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Simple Solar MPPT Circuit – Part 1

A simple yet effective solar panel MPPT charger circuit can be built using a couple of 555 ICs and a few other linear components. Let’s learn the procedures.

An MPPT or Maximum Power Point Tracker for solar panels is a method which enables deriving maximum available current from a solar panel throughout the day without disturbing its specified voltage, thus allowing greatest efficiency from the panel.

As we all know, acquiring highest efficiency from any form of power supply becomes feasible if the procedure doesn’t involve shunting the power supply voltage, meaning we want to acquire the particular required lower level of voltage, and maximum current for the load which is being operated without disturbing the source voltage level, and without generating  heat. 

Update (Must read):

Solar MPPT Charger Circuit PART – 2

Briefly, a concerned MPPT should allow its output with maximum required current, any lower level of required voltage yet making sure the voltage level across the panel stays unaffected.

One method which is discussed here involves PWM technique which may be considered one of the optimal methods to date.

We should be thankful to this little genius called the IC 555 which makes all difficult concepts look so easy.

In this concept too we incorporate, and heavily depend on a couple of IC 555s for implementing the MPPT effect.

Looking at the given solar mppt circuit using IC555 we see that the entire design is basically divided into two stages.

The upper voltage regulator stage and the lower PWM generator stage.

The upper stage consists of a p-channel mosfet which is positioned as a switch and responds to the applied PWM info at its gate.

The lower stage is a PWM generator stage. A couple of 555 ICs are configured for the proposed actions.

IC1 is responsible for producing the required square waves which is processed by the constant current triangle wave generator comprising T1 and the associated components.

This triangular wave is applied to IC2 for processing into the required PWMs.

However the PWM spacing from IC2 depends on the voltage level at its pin#5, which is derived from a resistive network across the panel via the 1K resistor and the 10K preset.

 The voltage between this network is directly proportional to the varying panel volts.

During peak voltages the PWMs become wider and vice versa.

The above PWMs are applied to the mosfet gate which conducts and provides the required voltage to the connected battery.

As discussed previously, during peak sunshine the panel generates higher level of voltage, higher voltage means IC2 generating wider PWMs, which in turn keeps the mosfe switched OFF for longer periods or switched ON for relatively shorter periods, corresponding to an average voltage value that might be just around 14.4V across the battery terminals.

When the sun shine deteriorates, the PWMs get proportionately narrowly spaced allowing the mosfet to conduct more so that the average current and voltage across the battery tends to remain at the optimal values.

The 10K preset should be adjusted for getting around 14.4V across the output terminals under bright sunshine.

The results may be monitored under different sun light conditions.

The proposed MPPT circuit ensures a stable charging of the battery, without affecting or shunting the panel voltage which also results in lower heat generation.

Note: The connected soar panel should be able to generate 50% more voltage than the connected battery at peak sunshine. The current should be 1/5th of the battery AH rating.

An enhanced and a technically more correct version of the above design using buck converter can be seen in this Simple Solar MPPT Circuit – Part 2

How to Set up the Circuit

It may be done in the following manner:

Initially keep S1 switched OFF.

Expose the panel to peak sunshine, and adjust the preset  to get the required optimal charging voltage across the mosfet drain diode output and ground.

The circuit is all set now.

Once this is done, switch ON S1, the battery will start getting charged in the MPPT mode.

Adding a Current Control Feature

A careful investigation of the above circuit shows that as the mosfet tries to compensate the falling panel voltage level, it allows the battery to draw more current from the panel, which affects the panel voltage dropping it further down inducing a run-away situation, this may be completely against the MPPT law.

A current control feature as shown in the following diagram takes care of this problem and prohibits the battery from drawing excessive current beyond the specified limits. This in turn helps to keep the panel voltage unaffected.

RX which is the current limiting resistor can be calculated with the help of the following formula:

RX = 0.6/I, where I is the specified minimum charging current for the connected battery

A crude but simpler version of the above explained design may be built as suggested by Mr. Dhyaksa using pin2 and pin6 threshold detection of the IC555, the entire diagram may be witnessed below:


    • I indeed enlarged the diagram before I posted my question, but there are two diodes written 6A4x5 (I can't find a diode part number like that), D1 has a funny sign with a value 2V7 that part was also not found at any electronic store, and a part number for p-channel mosfet would have been helpful. Please rest assured, I would not have posted my question here if the enlarged diagram had clear part numbers.

    • 6A4 stands for 6amp diode, put 5 of them in parallel.

      D1 is a zener diode

      mosfet rating will depend on the battery rating, select as per the AH rating of the battery…. mosfet current may be 50% of battery AH rating, voltage should be at least twice that of the battery voltage.

