Is Charge Controller Necessary?

lwilli01lwilli01 Registered Users Posts: 12
Do I need a charge controller with this inverter?

AIMS 3000watt pure sine wave
Specifications
Continuous output power: 3000 Watts

Surge power capability (peak power): 4500 Watts

DC input / operating voltage: 10 to 17 Volts

Output voltage: 117 Volts AC

Output frequency: 60 Hz

THD: <5%

Efficiency: 86%

Battery low voltage shutdown: 9.48 +/- 0.6 Volts

Battery high voltage shutdown: 17 Volt +/- 1.5 Volts

No load current: 1.5 Amps

AC output socket type: 4 110 plus 1 direct connect

High input voltage protection: 17V

Low input voltage shutdown: 10V

Product size (W x D x H): 15.37" x 8.27" x 5.0"

Weight: 16.5

CE approved
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Comments

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Is Charge Controller Necessary?

    Okay, a bit of a discussion about things.

    Charge controllers don't actually have anything to do with what inverter you have (unless it's a tied-together system like Outback). They regulate the charging of the batteries that power the inverter.

    Pretty sure that AIMS inverter is 1). MSW type (not true sine as claimed), 2). without a built-in charger, 3). a piece of junk.
    Sorry: I have a great personal dislike of AIMS inverters. :roll:

    So how are you going to recharge the battery? Solar (in which case a charge controller is needed), Generator or Utility Power (in which case a battery charger is needed), wind (in which case a charge controller for wind turbines is needed), or hydro (in which case a charge controller for hydro is needed)?

    Before you ask "What's wrong with the inverter?" take a look at the specs: 3000 Watts off less than 10 Volts would be over 300 Amps DC. Very bad idea, that.
  • BB.BB. Super Moderators, Administrators Posts: 29,702 admin
    Re: Is Charge Controller Necessary?

    From the specs. you have provided, there is no AC to DC battery charger in your AC inverter (there are Inverter/Charger devices available--just not this one).

    So, you will need a charge controller... Either once connected to your solar array and/or an AC battery charger for your utility/backup genset power.

    Some generators have a small 12 volt battery charger--but, in general, they are not useful for charging a full sized battery bank--more designed to charge a car battery enough in an emergency to restart the vehicle.

    You are sort of starting in the middle of the problem--with an AC inverter...

    Generally, we do these steps:
    1. Conservation
    2. Measure your AC/DC loads
    3. Size the Battery Bank (to daily loads--1 to 3 days + 50% max discharge)
    4. Size the Solar Array (both to daily loads and capacity of battery bank)
    5. Size the Solar Charge Controller (to size of solar array)
    6. Size the Generator/AC battery charger combination (to size of battery bank for ~50% minimum genset load for good fuel consumption)
    7. Buy stuff
    We can size a battery bank (step #3) to the surge capacity of the inverter--But it really does not tell us if you are using a little power 24 hours per day, or a lot of power less than an hour a day, or even a lot of power 12+ hours per day...

    Probably my guesswork will not come close to your true needs.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • lwilli01lwilli01 Registered Users Posts: 12
    Re: Is Charge Controller Necessary?

    So, a charge controller is always necessary unless you're buying a "kit/all inclusive" solar generator?

    I also have a tigerclaw 3000watt inverter and it says "with built in charger function" - what does that mean?

    On the topic of charge controllers I have two 12 volt 30 amp Sunforce chargers but they seem to not work properly at least according to their manuals.
  • BB.BB. Super Moderators, Administrators Posts: 29,702 admin
    Re: Is Charge Controller Necessary?
    lwilli01 wrote: »
    So, a charge controller is always necessary unless you're buying a "kit/all inclusive" solar generator?
    In general, you will always need some sort of charge controller to allow you to quickly recharge the batteries (higher voltage and current like 14.5 volts and 30+ amps) and then cut back ~13.5 volts and less than 2 amps once the batteries are full (numbers more or less made up for 12 volt system).

    I tend not to like the terms "solar generator"... It papers over the details of the proper specifications and design of an off grid solar power system with a "marketing term".
    I also have a tigerclaw 3000watt inverter and it says "with built in charger function" - what does that mean?
    Usually, this would be an Inverter/Charger... It is a lot like a UPS without the internal batteries...

    Inverter/Chargers are usually designed to plug into AC mains (sometimes a generator) and pass AC power through to the load (and at the same time, uses a bit of the AC power to recharge the battery bank)--And when the AC power fails, an internal transfer switch disconnects the AC power and instead allows the inverter to supply power to your AC loads.
    On the topic of charge controllers I have two 12 volt 30 amp Sunforce chargers but they seem to not work properly at least according to their manuals.

