Main Solar system upgrade

Alternative energy sources
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The usual. As I have two large solar PV systems here, and my lab assistant just put one in, and others are interested in things like this, here's where that stuff goes. This is mostly for things that work now, not "gee someday a fusor will do this" -- we know that, but it's not someday yet.
The hope is to save anyone embarking on this sort of thing a lot of wasted time and money, as at least I have been off the grid since 1980 and have had a lot of practice (and made mistakes you won't have to).

Re: Main Solar system upgrade

Postby Doug Coulter » Thu Aug 23, 2012 11:20 am

Still a work in progress. Now that it's cooling off enough to be on a roof again, we'll rent that crane again and finish up. The current state looks like this:
SolarMax.jpg
A mess, but one that works well just like it is.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: Main Solar system upgrade

Postby solar_dave » Thu Aug 23, 2012 12:22 pm

Doug have just considered building a ground mount system? It might get you optimal angles and be adjustable to the time of year, helping shed snow and such.
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Re: Main Solar system upgrade

Postby Doug Coulter » Thu Aug 23, 2012 1:40 pm

This replaced such a system. I found adjusting for time of year too much trouble, personally. The issue here (that doesn't show in the pic) is there is a line of trees to the south - my "hedgerow" between me and the road, that I don't want to cut down, so I really need the panels up in the air - it's made a huge difference compared to the mere 8-10 feet I could get on the ground racks. Now that it's cooling off, the rest will go up there on the roof.

There's a secondary advantage to this - there is one huge convection current going on under the panels, which cools both them, and my roof. Despite 6" thick insulation, I can run around with an IR Thermometer and really see which parts of the roof are under the dual-angle rack - it's a 10 degree difference on the indoor side. As a bonus, in the winter I can stuff this channel with foam rubber and have an insulating air pocket if I want. The summer wind through that channel created by the 2x8 is such that it will blow out a cigarette lighter even when the prevailing wind is from the north! It's pretty impressive.

Remember, I don't live in the desert, rather the opposite. Here's a view south from standing in front of the building.
GroundSouth.jpg
View south from the ground in front of the building


And here's one from the peak of the roof on the left. I actually used the top panel to rest the camera on to stabilize it.
RoofSouth.jpg
From above the roof peak


Since I live well north of you, in winter the sun doesn't rise above those treetops...most of the winter. And some of those trees take forever to lose their leaves, despite I've cut down the pines.
But there are more tall trees on the other side of the road I don't own - so I'm stuck with what I've got. This is actually the best solar site on my land except way in the backyard where it's not very tenable in the summer - big south facing hill, but...either not enough breeze or too much wind, and not that easy to get to.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: Main Solar system upgrade

Postby Doug Coulter » Mon Oct 22, 2012 10:24 am

Slight improvement. The interesection of worthwhile weather and available help has been a null set of late, but no way was I going through winter with two racks of panels laying flat (north facing a bit) in the garden, so a stop-gap had to be done. At least this way we get something out of them, and those sparkly multi-crystal panels are the best performers in cloudy weather when the light is coming from all directions.
SlightImprovement.jpg
Stood up the older panels


Next time there's a chance, those black ones leaning on the wall get the middle position up on the roof, like the ones to the right (except, this time they'll be put on straight). Those two that aren't even wired in, I've bought some more angle etc and will hang them off the similar ones on the left - not sure yet if I put them above or below the existing ones. Those BP panels rock too....want to get all I can to keep my Volt all-electric numbers high in the winter, unlike last year when I was forced to buy a fair amount of gasoline for it (lifetime - 95 mpg, since January this year, 182 - and increasing).

Looks like behind those I just stood up, I get a damp shady area in spring so I can grow cool season crops up here there. I used to have to attempt to maintain a garden down by the creek to do that, but the hungry critters managed to evade even 6' tall tight chicken wire fence and buried fence to 2 feet deep, it kind of wasn't worth it. It'll be nice to have peas and spinach and carrots again.
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Re: Main Solar system upgrade

Postby Starfire » Wed Oct 24, 2012 11:05 pm

Doug - What is the total capacity?
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Re: Main Solar system upgrade

Postby Doug Coulter » Thu Oct 25, 2012 11:53 am

I'm going about measuring that now. Some of those panels are 30 years old and not putting out spec (the smaller light blue ones). The newer ones are beating spec, but there's enough capacity that it can be hard to measure in winter (which is coming on here) since some are shaded and by the time they get out of the shade, they're at a bad angle -and my house and car are both charged anyway. In theory, what we have here goes like this:

Those on the far right on the roof - 12 total, are shcott panels and rated at 240w each. They are making spec at least, so call that 2880 w
The black ones are BP Solar, new production (they shut down their plant, though, darnit) are 175w and making spec, 14 of them, so another 2450w
The light blue sparkly ones are the older BP solar, rated at 120w. 13 of those, lets say they make 100w, so another 1300w.

