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Forum Index : Windmills : LiFePO4 vs Lead Acid
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electrodacus Newbie  Joined: 30/03/2014 Location: CanadaPosts: 39 |
Here are the results for 3 locations with 1000W solar panel. First is my location 
Second is Sydney Australia. 
Third is the highest I was able to find. 
Now you see that solar radiation at my location average / day /m2 is exactly the same as in Sydney over a year the AC energy has a rating factor of 0.77 (77%) this is default there includes some loses on battery cables and AC inverter. At my location there is about 6 to 7% more energy from the panels than Sydney even if it is exactly the same solar radiation probably because PV panels like a bit colder climate. So if I divide that 1387kWh / 365 day = 3.8kWh / day from 1000W panels. This is AC if you add back those 23% then DC directly from panels will be 4.67kWh/day no losses included this is quite close to that 5.04kWh/day and the difference is do to heat affecting the panel performance that is calculated for standard condition in the lab. No for the highest solar radiation location that I found you get 7kWh/m2/day and 1732kWh/year / 365day = 4.75kWh/day from 1000W panels usable AC now adding the 23% loss you get 5.84kWh/day direct from PV no loss included still a bit far from those 8kWh/day. Now id true that all this is for fixed tilt if you rotate the panels then is a bit more I will need to check but at the current price of solar PV panels the rotation mechanism will not make any economic sense. I don't know if you have one maybe 7 years ago was a good investment but is not now at 1$/Watt. PS : I just checked for Port Hedland and you get with 2 axis traking 7.95kWh/day directly from the panels no cable, battery and inverter loss. But I will say today a two axis tracking will not be worthed not even there for about 35% increase in output. For 1000W panels 35% is another 350W panels that is 350$ Not sure you can get a 2 axis tracking at that price to be able to rotate 1000W of solar panels. What do you think? http://electrodacus.com/ https://www.youtube.com/user/electrodacus |
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yahoo2 Guru  Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
If you want some numbers to compare. My parents have a 5kw system in for over 3 years they have generated over 30,000 Kw. their average is 4.6Kw/ 1000w installed Lat 34.40 (below Sydneys Latitude) They are coastal and in 34 inch rainfall country. I am latitude 33 deg and inland (dry), well installed grid connected systems around me average 5.8 to 5.9kw. for off-grid systems now that the price of panels and racking have come down dramatically, it is the lowest cost part of the setup (here we go , back on my hobby horse). for us southerners, that have a winter, I have been advocating a second and or third bank of panels that are driven by the Aux out on a small solar controller through a Solid State Relay. The difference in price compared to multiple networked controllers is staggering, so provided you are not trying to step down the voltage from the panels it works a treat. the theoretical efficiency is not and issue, it is back to $ per used Kw, like it should be. The LFP batteries offer an advantage for this situation as we are not restricted to the 0.12-0.15C charge rate for VWLA batteries. its a loooooong winters day charging if the panels are undersized and the batteries are well down. Just the sort of day we need the power to live in comfort. Re the skin cancer: Vic, you might do us on total exposure (and I have seen my share of young leathery skinned QLD girls) but that hole in the ozone layer that snuck over us for a couple of years and the UV on my meter was OVER 16 everyday, without protection some days I would burn in less than a minute. I'm confused, no wait... maybe I'm not... |
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| electrodacus Newbie Joined: 30/03/2014 Location: CanadaPosts: 39 |
That seems to be exactly what that calculator provided if that is measured directly from the PV panels and dose not include battery, inverter and all other losses. I will also install a 6 or 7kWh PV panel array used just for heating no battery inverters or controller just direct connection to in floor resistive heat wires. The floor is an insulated concrete slab (14 cubic meters) that can store 100kWh at a temperature delta of 10C I agree that efficiency is not important as long as there is enough space but that is valid for the same panel technology mono or polycrystalline if is about amorphous or some other types that only last for 7 years or less and degrade fast the is not that easy. Same analogy as for LiFePO4 and Lead Acid. I try to use most of the power during the day when is directly form PV and not from battery. That UV level seems extremely high. I did not even new that there is something over 10 :) http://electrodacus.com/ https://www.youtube.com/user/electrodacus |
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norcold Guru Joined: 06/02/2011 Location: AustraliaPosts: 670 |
OK, my readings are real life readings taken from the last 2 years logged off a grid tied system. 8.1 kwh/day average for the last two year period at 17 11 45 S latitude 1000 watt mono panels ( they have only been in operation for 2 years) . No you will not find figures as yet for mono panels simply because official figures are taken over a 10 year period and to my knowledge mono panels have not been evaluated for that period as yet. But as you see OZ has ample sunshine, we are very slow in utilizing this but we`re getting there. Allowing for the recent suns increased activity cycle they have been trimmed conservatively to 7kwh/day per 1000watt (500m elevation) to give as close as possible a reading to the 10 year average required for the industry. I have recently proposed a solar farm project on my land, that is why I have such up to date figures. Let me assure you they are accurate. Sydney is 1000 km plus south of my location and Port Hedland 2000km plus a little south of west. OZ is a bloody big island. But from the figures you have downloaded you can see where I`m coming from. As you can see from Yahoo2`s figures and mine we are very fortunate in OZ and it should become the solar capital of the world if we can find the will. Like yahoo2 I share the same hobby horse, he`s obviously been perving on bikini clad Queensland shielas, a national pastime. 
