hi, I want to buy a 50w panel solar, a charge controller, a 67ah deep cycle battery and a 500w inverter. I would like to know if the panel solar will always keep the battery charge while im taking out power of the inverter. Or would i have to disconnect the inverter from the battery to let it charge and also how long would it take for the 50w panel solar to charge the 67ah battery. help please, im a new guy!
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Re: help
07/14Depends on how much power you are taking out of the battery. If you are pulling 10 W then the 50W panel will still be doing some charging. If you are pulling 500W then you and not charging just discharging with a 'boost' from the panel. It's just all about current flow.
Now the time to charge. Again current flow. YOu convert the 50W panel to the number of amps you are pumping into the battery using the charge controller. That depends a little on your charge controller. Some are efficient some waste power. With 50W you don't have a lot to waste. Let's say that you are about 90% efficient. You would be pumping 3.75 A into the battery to charege it.
Now a deep discharge pattery should never be run below 50% charge and 80% is good to give you a long battery life. So let's say your battery is 50% drained. That is 33.5 Ah down so it would take about 10 hours to charge your battery.
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Re: help
07/14I am assuming 12 V battery because that seems to be what everything cheap is built for.
Myself I would go for a higher voltage to be more efficient. Like 48 volts. But then everything gets more expensive. The charge controller the inverter.
For a system that can handle the widest range of solar panel and battery look at the Outback MX60. It will handle panels up to 60V (125V OC) and batteries from 12 to 48V (I have seen some claim 60V but I am not sure about that). I don't know if it will handle lead acid and NiCd chemistries. That would be really nice.
But the low wattage, single attery systems are almost always 12V systems.
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Re: help
07/20thanks guys, so i should go for a 48volts battery and a 134w panel solar. What kind of charge controller should i look for is it a 48volts also. -
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Re: help
07/20You probably don't want to go the 48 volt route. Once you get up to that voltage everything gets a little more expensive.
What I am looking at is an Outback MX60 which handles battery voltages of 12, 24 and 48, will handle solar panels from 12 to 60 volts. It is a MPPT and charge controller in one. It is around $500. Inverters for 48V are more expensive as well and then you have 4X the battery cost. So for a small inexpensive system you don't want to go there.
Ir really depends a lot on what you are trying to do. Put something together on a limited budget or power a certain amount of equipment. Those are two conflicting requirements. Which is more important to you? -
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Controller limits
07/24I have been steadily expanding my system and I was doing a little more study on the controllers and found that I could take advantage of higher voltage features and still keep a 12v battery bank.
I currently have a Xantrex 35C controller and in the 12v setting it can handle up to 55v DC input from the panels and still charge a 12v bank. This allowed me to tie my 12v panels in series pairs and double their operating voltage, cutting my line loss from my roof to my battery bank dramatically. I also installed a #4 trunk with a #6 ground in conduit all the way to the attic service blocks. This means that the current is traveling only a short distance in the factory wire before it is consolidated into a much larger wire. PV line voltages routinely reach 50v during peak periods but do not exceed the 55v limit.
A few other points:
a) I could afford the wire because I recycled off of a big project where I obtained the wire at well below market value. Salvage cost is still a lot lower than new. I did inspect the wire closely for insulation breaks on the lengths I used.
b) I have had no trouble running the 35C in this manner and in fact my overall efficiency has dramatically improved. So much so that I installed a large capacity inverter 2000w peak, 1000 watts continuous and I am now able to run a bank of fluorescent lights for my garage without even significant amperage at the inverter and much less line loss for the 120v AC long runs in the garage. I am even running large draw tools like my grinder with no problem since the usage is on demand as needed only.
c) The inverter I chose is a modified sine wave. I am not happy about it but it was a lot less expensive ($150 on sale) for its capacity (30 amps) and none of the items I am interested in running with that power are significantly adversely impacted by that.