So, 2880+2450+1300 = 6630w, or thereabouts. In general, I'd call it "enough" as on a sunny day, I can not only charge my car (13kwh) but also run A/C if I want.
In winter, I can charge the car most days (40 miles or so range from a charge, depending, like any car, how you drive etc). And in either case, keep up the house batteries, which have a 24kwh theoretical rating. I'd never know as I never run them down even halfway - it shortens their life and they were not cheap - submarine battery quality there. The electronics might as well be 100% efficient as far as can be told.

Most of these panels are hooked in series-parallel at voltages around 60 to 90v at peak power output, and this is "impedance matched" to the house batteries by a series of efficient switching supplies, which gives perhaps 30% better net output than a straight connection. Solar panels are a kind of constant current device up till near their open circuit voltage, where their diodes (each cell is a diode) start to turn on.
This of course varies with temperature like any diode. The batteries in turn are '"wherever they are", so a variable DC "transformer" really helps, and the wire losses are cut by higher voltages and lower currents in the wires.

The older sparkly looking panels are by far the best on cloudy days. Due to that sparkly nature, straight on light, which is what the spec for testing/rating demands, isn't their strong suit, and so they had to make them bigger for a given rating. When the light is coming from all directions - we get the one case I know of where specs-man-ship helps the end user, which is why I haven't ditched them for a later model.

Where I live, effective noon-equivalent sun hours average 4.5 a day so 5930*4.5 is 29.835 kwh a day. The reality is that we have some days with nearly "nothing", and in summer, have some almost 10 hour days.
The trick there is - you adapt to what nature is willing to hand you - drive more in summer, take more showers (the one thing I heat with other than propane or wood), use the machine shop more and so on.

Strangely, the refrigeration is one of the biggie loads, since it draws power at night (with a round-trip loss in the battery system) and you can't turn it off. But what I did do is put a top loader chest freezer in an unheated building in the shade, so it draws almost no power in the winter. My best power time is actually spring - we get the most sun, but it's not hot yet so the reefers don't draw much. Worst is right now - sun hours already short, but things are still warm. As the system grows and I get better at using what's there, I am smoothing out the peaks and dips with things like air conditioning, electric heat for water and air, water distillation, and other things like that. Because once the car and house batteries are "up" - you may as well use any extra power rather than let it fall on the ground unused.

I will gain about 20% net out of those big black panels leaning one the wall when I put them up on the roof, like the two sets on the right, and rejig the light blue guys already up there with the two-slope approach too. As it turns out, I have one good spare so that three panel rack will be filled to 4 by that time, should be all good, and I'll be done with this for the foreseeable future. There is a row of trees to the south of me, some on land I don't own, so I have shade issues in winter at low sun angles. I'm willing to work with that, but the more of this that makes it to the roof, the better for me.

A side benefit, which I had planned, is that when I used those wood 2x8" to support the two slope racks, I get one heck of a convection current - it will even overwhelm a fairly stiff wind coming from behind and blow out a cigarette lighter. This keeps the roof (there's no attic, I'm on the second floor right under these) and panels cooler in summer - more power and less need for A/C. In winter, I'll try plugging up that channel with foam rubber to see if I can trap more heat in here. I have a skylight on the backside of the roof that serves as a door to get up there from inside easily to do things like that. I'm also hoping the new arrangement will shed snow on the steep parts, but provide some heat to melt it off the top, flatter ones, which I used to have to go up and scrape after every snow - not fun on a slippery roof.

Here is a typical curve of solar panel output vs voltage under standard conditions:
MPP.gif
Solar panel curves

Another benefit no one seems to mention is that in very low light, a 30v nominal panel may still be willing to make some fairly decent power at say 19v. So hooking a bunch in series with an automated max power point regulating controller gets you about another half hour at each end of every day of at least some useful output.