I agree at panel costs these days add a few extra and fix them, my figures are for fixed panels. We come from the land downunder. Vic |
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| electrodacus Newbie Joined: 30/03/2014 Location: CanadaPosts: 39 |
So are your panels on a fix location or do you have solar tracking? The type of solar panel is not important that much mono and polycrystalline are almost indistinguishable in regards to temperature effect. How did you logged that data ? With the solar controller ? What type? In order to log that on an off-grid system will be quite complicated. I know I had a Steca controller that shorts the PV panels when the battery is full and continues to log the current but that one is short circuit current not the same with current at nominal battery voltage. Still is true that in North Australia there is plenty of Sun and Sydney seems to have almost the same output as here in the middle of Canada. Where there is winter the bad part is those two or 3 months when solar radiation is just half what you get in the rest of the year and that require a bit of solar array oversizing or use of small wind turbine as in my case where there is also plenty of wind. The fact that I added that small 300W wind turbine allowed me to reduce the battery size to half. That is quite an important saving. 500$ for the wind turbine vs 1400$ for the battery. Not sure yet witch will last longer :) so maybe there are no savings. http://electrodacus.com/ https://www.youtube.com/user/electrodacus |
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| norcold Guru Joined: 06/02/2011 Location: AustraliaPosts: 670 |
The panels that gave the figures were obtained from are not mine, I`m off-grid. The panels are fixed grid-tied , mounted on north facing roof approx. 15 deg slope. The data was manually recorded daily from the grid inverter readings, mono panels. I do not know the inverters brand but will find out. The figures were verified from a fellow in the industry who has been installing off-grid systems for 20 plus years in this area. The elevation is 500m, which is a plus, much same as yours. As said they are accurate figures, but I understand your sceptism, I cannot give you official figures, they do not exist as yet for mono to my knowledge. Solar radiation in winter at my location is also a plus eg todays 9/4/14 daylight length is 11hrs 48mins tomorrow will be 56 secs less as we move towards mid winter which is 22nd June. Summer because the sun actually goes south of us to over the Tropic of Capricorn and panels being mounted at slope to north, we do get a slight noticeable decrease in output when the sun is over that latitude, something I figured for interest sake way back. Unfortunately I can not give complete figures from my poly panels as they are usually floating the battery by midday but my total draw from the batteries since installing is 13519Kwhrs (sealed 240v meter on inverter output), but as posted earlier I have the found by setting the battery efficiency at 87%, the logging capacity agrees with hydrometer testing. This morn my PC notes my min capacity was 92%, some cloud cover as we prepare for a cyclone. My experience with mono panels is they start up earlier and finish later each day and are not affected by cloud cover as much as poly panels, they also get up to max output earlier in the day maintaining max for longer. I have mono panels operating a surface water pump on a dam, and poly panels on off-grid system and on a bore water pump. Also a couple of mono panels on camping vehicle. I have a diesel 5k generator coupled to a 48v 50 amp battery charger for emergency use, so far only start it once a month(when I remember) for an hour to ensure it works. Have not needed it as yet, also have 3 small wind turbines (total 1200 watts) which I switch in manually during the very few cloudy days we experience. Not being in a wind site they are really toys. They have not been used for a couple of weeks, have been away fishing. Reading back that's a lot of info but heh its my hobby horse
We come from the land downunder. Vic |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
Mine are all metered at the powerbox at the grid connect point. I cant comment on any power factor involved but I will admit the systems are tailored to take best advantage of the panels voltages. Also we have had a run of overspec panels recently, I have made it a habit of testing the panels and putting together matched sets that are right on the limit of what the grid inverter can handle. I'm confused, no wait... maybe I'm not... |
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| norcold Guru Joined: 06/02/2011 Location: AustraliaPosts: 670 |
Yeah recently purchased a advertised 24v 180 watt mono panel, conx to pump, run ok for a few days than blue the pump maximiser. Checked open circuit max voltage midday of panel it was 46v. Suspect that is what let the "smoke" out. That sealed meter I spoke of is on my off-grid system was compulsory to be installed to get the rural household subsidy. Cynically suspect, govt will turn up one day read it and charge me for sun. But being wired on output of inverter should be handy to show inefficiency, comparing to solar input on regulator to battery. Must monitor it one day.We come from the land downunder. Vic |
