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Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578
Posted: 01:49am 15 Aug 2019
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I have been playing with solar a couple of years now and the main thing I have learned is like everything else,there are a lot of cavets and exceptions to the advise and rules given.
One of the big ones for me has been tilt of the panels. The advise pretty much always goes tilt to your Latitude. The reality is the sun in moving up and down in the sky all the time so the "Ideal" tilt as latitude is made out to be is only "ideal" for a certain time of the year. Flat panels with little to no tilt are a lot better in summer, steeper panels better for winter. Ideal tilt gives the best overall generation for the year but that may not be everyone's goal.
I have a lot of my panels at a very low pitch on the shed roof, 5o and 13o. I also set an array up at the 34o optimal where I am. The 5 and 13's are on 2 trackers on the same inverter. I can easily see what each array is doing at any time. I am yet to check where the voltage is more than 1 or2 V different and the output is always within the same narrow margin. That surprises me as I would have thought manufacturing tolerances and a blob of bird crap would have accounted for more than that but it's the numbers I get every time, any time, sun, cloud,winter summer.
The other thing that has been a surprise and an eye opener is the reason they say not to do flat panels being dirt run off. I can't see any difference between the dirt on my 34o panels and the crap on my 5o ones. I will say that there may be a dirt line on the edge of the 5o array where in a light shower, the dirt has washed to the lip of the panel and evaporated leaving a distinct dirt line but that line is on the border of the panel and I've not seen it intrude into the cell area. It's close on the edge as there is less clearance than on the ends but none the less, the cells are uninhibited.
Yesterday while catching my breath after Digging the Mrs the long harped about fire pit and starting the paving, I was looking at the side of the shed where I just cut down the overgrown hedges. I took 7 ft off the things so I mean overgrown. The sun was hitting the shed wall at not too steep an angle and of course got my Tiny brain thinking.
I have 9M x 3M bare colourbond there doing nothing. What if I put panels there as well? Obviously it will do crap in summer when flat is best but I don't care about summer, it's winter generation I'm always after.
Having found the projections from the PVwatts website gives amazingly accurate numbers to what I see in the real world, I crunched the options for mounting the panels flat on the sidewall of the shed. I saw an article where they are doing this on tall buildings where there is miles of side area but no roof proportion so thought I'd see what I came up with.
The results again surprised me. From April to august there is just 1.2% efficiency loss over having the panels at the "ideal" 34o angle. In September that blows out to 1.5%. Still to me within the margin of birdcrap as I say. For the averaged roof angles of the shed being 8o, Wall mounted panels would do better than those on the roof slightly for the winter months!
The worst result would be in summer where the wall panels would do exactly 1/3rd of the ideal output which is somewhat behind the flatter 8o average and no where near as good as the flat ground mount I had the summer before.
Surprisingly, while wall mounted panels would over all average about 60% of the output of ideal mounted panels ( which for me and most is a VERY limited option) the ability to have more panels where there was no roof space or decent orientation would be quite worth while. In comparison, an east or west array would average 80% of a north facing array so the wall mounted system would only be 1/5th less the output of an east or west string.
The thing for me is winter generation. Summer takes care of itself with so much stronger light and almost double the winter sunlight hours. Unfortunately I have plans to put a carport on that side of the shed so the wall will be shaded although I'll have more roof area to compensate. I'm seriously thinking about just making the roof itself out of panels. I have been buying them cheaper than I can buy roof sheeting for the same coverage area and roof sheeting has no pay back. I would just have to carefully seal between the panels with some silicone and maybe leave the securing fasteners with some margin for expansion.
Anyway, I though it was interesting that wall mounted panels would be far from a waste of time and how good a return they could make especially in winter. Of course this is in my area, may be the complete opposite for others though I think in most cases would be similar. Probably not as good north of Sydney and better still south.
I would not have thought wall mounted panels would have been that good but seeing the angle the sun was hitting the wall and then confirming it with the research showed it's far from a waste of time or money particularly for those like me whom want to chase winter generation. Given the choice, I'd always optimise for winter because that's when you want the power the most. The days are shorter, the radiation is lower and the generation turns to about 1/3rd of less of summer outputs. I also think panels on a wall could look pretty Funky.
I'm thinking I might mount a panel on the wall anyway till the carport is done just for battery charging the mower and a couple of other things. Max output is irrelevant on those anyway. Just needs a few hundred Ma to keep them from self Discharging.