d) I am currently running a bank of 8, 12 amp/hr 12v sealed gel type batteries. I am not thrilled with this either but they were available since I am upgrading my electric bikes from lead acid to NiMHd. However the charge capacity during the summer of my 180 watt system has been more than sufficient to charge the bank up through float because my consumption is not continuous. The Xantrex is a programmable 3 stage 35 amp charger and has no problem with a system designed to grow.
e) I am currently buying a Xantrex XW MPPT. It is a significantly more expensive controller ($120 versus $500) but it will allow a lot more growth of panels as I can afford them and also is more efficient. It can handle solar panel operating voltages of up to 140 volts and still maintain a 12v battery bank if desired, however it also will charge 24, 36, 48 and 60 volt battery banks. It only draws 2.5 watts while in operation.
f) I am also moving steadily toward grid tie as FINALLY low power rating, stackable units are becoming available at reasonable costs. I found one 200 watt grid tie inverter that can be stacked in parallel and run a 230 volt single phase system for only $350. However how I integrate grid tie with a battery back up will be a design issue I am still working on though the simplest way may be the easiest and I might just run the grid tie inverter with a photocell switch directly off the battery bank or without a photocell switch switch directly off the solar panel feed since it can handle the higher voltages and operate in parallel with the Xantrex controller. I won't install a grid tie system in this manner until I pass the 500w production level.
BUT if you do not yet have a large battery bank purchased and do not need to have battery back up, then you might consider going directly to grid tie with the new generation of light duty grid tie inverters.
(A couple of examples)
SSI-200w cgi.ebay.com/ws/eBayISAPI.dll
250 230v cgi.ebay.com/ws/eBayISAPI.dll
g) I have kept the wiring distances to an absolute minimum after the controller and also kept the wiring as high capacity as feasible in order to handle future growth. This way the 12v line loss to the batteries and a few other items (lights, shop stereo and 12v chargers) is kept to a minimum too. Some items I am charging on demand from my system quite successfully include my 36 volt electric bikes from the AC side and my 18v Ryobi batteries which aside from the normal drills, saws and sanders that see regular use from the DC side. I also now have their weed whacker, hedge trimmer and chain saw, so I can honestly claim to be using these as solar powered too.
The hedge trimmer and weed whacker are remarkably good though I have doubts about their longevity and the chainsaw is light weight and light duty but excellent when climbing
I will get some photos soon of the current system and post them.
I have also found some 2 axis tracking controllers at remarkably lowered costs ($250). I am working toward also developing a tracking system and will post some photos the prototype modules when they are completed. The interesting thing about these new controllers is that they can run very large tracking arrays or just a single one. The controller circuits can handle up to 15 amp servo motors and that is easily able to handle daisy chains of very significant capacity. Here are some links (they vary widely in price) on those too but they are not needed for the basic issue of this thread.
www.sunpowercorp.com/Product...ers.aspx
www.theanalogguy.com/EST1%20...7-23.htm
www.theanalogguy.com/ST2-5A-...2005.htm
zomeworks.com/products/pv-trackers
www.wattsun.com/
www.npges.com/Solar-Azimuth/products.htm
www.ecobusinesslinks.com/solar...rs.htm -
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Re: Controller limits
07/24long time,
good to hear you are going with the mppt controller. with your high voltage way of doing things, it will boost your production by 10-30 %.
only down side i have found, is that , that gain, is only when the batteries are in a lowered state. ie. when in the taper, top off of the last 10% YOU GAIN NOTHING.
so for a person that has too many panels, and not enough batpac capacity, like me, the mppt has very little advantage.
headed out to burning man- gerlach today. so will be out of touch for a few weeks.
may the sun always shine on your panels.
solarcharlie -
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Re: Controller limits
07/24Good point Charlie and good to hear from you too but in my case that is not a problem because I randomly load the batteries and can draw them down occasionally pretty far. I also work in the garage during the day and put some low level load (radio, recharging portable packs and my LED work light) on the system continuously. When I turn on the inverter (I don't keep that on continuously) I also try and run multiple items besides my lighting and usually charge the bike batteries then too.
