Julian's Postbag: #48 - MPPT Solar Buck Regulator LED Display

[@TheRadiastral]

I've been using this exact board in my shed for the last 2 years. One thing I did differently, is instead of connecting a cheap 1N4001 diode, I bought the SM74611KTTR diode (less than 30mV forward drop, pretty incredible). It's fed from a 20W solar panel and charges 4 small 12V scooter batteries in parallel, which power my DIY night-light. The shed is very humid at times, when it's raining outside, but the board never gave up and it works to this day. Very happy with it.

[@jamespayne5570]

I have a 10A4 diode. Will that work?

[@theo2378]

That's nice to hear

[@dnc23x]

doing the same setup today.. solderin' paaaaartyyyy

[@Debjyoti-s3p]

Does it auto cut off

[@budi0251]

Hi, I just got one of this without volt-amp meter. I guess MPPT for solar panel would works as CV input as most pv panels would have pretty constant voltage despite various changes to the light levels, they just dropping amps as the sunlight goes dimmer. Hence the module will try to buck convert the voltage to whatever setting you have and max current from CC pot and draw as much power possible/required. As the light level dropped then the module would lower output current and trying to maintain a constant input voltage without overloading it below set voltage. Basically a true CV regulator, sacrificing current (out and in) by respecting whatever voltage it has been set to work with.

[@JPK90]

To simplify: MPPT voltage = minimum input voltage Input voltage above mppt voltage = everything ok - works like any switching regulator and puts out any power you want Input voltage below mppt voltage = keep droping output power

[@PatricksDIY]

The Panels output Max is 1.7A. When your panels voltage drops, the buck converter tries to increase the current to keep up with the load of 20 watts for the bulbs, So when your Panels drop to 10 volts, it now needs 2 Amps to run the bulbs 10v*2a /20w. and that is saying the panels are at 100% efficiency. Nice video my friend, I picked up one of these a few days ago and was looking for peoples experiences .I appreciate the time you took on the video :)

[@southerndiscomfort2412]

For those people who wish to know what diode to use: For the diode size it is best to go 1.5x the rated current output of the solar panel (1.5x the Imp) ie: panel puts out 2 amps = 3 amp blocking diode so an example would be a 1N5822 40V 3A Schottky diode.

[@dubsnip1636]

Many thanks, could not find this anywhere and too noobish to figure that out myself.

[@drkastenbrot]

I used one of these to build a cheap lab psu. It now has a nice case and standard pots + fine adjustment pots, all accessible without screwdrivers, just nice knobs. Banana plug output and both computer psu and lipo input connectors. I also added a little temp controlled fan, mainly because it looks cool.

[@dnc23x]

share a pic please

[@jimthvac100]

I believe the MPPT adjustment pot is really just part of an adjustable Low voltage cut off circuit. It works similarly to an MPPT but a True intelligent MPPT circuit would not need to have an adjustment pot to manually adjust it; However I believe it is better than nothing.

[@Da9eI]

I already bought one of theese right after you tweeted about it a while back and it seems to work well for me. Mine however had cold solder joints on the microcontroller for the display and needed to be resoldered. I found that Its much easier to calibrate the MPPT function with a bench psu that has Constant Current adjustment: WITH a load connected trough the buck converter and psu in CC and with a voltage set to more than "minimum needed" (20+v in most cases), set the mppt pot until desired INPUT voltage to the converter (Vmp from solar panel, or lower) while the PSU is CC. Did this with a lipo as load, but was discharged enough to keep the buck converters mppt function in CC mode. This last bit seems to be important, otherwise when it goes constant voltage the input voltage will also rise, thus no longer "mppt's". I did this without the output reverse diode, in my case the reverse current never exceeded 80mA, but that was with a output voltage set to 5V - even when connected to a 12V battery.

[@jagdeepsharma8170]

Mate, I have a 32V 1.9A rated panel. How do I calibrate this unit to get MAX our of pannel. PS: I'd need 27.6 volts for batteries and 2A current.

[@BrainHurricanes]

7:18 You probably figured out by now, but if you stopped turning the pot at 17.3V it was almost perfectly adjusted. You could eighter wait for the sun to shine a bit less, or put a larger load on the output, and turn the pot exactly at 17.1V (as written on your solar panel). Then you would allways get the maximum power out of your solar panel.

[@trif55]

came here to see this in action as I have one that's just failed and realised he'd not figured out how the "MPPT" worked

[@Peeki]

Thanks, not sure how it works but this helps me hahahahha 😅.

[@detaart]

I would write a stern letter to the weather service about these clouds.

[@DantalionNl]

I guess with tracking they mean you can track it yourself by adjusting the pot.

[@Da9eI]

Also, I forgot to mention: if you botch a blocking diode where the "jp1" bridge and diode symbol is on the back side of the board instead of the bridge, the regulator will compensate for the voltage drop across the diode. There is a small pcb track going to the positive terminal from the CV pot, I suspect this is the sense wire. I have not tested this fully yet, mine oscillated slightly without a load on the output. This might be caused by the placement of the schottky diode I used, or the output cap I replaced (mine was damaged in shipping).

