaffold and orientated and tilted Correctly.  When I changed the other day from the winter to summer angle I picked up an average of about 2 Kwh a day. More than I was lead to believe from my readings I would gain. Seriously thinking about a tilt panel setup now.
Love to see and hear about yours if you are Reading Bruce.

The 12 panels are lying flat on the grass. Interestingly, they still produce more power every day than the near perfectly orientated ones. On the real overcase days, they are significantly better although of course well down on max power.  Should start keeping bit of a log of outputs and the days weather.  I was really interested to see what they would do the other day when it rained all day. I did go to check but both inverters were off line wth grounding faults.  Suffice to say the wiring on the setups isn't exactly Kosher on the DC side and the inverters must have picked that up with the water on the wiring and causing ground leaks.  The AC side is spot on. Might be rough but I'm not completely stupid!

I am getting ready to put the panels on the shed roof which is also nicely facing east so gives me one whole side facing true north. Being an American barn roof design, even the south side gets sun most of the day so could be a possibility to put more panels there.
I'm " trimming" trees down to make sure the shed roof is completely clear of shading.  Council regs here say you can trim trees but you can't cut anything down over 3m tall without approval.  Being one to always follow the rules no matter how stupid or inconvenient, I am just trimming the trees rather than removing them.  Trimming them to 2.7 M that is!   :laugh:  Being under 3m, if I decide to take them out later, given they are hideous  non native things that are declared invasive species in other states, Whe..... if, I decide to take them down, there will be no problem with me doing so without paying the council their money grab.

Next thing is to build a frame to mount them. Proper framing is stupid expensive here, more than I'm paying for panels per panel so it's going to be a DIY job.
The winds here get very strong. Records say up to 50 Kmh but I don't believe that for a second.  It's howled since we have been here and the locals didn't think a thing of it. I'll allow for double wind speed at least and then some. 
The shed is 9M long which means I can squeeze 10 Panels along the length with a bit of overhang on the ends. One step in the roof is 3M long, the other 1.5. The roof is at a 5 o angle and ideal here is 34 o. Not sure If I can get 2 runs of panels or 3. 2 will do, 3 ill be better.  I plan to add to that side of the shed soon anyway so will have more area even if I do have to lie the panels low to avoid shading the ones behind. Not much problem with doing the shallower summer angle anyway. Seems to work better on overcast days anyhow.

The house roof is east west and at the perfect tilt angle which is very unusual here. The west facing side gets full sun by about 10 am. The east side gets nothing thanks to the biggest tree in the area in the front yard.  that too may dissappear one day as although bit of a landmark, has been approved for removal due to a disease in the thing.  Just going to cost $20K to get the damn thing out!
I could probably put at least 15Kw on the house roof so I'll never be short of roof space and I'm also thinking of putting a solar panel roof on another shed I want to build up the back.  Wondering If I can make that a total lean to design with a high wall on the south side so the whole roof faces north?

A " mistake" or illegality I have made is over powering the inverters with panels. The 2Kw inverter has 2.5 KW of panels on it. I have learned that the current trend now with new installs is to do exactly this.  A kw of panels does NOT give you a KW of power. I'd estimate I'm getting around 700W output from every KW on a good day. This being the case, you can now Legaly over clock the inverters by 33%.  The benefits of this is the power company that controls the greater area of Sydney has mandated that the max output INVERTER that can be installed on a single phase connection is under 5 KW. All sorts of guff about overloading the system etc but obviously in reality they want to limit their revenue losses.
By putting on 6.5 KW of panels, you have a better chance of getting that full 5Kw ( or 4.9 as it may be) of output from your inverter. You'll also have more power earlier and later in the day and make more during overcast weather.

I have 2.6 Kw on my 2 Kw inverter and the best I have seen, briefly, is a 1900W output. The 3 KW inverter having only 3 Kw of panels presently could go at least another KW of panels, probably 1.5 before it maxed out.
As long as you keep the voltage within limits, there are no limits on the current you can pump in. The inverters just clip and ignore the excess and produce their full output. Does not hurt them, shorten life or anything else.



The thing I am interested in now is heating the water with solar. I can't rewind that meter but the power is only 11C kwh rather than the 30 C for the regular power.  I have a bunch of thoughts on this.
Maybe I'm better to pay for that power and devote the solar to the other 2 phases. haven't worked out where my consumption is yet given we are in spring and the AC is not needed. Sure will be in summer and winter that's for sure! Thinking another 3 Kw might be good.