In my system, both battery and panel temperatures are monitored to keep everything as happy as it can be. Batteries especially will be ruined by overcharge when they are hot and "want" a lower terminal voltage.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: Main Solar system upgrade

Postby Doug Coulter » Mon Apr 29, 2013 6:35 pm

OK, I admit I've been slacking on updating this thread. It's because, well, winter, then we got busy again finishing the job, which is almost done - building 1 IS DONE.
Qualitatively, getting the best panels to the best place has made a large improvement, but quantitative numbers will have to wait for some real-life experience.

A local farmer helped me last week finish up the main building - we rented a crane (bucket lift) to help us get the stuff into the sky, and mostly his brains to get stuff we can't lift solidly mounted into places we can't reach. Don't even let anyone tell you dirt farmers are dumb. To jump to the end, here's what it looks like now:
https://www.youtube.com/watch?v=F4IM2VjkRXM

We had an issue with the crane. We didn't even realize it had hydraulic brakes along with the manual brakes we used to lock it in place to unhitch it, and some how those got set, and refused to un-set, so it wound up taking 2 trucks and a tractor to pull it back to the road where we could discover and fix this so it was towable back to the rental place again. Whew, what a thrash. The rest went relatively smoothly, to the point where putting up the last rack was "simple" by comparison to all the others.
Why is the last one always so easy? It's because by then, you've learned how, I suppose.

Here's a neat view of one of the heavier, better racks going up. Mark is doing the guiding while I goof off and take a short video of this - we hope never to see this again!
https://www.youtube.com/watch?v=RhfU5DF0wtI


Doing all this resulted in two spare racks, some of the older panels mostly, spared out - we left room for one more on the big building, but the issue there is that being so close to the road, and the trees on the other side to the south, I actually get much better winter sun on a trailer building about 60 feet further north (behind) the big building, so we used the crane to set those on the nice, flat roof. Those are still to be stood up and wired. Due to the history of that trailer losing roofs in windstorms before I got it - its roof is actually 3/4" plywood with real 2x4's supporting it - it will handle us walking around on it and adding a big heavy load. This will shade that roof in summer (required, it gets way too hot in there) and make for better capture of power in the winter, when I actually need it more. That's yet to be done, but it should be pretty easy at this point - all the heavy lifting is done, just need to make a 40 degree or so stand and bury a 50 foot wire to the rest of the system for those. No time pressure either - they will do most during the winter, so till then, no urgency. Also, no worrying about the $/day of a crane - they're already "up" in that sense. The other urgency is that my veggie garden was on the south side of the main building, touching - the crane would have destroyed any garden I'd planted, so after 2 years, I get to plant at least late crops again in my main garden. Whew!
So, here's the what's left to do on the back trailer:
https://www.youtube.com/watch?v=qhOOm4e ... jA&index=5


Some other movies of progress to get to where I am now. Though I don't have quantitative measurements averaged over time/weather, I can say that on the first sunny day, with all but one of the racks wired on the main house - I charged my Volt from dead to full (13.3kwh), cooked a shower (5.5 kwh), and ran the computer all day, while charging the electric/hydraulic crane from the system (?? kwh) and running the computer (2kwh) all day. And oh, the house batteries (again, unknown kwh) got full by 10 am, before doing the other stuff - probably 2kwh or thereabouts. So, finally - plenty, plenty, plenty. In fact, yesterday and today were rainy/cloudy, yet I have enough. I admit to not using the welders and so on for those days - but that's what I do normally. You adapt to making hay when the sun is shining, and hunker down a bit when its not - don't waste it when you don't have it, keep from having to run that generator to keep the house batteries (24kwh, but rarely used to near that capacity) near full.

What you might not notice on looking at this, or wondering why this took so long, is that the same panels that *were* on the top of the roof aren't anymore. Every single rack was taken down, rewired, and put where I thought it belonged in this process.
https://www.youtube.com/watch?v=XR6EHgLErMo


So, while many of us dream of man-made fusion power, at least I'm living on fusion power - just that from the sun, not my lab, for now.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: Main Solar system upgrade

Postby Doug Coulter » Mon Apr 29, 2013 6:43 pm

Some other notes. One of the reasons we rewired the racks was to get as many compatable on the same MPPT (max power point tracking) controler. Those things are expensive, but worth it - they amount to a smart, variable ratio DC transformer - a buck switcher with high efficiency (they didn't skimp on the inductor or switch quality) that finds the max output of a panel set and matches that to wherever the battery voltage happens to be. There's a system limit, due to lousy programming of the CAN bus interface on the Xantrex stuff, to how many of those can "talk" to co-ordinate charging, and we were tight on that one.