[@1kreature]

9 years later and this is still the first video that pops up relating to this controller. So sad since it is so misunderstood. The unit works in CV/CC mode so both need to be set correctly for any load to be supplied, initial tests in the video has not even checked these. Then the tracking is not set before later. If set correctly the larger bulb would have been supplied with as much current as possible at the set output voltage but not overloaded the input panel based on the MPPT target. Automotive bulbs need 13v or so to allow rated wattage (not 12) and then there's the question of what the output current limit pot was adjusted to. It is not "enabled and disabled" it is always active.

[@jensgoerke2863]

It seems you didn't take the voltage drop across the diode into account - the output voltage should be at 14.2 Volts to get 13.5 to the battery.

[@sksdiy]

is that same for every diodes. the voltage drop ??

[@MrBrymstond]

@@sksdiy No, but a Schottky Diode I believe works best. I wish he would include the part number of the diode, but never.

[@websitesthatneedanem]

Ahhhhhh.... remember great old video like this, that Julian used to do ..... sigh! 😢

[@MichaelBeeny]

That's why we now live in New Zealand!! We do get some cloudy days.

[@ElektroLUDIKITS]

12V Lead Acid batteries are supposed to be charged around 14.4V. 13.6V is the "floating" charge mode... but with the diode, if it is a schottky one, the battery receives only ~13.2 volts wich is not enough to charge it (and if it is a standard one, it is even less, of course).

[@chveyk]

потому. для "12в" системы напряжение, выдаваемое солнечной панелью ДОЛЖНО быть не ниже 16в в "точке максимальной мощности", ну или 18-20в холостого хода! Только тогда .пройдя все диоды и регулятор всё ещё хватит напряжения для зарядки "кислотного" аккумулятора - 14.2-14.4в(в зависимости от системы - гелевый или обычный)

[@jamest.5001]

It must be set the MPP,and hope for the best output,

[@maktheturd6220]

Hi! I'm a noob to the solar thing. I have a question. If i have a solar panel that gives max voltage of 24 vdc and use this mppt, how do i set to charge 3 of the 18650 batteries while the led is running? Thanks!

[@ErlankBru]

I would like to know as well. I have two 18650 unprotected batteries I would like to charge, but I still need to figure out where to apply the diode and whether I still need to use protection circuits.. not sure if the MPPT "automatically" serves as a protection circuit, but I doubt it. :D

[@johndii2194]

I like the streaks of Sunshine on your desk. It is a good Solar indicator.

[@jacquesb5248]

not mppt compatible

[@adisudana]

Hi Julian, still wait your next review with the normal weather condition, hope u can make it soon and make step by step how to adjust the trimpot. because this product send without manual documention to use it. thx

[@andrewtitcombe8378]

Wish i had seen this first. I fired my module . Did not know about the blocking diode . Also that the negative wire on solar must not be joined to the negative on the output. Second board has been ordered .

[@13panda13]

I didnt connect a diode and mine worked fine connected to a 100ah battery. But I certainly didnt share the earth. Thats why it made u some magic smoke.

[@HowToGuys]

is there anything better in this rather than normal buck converter (like lm2596),Thanks Very neat video.

[@RakshithPrakash]

Kedar Nimbalkar glad to see you here !😁

[@alexisjohnR]

Useful video. Just wondered if you had adjusted the output voltage to compensate for the voltage drop across diode (ie added a volt for normal diode or about 0.4 for a shotkey) then we might have got some power in to charge the battery.

[@djbare9]

I use a boost converter to get the max from the solar panel, I have the output set to 19 volts which is then fed to a PWM solar controller, the booster will attempt to maintain the 19 volts by drawing more current from the solar panel, this will obviously cause the voltage across the panel to drop, it works and it's cheaper than a decent quality MPPT solar controller. By the way readers, watch out for sellers using MPPT in title and description, most of the cheap Chinese controllers are most definitely PWM not MPPT, MPPT will try to maintain output voltage even when the solar panel drops below the set output, as an example, if the output is set to 12 volt, an MPPT will attempt to maintain this even if the voltage on the panel falls to say 10 volts. Cheap PWM controllers on the other hand will follow the solar panel voltage, so if the panel is only delivering 10 volts, then that's all you're going to get at the output of the controller.

[@iceberg789]

Hi julian, its a nice device i want to build 1 for myself to charge a 6v lead acid as well. the principle looks quite straight forward - hold the solar panel o/p at a large cap@ 17.5v and then the buck conversion. but what i m not so sure about, to use a comparator or an opamp to hold the cap from buck. any ideas ? (this one appears to be using 358 opamp) about charging the lead acid, i guess you forgot the diode voltage drop from 13.5v. and 11:05 was quite funny screw terminal to screw terminal conversion. :-) thanks for the video, as usual !

[@GorkemYildirim]

great video, very nice new product. now we need 10A version.

[@macro820]

Ain't no sunshine when she's gone

[@JulianIlett]

I know, I know, I know, I know, I know, I know, I know, I know

[@macro820]

Sorry it's so cloudy buddy, that song just popped in my head idk

[@Designandrew]

+Julian Ilett why not use your 200w LED light to power the solar cells?