    • Thanks. It has been a while since I visited this page and seems like you have updated the circuit by adding a 14V Zener parallel to 10n capacitor on the bottom right corner, if my memory is correct. I was wondering if this zener can be higher or lower than 14V or it has to be exactly 14V? I can't find 14V zener but they have either 12V or 18V. Thanks for your explanation.

    • Yes it's for clamping pin#5 of the IC at 14V so that the battery voltage is never fed with higher voltages than this value.

      you can use a 12V and a 3V zener in series to make it 15V. A 15V to the battery will not do any harm.

    • load handling capacity will depend solely on the ratings of the solar panel and the mosfet, dimension them as per your requirement.

      the current from the solar panel should be around 1/5th that of battery AH

  1. hi sir,
    whats the current in the above circuit?
    in the above circuit how can we regulate the current explain me once please
    how to increase the current in this circuit.

    • Hi Seetha,

      The current will depend on the panel wattage which should selected as per the battery AH rating. The mosfet should also be selected appropriately for handing the specified charging current.

    • Hello Ninka,

      mosfets will need drivers only when they are configured in a bridge format or some other complex format, for single mosfets whether n or p a driver won't be required.

  2. Hello Sir,

    Value not given a component after 6A4 X5. and whats a part i think they are transister, what is ?

    6A4———————–S(-I–I I-)-D————6A4X5

  3. Hello Sir,
    Do this ciruit have overcharge protection of the battery,if not can you add bottery overcharge and low charge protection to this circuit.Can this circuit used as wind charge controller having input 60 to 100volt dc and 40 to 100 amps.pls give your email id.

  4. Suppose instead of battery am connecting some load… say 12V cpu fan, LED light…. any load etc.. so battery is completely avoided. Will it track maximum power from solar panel as before ? If so, can i directely connect the DC supply to small inverter ?

  5. all components are collected ready to assemble, by the way sir is it ok my diode is rated 6A10? bec is not available in the elec. shop, is it the same with 6A4? and my c3 is 1uf 16v …and also how much the drop voltage of this circuit sir? tnx

  6. I've almost done with the circuit sir… im excited to try the circuit…i have some question bec. im too curious, what voltage level will stop charging when the battery is full? or what voltage the battery will start to charge?

  7. ive already finish the circuit sir πŸ™‚ and i will test.. it sir.. i have a simple charger that i make using a relay it will automatically trigger when the battery is full.., can i add this to the circuit sir? or any suggestion? tnx πŸ™‚

  8. tnx sir… i set to 14.5 volt and the external is 13.7 is it ok the adjustment sir.. can i get the same out put when i add the external circuit can i get mppt?

    • what did you set to 14.5??

      the above circuit should be set at 14.4V and the external circuit must be also set at 14.4V, both should be identical.

    • the average voltage at the output of the mosfet should be around 15V, and varying the pot should enable 0 to max adjustment, if this is not happening means your circuit is faulty or some issue might be there.

  9. when i adjust the pot i noticed that it is very slow to drop the voltage when im in testing… how ever my shunt is set to 14.6v it is fine that i adjust the mppt circuit to 14.6 what will happen? or i will still set it to 14.4?

    • if you are using a shunt regulator then the above circuit becomes meaningless.

      the above circuit should be used directly with the soar panel and the solar panel voltage shouldn't be less than 20V.

      the above circuit will require an input of 20V to function correctly.

  10. OK you mean i could not used this circuit? bec. im only using solar 10w open voltage 20v? i mean a linear regulator im using… but you said i can add a controller to the above circuit? what do you mean sir? tnx

    • In your previous comment you mentioned "my shunt is set to 14.6v" I assumed it to be an external regulator….could not actually understand what you meant by it.

      The above circuit is a controller by itself, you just have to feed 20V to the circuit, and do the settings as suggested in the article, that's all.

  11. yes sir it is an external so i dont need the regulator.. when the battery is full the circuit it self will float charge? tnx for reply sir.. im just too curious to the circuit and excited to use it

    • The above is a simple PWM controller which will reduce it's output voltage proportionately in response to a rising input voltage, so in case the solar voltage rises, the output voltage will get controlled proportionately without generating any heat.

      Adjust the output after the diode, refer to the explained setting procedure.

  12. i put an external regulator so that whenever the battery gets fully charge it will dump the excess.. so that when im away or im not in my house it will be manage.. is it ok sir? i will not change the output voltage of the mppt it will remain 14.4

    • dumping doesn't mean the battery will stop charging, it will keep on charging.

      It will only regulate the voltage to 14.4V, it will not cut off the supply, just as my circuit.

      you will have to employ a IC741 stage for over charge protection.

      if you already have a shunt regulator no need to connect the above circuit, because both are identical.