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| electrodacus Newbie Joined: 30/03/2014 Location: CanadaPosts: 39 |
Polycrystalline made in the last two or three years are within one or two percent from the mono crystalline. It was a larger difference in the past but they improved so much the polycrystalline that is almost mono :). This can be seen also from the price there is no price difference. I have 8A 240W panels and they put out as much as 10.5A when is really cold and sunny. For the 24V pump use 12V 36 cells panels and will work just fine. You can only measure energy from a grid tied system or a test setup specially designed to measure energy. Anyway 8kWh/month is only possible with a two axis solar tracker based on that calculator. That solar PV Watts calculator seems to be quite accurate it was what I used to design my system and worked great. November and December are the worst two months here very short day a lot of snow but at least is windy. The highest wind this winter was 80km/h with gust of 106km/h I was surprised the small turbine survived not the greatest quality but it works for now. I will soon upload a video about that on my youtube channel. I have the footage from this winter just need to edit and upload. http://electrodacus.com/ https://www.youtube.com/user/electrodacus |
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| norcold Guru Joined: 06/02/2011 Location: AustraliaPosts: 670 |
Price difference narrowed as mono`s production cost decreased I believe, been a player in solar since the 80`s at $20/watt. Learnt early real time data from working systems have always showed output higher than industry shown averages. Suspect the below is why. UV for Janruary Have you grid-tied mono systems you can access, I think you`ll find the data surprising. But the above UV map says it all cycle through the months. Checked out Canadas such map and see what you mean by a UV index of 10. 15 minutes of exposure to our summer sun on my bare lily white skin and I`m in trouble. I wear longs always in the sun and heaps of UV cream on face even in winter.
As my posts explain my data, re. daily output, is from a grid-tied system, and currently I`m backing it big time. I believe our different experiences are simply because our different latitudes and thus longer average days year round, combined with our UV yearly averaging above 11 maxing out at 15 that and cloudless days in excess of 300 per year. But heh no drama if you aren`t convinced. If my plans of a solar farm on property are realised, should be able to demonstrate beyond doubt. Your right about the pump, another one I have been running for many years no drama has 2 arrays of 2 in series 12 volt wired together in parallel. But I believe the 24 v one would have been no drama if its open circuit voltage was 36v as it is plated. Panel voltage on the newer panels are all over the place whereas going back a couple of years they were pretty constant. We come from the land downunder. Vic |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
Uv is only good for frying bundy drinkers! visible spectrum is what we are after. Infra Red and UV dont have enough kick to dislodge an electron. Here is one I prepared earlier! Christmas 2007 temp was low 30's Celsius. visible radiation on the left (yellow) UV on the right (appropriately pink) 
I'm confused, no wait... maybe I'm not... |
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| electrodacus Newbie Joined: 30/03/2014 Location: CanadaPosts: 39 |
Yahoo2 - you are right about the UV that dose not help with anything but IR is on the other end of the visible spectrum and that has a huge influence in solar PV panels. I have both mono and polycrystalline and I cant see any difference. As for the open circuit voltage only with 60 cells panels (mostly designed for grid tie applications you can expect 36V) Single cell will always have the same open circuit voltage. Usually 12V offgrid panels are made with 36 cells about 22V OC (around 0.6V / cell) the 24V offgrid panels made with 72 cells (about 44V - 45V OC) and then the ones that I use for offgrid 60 cells but are designed for grid-tied applications. I use 60 cells since especially in my climate are way better value for money they put out the exact same current in my battery and costs less. My 60 cells panel is 240W and has a max power point voltage of around 29V excellent for LiFePO4 that are fully charged at 27V. A 72 cell may cost the same /Watt (usually more since offgrid panels are produced in lower quantities) and is 290-300W vs 60 cell 240-250W. And the battery will be charged as fast with a 60 cells as with 72 cells. 60 cells will probably not work well with Lead Acid and in really hot climates. http://electrodacus.com/ https://www.youtube.com/user/electrodacus |
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| norcold Guru Joined: 06/02/2011 Location: AustraliaPosts: 670 |