[@JulianIlett]

+Designandrew I just know that wouldn't work. If I remember rightly, the sun puts down about 1kW per square metre. For the solar panel I used, I reckon at least 500W of LEDs would be needed allowing for inefficiencies, inverse square law etc. It would make an interesting project though :)

[@MrOpenGL]

+Julian Ilett Oh, stop ranting about bad "Typical British Weather". It has now migrated to Liguria (Italy) which was anciently called "the territory of the sun" (Terra del Sole) and since I put up my solar panels system (inspired by Julian's) in 2011 we had two serious floods, not counting autumn and winter which are almost 100% of the time very overcast and often also raining... Here the summer is already gone (but not the heat), heavy rains are starting again... :-D

[@franciscoortunoabad3811]

Hello !! There is a second part / video of this MPPT Solar Buck Regulator LED Display. If so, can you tell me the link. Thanks

[@jducifjendn9085]

Helpfull video. I looked for this converter in my little diy solar system (very very little) more like an Not Portable Powerbank. And nö that i found your Video i'll definetly by it!

[@TheRealBurtL]

11:33 It would really help your video if you were to explain how to properly configure the device with each pot, LED bulb & LED screen explained for purpose and setting it correctly. Mine did not require the diode, however I did not need the voltage LED so I only have 1 LED version. I'm particularly interested in the MTTP setting. According to the Chinese English document I have, Clockwise is MTTP output on, counterclockwise no MTTP output. How do you tell if the MTTP is on or off? Does it have something to do with the two color LED between the potentiometers? Thank You

[@timbo01889]

HI would you not have to adjust for the voltage drop across the diode of about .7v

[@atubebuff]

Also, if you look under the board, there's a pad to install a diode (as indicated by the silkscreen). When shipped it has a shorting conductor across it. Why didn't they just put a diode themselves???

[@MrBrymstond]

@@atubebuff I know this is a late reply. Maybe because they make 24v batteries for trucks and other applications and you would have to change it anyway or add another in series where he placed this one, but you need to check the output voltage after the diode, but they should just solder one in for a 24v (27v) 12v (13.5) battery which I think still works and be done with it.

[@JamesSleeman]

AT 8:45 when you attached the 20W bulb again, looks like the device went into CC mode (red LED came on) which would have knocked the output voltage down (ohm's law) to do so.

[@gheorghepanait3421]

Hello! I am interested about the screwdriver for adjustable mini resistance. Where do you find it ?

[@CoherentPhoton]

Interesting... I wonder if there is any more circuitry under the LED displays.

[@T1nue]

I'm confused, why does one have to set the input voltage manually? Isn't the whole point of MPPT to find the optimal voltage automatically?

[@rilosvideos877]

Did you in the meantime find out if this module really has MPPT? I doubt it - as there is no controler chip for that - as you mentioned. But i am discussion with someone who claims this has MPPT and it works fine :-) It has kind of "manual adjustable" MPP - but no tracking at all. The tracking must be done by your own - which is senseless imho :-)

[@NunoFlyer]

Hello, Did you add the reverse diode protection on pcb back of the module? I'm asking because Im reading that I need add one diode if I use the module to charge batteries. Regards

[@kaikart123]

you don't, it's a buck converter.

[@13panda13]

​@@kaikart123 correct, Im not using a diode at all. Just make sure the input and output earths are seperated.

[@drgauravsingh9328]

Does this module needs to be recalibrated everyday for maximum PowerPoint tracking via that MPPT knob or it needs to be done only once? And If yes,then will I need to calibrate it even under various sunlight intensities at different times of the day?

[@Fabianwew]

this sooths my buying addiction.

[@gravelydon7072]

It didn't help mine. :-) I just ordered a batch more parts. In quantity. :-(

[@p1nesap]

Nice versatility with adjusting voltage and seeing result on LED. Is something like this the best value for a beginner to play with solar? I've got an Uno R3 and would like to have solar fun with that as well...suggestions appreciated, thanks.

[@jamest.5001]

Seems it would be better suited for a small generator, micro hydro generator, to prevent slowing it too much, I was hoping these had some logic, enough to keep the voltage from dropping anyway, I was hoping to use one of these to trickle charge/ maintain a car battery while parked, that the electronics run the battery flat after a couple weeks, I guess it will be a pen controller, with the 20w pv, maybe I will try a buck converter between, to drop the voltage closer to battery voltage, at least 15v, I'm not sure how this will effect the dc converter, I always wondered how a decent size capacitor connected to the pv would effect the charge controller, and panel output

[@ansomeBob]

To fully charge that battery surely you will need to set the output to 14.1V to allow for the diode?

[@JAKOB1977]

at 6:05 is that an pen intended for adjusting those small pot screws..tryed briefly to look such an device up, but doubt that i aint got the titel correct.. do they go under other names then obvius "pot adjustment pen" or likewise that doesnt seem to come up with anything.. ? thx Julian for any helping info..

[@Tore_Lund]

I use a bamboo chopstick or a bamboo barbecue stick. They are strong enough not to fray and non conductive, so perfect and free. I presume if I ever needed to do some adjusting on RF oscillator circuits, the capacitance of the chopstick would be relevant, but for stuff like this, don't rush out and spend money on tools.

[@rajkumarmukherji6043]

Hello, thank you for this nice video. Will it be possible for you to test the performance of this dc-dc MPPT module using the same solar panel at the input and by connecting five 100 farad supercaps in series? If possible please test the performance during those days that are NOT bright & sunny.

