How much current from a "200" watt panel. Is mine fake?

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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #32
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    I have little inverter on the boat for charging laptop, 75 or 100w max IIRC.  I'm not sure what making the square wave AC would do to the DC side with a small battery though.  It seems to work ok on 225ah house bank.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
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  • mike_s
    mike_s Registered Users Posts: 155 ✭✭
    #33
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    Photowhit said:
    mike_s said:
    It's not clear why you're being so critical of @unexpected. He's using the load terminals appropriately, has shown he understands his needs and the limitations better than you, and the system is clearly working for him.
    So another person who can't read?

    The Frickin' manual says NOT to...
    NO he is NOT using the load terminals "appropriately".
    Oh, I can read just fine. You're referring to a general warning advising the user to connect inverters to the battery, with no reason or rationale given.

    For those of us who understand electronics and have common sense, the warning is obviously based on the common use of high wattage inverters in solar systems, which can easily draw more current than the load terminals support. If one understands that a load is a load, and an inverter drawing 10 A is no different than any other load drawing 10 A, then there's no problem.

    Have you ever washed your hair? Why aren't you still repeating the lather, rinse thing?
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  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
    #34
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    I have actually read other reasons, I guess the manual says so isn't good enough for you, I can go track those down, but why waste my time...
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • unexpected
    unexpected Registered Users Posts: 30 ✭✭
    #35
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    If there are other reasons it would be good to know. So far I've only heard about overload (real) and another post somewhere about reduced efficiency which had no explanation.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    edited July 2019 #36
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    AC inverter DC input is actually a 120 Hz pulse train (specifically a sine squared wave form) and not a steady DC current.

    I don't know if it is an issue with the controller manufacturer or not--But I would be worried that the "noise" from the AC inverter would cause the charge controller is have inaccurate voltage measurement of the battery bus and cause charging issue (vs a continuous current waveform for lights--Which LVD is usually used for--And some LVDs are programable for security lighting like on at night, on for 4 hours after dusk, etc.).

    Also, it is possible that the AC inverter will surge much more than expected when first turned on or starting AC loads (most good quality AC inverters will surge 2x rated output power/input current).

    -Bill

    PS: Lead Acid batteries have very low internal resistance and pretty good "capacitance). Running the AC inverter (and other "noisy loads" directly back to the battery bank means better noise filtering in your system.

    Also, solar charge controllers usually have some sort of PWM output--Having controller PWM (on/off) current mixing with the 120 Hz of the AC inverter current input could cause more "noise" and voltage measurement issues...

    Just guessing.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • unexpected
    unexpected Registered Users Posts: 30 ✭✭
    #37
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    Thanks that's actually stuff I will look out for. Filter circuitry should take care of some of this in theory, depending on how well they made the inverter. The PWM fluctuation would explain the efficiency loss. I thought the lead acids had higher IR than lithium though.

    I've already been watching for surge and devices that just don't work well on this inverter, not being pure sine wav. Really wish I had an o-scope so I could see if there is a waveform difference when hooking to the battery vs normal ouput.

    Since I can still send back the gel, I bought some nissan leaf 66ah packs and am going to run that by next week. imo the 20AH usable of this thing is just not enough to justify what I paid. They go up to 16v in series and I can add more as needed.

    Only concern is the "float" on the charger but people have been setting that to wherever they are charging to and putting the boost reconnect .1v below. an ~90%-20% should give ballpark 40ah. I can also compare battery balancer voltage to charger voltage and see if the inverter is affecting readings.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #38
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    You are correct, the Li Ion batteries generally have lower internal resistance that Lead Acid.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Raj174
    Raj174 Solar Expert Posts: 795 ✭✭✭✭
    #39
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    I agree, large LFP prismatic cells can be 50 times less internal resistance than FLA and 10 times less than AGM batteries.
    4480W PV, MNE175DR-TR, MN Classic 150, Outback Radian GS4048A, Mate3, 51.2V 360AH nominal LiFePO4, Kohler Pro 5.2E genset.
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  • mike_s
    mike_s Registered Users Posts: 155 ✭✭
    #40
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    BB. said:
    I would be worried that the "noise" from the AC inverter would cause the charge controller is have inaccurate voltage measurement of the battery bus and cause charging issue...
    Why would that not happen even worse with the inverter connected directly to the battery?

    BB. said:
    Also, it is possible that the AC inverter will surge much more than expected when first turned on or starting AC loads (most good quality AC inverters will surge 2x rated output power/input current).
    Same as any inductive load - like an incandescent lamp, a water pump, or a furnace blower.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #41
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    In theory, inductive loads are near zero power factor (probably below 0.50 or less for induction motor). So inductive loads don't have much effect on DC battery current--Although, the phase shift of the AC side current could look like a 120 Hz discharge/charging cycle (reflective of the inductive portion of the AC waveform).