    Sunforce are (from what little I have seen) less expensive solar charge controllers... I would guess PWM type. You put ~17.5 volt solar panels on the input and connect the output to your battery bank. The solar array Imp/Isc current should not exceed the charge controller's input current ratings.

    It is possible that your charge controllers are damaged, or it is also possible there are issues with the wiring or even the connected solar panels.

    Unfortunately, it usually requires some debugging on your parts--And we can help you with that too--If you wish.

    We will have lots of questions--What solar panels you have, their Vmp/Imp ratings, how are they wired to the charge controller (series/parallel connections, AWG of wiring, length of wiring) and similar questions about AWG/Length of cable from charge controller to battery bank, what is battery bank (type of batteries, Amp*Hour rating, bank voltage, etc.)...

    And ask you to tell us some voltage measurements and why you think it is not charging correctly...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Is Charge Controller Necessary?
    lwilli01 wrote: »
    So, a charge controller is always necessary unless you're buying a "kit/all inclusive" solar generator?

    A charge controller is always necessary if the source of charging is solar, wind, or hydro. It may be included in a package.
    I also have a tigerclaw 3000watt inverter and it says "with built in charger function" - what does that mean?

    Some inverters have built-in battery chargers. They will have an "AC IN" as well as "AC OUT". When the inverter senses AC on its input, it switches to recharging the batteries via its internal charger. Loads will be switched over to the external AC source as well.
    On the topic of charge controllers I have two 12 volt 30 amp Sunforce chargers but they seem to not work properly at least according to their manuals.

    Based on?
    It can be difficult to judge the functioning of a charge controller. You have to have some method of measure the battery's State Of Charge, a source of power capable of charging the battery (sufficient solar panels, for instance), and the battery must actually need charging. If the battery is low and there's enough solar the battery should charge over time. If it doesn't, something is wrong and it could be the controller - but not necessarily.
  • lwilli01lwilli01 Registered Users Posts: 12
    Re: Is Charge Controller Necessary?

    We have two different "off grid" systems - here's the first one:

    2 - 90watt solar panels
    3 - 85watt solar panels
    parallel wiring

    Sunforce Charge Controller 12 volt 30 amp
    AIMS 3000watt inverter
    1 12v 225AH battery

    #10 cables

    The second unit:

    2 - 50watt solar panels
    Sunforce charge controller 12 volt 30 amp
    3000watt tigerclaw inverter
    1 12v 108AH battery

    We've sent the charge controllers back and had them replaced. The ones we received still work the same way - it's not charging properly however, when we remove the chargers and wire directly - it charges.

    Your thoughts?
  • dwhdwh Solar Expert Posts: 1,341 ✭✭✭
    Re: Is Charge Controller Necessary?
    lwilli01 wrote: »
    So, a charge controller is always necessary unless you're buying a "kit/all inclusive" solar generator?

    Basically looks like this:

    solar panel(s) -> charge controller -> battery -> inverter -> AC loads

    If you don't have solar panels, you don't use a charge controller. You use a battery charger instead.

    Some inverters have a built in charger, where they can take power from the battery (inverter mode) or put power back into the battery (charger mode). For them to charge a battery, they need to be plugged into some other source of AC power, like a generator or shore power.
  • dwhdwh Solar Expert Posts: 1,341 ✭✭✭
    Re: Is Charge Controller Necessary?
    lwilli01 wrote: »
    We've sent the charge controllers back and had them replaced. The ones we received still work the same way - it's not charging properly however, when we remove the chargers and wire directly - it charges.

    Your thoughts?

    Yes, with that much solar wattage, you need a charge controller to prevent overcharging the batteries. With something like a little 5w solar panel, you could get by without one, but not with the wattage you've got.

    My first thought is "exactly what do you mean by 'not charging properly'"?

    I mean, 4 controllers and not one works right? Sounds doubtful. Maybe they weren't hooked up correctly?
  • lwilli01lwilli01 Registered Users Posts: 12
    Re: Is Charge Controller Necessary?

    You'd think!
    But, I'm telling you - I've done everything! Re-done everything. Tested amps, volts, everything is right. I'm beginning to think these sunforce chargers are JUNK. All four operated the same way - they recognized the solar array and the battery but the "charge" light never came on - all four!