  13. my concern sir is it ok to put the circuit as a permanent to battery, i mean i will not disconnect it to the solar panel all throughout day and night

  14. Hello Mr Swagatam does this controler increase the current of the panel like the comercial mppt controler anxiously waiting for your reply. Thank you

    • I have just tried to imitate the actual version through a simpler concept, I have not tested the results so cannot confirm regarding its efficiency.


    • hello Mr Swagatm i am really interested in this mppt controller circuit I want to try it at 48v but what would i use for the 14 zener diode because the voltage from the pannels would be about 80 or so volts. Thank u

    • please Mr Swagatam u said the network resstors are 10k and 22k but in the drawing it is 1k and 10 k please make it cllear here thank u Sir I also looked at the buckboost circuit u designed I was wondering if u incorporate this in the stage between the fet and diode if this would work and increASE the current also. Please look into this . Thank u

    • try using an online potential divider calculator and find the values of the resistor/pot which determine the potential at pin5 of IC2. This adjustments should be equal to the charging voltage 14.4V at optimal sun light that is 80V, once this is adjusted the zener can be kept as given.

    • yes surely the buck boost stage can be inserted after the mosfet in the above diagram. The current output simply depends on the mosfet and the solar panel rating

    • thank u Mr Swagatam for ue reply on the divider but I was trying to say I am charging a 48v battery bank so if i would still use a 14v zener . My panel volts is about 80v coming in awaiting ur reply

    • I think you have made a valid point, in your case that is for inputs and outputs greater than 15V the iC supply must be protected with a resistor/zener network.

      The 14V zener should be included as shown, however the reset/supply pins4/8 should be connected via a 10K resistor and clamped with a 15V zener.

      After this you would be able to continue with the procedures as explained in the article.

  15. the PWM spacing from IC2 depends on the voltage level at its pin#5, which is derived from a resistive network across the panel via the 22K resistor and the 10K preset.

    but i dont see a 22k resister.instead a 1k resister is seen.

  16. Hi Swagtam, nice circuit !! I just wanted to ask if it was possible to insert a visual monitor of what's happening on this circuit during operation, (LED or LCD) , if yes how and where on this circuit should that be inserted? Thank you

  17. Hi Swagatam,
    I built this controller and can see the pulses at the gate of the fet. When I adjust the preset the voltage at pin 5 of IC-2 changes but not at mosfet drain diode output.


  18. Hello Mr Swagatam I am trying to build this circuit . I want to know at what frequency this circuit operates and which parts of the circuit deal with the frequency settings and which ic deals with the pulse width pulse . Thank u

    • Hello Mr Swagatam I built the circuit but I am having some problems with it . Should I be able to adjust the output voltage from 0 to the maximum panel voltAGE. If so I have 40 v coming in from the panel to charge a 24v bank but when I adjust I get from 0 to 22v only could u tell me where I could check for possible causes.

    • Hello Alex,

      Since the mosfet conduction depends on the duty cycle from the IC, means the mosfet output should become adjustable right from zero to max panel voltage, or almost near to max.

      However the 22V would have damaged the ICs in your case, because the ICs won't tolerate more than 18V.

      I would suggest you to replace the ICs and connect a 7812 with the new ICs for protecting them from the high voltage….and then check afresh.

    • Hello Mr. Swagatam I want to modify this controller to handle 60 amps. If I parellel three IRF9540n and diodes would this work or do you recomend a different mosfet and diode arrangement

    • hello Mr Swagatam thank u for ur usual quick support. I have a regulator already in the circuit for the ic thats ok but I was just wondering I am not able to adjust to maximum voltage could this be the fet I am using because the maximum 40v is at the source of the fet but not at the drain could this be my devider not right for the 40v panel voltage.. Thanks for ur support

    • Hello winston,

      Your idea would also work, just make sure to connect 0.22 ohm 1 watt resistors in series with the source of each mosfet and also include separate gate resistors for them.

    • Thanks Mr.Swagatam,
      I will try this modification,but the wattage of the resistors in series with the source ( 1 watt) seems low if each mosfet is to handle 20 amps.

  19. Good day Mr. Swagatam.

    I am am currently building your circuit to charge a 12V, 31Ah deep cycle battery via a 80W, 21.8V polycrystalline panel.

    According to the battery specifications the recommended charge current should not exceed 7A max, and the panel can supply around 5A in peak conditions. I was just wondering if the 5x6A diodes will not be overkill for my configuration, I am also using an IRF9540n mosfet able to drain -23A@-10V. Any other suggestions will be appreciated.

    Thank you very much

    • Good Day Christiaan,

      The diodes would be in parallel theerfore would drop just 0.6V, you can remove them if you want as they are only placed to safeguard accidental reverse polarity connections. The diode at the mosfet drain may also be removed.