I have the original 190 Panels I started with that on't match the others in size or output. I was thinking of using these for the hot water being 1.5 KW in total.  OTOH, I could probably sell them for the same price or better than I have a supply of 250's for so that might be smarter and then just couple the hot water to one of the other back fed phases and forget about the off peak all together.

I have played with direct coupling the panels to an old urn and that was a learning point as well. I can well see how unviably inefficient panels get like this.
The array has an open circuit voltage of around 350V but when I put the urn on it ( 2000w?)  it dropped to 80V. I measured the amps at a bit over 3 so maybe  250W out of a 1500w array.  Useless! Given the 4X Kwh ratio i'm getting with the panels on clear days ( Ie, 4 Kwh out of every 1000W of panels)' I'd be far better off to get more 250W panels and add them to my arrays.
There are converter/ controllers around but they are all too exy for my tight arse and I have read of simple DIY controllers but yet to find the schematics.
I believe I need to PWM the DC and ideally have some Caps to store the power during the off phase of the modulation and push it to the element when it comes back on.  Needs to be an inductor in there too but I'm just a dilettante when it comes to this stuff so it's a bit beyond me.  Can probably build it when it's handed to me but electronic design is something else.

I'll have to refresh myself on working out the power of an element through it's resistance and voltage. The water heater I have has a 3600W element presently.  I'll try to work out what putting a 1800W job on it would do for efficiency but I think it's still going to suck.  I had the idea a while back of having 2 heaters with teh solar heater in front of the regular one to pre heat the water for it. I see this idea all over the net now so either I was very original with the idea or someone stole the idea when I wrote about it a few places and it's caught on.  Like solar panels and everything else I'm looking to get, used water heaters have people asking stupid money for them.  I don't care how unmarked the thing is or what they are worth new,  I'm not paying $300 for a 10 YO heater which is at the end of it's designed life.  $50, I'll take the risk for learning's sake.

So that's where I am up to with the solar brain wave.  Next is to work out a mounting system and get the panels off the lawn and buy a heap of green  food coloring to spray  the brown dead grass that is underneath them now the Mrs hasn't noticed.  I have noticed the grass under the tilted panels is the longest and lushest of anywhere on the yard though.
Once I have the panels on the shed roof I'll hook them up to the new 5 Kw inverter I scored and hard wire everything with a proper sub board.  Seems the garage has 2.5MM wiring on the power circuit and I'm hoping the same on the light circuit. If it's only 1.5 MM I can still put 3 Kw down that phase with the other inverter to wind that side back.
From there I'll see how we go consumption wise and see if I need to ad more panels from there which I think I will.

Half a mind to just go get another 5KW worth now.  If I don't use them I can sell them for a small profit at worst.



BruceM

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Re: Blasphemy..... Solar power.
« Reply #162 on: October 22, 2017, 03:00:38 AM »
I'll try and get some pictures of my tilt rack design for my neighbors soon, Glort.  Possibly tomorrow if my leg is better.

I'm in AZ so steel racks hold up just fine here.  We just bolt the angle iron frame directly to the PV panel aluminum channel. I laugh when I see the prices for store bought mounting racks and hardware. 

We are in a very remote, rural area so we are concerned about function, not appearance.  Your area is very different.  We have no "councils" meeting unless the natives are angry ;).   Seriously, the Apaches are to the south, Zuni to the East, Navajo to the north just past the Petrified Forest, Hopi NE.  My land has much worked stone from the Pueblo related people who lived here 1000 years ago and is covered by both marine fossils and softball to basketball sized volcanic rocks as well as some large petrified logs.



 

glort

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Re: Blasphemy..... Solar power.
« Reply #163 on: October 22, 2017, 03:18:24 AM »

My Research and Development facility for the  improvement of quality of life in the civilised world through reduction of stress induced heart attacks initiated  by over the top and unjustifiable power bills.



Also testing hot water production through the direct coupling of an urn.  Not working out that great but it does work.... eventually.



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Re: Blasphemy..... Solar power.
« Reply #164 on: October 22, 2017, 03:42:57 AM »
Nice laboratory Glort very smart use of waste reflected sun to help dry the clothes :D  I think the only thing you're missing is a treadmill generator for your Border-collie...  if it's anything like mine she'd power your whole suburb :D

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