    Guess I just need to replace the chargers. Maybe I'll try one and see if that makes a difference before I buy two. Any suggestions on charger controllers? I'm thinking morningstar but, I don't have a clue.
  • dwhdwh Solar Expert Posts: 1,341 ✭✭✭
    Re: Is Charge Controller Necessary?

    Hrmm...well, they won't charge if the battery is already full...

    Does the display show anything? Battery volts maybe?

    What is the voltage (Vmp and Voc) rating of your solar panels?
  • BB.BB. Super Moderators, Administrators Posts: 29,702 admin
    Re: Is Charge Controller Necessary?

    If you have a Volt Meter, knowing the voltage from the solar array and at the battery would be helpful.

    Regarding the inverters--They are huge for those sizes of battery bank and solar array.

    I have a 3,300 watt Grid Tie Inverter and a 3,500 watt solar array... Different application, but a large inverter with a small battery bank/solar array does not usually make a lot of sense...

    Running those inverters anywhere near full load will drain the batteries dead in an hour or less... And would take days to recharge.

    If if the solar charge controllers are working correctly--I am not sure they can meet your expectations with 3kW inverters.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • lwilli01lwilli01 Registered Users Posts: 12
    Re: Is Charge Controller Necessary?

    Our thought was to go large on the inverters and then add additional solar panels and batteries when we could.

    I'll have to get back to you on the voltage readings.
  • JESSICAJESSICA Solar Expert Posts: 289 ✭✭
    Re: Is Charge Controller Necessary?
    Pretty sure that AIMS inverter is 1). MSW type (not true sine as claimed), 2). without a built-in charger, 3). a piece of junk.
    Sorry: I have a great personal dislike of AIMS inverters. :roll:

    Absolutely WRONG.

    Every time my “superb” Exeltech inverter failed (so, maybe not so “superb”), I used a borrowed AIMS MSW inverter that is 9 years old. It has ALWAYS worked flawlessly. AIMS manufactures great products, including TSW inverters. Opinions are just that: opinions; but if they are not based on FACTS, then they are just BS.

    Disclaimer: I have no relation whatsoever with AIMS Corp. But I know this: My 2 Exeltechs went kaput; my GO POWER went kaput (This one deserves to be called POJ). The old AIMS has NEVER failed.

    Disclaimer 2: I have always appreciated and thanked your opinions in this forum. But this time you are just plainly wrong.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Is Charge Controller Necessary?

    No, I'm not.

    I've never said they would fail. Look at the specifications. They are badly designed. It is absurd to expect that much power out of a 12 Volt inverter. They even have 10 kW 12 Volt units, which is totally in the realm of the absurd. It is not safe practice to have that kind of DC current flowing. They use parallel wiring to overcome the limitations of single run, which again is asking for trouble.

    AIMS banks on the probability that users will not operate their units anyplace near the rated capacity. To do so would not be a safe practice. Just because they work and continue to function does not mean they are good units.

    And that's a fact.
  • PhotowhitPhotowhit Solar Expert Posts: 5,023 ✭✭✭✭
    Re: Is Charge Controller Necessary?

    I've never used Aims and don't know, but I suspect if you fired up the 2nd system at close to 3000watts it would shut down inside of 2 minutes!

    If you have any one near you that has set up a solar array I would kindly ask them to check ut the wiring. basic PWM charge controllers are pretty simple, I had one fail after I used it for 5 years then my father used it for 3 years on a pontoon boat docked in salt water! This was a SCI unit

    I am only questioning whether there are other issues. I actually down loaded the manual, and it has just 4 connections, didn't even see a ground, though I didn't look hard. From the SCI (I know you don't own this brand) "Note that almost 50% of the regulators sent to us for repair HAVE NO PROBLEMS." Can't imagine 4 faulty units, I've set up or helped setup more than a dozen system and I can't recall ever having any other failure, though I guess this is on the "cheapest possible" end of the scale.

    Where are you located?
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • JESSICAJESSICA Solar Expert Posts: 289 ✭✭
    Re: Is Charge Controller Necessary?
    AIMS banks on the probability that users will not operate their units anyplace near the rated capacity. To do so would not be a safe practice. Just because they work and continue to function does not mean they are good units.

    And that's a fact.

    Cariboocoot:

    Well, with all due respect, that is not a “fact”, it is just faulty logic.