The other thing is roof shade. Gets hot here in the summer. Well, turns out we get much more advantage than just shade - due to my cheapskate use of 2x8" lumber rather than expensive aluminum racks - we have a convection channel. Theres a real wind blowing out the top - enough to make running a propane torch almost impossible, as we found out when soldering up there(!). I'd like to claim I designed for that, but it's purely adventitious. I have a half-fantasy that I will cut foam blocks from foam mattress material and stuff in there in winter (gets real cold here in the mountains too) to trap some of the heat as well. It won't matter as much, though - now that I am often swimming in power, I can run electric air conditioning and electric heat rather than let the extra power fall on the floor, as it does when the batteries are full and the normal house needs are met.

I didn't post all the vids I got. Fanatics can see it all (in reverse chronology) on the DCFusor channel on youtube here:
https://www.youtube.com/user/DCFusor

Finally, it's feet up and a beer time. Then I get to mow, till, and plant my garden, then it's really feet-up and fusor time. That super duper HV power supply is calling me to get into the shop and mill out some custom parts to get it finished...
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Re: Main Solar system upgrade

Postby solar_dave » Tue Apr 30, 2013 10:58 am

Congrats Doug on the big project accomplished. Looks like you will have more than enough to carry the short days of winter. Yes MPPT are sure nice and you can run higher voltage to the controller to keep the wire sizes under control as well.

We are already hitting the 100+F days here and production is down now from our high day of 76.5 kWh on the 18th to about 71 kWh. Of course because of the temps we have now fired up the AC systems but for the month we are still on the positive side of consumption with 600-700 kWh going in the grid tie bank. May usually is a break even month between production and consumption so it looks like our bank size this year for the summer months is about 2000 kWh. That is less than I would like.

APS has done some more trying to get me off the super nice 9AM-9PM TOU plan by offering a EV charging rate plan with a super off peak @ $0.042 a kWh from 11PM to 5AM. The actual generation charges unbundled from the delivery and other per kWh charges is $0.00678. They are giving the generation away in effect. Because I push so much to them early in the year I usually don't hit those other charges until July or Aug. But I am not biting. I have about 10 months of 2 sec frequency raw data collected off the TED and will run my own analysis once I get some time. It is tough to find when your part time contract is taking 45-50 hrs a weeks! LOL $ :mrgreen: $ :mrgreen: $ :mrgreen:

https://www.aps.com/library/rates/ET-EV.pdf
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Re: Main Solar system upgrade

Postby Doug Coulter » Tue Apr 30, 2013 1:47 pm

FYI Dave, dunno how your system works - it might have the equivalent of MPPT - if it does, in a test here, I found that the power used by a tiny (computer case class) fan was less than the extra I got from using it to cool the backside of a panel (put thin wood over the back, fan hole in one end, air outlet hole in the other end). The way mine are set up now, convection handles that for me, but I have a better angle (for that) up north here. It's actually pretty fierce up there at the top of the convection column.

The reason for this is that solar panels are forward biased (by the photons) diodes, with the usual negative silicon tempco - so the cooler they are, the more voltage they put out at the same current draw. That's probably why your system peaked out in cooler temperatures.

Refrigeration (freezer) used to be the nasty load here (Now it's the Volt, but that's a joy and much more optional - I can choose when to charge it). I wound up putting my chest freezer in a shaded, unheated outbuilding in the woods. It then drew very little kwh during the cold season - just when I didn't have it to spare anyway. As a result, my peak power season was always spring - long sun hours, yet still cool to cold outside, and next to no freezer load. Just a tip for others in a situation similar to mine.

We found another cool tip. We used the freezer to freeze 2 liter soda pop bottles of water, then used them in large, high quality camping coolers in our living spaces (we have several) as a fridge. A couple of those bottles go about 2 days in a cooler. By choosing when to rotate the bottles for a time with max sun, we could then control when the freezer kicked in and drew real power, unlike a conventional fridge. Worked out pretty well, but these days, yeah, I just bought a real fridge to put in my place to save the walk and hassle - now that I have power to burn anyway.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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