True UV is only good for cooking us in bundy land but the rest of the spectrum is there with the UV, but here now technically but not commercially as yet, panels that use the whole light spectrum. Panels that don`t have the light blocking conxs on top but underneath. Imagine efficiency doubling with price dropping yet. Ok lets design a battery for my system, As said I use a max of 30% of 1080 AH. 324 AH usable capacity 48V need. I want 20 years life 20 X 365 = 7300 cycles. How high can we go with DOD to achieve this 50% sound reasonable or can we go better, with todays tech. 75% maybe. Remember we are replacing that tired old Pb, we know its capabilities from 100 plus years of working, I want something I know will work gotta have working examples of this. Must be a fair few out there now with a few years under their belt. Ambient temp range 40C to 10C. We come from the land downunder. Vic |
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| electrodacus Newbie Joined: 30/03/2014 Location: CanadaPosts: 39 |
Is not a good idea to design a battery for 20 years life for a few reasons. 1) Technology advances at an exponential rate so there will not be long before even the best battery toady will be out dated by both performance and price. 2) All existing chemical batteries (Pb,Lithium,NiCd) will degrade with time even if not used and kept in their best conservation state. 3) In Lithium battery world when the battery is at 80% of the initial capacity it needs replacement that is the reason max expected battery life is 10 to 12 years even if you do not use the battery. There are few manufacturers that specify the battery degradation over time and for good reason and those that do so they measure the battery degradation on a 12 to 18 month period and extrapolate this over time. So my recommendation is aim for 3500 - 4000 cycles 10 to 12 years amortization. Here is one that I just found but it seems to be on the market for some time they only have small 18650 and 26650 cells here is their data for the small one with 100% DOD They used a smaller 2h discharge rate most others use 1h or even half hour (2C) but for offgrid 2h discharge rate is more than enough here is the full spec 
http://electrodacus.com/ https://www.youtube.com/user/electrodacus |
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| norcold Guru Joined: 06/02/2011 Location: AustraliaPosts: 670 |
For me it is to aim for 20 years for that is exactly the question I asked the Installer of my system. He`d showed me his system which at that time was 18 years old, now 25 years and still going. His reply when I asked for 20 years was if you can get 10 years by proper maintenance with Pb you`ll probably get 20 years or better. Note the probably he was going by his experience no guarantees, but he had reserved confidence. I believe in OZ right now there is top opportunity for a smallish Li battery. One that can be placed in those grid-tied systems on the 1.4 million roof top solar we have. Only has to give say 2 hours of supply to the 5Kw inverters that are installed. Would have to have automatic switching incorporated to allow it to run when the grid is down(an often occurrence up here in NQ, nearly every household has a 2K Honda generator)and to make it idiot proof further auto switching that turns off the non essential items, plasma tv, A/c etc. Of course with a small balance charger incorporated also. Maybe such a addition is already out there and available. We come from the land downunder. Vic |
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| electrodacus Newbie Joined: 30/03/2014 Location: CanadaPosts: 39 |
I will not claim that I have huge experience with batteries regarding long time degradation. But they are made of chemicals that react even if they are just stored and not used. I do not understand exactly why will you want a battery with 20years amortization. Say you cost /kWh is the same for 10 years or for 20 years why will you want to invest double from the start and wait for 20 year recovery. Maybe you have a good reason that I do not understand. What do you mean exactly by two hours of supply to the 5kW inverters ? Do you need 10kWh or less ? Those small generators are extremely expensive to run I think at least 1$/kWh not counting the recovery of the initial investment (the cost of the generator) It seem like you want an UPS connected to essential items. There are quite a few not sure there is any with LiFePO4 mostly use small VRLA. I'm not sure A/C is on the non essential list there :) is like heating in the winter in Canada. http://electrodacus.com/ https://www.youtube.com/user/electrodacus |
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| norcold Guru Joined: 06/02/2011 Location: AustraliaPosts: 670 |
I believe capital cost is the thing that is most important to the off-grid purchaser. That initial outlay, at least it was to me then. But you have a good point to look at 10 years then upgrade to better technology for another reason other then better tech, better tech has, like in solar, got the potential to offer decreased capital outlay also. The 5kw inverter was the max allowed under the scheme to get those household into solar. Thus a battery that is capable of supplying that inverter at a capacity to run the essential items for 2 hours. The 2 hours is a figure I plucked from the air, that seems to be about the average time the grid is down. Your analogy of an UPS is accurate just would have to be a little larger then the UPS I`ve experienced(PC) and with the auto switching. The main essential item in our hot climate is our refrigerator, not so much the freezer it can go without power for a couple of hours. A average modern 240v OZ refrigerators draws approx. 250 watts whilst running but 1200 watts to start briefly. A refrigerator in a ambient of 35C and a couple of kids opening it often, food spoils quickly. Yes those small generators are not cost effective unless you factor in the food loss etc and inconvenience such power outages can cause. But your mention of heating in Canada, further displays our massive climate difference ie. You think heating I think refrigeration. 2 hours without power to your refrigeration, no drama and inversely here no drama 2 hours without a heater. We come from the land downunder. Vic |