[@allamesancak9067]

Hello, I have attached a lifepo4 battery to this voltage reducer and connected it to the solar panel. When I wake up in the morning, the regulator does not charge. you have to remove the battery and when you reinstall it this error doesn't happen i don't want to deal with it what should i do

[@Magma_Boy]

What did you use to turn the pots? It looked so nice!

[@13panda13]

It was lame how he complained the pots were in not accessible. Just use a mini screwdriver, his tool was the problem, like his affectation.

[@electrodacus]

In order to test if there is any merit to this buck converter used for solar you will need a sunny day no clouds :) probably hard to get there then measure the input power in to the battery with two multi-meters (battery current and voltage) then repeat that in the same conditions only with the PV and that diode directly connected to battery. Then you can see if there is any gain. I assume there wont be any gain or an insignificant one in best case scenario. The efficiency of that buck regulator is probably not that great maybe below 90% When you connect a 36 cell panel to a 12V battery the charge current will be usually a bit higher than the max power point current much closer if not exactly the same with the short circuit current. Of course Lead Acid is an infective solar energy storage not just because of the low charge discharge efficiency but because the last 10 to 20% of the SOC is not done at constant current but constant voltage where not all available energy from solar will be used making any sort of max power point tracking useless at that point.

[@electrodacus]

+timemachine194 I'm not biased the SBMS was designed for my own use and if MPPT will have been of any benefit I will have included that in the SBMS. If you want to argue the use of MPPT you need to come with a demonstration based on numbers and facts as I did in that video and not based on popularity of one or other technology. Using 60 cells PV panels with 24V LiFePO4 battery will work very close to max power point in all weather conditions and I have no interest in Lead Acid since that is way worse than MPPT when it comes to cost or unit of energy stored. There are no diode losses in my charge controller I use so called ideal diodes. The voltage drop on my charge controller is at most a 100 to 200mV at full charge current for the SBMS4080 will be even lower in the SBMS100. The max power point voltage can be even lower than the battery voltage and you will still have a reasonable charge current. Power will be less than max power point in this condition where max power point voltage is below battery voltage but that is not important because thee is huge amount of excess unused energy in summer anyway especially in sunny summer days when panel is hot. That mppt charge controller I used in the video is one of the most popular in offgrid solar applications if not the most popular and that was the reason I chose that. An MPPT controller will always be more expensive than and non MPPT one because of the DC-DC converter. The SBMS is not a PWM charger since PWM is not necessary for LiFePO4 (constant voltage charging is detrimental to Lithium battery life). You look at this inexpensive $7.5 toy but the same people that build that will also be able to build a similar performance charge controller without MPPT (no DC-DC converter for probably $2.5). Also this $7.5 DC-DC converter can be used with a max 40 to 50W PV panel so that it never exceed 5A (5A is a bit of a stretch without additional cooling that will add to the cost) so say 50W PV panel at 80 cent/Watt costs about $40 then if you consider the 5$ difference between this 7.5$ charge controller with MPPT and the possibly $2.5 non MPPT controller that 5$ can get you a 12 to 13% larger PV panel so 12 to 13% gain in any whether conditions and that is more than any MPPT will be able to do in real life as average gain over a year. Also PV panel will last 25 to 30 years where the DC-DC converter will probably fail a few times in this period so the difference over 25 to 30 year is not just $5 it can be $15 if you need to replace the MPPT controller every 10 years. This are about the same arguments I done in my video. But one large pint I made there that many do not understand is how much unused energy you have in an off grid application. I live offgrid for over 2 years now and I have 10 to 20% of unused energy in winter and 40 to 50% unused energy in summer so all will an MPPT be able to do in this case ignoring the cost is to increase this unused energy even a bit more :) or have the battery fully charged 10 to 20 minutes earlier each day that will not help with anything. As for grid tie where over 95% of solar is used (I mentioned this in the video) the MPPT HW is already there and is not possible do do that without so of course there will always be MPPT. But for complete offgrid situations MPPT is more than obsolete.

[@ValentTurkovic]

+electrodacus You argued that using more efficient mppt solar regulator over less efficient pwm makes no sense because mppt regulators are more expensive and people should just put additional cheap solar panel to offset less effective pwm regulator. Same argument could be used for not using much more expensive LiFePO4 batteries over Lead Acid batteries, right? Why not just put additional Lead Acid betteries and maybe also few panels instead of using much more expensive LiFePO4 batteries? I just did a calculation based upon 7Ah LiFePO4 battery with 2500 cycles which costs 140$ and 7Ah Lead Acid battery with 650 cycles which costs 20$ and unfortunately for small systems LiFePO4 is just too expensive and TCO is higher that with Lead Acid batteries.