Always best to crunch the numbers with something like the PV watts site for your individual circumstances because reality tends to fly in the face of the parroted mantras with solar like much else I have found.
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 02:36am 15 Aug 2019
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Its all pretty interesting stuff, and a lot can be gained by thinking the whole thing through, and experimenting with a few ideas of your own.
Definitely agree that winter performance comes first, and summer pretty much takes care of itself. There are really two quite different situations in winter.
The first is when there is a brief direct shot at the sun in a clear blue sky. The sun will always be at a fairly low elevation, and will not vary much either side of due north throughout the short day. For that you need north facing panels of quite a high elevation, in theory, its latitude angle plus twenty two degrees at mid winter. In Melbourne that is 38 degrees plus 22 degrees = 60 degrees. The panels will be "looking" only 30 degrees above the horizon in a northerly direction.
Vertical panels on a north facing wall should work pretty well too, but need to be located fairly high up if shading is not going to be a serious problem.
The second more common situation in mid winter is when there is total cloud cover, and only a dull even grey sky in every direction. It does not make much difference where the panels point, but you get very slightly more if the panels are dead flat and pointing straight up. These flat panels will also work pretty well in mid summer, but tend to produce a massive power peak around mid day, with less in early morning and late afternoon.
Panels even on a south facing sloping roof will work just as well in dull grey conditions, and would be worth doing, especially as second hand panels are becoming cheaper all the time.
I am pretty happy with what I have so far. 4.0Kw north facing at 60 degrees. Another 4.0Kw north facing at about 15 degrees. And an east/west facing passive tracker with 1.25Kw east and 1.25Kw west with all panels at 60 degrees elevation. Hope to add about another 4.0 to 6.0 Kw pointing straight up in the future, as the system struggles when there are several gloomy days in a row. Edited 2019-08-15 12:50 by WarpspeedCheers, Tony.
Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578
Posted: 05:40am 15 Aug 2019
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Having flat panels is also a bonus on the gloomy days and I see my shed panels will easily outdo the tilted ones on the house. Thing is though, for me the output of either is so pathetic the days are still a write off. If one were living off grid then I can see how every watt would be welcome.
I'm glad there is someone else out there with a panel Fetish like mine! :0) You are literally covering all the angles.
I haven't touched my north, south or east house roof yet. I have the biggest tree in the district in my front yard ( lucky me!) that shades most of the easterly sun. Still gets some but I do't want panels visable from the street which is also why I haven't got them on the north roof yet. I'm saving that if I have to get a legitimate System if they force the smart arse meters on me. I -hope- to be able to get certified for 10 Kw feedback and then put in a small system, 5 KW would work up there, and then I can hook up everything else and hopefully get away with that and generate enough FIT to cancel the night charges. Or I'll get a forklift battery pack and an inverter charger and see how that works out.
The south roof on the house does get some sun in summer but that's when I don't need it and the neighbours trees make for a narrow window to the sky the rest of the time. That said, the trees appear to be Dying. I thought it was just shedding in winter but one of mine on that side died as well even though it was clear of the house so I'm wondering if one of her yobbo kids hasn't poured oil or something around that has got to the roots or seeped through the soil?
The south shed roof does well in summer and on cloudy days. Unfortunately despite cutting the tree near it as far back as I can and clear of the roof by a foot or 2, The amount of bird crap on those panels have me not bothering with them atm. The wind does not generally blow from the treeward side to the shed side so I am assuming the strain on takeoff must cause some aerial bombing discharges which hits the panels. Last time I was up there they were a disgusting mess.
The tree is a pain in the butt and I'd like to get rid of it all together. In autumn it drops all it's leaves and I had to buy a petrol yard vac to clean them up.... about every 2 days for a month when it's dropping them. Nice enough tree, just is a stupid spot like everything else the previous owner planted here.
I had a theroy last summer that I could stand a panel vertical with it's back to the north and still make more power than I would on a winters day with the panel perfectly aligned. Seeing the numbers I crunched today, I'm more sure of that theroy.
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 06:46am 15 Aug 2019
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Oh, the many joys of installing solar panels
I arranged my flat panels to be mounted immediately below my steeper panels, so the rain runoff drains down onto the flat panels and keeps them reasonably clean.
As you say, wind loading is another issue to consider, but I have been lucky with that as well. The only really dangerous direction is a south wind from behind the panels, and these are pretty well screened from the south.
