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- เผยแพร่เมื่อ 2 มิ.ย. 2024
- This is a video that covers the basics of how solar charge controllers work, how PWM units prefer Amp over Volts solar input, while MPPT clearly prefer Volts over Amps. I go over the function of the PWM unit features and the Victron MPPT 100/15. I connect a power supply unit to emulate solar input and see that both units are very close on efficiency which i was surprised to see as i expected the PWM to show bigger losses. The video also demonstrates how the charge controllers distribute power to the battery or loads applied via the load outputs that each unit offers. Both SCC units made use of 5 Mosfets in case you wondered what was inside the units.
It may help those learning about solar the basics of operation. Learn more about off grid solar at dcguy.co.uk
The full Victron MPPT 100/15 user guide is available using this link - :
www.victronenergy.com/media/p...
My Amazon affiliate link to the Victron MPPT 100/15 - amzn.to/44uFrBz and they are also available on eBay (clicking this link will direct you to eBay) - ebay.us/eTxrFd
The bench top power supply is a 10A 30V unit from Amazon - amzn.to/4dvs3S4
Battery load tester is a 180W unit from Amazon - amzn.to/4dvs3S4 but are much cheaper from Aliexpress if your willing to wait - s.click.aliexpress.com/e/_DdB...
The PWM 30A Charge Controller is available on eBay (clicking this link will take you to eBay) ebay.us/QkPPwq or Amazon - amzn.to/3WAuRY5
Battery used is a LiTime 12V 50Ah - uk.litime.com/?ref=t2nvwo1x 5% discount with code Bill5%
Clamp Meter - Kaiweets HT206D - amzn.to/44AMVTW
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This video is for entertainment purposes only, please do not replicate actions in any of my videos unless you are fully confident in your abilities and know what you are doing. Always consult a professional if you are in any doubts about the safety of your electrical systems or equipment - แนวปฏิบัติและการใช้ชีวิต
Also to add, i've just seen in your tests your PSU supply voltage (14v) is only just above that of the battery (13.4v) for the PWM controller and yet you wound the PSU up to 28v for the MPPT!!!
In the first case, then you haven't even got a PWM converter, you've got a switch and a switch that is basiclly just ON all the time because basically outputV = inputV. Repeat you test with a realistic PV voltage as used for the MPPT test, typically twice your battery voltage, perhaps 3x, and you'll see a very different result as suddenly the switching losses are going to show as well as the resisitve ones, because the unit is actually going to have to voltage match (step down), and reduce it's PWM duty cycle. Worst case will be at 50% duty cycle, (PV = 2 x battery) where the current ripple is greatest and hence I^2r losses increase (losses go up with current ripple, even if the RMS value is identical) Which is where you tested the MPPT controller!
I made no changes to the power supply unit, the PWM and the MPPT simply handled the incoming voltage differently. The PWM throttled the incoming Voltage, whereas the MPPT accepted higher Voltage. I accept what your saying about actual solar voltage will show the MPPT is more efficient at harvesting solar over a PWM.
@@DCGUY You might not have made a change but the power supply impedance was very different and as a results your efficinecy measurements are not directly comparable! For efficiency tests you PSU must be in "constant voltage" mode, and able to supply sufficient current during the test so as to not enter current limiting mode.. if the PSU enters CC mode (current control) then it is, in effect, doing the job the DUT (Device Under Test) should actually be doing, and as you are measuring post PSU, then clearly that PSU is carrying some of the losses instead of the DUT!. You also need to be careful to ensure you measure voltages directly at the DUT, using Kelvin voltage measurement techniques (ie seperate voltage measurement wires that carry effectively no current and hence experience no voltage drop).
These might seem like minor points but they are CRITICAL if you want to accurately and fairly measure the relative performance of such devices. In fact, because typical RDSon for the sort of mosfet arrays used is less than 100mOhm, your test wiring will actually a similar level of loss to the system as the DUT itself (which is why your recorded efficiencys are so low)
@@DCGUY Please note that POWER OUT = (POWER IN minus LOSS) and that the power is just volts x amps, and resistive losses are the square of current, so you can see that the largest effect on transfer efficiency is the voltage ratio over which that conversion is effected!
@@maxtorque2277 Thank you for sharing you knowledge and experience with us, this is how we all learn. As far as I thought the PSU would simply output the same current regardless of the DAT and I put the low volts going into the PWM as internal resistance of the mosfets / circuitry pushing up the Amps. I'm going to be doing further tests with the 50A PWM when it arrives and will take all your advice on board. Really do appreciate you taking time to comment and help others, every day is a school day! , cheers 🍻
@@DCGUY PSUs can run in either Control Voltage (CV) mode or Control Current (CC) mode depending on the settings, er, set! However,in either case, when the output power hits the PSUs maximum limit, it MUST always drop into CC mode and reduce output voltage to protect itself.