[@electrodacus]

+Valent Turkovic The thing is that LiFePO4 is less expensive than lead acid that is one of the important reasons I chose LiFePO4 over Lead Acid. If all you need is a backup system (say in case of grid failure) then probably Lead Acid is a more economical choice. But if you are fully offgrid as is my case than LiFePO4 is by far less expensive (at least 3x less expensive). Is not about the battery capacity versus cost but about the amount of energy that battery can store over is life time and then cost divided by that. In your example that small 7Ah Lead Acid probably has a 650 cycles with 20% DOD vs the LiFePO4 that is probably rated 2500cycles at 80% or 100% DOD and that is a really big difference 650 x 0.2 = 130 x 12V x 7Ah = 10.9kWh over is life time vs 2500 x 0.8 = 2000 x 12V x 7Ah = 168kWh over life time So 140$ / 168kWh = 83 cent/kWh for LiFePO4 vs $20 / 10.9kWh = 183 cent /kWh more than 2x more expensive than LiFePO4 over the life of the battery if the battery is used heavily with discharge every day. Of course this small batteries are expensive the larger hundreds of Ah will cost just a fraction of this with Lead Acid at around 40 to 60cent/kWh and LiFePO4 10 to 20cent/kWh over the life of the battery.

[@electrodacus]

+timemachine194 I'm quite busy at the moment but since you took the time to give such a detailed replay to my comment I feel obligated to answer at least part of your comment. First related to battery cost. When you try to compare different batteries for cost amortization you need to use price per unit of energy stored over battery life time. So taking that 4ks25p battery as example at $1300 with a capacity of 1350Ah at 0.05C discharge rate you get 5.4kWh storage capacity then x 2400 cycles with x 70% DOD = 9072kWh over is life (extremely idealistic number with just 0.05C charge discharge rate is impossible to get to 70% DOD in a 24h day if the rate is so low 20h rate). So $1300/9072kWh = 14.3 cent/kWh extremely good number for a Lead Acid so if your choice is Lead Acid this is probably the best choice. But even so there are better LiFePO4 as an example a Winston WB-LYP400AHA en.winston-battery.com/index.php/products/power-battery/item/wb-lyp400aha This is a 400Ah battery at 1C (not 0.05C) and nominal 3.2V so 400Ah x 3.2V = 1.28kWh capacity At 70% DOD can do 7000cycles so 1.28kWh x 7000cycles x 0.7 = 6272kWh over life time and at the $550 price that gets you 550/6272 = 8.7 cent/kWh Still significantly better cost for the LiFePO4 and I will trust much more a LiFePO4 in a solar offgrid installation. First there is no maintenance with LiFePO4 (the Lead Acid above is flooded) then there is no need for a special ventilated box to the outside so that you do not have hydrogen build up and possible explosion. If you live in a cold climate as I do and you ventilate that Lead Acid outside and is -30C as is normally here in winter that Lead Acid will be almost non usable. While LiFePO4 can be stored inside the house at a nice ambient temperature since there is no hydrogen or anything else during cycling. LiFePO4 will love to stay below 100% SOC for any period of time is the preferred state while Lead Acid will hate that even if this is mostly the case in solar offgrid especially in winter with multiple day with cloud cover. Solar PV panels as I mentioned before have really low amortization cost below 3 cent/kWh so even if you double the size of the PV array (double than what you need) then is still 6 cent/kWh with the over sized array and much better choice than any battery. So my conclusion was have a small capacity LiFePO4 with an over-sized PV array and it works great for me as expected. I live fully offgid and have no backup system (most offgid people with Lead Acid have an expensive diesel or gasoline generator with cost /kWh of around $1 or more) As for 60 cells PV panels and 8 cell LiFePO4. I use the LiFePO4 charged at max 3.55V so for 8 cell is 28.4V max charge voltage and on the low end I stop at 3V so 24V cut off Max power point voltage for a typical 60 cell panel is around 30V at 25C standard test conditions. In summer this max power point can drop below 28V but that will not affect the battery charging that is max power point voltage and can be as low as 26V and battery will still be charged at full 28.4V even if the panel is not working at max power point. In summer I have 40 to 50% excess power for PV array since the system is designed to offer sufficient energy in the winter months where day is shorter so is just useless to try and get the max power point when you are anyway no using all the energy. Even in winter I have 15 to 20% of unused energy since is not needed so for this reason alone mppt is useless. People need to understand the difference between off grid where is next to impossible not to have excess energy and a grid tie installation where all excess can be sold to the grid (at least for the moment this will change when the amount of installed solar will increase and grid will not be able to buy all your excess energy).

[@electrodacus]