I only work with one style matched panel and I am also getting some more of those amorphous panels soon. I have had no problem with them and In fact I recently did have to repair the rack after a major windstorm (80 plus mph) and the panels that blew off the rack were not harmed at all. The glass plate cleans up very nicely, does not scratch, does not fade with prolonged exposure to the sun like some less expensive polycrystalline panels and has even survived a 1" hail storm without a single chip.
I am however designing and constructing a better racking system along with adding panels up to 250 watts.
Amorphous panels do take up 15% to 20% more surface area and operate at 2/3rds the efficiency level but I am experimenting with building a concentrator with them because they handle heat buildup better than poly and monocrystalline do. Apparently there has been a big problem with heat related failure of the more efficient cells in Saudi Arabia (ironic ehh) where they have been building some larger electric production systems and are now considering going back to heat concentrating turbines. -
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Re: Controller limits
07/24One thing that I have been rading is that the newer power tools with the soft start and variable speed electronics can be ruined (the electronics) by a modified sine wave inverter.
I have been debating the polysilicon and amorphous panels for some time. I finaly decided on the amorphous panels even though they are about hald the effdiency overal but then about half the price so it braks even. Found a panel that loaded puts out 60V. The good thing abou them is that they don't have the same power degradation in the heat of the summer as polysilicon. -
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This is the maximum depth. Additional responses will not be threaded.
Re: Controller limits
07/24"One thing that I have been reading is that the newer power tools with the soft start and variable speed electronics can be ruined (the electronics) by a modified sine wave inverter. "
Thanks B that is good to know but I am still doing most of my shop work with older generation capacitor start heavy tools and light duty rechargeable for most other things. I do have a few that fall into that category but I will make sure to run them from the house on an extension cord when I do. I actually charge the 18v Ryobi battery packs directly from the 12v DC battery pack because I got my hands on their car charger so I didn't have to run an inverter at all. In fact I charge a wide variety of light duty equipment using the associated car chargers instead of the wall chargers and that was one of the reasons I stayed with a 12v system as I said earlier: there is just so much out their for 12v that is not duplicated in 24 or higher. It is also far less expensive.
Do you have any links on the 60 watt amorphous panels they sound interesting?
My intended goal on the next phase of expanding the array after I install the new controller will be to put a number of the panels in series and get the line voltage up to 60 at least (5 X 12v at 15watts @ ) however a lot of that will also depend on the operating voltage limits for the grid-tie side. The resistance to heat is a factor I am working with too because I think I can beat the issue of their inefficiency by using concentrating mirrors on them.
I did a few tricks with a small system in Florida recently to test my hypothesis and the voltage spikes up fast along with a significant increases in wattage when using reflected sunlight. The lack of efficiency ends up not being significant when this method is applied. In fact they can be pushed to provide higher efficiency than polycrystalline under these circumstances.
I am surprised they didn't take this approach more at Burning Man -
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Re: Controller limits
07/25The panels I am looking at are the Kaneka K60. I have seen them as low as $219 each online. Theya re also smaller and that works out well because I want to use them to build a "portable" solar power system. At least truck portable.
I know what you mean by so much out there for 12V. Thanks to the auto industry mainly. But more equipment is being designed for higher voltages simply because the cose of copper is too high and the losses at 12V are too high for high wattage systems. Also DC to Dc convertes are pretty cheap for low power applications so you can always go back to 12V easily.