Its only multiple really gloomy days where I get about ten watts per panel that remains a problem. Bigger battery is not really a solution, the gloom can continue for several days in a row. So the answer is bulk extra panels pointing straight up. And maybe a put-put generator to refill the battery for maybe two or three short periods through the worst of winter. That may also help with running airconditioning at night when we get about two or thee 40 Celsius days in a row which might be a bit much for the battery.
I don't think planning to break even with feed in tariff is ever going to be realistic hope long term. The buggers still need to have sufficient revenue to maintain the distribution system, and the shareholders expect a dividend that increases every year.
So the power utilities and the bought and paid for politicians will keep moving the goal posts to keep the system financially viable. So there will be more rules and greater restrictions as time goes on. Only way to win is NOT play their game, give them the middle finger and go completely off grid.Cheers, Tony.
Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578
Posted: 10:20am 15 Aug 2019
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The problems with Off grid systems for private properties with things like bad weather I think are a good insight to the magnified problems of the green motivated ideal of 100% Renewable grid. It's nice in theroy but in practice the HUGE problems are always downplayed.
At least at home scale you can have a practical amount of batteries. On a grid scale that is pure and utter fantasy.
I intend to play the corrupt system for all I can for as long as I can. Won't last forever or I think all that much longer in fact but I'll make hay while the sun shines. I'm more than self sufficient in power generation 9 Months of the year. I'm about 400KWh behind on the billing quarter just gone which isn't too bad given we are entirely electric here. I have forced an estimated reading of the last bill so I can catch up on some of the useage for the next quarter. We pay so much off the bill every week in advance so like last time I believe we will still be in credit with their estimate anyway.
My panels, Generators and wiring upgrades are all working towards going off grid should I decide to go that way. with all that in place, it will neither be a big expense or take much time if I want to do that. If I don't and luck holds out, then it's still paying for itself well and truly.
I do read of some people making credit on their bills with solar. You have to take that with a grain of salt sometimes though. I was reading a comment from a guy the other day saying he had gone solar and was now getting a $40 credit on his bills. The bigger story was he has spent something like $22K on a large solar setup and a Power wall battery. I groaned when I read that. Battery will be dead before he ever comes near getting his $15K back on that and he will end up costing himself more than if he went with the solar and left it at that.
As someone else pointed out, with his provider the credit is always that, a credit. There is no cashing out so in 10 years he may have $1600 in credit that will sit there in perpetuity.
There is much talk of the grid death spiral but I don't know about that. With more people moving into apartments and housing blocks of sub 300SqM and having double story homes with tiny roof areas, I don't see a lot more people being able to go it alone in the future. Then you have business and industry who can only do token gestures as well over all.
If there is one thing that WILL spur more people to become independent it's the lights going out and that I think is going to be gauranteed for at least 3 states in the coming summers. I';m already seeing US style Home generator ads on the net I have never seen before so a few more power shortages and they will be selling like hotcakes as well all the battery setups.
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 10:38am 15 Aug 2019
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There are many different facets to all of this quite apart from cold hard cash.
I plan to keep my grid connection going, mainly for convenience and especially for access to three phase. Meanwhile, have the capacity to be almost self sufficient if the grid does go down for an extended period.
Quite apart from all of that, its interesting, a challenge, and all jolly good fun to slowly tweak and add to the system gradually over time.Cheers, Tony.
Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578
Posted: 10:30pm 15 Aug 2019
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I got the impression you were off grid Tony. Your approach is the same as mine. I think being on grid is going to be the cheapest for the meantime but id like to prepare for outages and going it alone if need be in the future.
There is no way I can put up enough panels to cover out winter use. The only way that would work is to have an alternate heating. The AC sucks about 80% of our power in Winter. Gas would cost more to heat with here and been down that road and I'm not keen on Combustion fires. Takes me all my time and more to keep the wood up for my father. I think something burning waste oil will be the best alternative there as it's plentiful, I can stockpile it easily, it gives great heat output and it's not labour intensive other than collecting it which I don't mind.
It is certainly a learning curve. Crunching the numbers on wall Mounting the panels was a bit of an eye opener and showed that every idea should be investigated because some are better and worse than one may predict. I have enjoyed playing with this and the best part is the significant money we have saved with it. Forget about paybacks in 3 or 5 years, Everything I have done has paid back in one or two billing quarters!