+timemachine194 That 7Ah battery was mentioned by a different user and since he did not provide a spec just a low cost of $20 and a generic 650 cycles. I think I was more than fair to assume those 650cycles where at 20% DOD for that 7Ah $20 battery (I'm sure it will never get that in real life). The size of the battery is not relevant when you compare cost / unit of energy stored over battery life time but it is important in a different context that I will mention below. With Lead Acid for solar energy storage you usually select a relatively over sized battery so that typically DOD over 24h is around 10 to 20% while with LiFePO4 my recommendation is to use a small capacity battery and an over sized PV array (the same is not possible with Lead Acid because of the low charge discharge rate required by that type of battery). Now for both Lead Acid and LiFePO4 is not safe to assume more than 20 years life in best use condition so with the large flooded Lead Acid you mentioned before it will be next to impossible to store and retrieve that amount of energy theoretically calculated earlier making the cost of storage per unit of energy much higher. Having a smaller capacity battery that you stress harder will get closer to those numbers. I intentionally selected a relatively small battery capacity for my offgrid house just 2.5kWh 24V x 100Ah even if my monthly energy use is between 60kWh in winter months to around 80kWh in the other months so an average of 2 to 3kWh most of that for electric cooking during the day. In a sunny spring or summer day I can use even over 4kWh and from that around 2 to 3kWh can be trough the battery. Yes 3kWh in a single day is possible from a 2.5kWh battery because there are many shallow cycles during the day even if battery is probably never below 70% SOC that day. My low power mode consumption is just 0.8kWh so I can survive easy 4 really bad days with 0.3kWh from PV array only and 0.5kWh from battery to a manageable 2kWh. Most of my power consumption is from electric cooking but I do not do that in bad days all the other basic stuff works small fridge, two computer 10 to 12h a day, LED lights all of this from DC so the inverter is not used that inverter alone saves me over 20kWh/month because working just about an hour or two per day when I do electric cooking mostly all basic stuff work directly from DC. I will probably increase my power consumption a few times but still keep the same battery. I will install a large 9kW PV array to heat my home in winter with 100% electric and that array can also be used to charge the battery in overcast days since that array worst energy output in a cloudy winter day will be about 3.6kWh The energy for heating will be stored in thermal mass I have a 100kWh thermal mass storage at 10C delta that is the concrete floor with a 14 cubic meter mass and my house needs in the worst winter month about 1000kWh/month Yes there is a lot of unused energy with an over-sized PV array for example in spring summer months my 720W array produce up to 120kWh/month while I only use 60 to 80kWh so up to 50% unused energy and that is fine since all that unused energy costs 3cent/kWh and is much more economical than to have an over sized battery that cost way more than that per kWh stored. Even if you have an over sized battery you can not use all the available energy (for that to happen the battery will need to allays be below 100% SOC ) ass soon as your battery is fully charged there will be excess unused energy. Not to mention Lead Acid will degrade quickly if it never gets to full charge. Having unused energy is just a fact in any offgrid solar setup and trying to use all the energy is a wrong approach since producing is way cheaper 3 cent/kWh or less compared to storing it real life number close to 10x higher or even more with Lead Acid. Problem is complex but I had time to think about all aspects in the last 4 years or so when I started getting interested in solar offgrid and energy storage. Even during this time many things have changed I will not have imagined that solar heating with PV panels will be the least expensive heating solution even better than natural gas that was for some time the least expensive. Building a solar heating controller is my next project after I'm done with the SBMS that will of course also be an open source project available to anyone.

[@AfsalPA]

please make another detail video of this same thing with input current input voltage output voltage output current etc ..

[@joancaparros]

Is it possible to turn the display off? That is useful to set it up but after maybe I would prefer not showing any data

[@JulianIlett]

+Joan Caparros Yes, that's the function of the little slide switch

[@MrBrymstond]

Did they include a diode or which one works best, how about a 1N4007?

[@atubebuff]

No, the underside of the pcb has a spot for it but it's shipped with a short.

[@MrBrymstond]

Probably because the diode gets to hot, but you would think they would throw you one.

[@luongmaihunggia]

Put duct tape over the display.

[@radheshvideo]

Greetings Julian, 1. To use these PCBs that you bought off china on a regular basis, I would like to get some plastic enclosures/boxes. Do you have any idea on how to get them and do they have adjustable mount points? Since these stuff get hot, should they need ventilation and stuff? 2. I am also curious on the CCTV Adapter thingy that you used. Where to get them? I have mess of different connection terminal, wires and adapters. May be you could do a video on the different kinds of pins and plugs and what should be used with respect to DC and solar. I am spending probably too much time in soldering and troubleshooting joint problems when I mix and match and make and take systems apart.

[@stevec5000]

Julian, where can I find directions telling how to tune up and use one of those MPPT controllers? I have one but I've got no idea how to use it. Also my unit was acting intermittently and I found the display board shorting out against the heat sink underneath so I removed the board and mounted it along side the other one.

[@stephenshop4946]

How about decreasing the output voltage to 5v to charge the phone directly, will the current improve?

[@proluxelectronics7419]

Hi, It must have some micro magic to drive the display, or are they stand alone meter boards? Big Thumbs Up.

[@philippebillig5487]

Hi Julian Thank you for this presentation. I just ordered this MPPT controller. Question: What type of diode did you use between the regulator and the battery ?

[@knutposchel2165]

You need a diode to protect the controller for reverse voltage ..... JUST WHAT I WAS WONDERING!!! I did that on on of my DC-DC to while I connected to battery. Only 1.5A and the diode got warm! Before I put the diode between battery and charge while having about 8A and the result was the plastic of my connector MELTET!!! Voltagedrop of 0.7V * 8A = 5.6W so that's the reason :( I never mind about it is so much - but it is enough to melt some plastics!

[@fraaggl]

I'm searching for a cheap solar charger like this one but for charging 36v or even 48v batteries. Do you know any ?

[@proyectosledar]

Wooowww. is it true???

[@rafa6694]

Hello Julian, I need your help, which one diode gets into the positive?, thanks

[@chrisrix7645]

I have rigged one of these onto my solar panel and started charging a lead acid battery, as you mention the unit will back feed without a diode, will a 5 amp rated diode be ok to use, the back feed didn't seem to wreck the unit but a red led lit and there appeared to be current flowing back to the panel.