Hence,
1) with a High Output impedance ( low output load) the output voltage can be set by the CV knob, and will track up and down following that control setting, as long as the Current limit is set high enough so as to not become limiting
2) Low ouput impedance (high load) you will find that withing the power envelope of the PSU it will follow the "Higher" of the Current and Voltage setpoints, ie it will increase the voltage up to either the point the voltage limit control is reached OR the point where that increased output voltage pushes enough current through the load so as to reach the Current control limit
For your tests, you will have to find a suitable setting that stays within the Voltage, current and Power capability of your PSU
As Power output from a PV controller is Output Voltage x Output current, the easiest way to limit total power is to simply keep the ouput votlage low. For example, at the 15amp output current limit of the Victron MPPT, 10v is 150 watts (10x15) and 20V is 300W (20 x 15).
The victron MPPT actually has quite a nice feature in that it can start even with an output voltage of zero volts, in no battery connected. Ideally a DC load that has a selectable drop out voltage, ie a voltage below which no current is drawn, would be used, and the drop out voltage set appropriately to limit the maximum power required during the test
Actually apart from the non VI conversion the PWM is much more efficient, which is why PWM is better for small battery/panels setups (unless your panels are far above the battery voltage).
Essentially, MPPT prevents voltage collapse of the panel when power/current is taken from it. As seen by the voltage at the maximum PowerPoint - Vmp, and this varies with the PV type used and its environment.
Appreciate you taking time to watch and comment, thank you
Good job. Quality info given and the PSU you use is a great price using the link provided. I have V.100/20 sitting next to my new Phoenix 48/1200 . Not the perfect buy but I wanted/needed another inverter in a hurry. Better to have something right away, power can go out so so quickly. Thanks for the upload, keep at it, keep improving.
Thanks for watching and taking time to comment, it is appreciated and yes it's wise to be prepared for power cuts.
You'll be surprised at how versatile the 100/20 is. The next step up from there (for 48V) is the 150/35. The 100/20's are great though, I use tons of them because they are so small and useful. ~20A x ~54V = greater than 1000W of solar going into one little unit. Hard to beat that.
You can also use the Victron charge controllers to down-buffer to lower-voltage batteries. I like them better than the Victron DC-to-DCs. So 48V main system voltage but you still have some 12V gear, or even some 12V "emergency" gear like a radio (say on a boat).
You run the 48V through a fuse to the "solar" input of a victron 75/15 and the output to a 12V battery and, bang, just like that you have satellite (localized) emegency backup on top of the 48V emergency backup. Plus the 12V gear can deal with high surge loads since there's a 12V (well, 12.8V LiFePO4) battery in the mix.
(fuse is mandatory just in case Victron's solar clamp feature ever activates, which it won't under normal operation. But still... fuse mandatory on "solar" side for that use case).
-Matt
Briefly explained, PWM controller is just regulator, MPPT is conventer and it can utilize higher panel voltages for current..
I have EPEver 20A controller, panel 360W and sunny day panel gives 30 ish Volts what gives roughly 10A , output current from controller is roughly double when my system is 12V and max charge set to 14.2V for Lifepo4 battery.
Sorry my bad English im from Finland.
Appreciate you watching and taking time to comment, thanks
Very good video, with a surprisingly deep dive into the settings and options of each controller. For most folks, the increased output of the MPPT, particularly during partially shaded conditions, makes this discussion largely academic. Also, I think you'll find a lot of people are opting for lithium iron-phosphate batteries and advanced communication throughout a comprehensive system of components. PWM contollers still work quite well for a more simple, and some would argue, more reliable solution. From a cost/value perspective, I think you're really further ahead to go with an MPPT controller, higher voltages, and the much better LFP batteries.
Thank you for taking time to watch and comment, it is appreciated.
Yes, I learned a few new things here, thank you.
Thank you for watching and taking time to comment its appreciated
If you have a 100W solar panel that outputs 20V mppt is not going to make much difference, just marginally at dawn and dusk. But is you have a 320W 40V panel you must have a mppt controller. Several 100W panels can be connected in parallell to increase the charging of the pwm.
Thank you for watching and taking time to comment, it is really appreciated
Maximum Power Point Tracking
Pulse Width Modulation
That's what I said, only in Scottish 🤣🤣🤣
Interesting, but not a test of solar performance. Repeat the test using solar panels and you will find the MPPT, (maximum power point), controller is able to convert much more panel power than the PWM, into useful battery and load power. The load outputs, other than for controlling lights, say street lights, are rarely used for most applications. Usually loads are connected directly to the battery.
What was not investigated is the actual charge process . A PWM controller will have a badly configured charge profile, typically overcharging the battery and reducing battery life. The Victron MPPT, with preset charge profiles for all battery types, will correctly charge the battery. In addition the Victron controller has detailed information on the charge process and battery condition. You also get a 5 year warranty.
Absolutely, it wasn't a test on solar performance and MPPT are way more efficient at gathering solar energy over a PWM. Appreciate you watching and taking time to comment, many thanks
what's the best type controller and setup for 2 solar panels mounted on a vehicle that will be in near constant motion and can't be sure it'll be in full-panel sun conditions - eg partial shading might happen. is this something a buck/boost charger is used for and are there any available that would fit where one of these common MPPT type would be used otherwise ?