The Mrs has seen it too. I think she forgot how much our Bills might be till the sister in law whom lives round the corner mentioned their bill which was around $1800 it dawned on here again. In any case, If I tell her to bring me home $600 cause I want to buy more panels or whatever, there is never any argument, just interest as to what I'm going to do with them and where this lot is going to be put.
It can be a bit involved trying to set people straight on different things though. The ideas people can have is interesting to say the least. My fathers neighbour is a real tight arse and bit of a twit as well. Last time I visited I could see he was most keep to talk solar. he told me he had bought a number of panels and what controller did he need? I asked what he wanted to do and found he wanted to charge a couple of car batteries which he complained about the price of and tun his Tv, a lamp, fridge and a radio from them.
I tried explaining that would never recover the costs involved and car batteries were not what he wanted. I was then informed he's also paid about $600 for a wind turbine. His property is covered in trees and you can't see the house on google earth. I can't imagine where he would put panels other than the front yard and while cleared, would still be shadowed about 9 months of the year.
He's clearly read as far or been told at the pub you can do this or that or someone has some camping set up and got an idea in his head without doing the rest of the research. He has also installed 3 large water tanks even though he has no garden to speak of. I think he's going to try and go it alone on water or at least save water use. My Dads bill is about $120 a quarter and he runs a home business. I'd be surprised if this guy uses as much so the payback on $8000 worth of tanks and pumps could take a while.
I think he was Motivated by me putting panels on my fathers shed. I knew they were limited use with the direction and shading but they have non the less halved 3 of his yearly Bills. In winter I think they are dead useless. In spring and autumn although the output isn't great, his consumption is lower through less need to heat and cool. In summer when the things do well, he's using the AC so it still works out nicely. I did overclock the hell out of the inverter knowing it would rarely if ever make full power but it does a lot better than I expected.
Not that Dad needed to save money so much but I knew it was more a " Motivational" Thing where he can point to them and tell people he's up in technology by having them :0) I can tell him to just put the air on in summer now to keep cool and sleep better and he's not afraid of the Bill.
This is what we are enjoying. ( months of the year we can do whatever and not have to worry. The women are now learning that winter and summer are different and they can do things in summer they can't in winter.
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 11:01pm 15 Aug 2019
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I now have the "capacity" to go completely off grid, but choose to optionally draw absolutely minimal grid power occasionally, just to keep the connection.
I have three phase lathe, milling machine, air compressor and MIG welder which can all be quite useful sometimes.
My battery is quite small only 5Kwh, and on some winter days it falls a bit short so then a three phase dc rectifier kicks in to supplement power on the dc side of the system. Everything still runs off the inverter.
I don't run a grid tie inverter, all my power combining is done on the dc side.
Fortunately I have very low cost natural gas here for cooking, heating, and hot water.Cheers, Tony.
Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578
Posted: 06:32am 16 Aug 2019
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If I go offgrid I think I will go with a forklift battery pack but a smallish one. Not sure trying to have days worth of capacity is the way to go. My thinking is have a ship load of panels to try and recharge the batteries you do have under the worst conditions and when that does not happen, fall back on a generator.
Only thing I have in 3 phase is the AC and I think that's getting about due for replacement and all the new ones now are single phase. Same as the stove. That is 2 phase ( which I hadn't heard of before) but the new one is single 20A so I can just use one of the current phases when the new one goes in.
I don't which is better, to recharge/ cycle a smaller pack or deeper discharge ( long as it is above 50%) a larger one? The amount of power you will get on a given crappy day or run of days is the same so not sure if big packs have any advantage?
Friend of Mine in the country has " Bottled" gas. He has a large tank in the back of his ute he fills at the service station in town and has that connected to the house. Much cheaper than the bottled delivered gas and despite people saying it's a different mix, he's been using it for years just fine. He has 2 Tanks and just swaps them as need be and lifts them out the back of the Ute with his tractor. Has the connections on the side of the Ute so it looks legit and he just undoes the pipe when he gets back to the farm.
unless your mate lives near the city its a good chance their putting house gas in the service station tanks and not autogas,where I live 550km from the nearest capt city that's all we get,1 gas does all!as long as your mate only fills a 45kg cyl with 80 litres of gas it will be ok and about half the price of home delivered house gas
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 09:23pm 16 Aug 2019
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Yup. That is my thinking as well. I prefer lithium because almost all of the charging energy can be recovered which is important in dismal conditions. Also, there is no gassing, acid or topping up. Flooded lead acids are much cheaper and well worth consideration. Its just personal choice really.