    When you connect your loads (and charging sources) directly to the battery bank, you have the battery's ability to look like near zero impedance--And any current wave forms have very little effect on the battery voltage.

    If, for example, you have a 5 fool cable from the battery bank to a "common" point (bus connection to charge controllers, loads, etc.), you now have the non-zero impedance of that 6 foot of cable. The inductance (and somewhat increased DC resistance) of that cable now blocks the "shorting of the noisy signals" through the battery bank to ground. And you can get "ringing" from fast rise time signals (PWM charge controllers, etc.).

    This website has a pretty good overview of many issue related to gensets/inverter/lighting technologies.

    http://www.screenlightandgrip.com/html/emailnewsletter_generators.html

    To be honest, I cannot say if placing a small AC inverter on the LVD output of a properly rated charge controller will cause problems or not.

    We have had issue where a Deslufator (which is a fast rise time "impulse" wave generator--more or less)--Cause a older Outback MPPT charge controller to dramatically reduce its share of charging current--Apparently due to the noise imparted by the Desulfator. When the desulfator was turned off, the second Outback MPPT charge controller started producing the expected charging current/profile again.

    Cross talk, harmonics, beating frequencies (60 Hz AC inverter, XX Hz of the pwm controller), etc... all can affect hardware like charge controllers where you are expecting them to measure voltage down to 0.05 volts or less.

    If everything working OK--Then why not use it. If there are "issues or qauestions" about the charge controller's operation, then I would suggest moving the AC inverter and other "major loads" to the battery bank terminals instead (i.e., Star or Home run wiring back to the battery bus, vs "daisy chaining" connections from battery to charge controller to AC inverter input, etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • unexpected
    unexpected Registered Users Posts: 30 ✭✭
    edited July 2019 #42
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    Just measuring with DMM the voltage at the battery is within .1 of what is displayed by the controller and charging was the same. So no obvious problem on that end. Whether the battery could even officially take a 10-20A load is suspect since the datasheet from MK battery is devoid of most useful info. Same about charging it at 7A. That seems to be the larger problem on my end, hopefully to soon be remedied.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #43
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    Did you get a BMS system of some sort? Many times, that will be the current limitation (BMS would shut down or be damaged if too much current).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • unexpected
    unexpected Registered Users Posts: 30 ✭✭
    #44
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    Nope, no BMS yet. Didn't think I needed one for lead acid and people are getting away without one for these batteries. If I start seeing overcharging on the cells I probably will.
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  • mike_s
    mike_s Registered Users Posts: 155 ✭✭
    #45
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    BB. said:
    In theory, inductive loads are near zero power factor (probably below 0.50 or less for induction motor). So inductive loads don't have much effect on DC battery current
    ...
    We have had issue where a Deslufator (which is a fast rise time "impulse" wave generator--more or less)--Cause a older Outback MPPT charge controller to dramatically reduce its share of charging current

    Say what? Not sure what PF has to do with DC loads. Are you claiming that DC inductive(-type) loads don't draw more power ("surge" in your words) when turned on?

    If anything, your desulfator example would serve as an argument for not connecting an inverter to the battery. I'm assuming you weren't trying to desufate a battery by connecting it to the controller load terminals.
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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    #46
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    mike_s said:
    BB. said:
    I would be worried that the "noise" from the AC inverter would cause the charge controller is have inaccurate voltage measurement of the battery bus and cause charging issue...
    Why would that not happen even worse with the inverter connected directly to the battery?

    BB. said:
    Also, it is possible that the AC inverter will surge much more than expected when first turned on or starting AC loads (most good quality AC inverters will surge 2x rated output power/input current).
    Same as any inductive load - like an incandescent lamp, a water pump, or a furnace blower.
    An incandescent lamp by the way is a resistive load, not inductive, just for clarity 

    The problem with inverters on the load terminals of a CC is that their load is not constant, the inverter takes bites of energy from the battery rather than a constant draw, if there is a sudden draw on the AC side there will be a corresponding draw on the DC in response, the DC current however will be exponentially higher than the average perhaps overwhelming the CC's switching current rating.
     
    Power factor is strictly an AC phenomenon, if an AC load has a poor power factor it increases the apparent power, the limitations of which will be determined by the generaton source, the inverter in this case. For example a 500W AC motor with a poor power factor may draw 700W apparent power so the inverter would need to be able to support at least 700W, the drew from the battery will however be 500W, hense the expression apparent power. This is why industrial consumers are penalized for poor power factor over a given time period because it limits the generation plants ability to supply other customers without increasing generation capacity.