[@AxellTh]

can one switch these onboard pots with chassis mounted ones and do they have to be multiturn?

[@gazzat5]

@julian ilett interesting choice of connectors lol

[@radheshvideo]

The module does not measure input current. If you are playing with this again, can you please measure the input current and the conversion efficiency?

[@arrowstheorem1881]

Am i right to say that this can be used to charge lithium cells too, as long as the charging voltage is at the right constant voltage?

[@jaaasgoed]

Isn't the problem with the 20 (21) watt load that your panel is 20 Wp? Even with full sun you probably aren't getting the full 20 Watts out of it, so the regulator also drops out.

[@Coolkeys2009]

+jaaasgoed It would have been better to connect it to a variable power supply first, and just adjust the input voltage to see if it worked as expected, then test it with a solar panel. So far It looks to works as expected.

[@Eratas1]

Wondering is there any cheap DC converter or volt/ah meter etc with serial output to PC?

[@nor4277]

Did you make that adapter you use all the time,if you didn't where can I buy one

[@BAKKER2727]

Output voltage: 1.25-32V continuously adjustable...???????

[@maxphipps2]

Julian, you have ordered many items from Chinese sellers. What percentage of these orders were never delivered.

[@diydsolar]

Hi Julian, could you recover this project and usa an arduino or esp8266 with a digital I2C potentiometer to control de Vmp and get always the MPPT from the solar panel to charge a seal acid battery? Also, we can change diode with a mosfet no to drop output voltage, can't we ? Regards,

[@techspear7105]

what is the name of this compenent on the beginin

[@harveyboy45]

Julian is this solar controller useful for 18650s? Thanks

[@rpgquestboard]

Do you still have this module? Have you thought about using it for charging Lithium Ion cells from solar? The CC/CV feature would be really helpful.

[@nathan100tz]

Does the maximum power point of a particular Solar panel change based on how sunny it is? If it does, it makes this type of "MPPT" controller useless.

[@SupremeRuleroftheWorld]

i am curious on how the mppt pot actually makes a difference considering there is not mppt hardware visible...

[@caribbeanchild]

I think "Digital LED" actually refers to the digital led's on the module.

[@NoFear4XJs]

Could you post up what rated size diode you used. Thank you and have a great day !

[@lukeskywalker3891]

I have the same question. Where can I buy the diode? I am afraid to burn mine using it without a diode. Thanks

[@slybunda]

can you use this to charge a car battery?

[@13panda13]

Yes

[@electrojessy4270]

What diode does he use i want to pull max 5a? Maximum voltage is 16v dc

[@Edmorbus]

Thanks for sharing

[@superblunt12]

Hi Julian I was wondering if you might know how this would work if you have 2 of them with 2 of the panels you use but on the output side connecting them in Series. Will they work together to charge a higher voltage battery system.

[@ValentTurkovic]

Are pots on these board 10k ones? If they are I'm interested in using some digital pot like x9c103 and drive it with arduino, of course I still need to have voltage and current meters to close the feedback loop. Anybody already tried this?

[@oliverjimenez8594]

Will it work if I use this regulator with 12v to 220v ac inverter? Thanks

[@jimmcdonald2148]

ever had any higher voltage DC-DC regulators in the post (IE nominal 24v and 48v)?

[@SimonDambro]

Anyone.... Did it work? Did the Amp increase? Or is i just like a PMW?

[@davidriostanczak2443]

I would like to see the solar cell hooked directly to the battery with the power volt amp meter in the circuit, just to see what the results would be.. I understand the need to protect the battery, but I don't feel that the MPPT part of the charger really works. Possibly simple pwm controllers are enough.. Also. setting the maximum power Voltage setting, from the panel specs.. is a bit confusing... What happens if part of the panel is covered by shadows? The rest of the panel should still be putting out max amps, but the charge controller will try to reduce power, stretching to find that max pwr preset voltage.. Thanks for the vid...

[@guydvir2]

Can you please explain the functionality of each pot. I have the no-display version. Thx

[@dlinnoedlinnoe]

Left - MTTP value adjustment: clockwise - there's output, ccw - no output; then left of the three: LED current adjustment (I guess it sets when LED charge/ready changes), middle: constant current adj. i.e. max current, right: output voltage (constant voltage) adj. i.e. max output voltage.That's what's in their description. The switch: voltage meter power switch, an output ten :D I know, but It says so. I've just ordered it, so I just hope I understand that right.

[@electronics3992]

will this mppt module work with 50W (18V , 2,78A max) solar panel ??? I dont have money for bigger mppt!

[@1981dasimpson]

i would guess the other 2 pots or cc and current low limit to indicate when battery is charged like the smaller cc/cv chargers ?

[@JulianIlett]

Yes, voltage adjust and current adjust. Also, the LED colour change point. These regulators are not ideal for charging lithium cells because they don't cut off completely.