Many older houses have a supply of two twenty amp phases, and the electric stove is split to use both. Even if you buy the latest model electric stove today it will usually be wired for optional two phase operation.
A battery is obviously needed for night time operation, but I agree, battery storage comes at a very high cost and more than 24 hrs storage is just not practical or economic. However a larger battery only discharged partially will potentially have a longer and much easier easier life. It will also have a lower internal resistance, especially near end of discharge, where it may still need to provide very high short term surge current for motor starting. A small battery may really struggle. I plan to eventually double up on capacity mainly to give the battery an easier life and lower the internal resistance.
Many home appliances can be purchased either to run on natural gas or bottled propane. The only difference will be the gas metering jet to the burner. Often the rating plate or service manual lists the alternative sizes, and replacement jets should be readily available. Don't really know much about butane or what the jetting requirements are. But a fair idea can be had by just looking at the tips of the flame.Cheers, Tony.
Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578
Posted: 12:50am 17 Aug 2019
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I keep hearing about cheap Lithium and it being cheaper than lead now but I have not seen it. All the lithium I can find here is very expensive. perhaps the Cheap hype is just marketing propaganda spread by the battery companies selling Lipo?
I also think lead may be a bit more forgiving to a noob getting into this. I have a fair knowledge of batteries but I'd bet I'll make some mistakes and I think lead will be more forgiving of my sins that Lith probably would.
I have seen those power walls made from re purposed 18650 cells and while I have reservations about them, I'd love to find an adequate supply of cells to give one a go. Win, loose or draw I'm sure there could be a lot to be learned and more parroted mantras to be shot down.
Yes, that was my initial thoughts. Maybe triple 1 Nights requirements. That will get me a bit into the day where I can run a genny if solar input is not sufficient and still only be discharging the batteries no more than 50%
A remote start / Shutoff on a genny would be a very handy thing as would an automatic start up when the batteries got down to a certain level.
I see there are more GTI's starting to come out now that will run direct off solar with out batteries through a special outlet or can be hooked to batteries as well. The DC input for the batteries of one I was looking at is 64-600V. Might be harder to get a charger at those voltages though, not everyone has the smarts to design and Build their own. :0) I have a feeling some forklifts may run at 96V which would be a good sizing for one of these inverters as a battery pack voltage.
I think A small battery backup would be good when running off solar as it would allow the inverter to keep delivering power when there was intermittent cloud like there is where I am today.
I have a fan coupled to a panel in the shed and one I brought down and put in a window at the end of the house to push some fresh air through. They are a very audible indication of how much the solar radiation changes even on what appears to be a clear day and the variation is visually imperceptible. The change in tone of the fan seems to be amazingly accurate in indicating the variations one would not otherwise recognise.
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 04:26am 18 Aug 2019
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Lithium is expensive and if you have grid access, will have a payback period so long, its very likely just not economic. Unless of couse you factor in the advantage of being self sufficient if TSHTF.
Definitely agree, Lithium is not for the ham fisted or accident prone idiot, or even the unlucky. It can very easily be permanently damaged or destroyed by one little accident of over charging, or over discharging. You need an absolutely bullet proof battery management system with multi layered protection.
I think we need to consider this as layers of power access. First layer direct solar. When the sun sets, batteries, When the batteries are done, maybe keeping the batteries alive via the grid, through a rectifier.
If all of the above, and the grid is down, a standby put-put generator.
Something with enough grunt to replenish twenty four hours of battery capacity in perhaps two hours of running. We don't need to fully recharge the battery, no running for hours in absorb charge just to get the last 99.99% recharge. Just a couple of hours running at full flat out current limit to put back enough ampere hours into the battery, to keep the system running for another day.
That is where an oversized battery will really repay you in reduced generator hours, and fuel consumption. Edited 2019-08-18 16:17 by WarpspeedCheers, Tony.
Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578
Posted: 10:42pm 18 Aug 2019
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That makes a Lot of sense and would I think be a good design basis. I'd probably ditch grid dependence all together if I had to go to batteries. I would just add a generator capable of carrying heavy loads the batteries/ inverter may not be capable of and would only be an infrequent use anyway. The other generator could be a smaller one just for Charging. Even a 6 Hp Lister will run 3 Kw and that's a fair wack of battery charging. I can run 2 Car alts on mine of 80A ea @ 12V and that's with the standard crappy onboard charge controllers. Go to a big Leece Neville with an external staged controller and you can do a lot more than that.
Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
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