Several companies have been working on concentrators for a few years now. Problem is the cost of the concentrator. The other main problem is the added solar intensity gets converted to heat at the same percentage as unconcentrated. The cells only convert %% to 15% (depending on the cell) to electricity the rest of the power has to go somewhere and goes to heat. Problem is as the heat increases the life of the cell drastically decreases. That is true of all junction semiconductors. Even 'mil spec' semiconductors are only rated for junction temps of 125C beyond that you risk destroying the junciton and you do reduct the lifespan of the device drastically. All concentrator designs so far have a colling system. Either large heat sink fins or water cooled. -
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Re: Controller limits
07/26Great product B and I found a link to the panels at an even cheaper price; $213 but you have to buy 2.
store.oynot.com/kak6060wasop.html
The specs on the product are a little confusing because they give a maximum power voltage, not a nominal operating voltage, and I want to do some experiments with my 15 watt panels that are physically very close to the product in general specs, only scaled down. The maximum open voltage for the panel is 91.8v and if I daisy chain stack 4 of my 15 watt panels I can achieve the same result however those panels are clearly more compact to achieve the result. Here are the PDF spec's on them.
www.oynot.com/media/Kanek...-inside2.pdf
www.oynot.com/media/Kanek...neka-K60.pdf
I am focusing on building the infrastructure for panel expansion at the moment or I would be converting to those right now and selling off my smaller ones or using them for my tracking project.
As for the tracking model, that is based on using a coolant and I am curious if you (or anyone else) have suggestions for a relatively safe substance that will change phase at lower temps (35*C to 40*C or lower)? I am already planning on utilizing a coolant to the concentrator model along with an integrated power reclamation cooling tower.
I did some temp performance experiments recently on my panels and I found as much as a 10% drop in performance as ambient surface rose from 30*C to 52*C and this was well within design limits. I also think that surface temps in climates like the southwest would take ambient panel surface temps much closer to 100*C and I suspect (though I have not done the actual tests) that performance efficiency doesn't drop off in a straight line with respect to panel temp but hyperbolically. If so that means that that the difference between 30*C and 50*C was about 10% but the difference between 30*C and 70*C wouldn't be 20%, it would be closer to 25% or 30% or even higher and as this diminishing performance curve approached design limits the difference in performance between 100*C and 125* might be as little as 1% or 2% rather than the roughly 10% indicated in the middle of the performance curve.
I want to work to keep the panels as cold as possible and this might even improve efficiency enough in winter to make up for for the shorter hours of output somewhat. To achieve this I will use R134 if I have to but I would like something a little more environmentally friendly but price and availability are factors too, as well as system pressure since I want to keep that relatively low as well. The medium would be in a closed loop to a sterling-wind driven cooling tower generator and could even bury heat geothermally in in a thermal mass ground sink that can be tapped for home heating use with geothermal tapping in winter.
No one idea is going to get us to where we need to be but the more we can smoothly integrate hybridized technologies the effective and efficient the applicability of our presently understood tech might be. The approach I am offering could offset the relatively low efficiency of solar panels alone by reclaiming the waste heat, essentially another part of the spectrum (infrared), in multiple other ways.
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Re: Controller limits
07/26For phase change storage at low temperatures look at paraffin. There are different paraffins with different temperatures in the room temp range. Note you have to get pure paraffin not the stuff mixed with wax for home canning use.
As far as heat storage it's hard to beat water on a per unit volume / cost basis. You wuld think there would be better but not for something reasonable in price.
I was planning on building a portable tracker myself for groups of four panels. -
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Phase changing
07/26Paraffin would be great, but as a coolant medium I am looking for liquid to gas rather than solid to liquid. Water is on my list as well utilizing antifreeze but it doesn't provide the phase changing properties, which provide the more extreme temperature and pressure differentials I am seeking.
I want to recover some thermo-mechanical heat energy and phase changing materials are better for that. Also water doesn't work until the temperatures are too high to be effective for cooling the panels to higher efficiency temps without a secondary cooling cycle capable of lowering the water temps significantly. If you have a large thermal mass sink like a river, lake or water you can use the water more effectively but it still requires a pretty large cooling facility for even a smaller concentrator.
There are advantages to utilizing refrigerants but there are also associated problems; toxicity and climate impact to name just 2 big ones, however they allow a wider temperature gradient and a lot more thermodynamic potential in a much smaller closed loop, with higher efficiency transfer even with using only an ambient air thermal sink.