    You have written that “just because they work and continue to function does not mean they are good units…” This, in good logical science, is a fallacy (an invalid reasoning). If the fact that a given product works as it should and continue to function for almost a decade of hard use does not mean it is a good product, then, what should be necessary to prove it? Advertising? Price? Brand hocus pocus?

    Indeed, the best, and maybe the only way to prove that a given gadget is good is, precisely, the test of time, together with the fact that it does whatever it is supposed to do.

    A $2,500 Xantrex that fails during the first 6 months of use is not a good product just because it is a Xantrex, it is expensive, and a bunch of people recommend it. If price and publicity are the criteria, then the only thing AIMS Corp. needs to do is to raise the price of their products, and advertise them in The New Yorker.

    P.S: I am not "selling" any given product. In fact, I have never bought an AIMS! (The one I have used I have borrowed from a friend.) Maybe they are, in general, mediocre. But if they are, there should be better and more logical ways to prove it.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Is Charge Controller Necessary?

    I suggest you reread what I wrote which explains quite clearly why the AIMS (or any other high-output 12 Volt inverter) is a bad product. Quality doesn't enter into it; it's all about the physics and good, safe electrical practices.

    I'm not selling any product either (none of the moderators work for NAWS), but several decades of working with (and in the field of) electronics gives me a fairly substantive background as to what is safe practice and what isn't. Drawing hundreds of Amps DC isn't.

    At the outset I stated it is my opinion that AIMS inverters are not a good choice. I stand by that statement for the reasons given. I have also repeatedly said no one has to agree with me.

    This is also swaying way off topic, so we'd best leave it alone.
  • bmetbmet Solar Expert Posts: 630 ✭✭
    Re: Is Charge Controller Necessary?

    I am wondering if the inverter has kept your batteries drained past the point of recovery.
    BB. wrote: »
    If you have a Volt Meter, knowing the voltage from the solar array and at the battery would be helpful.

    Regarding the inverters--They are huge for those sizes of battery bank and solar array.

    I have a 3,300 watt Grid Tie Inverter and a 3,500 watt solar array... Different application, but a large inverter with a small battery bank/solar array does not usually make a lot of sense...

    Running those inverters anywhere near full load will drain the batteries dead in an hour or less... And would take days to recharge.

    If if the solar charge controllers are working correctly--I am not sure they can meet your expectations with 3kW inverters.

    -Bill
  • BB.BB. Super Moderators, Administrators Posts: 29,702 admin
    Re: Is Charge Controller Necessary?

    Bmet,

    I am probably just confusing you with my system... It is a grid tied system and has no batteries...

    Back to your system. Typically the inverters will operate down to ~10.5 volts dc...

    You should really never take a lead acid battery below 20% state of charge or it will be permanently damaged. That is about 11.58 volts resting voltage.

    And for long battery life, you should not draw down a battery below 50% very often (around 12.06 volts resting voltage).

    The problem is, the output voltage of a battery under load or under charge does not really give a good idea of the battery's state of charge.

    So, the cutoff voltage of an inverter really does no good at protecting your battery bank--And is there, instead, to prevent the inverter (or your AC loads) from burning themselves out with too low of battery voltage...

    So, the correct answer is that 10.5 volt inverter cutoff is not there to save the battery. And, most likely, you will have over discharged your battery and probably damaged it if you rely on the inverter cutoff circuit to let you know when your battery is discharged.

    There are devices that can estimate the battery's current state of charge... Battery Monitors do this by measuring the current flow into/out of the battery bank (using a shunt resistor) and keeping track of time (i.e., 20 amp discharge for 2 hours is 40 Amp*Hour used--if battery was a full 100 AH battery, then you have used 60% of the battery's capacity).

    It is sort of like keeping track of the fuel in your gas tank by logging how many gallons of fuel have been put into or out of the fuel tank through the gas line.

    You can read more about batteries here:

    Battery FAQ
    www.batteryfaq.org

    Interestingly enough--There are very few (if any) integrated inverters that monitor the battery state of charge and can turn themselves off if the battery falls below XX% state of charge.

    There are a few Battery Monitors that can be programmed to turn off an inverter at specific state of charge levels--and this is a good way of protecting your battery bank if this is an unattended site.

    Otherwise, most people keep a very close eye on energy usage and battery state of charge (measuring specific gravity with a hydrometer or using a battery monitor) to ensure they do not ruin their battery bank with over discharging or under charging (deficit charging). Over charging can also be a problem--but is usually well handled by the charge controller(s) in the system.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • bmetbmet Solar Expert Posts: 630 ✭✭
    Re: Is Charge Controller Necessary?

