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Forum Index : Solar : Solar Setup Components
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| Georgen Guru  Joined: 13/09/2011 Location: AustraliaPosts: 462 |
I would like to make stand alone little system. Right now I am bit confused with charge controller and MPPT I understand that charging amperage should be about 10% of battery capacity. To start, I thought to use 12V battery 17 Ah and 40W solar panel. And not much idea on charge controller and MPPT components. As I would like to avoid overcharging the battery and to have system to work at optimum parameters. My target is to charge mobile phones, cordless phones, battery for digital camera, possibly to run laptop computer too, maybe even to charge cordless drill and cordless screwdriver. I would also like to have some kind of “Grow Plan” so I can expand later on with finances permitting to get larger battery and few more solar panels. Or better it is to make up final setup without allowance for system expansion and just build another larger system independent of this initial pilot set. Are there any U-Tube instructions for Australian components? (Or it doesn't matter where instructions come from) I did few searches, but looks that I have to make some decisions and here is bit of problem for me with my knowledge. George |
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Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Georgen, you are at the low end (40W solar panel) for useful application of the MPPT (Maximum Power Point Tracking). Perhaps it might be cheaper to start with just a good regulator. Having said that, I bought a 15A "wellsee" MPPT a while ago, tested it and found it is NOT doing any MPPT. However, it is working as a good regulator and I installed it on my boat to keep 2 x 105Ah/12V batteries charged from 140W of solar panel input. This regulator was quite cheap on E-bay and might do you for a start - you can see how far I expanded it with extra batteries & panels. For later, if you want your 'grow plan' to supply considerably more solar power, then I would suggest you steer away from a 12V system and opt for 24V or even 48V equipment. Suggest you do a lot of reading here and elsewhere on this subject as one easily can run into 'dead ends' with under researched growth plans. Klaus |
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| Georgen Guru Joined: 13/09/2011 Location: AustraliaPosts: 462 |
Thank you Tinker for reply. Had a look through quite a few posts, but don't seem to get yet, what I am looking for. Any chance for a link? As to 24V and 48V systems, I understand you use 2V or 12V batteries configured accordingly. Also, does it make sense to have surplus Voltage? Like 7 batteries to make 14V instead of 12V, so when battery bank is getting exhausted it keeps the Voltage up. George |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Georgen Putting extra voltage in the system is OK if you go to a complete 48 volt system as it is more efficient than a twenty four or twelve volt system. just adding a extra 2 volt cell to a 12 or 24 volt system creates problems with availability of off the shelf regulators and powered devices, also it may exceed the voltage range of inverters and cause magic smoke to dissipate. As systems are rated as nominal voltages actual voltages are considerably higher in charge mode. eg 12 volt system can see a charge voltage of 15 and a 24 volt system can see a charge voltage of 30, and a 48 volt system can see a charge voltage of 60 volts. As you can see that with extra voltage it is possible to exceed the safe working voltages of components in the system. All the best Bob Foolin Around |
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| windlight Guru Joined: 03/03/2007 Location: AustraliaPosts: 331 |
You may find some help from these guys...... Rainbow Power Allan "I like this place and willingly could waste my time in it" - (Act II, Scene IV). |
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| Georgen Guru Joined: 13/09/2011 Location: AustraliaPosts: 462 |
Rainbow Power looks impressive, but prices look very high. Got some $300 dollars that I can spend as I wish, in a month it might grow to $500 and that'll be it till the end of year. Found some panels on E-Bay: For just under $135 (Thought about getting 2 of them for now and possibly getting 2 more at the end of year) Mono-Crystalline 65W Size 890 X 540 X 35 mm Weight 8.5Kg Maximum Power Voltage - 18V Maximum Power Current -3.65A Open Circuit Voltage - 21.8V Short Circuit Current - 4.15A Module Efficiency 17.3% Number of Cells - 36 Cables Length - 900mm Would like to get 20A or 30A controller as 10A would not be enough for 4 panels Found 30A one for under $30 30A 12-24V SOLAR CHARGE CONTROLLER, Digital LED Display Package: 1.1PCS 30A solar charge controller 2.1x USERS` Manual 30A 12-24V SOLAR CHARGE CONTROLLER 12V 360W(max) / 24V 720W(max) Light & Timer Control included. Would getting MPPT too make improvement to this setup? Also, my suspicion is, that I should rather get all the panels in one go, as if they are from different batches there might be some problems. Not to mention that the same panels might not be available any more even after few month. George |
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| windlight Guru Joined: 03/03/2007 Location: AustraliaPosts: 331 |
George, in my experience maximum power point tracking (MPPT) works best when solar panels are placed in series so a higher voltage is available to the MPPT. This make's use of the shoulder periods of the day and times when some thin cloud cover exists. System size and your local weather play a part in determining the viability of MPPT, for your stated objectives in your opening post I doubt if the expense on a real MPPT would be justified. The batteries you mention will probably all recharge in the 4-5 hours of mid day sun. As to purchasing all panels together, yes that would be ideal but we don't live in an ideal world, unless the panels are being used in series with a MPPT I don't see a major problem with using different panels that are rated at the same voltage. Allan "I like this place and willingly could waste my time in it" - (Act II, Scene IV). |