The point of using refrigerant is to go well beyond simply cooling the PV panels and actually tapping the thermal energy side of the problem for added electric recovery on the mechanical side of cooling potentials with a sterling motor interface. The problem with using refrigerant is environmental and toxicological but it can be safe with responsible handling however I can't get around the issue of the system being pressurized and thus if there is a catastrophic failure the gas would enter the atmosphere. -
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Re: Phase changing
07/26Actually what is the real advantage to a phase change material? What you are really doing is moving heat. If you are going from liquid to gas you are also having to deal with large changes in volume and pressure. If you just want to move heat then there are heat pipes that work at all temperatures that will transfer the heat. Of course the best thermal transfer fluid is helium it has a specific heat of around 10,000 yep that high. It is used in several solar designs to transfer the heat from a collector to a sterling engine. Problem with helium is the piping.
Phase change doesn't provide large temperature differentials, in fact that is the advantage of the phase change; you consume heat without the material rising in temperature. But you do get the volume and pressure change from liquid to gas. I really don't know of a nice i.e. non-toxic liquid that will boil at that temperature. The ones that come to mind immediately are the hydrocarbons. All flammable or explosive as a gas.
The florine based fluids are all bad for the environment as you state and know. Hard nut to crack. -
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Re: Phase changing
07/27The phase change would be nice to generate electricity. Think of a low temperature steam engine connected to a generator. I have a solar heat collection system on my house for domestic hot water and space heating. In the heat of the summer when I can collect the most heat, I have to throttle the system as I have no use for all that heat. I have even considered installing a hot tub just because I have the extra heat. If I could use a phase change to run a modified steam engine, I could use all that surplus heat to generate electricity. Ideally it would change phases around 120*F and then even with efficiency losses I could generate 20-30 KWH per day. Like you say, the only materials I can find that change phases near this temperature are either toxic or explosive, so I will continue to throttle the system and waste that extra capacity for five months of the year. -
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Re: Phase changing
07/27Star Geezer got it in one. Aside from the *increased efficiency* by keeping the solar PV panels as cold as possible, the use of phase changing materials make driving a closed loop Stirling generator feasible as long as a sufficiently sized heat sink is available for the cold side of the loop in what amounts to a Rankin style heat pump.
What this is doing is absorbing a much wider spectrum of the Sun's energy and converting it all to electricity and waste heat that might have other uses. Also the idea is to be able to both up the efficiency of the panels by using concentrators and then be able to move the excess heat that process creates away from the panels and into a practical conversion process.
Now there can be added two more reasons to take this approach but essentially what I am trying to do is not only improve the efficiency of the primary PV panels but tap the much greater amount of energy that is just dissipated or reflected by the panels as *unusable*.
The first big breakthrough may be just around the corner because a material is being developed that converts heat energy directly into electricity. The current plan is to use it to offset the alternators in cars and tap exhaust heat directly but I think I could make it the third stage heat sink in the closed loop.
news.yahoo.com/s/nm/20080...terial_dc_1
The second trick is one that is subtle and vastly more intriguing. While I was researching the application of refrigerant gasses I noticed they didn't just absorb infrared and heat energy, some also absorb UV and get ionized at the same time. This means that it might even be possible to create a form of fuel cell in that closed loop on the cold side of the Stirling engine that helps compress the gasses through taking back those photons of UV and helping the reverse phase change.
www.cstl.nist.gov/div838/g4...lkenes.PDF
This might be made even easier during the highly energized state of the gassified r134 as it was going through phase change and accelerated exothermia in the presence of appropriate catalytic materials that are also the electrodes of the fuel cell stage.
This is also because I have been spending a lot of time analyzing the qualities of these new generation amorphous cells and have marveled at their rugged construction utilizing tempered glass plate on both sides of the sandwich. These cells are able to stabilize their temperature rise in part because they are *translucent*, in particular to IR, which is why they are so red when viewed from underneath. This got me to thinking about building on that characteristic.
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