    B.B.

    I was responding to your statement about how a large inverter would drain batteries, and take a long time to recharge. Enough of this pattern would eventually kill them, and I wonder if that is why the controller doesn't sense them.

    And if it really is a large inverter, do those turn off completely, or is there a residual amount of 'standby' current always pulling a battery down?
  • BB.BB. Super Moderators, Administrators Posts: 29,702 admin
    Re: Is Charge Controller Necessary?

    Bmet,

    I am not quite sure I understand your question... Which controller? The inverter's controller, charge controller???

    Generally, few people need a very large inverter for a handful of minutes per day...

    For the most part, they need them for a number of hours in the evening (as an example).

    And that would tend to mean smaller inverter on for 6 hours an evening rather than a large inverter on for 20-60 minutes at a time.

    Also, large inverters can have significant "tare" losses... On the order of 30-60 watts for the bigger ones. So over-sized inverters can waste a lot of power too. If the loads are small, then a smaller inverter will be much more efficient at the lighter loads.

    Also, large inverters require a fairly large battery bank. If flooded cell, a good rule of thumb is to size the battery bank ~2.5x the maximum rated surge current of the inverter. And with a large battery bank, you have higher self discharge and higher minimum charging current (again, another rule of thumb is 5% to 13% of battery bank AH capacity for charging current)...

    The taking a long time to recharge was a comment on "lwilli01" initial system design... Any (assumed on my part) use that would load the inverter nearer is full power rating for hours, combined with the fairly small solar array--lead me to guess that the system would not meet "lwilli01" expectations of usefulness.

    With off-grid power, it is very difficult to build out a system over time... A small system would typically use small inverter, battery bank, and array...

    In keeping to a balanced system, enlarging any one part pretty much needs the other items to enlarge too (larger inverter, high voltage battery bank, larger battery bank, larger charge controller, larger array to keep up with the power and battery charging requirements).

    I don't know if the inverters shutdown completely at cutout voltage or still have a small current draw--but I would not be surprised if there were still a small load (like 1 watt+/-). But, from my point of few, the standard cutoff voltage of 10.0-10.5 volts has already taken the battery bank pretty much to dead--so a little more current draw is not going to make a huge difference.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • PhotowhitPhotowhit Solar Expert Posts: 5,023 ✭✭✭✭
    Re: Is Charge Controller Necessary?

    In questioning the need for such a large inverter, it might be good to point out that standard 15Amp home curcuit represents just 15Amp x 120Volts = 1800watts available. Even a 20Amp curuit represents just a 2400watts available.

    Not to mention many of use who live off grid run our whole households on 1800 watts or less. Some as little as 300watts with a larger inverter available for the once in a while big loads.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • thesolencothesolenco Registered Users Posts: 6
    Re: Is Charge Controller Necessary?

    Hello All,

    I have 4X250W solar panels
    30.1 Vmp
    8.33 Imp
    24V Inverter 980W
    2x12Volt batteries with 155Ah each

    Do I need charge controller?

    Please tell me the best charge controller for my Solar energy system..

    I'm Waiting for your quick reply
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Is Charge Controller Necessary?

    Yes you need a charge controller. You will need a good one too, as the panel Vmp is not high enough to properly charge a 24 Volt system. As such you need to put two panels in series to achieve sufficient charging Voltage, and then you have the opposite problem: Vmp 60, which means without an MPPT type controller most of the power would be lost.

    Your battery bank is very small at 155 Amp hours @ 24 Volts. It really does not need 1000 Watts of array to recharge it. Again you need a good MPPT controller to prevent the current from being too high (program a maximum current). You're looking at about 32 Amps from that much array, which would be 20% peak charge rate. That would definitely be at the maximum for flooded cells.

    Are you sure you don't want more battery capacity? 155 Amp hours isn't much: about 1.8 kW hours worth.

    I've never heard of a "980 Watt" inverter. What make/model is that?
  • thesolencothesolenco Registered Users Posts: 6
    Re: Is Charge Controller Necessary?

    Actually We APC inverter for solar system usage because it has high efficiency and good quality as well while in rainy days we can use our nation line to charge the batteries.

    in future we will increase our battery bank to double 300Ah.

    Another thing please tell me

    Can PWM charge controller can properly charge using this 30.1 Vmp for 24 Volt battery bank?

    Please suggest me any PWM charge controller of 24Volt and 40 Amps for my solar energy system upto $120.