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| Georgen Guru Joined: 13/09/2011 Location: AustraliaPosts: 462 |
Thanks Alan for reply, Further looking into MPPT device, got impression that should I have MPPT then other controller is not necessary. There was 15A MPPT controler for under $100 Information said, that it not only takes care of Sun output, but also looks after Battery, to the point that it will not overcharge battery. Will have to look if panels I want to get, when connected in series, will give good Voltage for MPPT to take advantage, and for me to reap the benefits. I tried my Wollongong Library (NSW 2500), but there is nothing on solar power setups. Some books cost quite a lot and because I only want to make little system it will be read once and never used again. Have to find some basic info on the internet. (would be fantastic if somebody could give me good link, Rainbow Co has some free info, but emphasis is rather guiding future client to use their services) George |
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| windlight Guru Joined: 03/03/2007 Location: AustraliaPosts: 331 |
George you already have the best source of information. "I like this place and willingly could waste my time in it" - (Act II, Scene IV). |
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| Georgen Guru Joined: 13/09/2011 Location: AustraliaPosts: 462 |
Thanks Allan, Will have a better look around this site then. George |
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| windlight Guru Joined: 03/03/2007 Location: AustraliaPosts: 331 |
George, as far as OZ sites go this is it, there are others around the world but what it comes down to is asking the right question, which is not always simple when one does not know about the subject. Have you pressed the "home" button on this site? behind that is a wealth of information free of charge for our consumption. So what one needs to do is describe what one would like to achieve as clearly as possible, even that is not easy because all of us started out, become hooked and before you know it your system grows beyond anything you you initially imagined. Tinker told you about cheep MPPT units from his experience and he is correct in my experience, I recently purchased a $25 'e' bay regulator to use on a single solar panel for a mate, it works fine, promised to turn the street lights on even. As a regulator it performs well, what it is not is a MPPT, even though it's Chinese supplier claims it is. My system has 3 MPPT's each valued at just under $1000, because that is the cost (not saying value) of a reliable MPPT, for what you initially described you would never pay those dollars for a MPPT, it would not be cost effective. The easiest thing to do with renewable energy (as with most things in life) is spend your dollars twice. You are taking the correct route and asking. Allan of the jungle "I like this place and willingly could waste my time in it" - (Act II, Scene IV). |
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| Georgen Guru Joined: 13/09/2011 Location: AustraliaPosts: 462 |
40W SOLAR BATTERY: Maximum Power Voltage - 17.8V Maximum Power Current -2.14A Open Circuit Voltage - 21.7V Short Circuit Current - 2.18A 65W SOLAR BATTERY: Maximum Power Voltage - 18V Maximum Power Current -3.65A Open Circuit Voltage - 21.8V Short Circuit Current - 4.15A 30A MPPT CONTROLLER - Always keep the battery on full voltage condition. - Prevent the battery from over-charging. - Prevent the battery from over-discharging. - Prevent the battery from reverse charging to solar panels during nights. - Reverse Polarity Protection for Battery - Reverse Polarity Protection for Solar panels - When the current of the load exceeds the rated current of the controller, the controller will activate the protection mode and lock up. - When the load short circuited, the controller will activate the protection mode and lock up. - When the battery voltage is low, the controller will automatically cut off the load from the system. If the voltage of battery is back to normal and the load will restart working. - Thunder protection - According to the battery voltage grade, the controller can automatically set charge-off voltage, the load-off voltage, the load-restore voltage (The parameter is default under 25¡ãC condition, locked by the CPU procedure, cannot adjust). - The controller will automatically compensate the temperature of the charging voltage according to the changes of ambient temperature. - Rated Voltage: 12/ 24V (Automatic detected) - Max Load Current: 30A - Input Voltage Range: 12V - 20V/ 24V - 40V - Full charge cut: 13.7V/ 27.4V - Low voltage cut: 10.5 - 11V/ 21V - 22V - Length <1m Charge loop drop: 0.25V - Length <1m Discharge loop drop: 0.05V - Temperature compensation: -3 oC - No load loss: ¡Ü10mA - Over voltage protection: 17V/ 34V Information above is from 30A MPPT controller. After reading bit about MPPT¡¯s I must say that I am bit confused. My understanding is that MPPT has window of Voltage that it performs best and Voltage under which it goes to sleep. Here input Voltage is 12-20V Looks that Wake-Up voltage is 10.5-11V For this MPPT controller solar batteries wouold have to be connected in parallel Now I think, things slowly start to make sense. Have to find now "which Controller" qualities are most important for small system. George |
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yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