[@1981dasimpson]

+Julian Ilett damn struggling to find a unit that will take my 4x 6 volt 10 watt panels in series and charge a 3 series bank of li-ion only other I have done 4 panels parallel and the battery bank set to all parallel but I'm wasting so much power stepping up the voltage

[@1981dasimpson]

+Julian Ilett I did find with the cc/cv unit of you set to say 4.19 that the current drops to 0 but stays in cv state plus they prob won't reach fully charged with the pack running lights and charging phone

[@vgamesx1]

+David Simpson So why not use a simple BMS circuit such as this r.ebay.com/g6SeW3 which says it supports up to 26V? That or I'm not sure if its true but one this one r.ebay.com/Md0Xey says it will charge at 4.25V in which case you could simply re-wire all your panels in parallel and use a voltage regulator to drop the panels down to around 4.3V

[@1981dasimpson]

+vgamesx1 the first pcb I have on the pack at moment the cells still go out of sync if the 2nd one is 11.1 pack them not sure how putting 4.2 volt in will charge I think the specs are prob not for said item or info for single cell in a pack control if it does charge a3 series pack from 4.2 volt then it would be perfect

[@lookmush]

Julian I just bought 150W mono solar panel. The prices of the MPPT 10amp are 90 USD +. so looking for cheaper route and not using PWM. Do you you think if I use 2 5amp mppt converters will do the work if I use them in parallel? I just got into this field and wanna learn more.. Thanks in advance.

[@bryankraemer1682]

I was thinking the same thing. Did you ever test if the outputs could be matched and ran in parallel?

[@hamburgelbstrand5748]

With real MPPT controllers this would not possible, because finding and using the mpp point at one controller will interfere the tracking of the other one. They will probably start to oscillate.

[@mechrekt]

I cannot find that useful pot adjuster

[@Ferdy00F]

O diodo é pra colocar antes e proteger contra inversão de polaridade, não precisa depois

[@JerryEricsson]

Long ago, you have peaked my interest in these dc-dc converters, thanks for showing another! By the way, have you played with the Arduino Due as of yet? I just received mine today, not a clone but the real thing (not sure if there are clones yet) and with an 82 MHZ ARM processor, it seems very fast compared to the UNO. Programs with the normal Arduino front end so that's not a problem. Interesting with two different USB connectors, both work fine but must be selected in the software on the PC. Both are labeled on the back of the Due. Ordered mine from Alice... my new favorite China Seller, and it came right on time. I recently read a DIY article where a fellow hooked one of these up to VGA and added BASIC to it, making a small computer like the old days with the Commodore or Tandy running on BASIC. thought i might give that a try this winter when the snow flies and I am stuck indoors. (coming soon to a Dakota near you) By the way, your outdoor video on this one shows a wonderfully blue sky that reminded me very much of BIG SKY country in Montana! Our Dakota sky's do get that blue once in awhile but not as much as our neighboring state of Montana, as well as Wyoming both great places to visit!

[@jebe5247]

what type of diode is that?

[@whatever465456]

It seems like a 6a or 10a blocking diode.

[@ralfboecker3646]

Has this module proven useful long term for solar charging a battery ? (should adjust output voltage at 14.3 V rather, to compensate Schottky-Diode to the battery) Does voltaqe rating cover charging ~28 V into a 24 V battery using a 60- or 72-cells solar panel ?

[@JulianIlett]

Don't think I've used it since :)

[@ralfboecker3646]

@@JulianIlett Still have it around ? -- Much interested in results, if found useful for charging in small solar systems with 12V and 24V battery + maybe even adjustable for Li-Ion solar charge requirements. ==> Will the MPP-system pull power out of the solar panel in poor winter light conditions ? --- What are the limits regarding solar panel power ratings ? + An issue might be, if not able to stop charging after battery is full: then a good charger schould remove power, instead of permanently going on charge at upper voltage limit.

[@stevenanderson9532]

Add a boost converter for the clouds...

[@jamest.5001]

Would a dc to dc with vc cv work just as good, or does the 'mppt' actually make it more efficient?

[@Krzeszny95]

DC to DC is about as good as connecting something directly to the panel. Well, not exactly but it's too complicated to explain here. There are answers for this question you can find online.

[@stevec2196]

So did the device actually work as a MPPT Solar Regulator? Instead of putting a diode inline with the input and output have you considered using a power MOSFET? That's what everyone is using on new designs now to provide reverse voltage protection since it has very low resistance and low loss for more efficiency and that should work for this too. Check out the +5 volt input for the Pixhawk PX4 on page 5, sheet 2 upper left showing the power circuitry. pixhawk.org/_media/modules/px4fmuv1.7.pdf

[@jacquesb5248]

i got just the base board.so connecting and a volt and amp meter to the output i turned the last one to match battery at 13V(+ -) then the first one until it starts and charging battery. so it should stop when it gets to 13V. what is that second pot for? anyone?

[@1981dasimpson]

so would this do to charge li-ion 18650 batterys in series and parallel upto 3 series

[@richardnanis]

So, what is the difference of this "MPPT"-controller to an ordinary DC-DC-Buckregulator, where you can adjust CV and CC? I just use a CV Buckconverter as a very simple Solar-charge controller, but really there is no MPPT function here or there :-) But nevertheless you get better power usage to your load, if you can adjust the output voltage! But when weather conditions are changing you have to adjust it every time to get near the MPP :-) This is a fake MPPT thats quite obvious, isn't it?