It depends on the wattage of your solar panels, their VOC (current under no load), the type of battery or batteries your using as well as their voltages. MPPT Controllers can handle higher voltage systems where panels are wired in series and are more efficient. PWM are used for flooded or gel type batteries. Panels in series, if one panel gets any shading it affects both panels output, whereas a parallel set up won't be as badly affected as long as one panel gets sun. Once you know your voltages you can choose a controller to suit input range. Https://dcguy.co.uk may be of some help
A Victron 100/15 ? That's really quite ancient, haven't seen one of those in a long time. The Victron 75/15 and 100/20 are more current. In anycase, the 75/15 and 100/15 can only handle up to 24V batteries (roughly 30-some-odd volts) on the output. The 100/20 is the go-to for 48V batteries.
In anycase, there are some other likely serious differences, particularly when it comes to protection circuitry. Most no-name charge controllers are not current-limited devices (means you can over-current the input and burn it up), and also do not have real voltage protection circuitry. The Victron's have full current limiting and control (output current limit can be set in the app). The Victron's also have automatic temperature power derating above 40C ambient (60C on the heat sink, roughly) so it's fairly difficult to blow one up. Not impossible, but difficult. And the Victron has multiple over-voltage protection circuits, including a clamp on the solar input if all-else fails. The Victron is also nearly fully-potted and full of sand to help sink the heat while that little PWM controller probably isn't. And the Victron has much, much better bulk/float handling (its night and day really), particularly as the battery gets full.
So some fairly huge differences, actually, above and beyond PWM vs MPPT (DC-DC buck) operation.
The temperature compensation on the Victron monitors an external device, such as the temperature sensor connected to a Victron shunt. It won't compensate based on its internal temperature readings since those have nothing to do with the battery, and you can't connect a temperature sensor directly to the charge controller. You need a separate device that is smart-networked or VE.networked in.
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In terms of the "diverting the current"... no, the Victron isn't diverting anything. The "load" output is just a FET switch off of the battery. It is NOT regulated in any way. The load will take current from both sources if it needs to, but its just relative voltage. If the load is less than what the charge controller is outputting, most of the energy will come from the charge controller because the voltage draw-down won't be sufficient to pull from the battery. If the load is greater than the charge controller's output, then the battery will make up the difference.
Since the current draw is entirely related to the voltage draw down, and the battery has a different effective internal resistance at different currents, you do get decent current sharing between the two depending on the state of the battery. It won't generally be all one or all the other.
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If you have a full-time DC load and do not need fine ON/OFF control (i.e. depending on the battery's low-voltage disconnect), just connect your load directly to the battery or use the LOAD output of the Victron to articulate a relay.
Finally, note that the LOAD output on the low-end Victrons can only handle resistive loads. They can't handle inductive loads or even devices with input capacitors, at least not very well... they are very, very sensitive to short conditions and will turn off. The LOAD output is also pretty easy to burn-out... a failing off these smaller Victron's. The larger Victron's don't have LOAD outputs at all because they realized that they couldn't just use a cheap FET as a solid-state switch without a bit more protection and control circuitry.
In anycase, nobody in this day and age should be using PWM charge controllers. The Victron's are pretty cheap and offer an almost unbeatable set of features.
-Matt
Awesome information, thanks for your input.
I would be more interested in a test with solar connection to see what the differences in the 2 units
Yes, that's on the cards.
"efficiency" in terms of power transfer losses is ABSOLUTELY not the same in a real systems as "solar energy harvesting performance"
Both these units are using a pulse width modulated (switching) DC DC converter, of a BUCK (voltage reduction) architecture, and both will be using very similar components (N channel mofset(s) and wire wound inductor) to achieve that, and as a result, it's clear their power transfer efficiency, when measured statically is going to be very similar!
In fact, the unit with the greatest PV input voltage (Victron 100Vdc, cheap unit, 50V) WILL be the less efficient one, because RDSon (the resistance of a mosfet when it is turned on) is higher for a mosfet with a greater Vds (the max voltage it can switch)., so its resistive losses will be greater unless additional effort (and cost) is expended to reduce that resistance (greater number of power switches or better switch performance ie a "better" mosfet
So, in your static test, with a steady input voltage, and an effectively fixed output voltage, it's no surprise the units perform similarly.
However, in practice there are two rather important effects that will absolutely make the Victron MPPT unit massively outperform the basic PWM;
1) The resistance of a mofset increases as it gets hotter. Look at the thermal design of the victron unit vs the cheaper unit. No contest here, the Victron unit is going to maintain stay a lot cooler and hence, in practise and especially at high PV insolation when output current will be high, the Victron unit is going to deliver a higher efficiency. In fact, dissassmbling the pwm unit and looking at the thermal paths, this unit is going to be terrible for use at anywhere a sustained output near it's theoretical rating
2) A real PV panel or array of panels is absolutely of a complex impedance. The ability of any MPPT controller to dynamically impedance match the PV to the load across a wide range of insolation values and panel temperatures and states (including aging) is, in a real system, running for years in order to get a ROI, going to make an enourmous difference to its harvesting performance!
Really appreciate your input. Thanks for everything