    Batteries can supply enormous amounts of current, that is where the high loads should be connected directly to the terminals,  instead of through the charging conductors and through the printed circuit board to the load terminals which have limited current carrying capacity. Just my opinion........ apparently that of inverter and charge controller manufacturers as well.





     
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
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  • mike_s
    mike_s Registered Users Posts: 155 ✭✭
    #47
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    mcgivor said:
    An incandescent lamp by the way is a resistive load, not inductive, just for clarity 

    The problem with inverters on the load terminals of a CC is that their load is not constant, the inverter takes bites of energy from the battery rather than a constant draw, if there is a sudden draw on the AC side there will be a corresponding draw on the DC in response, the DC current however will be exponentially higher than the average perhaps overwhelming the CC's switching current rating.
    Which is why I later clarified that by saying "inductive-like", as bulbs aren't purely resistive, either. And, that's what incandescent bulbs are - they have a large inrush current when first turned on, similar to a true inductive load for the question at hand. As with the other examples given, there's no warning about connecting load terminals to bulbs. In fact, connecting them to lighting is a very common use. LED and CFL lighting also have high inrush currents.

    But, empirical evidence trumps - neither I nor the OP have had any issue with using a small inverter which draws less than the load current rating. My load circuit is rated for 40 A, I don't think I've ever used more than 100 W with the inverter, which is about 10 A DC draw from the controller. Even a large inrush is below the rating. Which is why a blanket statement of "you can't use them for inverters" simply isn't true. It's perfectly fine if done with an understanding of the limitations.

    No, the inverter's DC input is not exponential with output, it's linear.
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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    edited July 2019 #48
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    Well all I can say is shoot yourself, use the load terminals, it's your equipment after all.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #49
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    mike_s said:
    But, empirical evidence trumps - neither I nor the OP have had any issue with using a small inverter which draws less than the load current rating. My load circuit is rated for 40 A, I don't think I've ever used more than 100 W with the inverter, which is about 10 A DC draw from the controller. Even a large inrush is below the rating. Which is why a blanket statement of "you can't use them for inverters" simply isn't true. It's perfectly fine if done with an understanding of the limitations.

    No, the inverter's DC input is not exponential with output, it's linear.
    This is only true in your specific case, with your controller and  inverter and loads.  

    This is really bad advice for neophytes, who will see this, hook their 2KW inverter to the load of cheap CC and fry it .  They will surely thank you.

    Public forums excel at being hunted down by search engines and beginners take this "condition specific advice" as gospel for themselves.     That's why everyone is giving you static about this.   I won't disagree that it works for you, but i draw the line at suggesting it for anyone else.    What is your CC that has a 40A load output ?
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    edited July 2019 #50
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    Very well put, excellent statement  Mike
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
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  • mike_s
    mike_s Registered Users Posts: 155 ✭✭
    #51
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    mike95490 said

    This is only true in your specific case, with your controller and  inverter and loads.  

    This is really bad advice for neophytes, who will see this, hook their 2KW inverter to the load of cheap CC and fry it .  They will surely thank you.
    No, it's true in general. I've clearly stated the limitations - if someone takes what I said to mean they can "hook their 2KW inverter to the load of cheap CC", well, stupidity should be painful.

    It's a Prostar MPPT-40. I was mistaken, it's rated for 30 A load. No matter. As I said, I don't get close. Other than the inverter, everything else running simultaneously (ha! not gonna be running the fans and the furnace at the same time) would be around 12 A.
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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    edited July 2019 #52
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    There is a big difference between ignorance and stupidity, one is not knowing, the other is knowing something is wrong  but doing it anyway. Many readers are ignorant, not stupid, they take advice assuming the author has some background in design and may be misconstrued into thinking what they read is the actual way to do something, which in this case is not the preferred method. 
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,044 ✭✭✭✭✭
    #53
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    Curious as to how all loads are connected to the CC.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • unexpected
    unexpected Registered Users Posts: 30 ✭✭
    #54
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    A bunch of 12g wires, all under 1ft. I think I can cram 3 in the phoenix connector. I should probably bump the battery up to 10g
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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,044 ✭✭✭✭✭
    #55
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    unexpected said:
    A bunch of 12g wires, all under 1ft. I think I can cram 3 in the phoenix connector. I should probably bump the battery up to 10g
    Hmmm...   And where is all the fusing for these wires crammed into the connector?

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • unexpected
    unexpected Registered Users Posts: 30 ✭✭
    #56
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    I was going to get one of those 12v blocks with auto fuses, seemed like the best idea. I could also 3d print some holders but that would use up quite a few spade connectors.
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