    Another thing.... actually i want to ask can we use good quality 24 Volts 20 Amp charge controller in parallel for 1000W solar panel array to charge the batteries parallel connection B/W both charge controllers?
  • BB.BB. Super Moderators, Administrators Posts: 29,702 admin
    Re: Is Charge Controller Necessary?

    I am not sure where you are located... But if you are in warm to hot climate, the temperature corrected voltage output for your array (worst case hot weather, full sun, no wind, etc.) would be on the order of:

    30.1 volts * 0.80 temp derating = 24.08 volts Vmp-panel-hot

    Your 12 volt battery bank would need around 28-29 volts minimum to properly/fully/quickly recharge. ~27.2 volts for a 24 volt battery bank would be "floating" -- I.e., not charging battery bank.

    You can put two panels in series for 60.1 volt Vmp-array, and use a PWM controller (with proper input voltage rating), and it will be able to quickly/fully recharge the battery bank, even in hot weather.

    However, your solar array "effective wattage" would be about 1/2 its rated output.

    8.33 amps * 29 volts charging (two 250 watt panels) = 241.6 watts effective charging power to battery (from "500 watts" of panels).

    With a MPPT type charge controller, the effective power into the battery bank would be (typical worst case sunny day):

    500 watts * 0.77 panel+controller derating = 385 watts from array into battery bank
    385 watts * 1/29 volts charging = 13.3 amps into battery bank

    So the MPPT type charge controller, with two panels in series would:

    13.3 amps / 8.33 amps = 1.60x more current or ~60% more current from pair of series solar panels with MPPT controller

    So, look at it from your local costs... If getting 8.33 amps + PWM controller (per two series panels) is more cost effective than 13.3 amps+MPPT (more expensive) charge controller--Hard to argue the facts differently.

    If you can find a PWM charge controller rated for proper current that has 24-48 volt capability, and can be set to 24 volt battery bank, any PWM controller should work (l.e., you need the "high voltage" parts in a 48 volt PWM controller because of Voc-array>>60 volts--but only want 24 volt output).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • thesolencothesolenco Registered Users Posts: 6
    Re: Is Charge Controller Necessary?

    Actually I live in Punjab,Pakistan. weather is very hot and temp goes to +50c. I have connected all panels in parallel and charge current is 24Amps almost but the voltage are 30.1Volts. can it charge using PWM?
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Is Charge Controller Necessary?

    A PWM type controller is not going to be a good choice here because of the Voltage drop issues: a "24 Volt" system actually charges at around 29 Volts (for Absorb) which leaves you a margin of 1 Volt. Once the panel gets hot (operating temperature will be above ambient temperature) that 1 Volt will be gone, and so might some more. Feed the power through the resistance of the wires and more Voltage is lost. So as Bill said you end up with 24 Volts output where you need 30: the batteries never charge.

    If you put the panels in series on a PWM you have enough Voltage, but most of the power of the second panel is lost because it can not convert the higher Voltage to current. You end up with two 250 Watt panels in series which produce about the same as (8.33 * 35) one 292 Watt panel - a waste of 208 Watts of power.

    As of June 19 Rogue had fully assembled some units. No word on shipping yet.
  • thesolencothesolenco Registered Users Posts: 6
    Re: Is Charge Controller Necessary?

    Then what should I do now? I have purchased and installed that panels now. how can i replace them? any better idea? will PWM not make the voltage stable for battery charging? because on the data sheet of charge controllers it written that if voltages goes low then it will step up the voltages to battery level and somehow low the current for making the battery charging more quickely?
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Is Charge Controller Necessary?

    A charge controller needs input Voltage above the charging Voltage in order for charging to take place.

    It is rare (but not impossible) that a charge controller includes the ability to boost lower input Voltage to a high enough level to charge the batteries.

    This is not the same thing as regulating the output Voltage to proper levels. With a "24 Volt" system the array normally has a Vmp around 35-36, and charging Voltage is around 29. It is easy to take a higher Voltage and regulate it down, much more difficult (complex) to take a lower Voltage and boost it up.

    A PWM type controller regulates the charging Voltage by the very simple method of turning the connection to the battery on and off as rapidly as needed so that the output Voltage is effectively held at the right level.

    An MPPT type controller does much the same, but has the ability to turn higher input Voltage into greater charging current (buck converting).

    Do you have a particular controller in mind? Beware that there are many units out there that make exaggerated and unsubstantiated claims about performance. In other words they lie, calling a controller "MPPT" when it isn't and so forth.
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