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| electrodacus Newbie Joined: 30/03/2014 Location: CanadaPosts: 39 |
When you select LiFePO4 battery you are thinking mostly on energy needed and not power since with LiFePO4 you can provide huge amount of power even with a very small battery. You can full charge or discharge a LiFePO4 in 20 minutes that is not possible with Lead Acid. What is the average house monthly energy consumption ? I know here in Canada and US is around 1000kWh/house hold but in most of Europe is just 150 to 200kWh so there are huge variation. I guess there is relatively high do to use of A/C but if that is not used as backup I expect the highest used will be from refrigerator and lights but this can still be quite different. Again I guess most have LED lights since the incandescent will produce a lot of heat. Also if 5kW inverter is just for peak do to inductive loads then maybe that can also be smaller. My main inverter on my off-grid house is just 2.4kW it can do 3.6kW for up to one hour or 4.8kW for 10 seconds. The most I ever used is 2000W Maybe the refrigerators in the near future will be sold with 2h LiFePO4 backup :) So I can not really speculate how much energy is needed in those two hours it can be as low as a 250W refrigerator with 50% duty cycle so 250Wh over two hours + 100W worth of LED lights so a 350Wh total energy over those 2h that will require a 500Wh LiFePO4 battery to cover the inverter efficiency and not discharge lover than 20% SOC But it can also be two, three or 4x higher. The price for LiFePO4 is about 0.5$/Wh so the battery can cost as low as 250$ for a 500Wh one but there is a BMS charger and inverter that need to be added to the total. http://electrodacus.com/ https://www.youtube.com/user/electrodacus |
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| norcold Guru Joined: 06/02/2011 Location: AustraliaPosts: 670 |
Thinking more along your UPS suggestion. That really is probably what is needed a self contained ups just to power the refrigerator, connected from the power point to the refrigerator. Whilst the power is on battery is getting maintenance charge, refrigerator is running, power goes off the UPS cuts in but with that say 2 hours of battery power No installation needed, home owner just plugs it in behind refrigerator, just larger then the PC UPS. Would go higher to probably 75% duty cycle, remember those kids opening the refrigerator. That would be a top application for Li as I see it. Lights are no big drama, everyone has a torch. Not just for solar households, all households. Heh!!! Yahoo2 you got your ears on? Is there a market in OZ for such UPS? Would you consider the refrigerator the most essential in households down your way? Would 2 hours be enough? Such a product out there? doubt it, tailor made for Li. More questions than Quiz Kids
The "bundy" Yahoo2 was referring to, is Bundaberg Rum a product from Queensland using our locally grown sugar cane, keeps us Queenslanders sane!!! Whoops, OZ households have an average of 20Kwhr per day usage. We come from the land downunder. Vic |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
You guys are about 6 months ahead of the inverter companies. They have all dipped their toes in the water and gone back to the design board. Yep, we need about 2 days backup here, fridge/freezer computer tv phone. fridge and freezer are only on about 25% of the time should be easily under 900 watts per day, probably another 250 watts for the led telly, set top box and the laptop and network plus phone. 2kw would get me well into day three of a blackout (most of our outages start in the afternoon/early evening). I have thought that it would be possible to rig just one or two fused power/lights cables at the powerbox to switch to backup. SMA introduced a 5kw inverter charger unit that sits along side their grid connect inverter, these can be daisychained. However they have slightly hidden the details on their website recently so they are not actively pushing them here yet. Morningstar Corp have just introduced a 48 volt battery solar controller that will handle a max of 600 volt of panel (490 volts working volts) I see RFI have got a few. So a pair of these will handle a 6 Kw grid install and share the load with the batteries and a standard off grid inverter provides the backup. Outback power inc have been there forever but their setups can be very complex load sharing systems, you need to hire someone good to make it work really well and they are quite expensive. I think the problem in the past has been punters want to power their whole house. And they are oblivious when the switchover to backup happens. I'm confused, no wait... maybe I'm not... |
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