Hi george, I personally like a book called Solar Success by Collyn Rivers. I guess the thing to keep in mind is that every electrical component has an Amp limit. A solar panel without heavy duty bus bars gets unreliable over 10 amps. an inverter run continuously is reliable to about 80 - 100 amps (with paralleled components manufactured as a matched set) before heat becomes a factor. this means 12volt 1000 - 1250 watts 24volt 2000 - 2500 watts 48volt 4000 - 5000 watts 60 and 80 amp MPPT voltage buck regulators cost a small fortune because the components inside them need to be top shelf and perfectly matched, they are very worthwhile in a 48 volt system with a panel bank wired to run at 70 to 110 volts. my opinion is that ultra cheap 15 amp regulators are fine because they use a single diode, at 30 amps (matched pair of diodes 15 amp x 2) I would expect 7 years + out of a quality regulator. Above this amperage, regulators that have poor quality components or are in a badly designed system that subjects them to high heat and/or load will have a short life. With the cheapest panels in the market (24 volt 72 cell panel) 190 watts for just over $200 I would be hard pressed to think of a reason for building a 12 volt system if I was starting fresh with a clean sheet. My personal favorite for little systems is the morningstar prostar30. they are a 12/24 volt 30 amp PWM regulator. there is a version with a lcd meter for less than $250 (handy if you don't have separate volt and amp meters)and the cheapie without the LCD. I see that it is $168.30 today at Apollo energy, that's pretty good value. I'm confused, no wait... maybe I'm not... |
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| Georgen Guru Joined: 13/09/2011 Location: AustraliaPosts: 462 |
Yahoo2, Thank you for help. Thought about having spare Amperage on components “My System” would be between 8.5 and 14.4A depending if I go for 40W or 65W panels in 12V configuration. That’s why I thought about from 20A for 40W panels to 30A regulator, so regulator doesn’t get too hot. I hope that if I get (for starters) 2 off 40W panels and 30A regulator it will work too, despite that panels will only make up to 4.2A max Are E-Bay components acceptable? As they cost quarter to third of the price of what you say. George |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
They are talking about two different things George. the input voltage is the range that the controller will work in, the lower limit is a bit academic most batteries voltage will rise above 12 volt when a small charge is applied you will find that the only time the panel may be over 20 volts the batteries are fully charged and the controller is in float mode so power point tracking is not needed because you are only using a small fraction of the panels output. the other voltage quoted is load cut off. You would wire any electrical load through a voltage sensor and relay built in to the controller. this is very important to stop your battery from discharging to a dangerously low level and damaging the battery bank. An example would be running a fridge that will switch on at night and pull a 3.5 amp load. Once the batteries get down to a set voltage under load the controller will stop you from using the battery power until they start to recharge. I'm confused, no wait... maybe I'm not... |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
If you want to go 12volt the 36 cell 80 watt panels are about $140 that is a pretty standard size, it has been around for years. the key to a good system is to aim to have the batteries fully charged to the correct voltage for the battery every day, this will get the best dollars per watt per year as replacing batteries after 3 years costs a lot more than replacing them after 10- 15 years. Most 12 volt systems I see with problems have not enough panels, with battery banks that are too large (and usually dead flat), non functioning regulators, poor connections and undersized wiring everywhere. The system owner is often adamant that there is nothing wrong the setup, we just need more batteries.  
I am sure there are good controllers on eBay there are also plenty of lemons, I cant afford for my customers to be guinea pigs and risk damaging expensive batteries. I know these are a good match for the batteries I use. cheers yahoo I'm confused, no wait... maybe I'm not... |
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| Georgen Guru Joined: 13/09/2011 Location: AustraliaPosts: 462 |
Makes sense Thanks a lot for help and patience. George |
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| Georgen Guru Joined: 13/09/2011 Location: AustraliaPosts: 462 |
80W solar panel that I would like to buy, looks to come without diode. Should I look for one that has diode, or could you tell me what diode should I get? I want to set up 12V little system. Specs are: Max Power Voltage: 18V Max Power Current: 4.44A Open-Circuit Voltage: 21.6V Short-Circuit Current: 4.88A George |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
I think there is not much point. your regulator will have a blocking diode in it to stop power draining back to the panels at night. The cells in your 80 watt panel are in series. if there are three strings in the panel that are joined in the junction box (like some of the really old BP panels) then bypass diodes may do something but the risk of overheating a shaded cell in a 12 volt system is pretty low. More than likely there will be only two wires in the junction box on the panel and you only have one panel so there will be no power to bypass. it is only when you start stringing multiple panels in series to increase the output voltage that you need to worry about diodes. cheers yahoo If you keep the bird poo and leaves (and snow  ) off your panel, it will charge like a wounded bull  I'm confused, no wait... maybe I'm not... |
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