      The mosfet is fine, it's capable of handling -23A @ -100V to be precise.

    • Thank you very much sir, I thought the diodes was solely for reverse polarity protection, I didn't realize the paralleling results in a much needed lower voltage drop than adding only a single diode -basics! Yes that is -23A @ -100V for the mosfet sorry.

      Thanks for your reply

    • You are welcome!

      Actually a rectifier diode will drop 0.6 volts doesn't matter whether a single is in the line or many in parallel, but will add up if they are in series.

  20. Hello Mr. Swagatam! You've been doing a great job by helping the electronics hobbyists. Please I have massive interest in this circuit, but i like to ask if a heatsink should be placed on the mosfet.
    Thank you sir.

  21. Thank u Mr Swagatamfor ur refrence to the motor driver circuit. i will use a different fet and see the results and let u know because this is the best described mppt controler I see that looks pratical. Thanks for ur support

    • Thanks Alex,
      Actually the above circuit is an MPPT simulator not exactly an MPPT because it does not track the IV curve of the panel…you can say it's kind of a solar panel optimizer.

    • I am trying to understand your explanation here about a mppt simulator.So the devider network does not work as a data colletor to tell the circuit what to do.Could u explain more clearer.Than u Sir

    • thank u Mr Swagatam I am folowing all ur post on mppt controllers becaue I want to build a working one. I changed my fet and used the irf9540 I am getting the maximum panel volt out now at the output of the diode but the problem is when I adjust the pot the voltage does not vary. It varies the voltage at the gate of the fet yes but not at the output could u help me here. Thank u.Now I see ur new circuit I dont know which one to build ???? sir

    • It can be a little tricky, you will have to check, and set by comparing the input voltage, the voltage at pin#5 and the drain voltage through some trial and error. Check how the drain voltage responds to the other two voltages and then try to figure out the most optimal relation between these three such that when the panel voltages dips, the drain voltage rises (opposite response)

    • Mr Swagatam I am having problem with this circuit and I see some other guy is having the same problem . The voltage at the output drain of the fet is not changing with the setting of the pot. even if u disconect the gate of the fet the voltage is there passing from the panels. Please recheck to see if something is wrong somewhere. The voltage at pin 5 change as u say it should and the frequency is somewhere in the hz so i think the two ics are working correctly but the controling of the voltage at he output not able to be adjusted. Please help us here this guy posted his coment on the 28 of august. Thank u for ur help

    • Mr Alex, I am always helpful to the readers here, but it's the responsibility of the readers also that they understand the presented concept from the core and only then proceed with the construction, because otherwise it would become very difficult for them to troubleshoot even with my help.

      Anyway, in the above circuit the response of the mosfet will be opposite to the response at pin#5 or at pin#3 of the IC2, meaning as the voltage drops, the conduction at the drain of the mosfet would increase.

      You are saying that even if you disconnect the gate, the mosfet conducts…. it simply suggests that your mosfet may be faulty, do one thing use a TIP127 transistor in place of mosfet and check, because transistors are easier to handle than mosfets.

      Apply an equivalent solar peak voltage and adjust the preset to produce about 15V at the collector of TIP127, now as you reduce the input voltage, the collector voltage should try to compensate by maintaining its collector voltage to around 14/15V.

    • Thank u Mr Swagatam for your usual support . I will try as u say and let u know the result because we all want this circuit to work

  22. Hi Mr. Swagatam, if I were to use this circuit for a very low voltage (3.8V, Imp: 800mA) solar panel. How do I change the resistors and capacitors values?

  23. What a good circuit design, Swagatam. But I'm really sorry to say that I thing the above circuit is not MPPT charge controller, It's PWM.

  24. Dear Sir,
    thank you very much for your support for us.. we are looking forward for your simple mppt controller with I/V tracker system.. thank you very much sir

  25. Thank u sir ….i have still having some problem in solar MPPT charger…
    1)sir the 1uf ceramic capacitor is not available but 1uf 400v ceramic is available can i use this here.
    2)There is a formula used (0.6Γ—RX) it is for resistance calculation but sir why 0.6 is used.
    3) I got a zenor diode of 14v but there is a color code in it is it a zenor or not???… the color code is 1st band is yellow & 2nd band is brown….
    4)Here 20v solar panel is used but i want to connect 12v solar panel for charging the battery of 12v 7Ah… it is a UPS battery….sir can it be possible
    Please sir help me ….Thanks..

    • 1) yes 1uF/400v can be used.
      2) 0.6 is the trasistors minimum biasing voltage
      3) I'm not sure about the color codes, you'll may take the help of any online zener color code chart.
      4) a 12V source will never charge a 12V batt…you will need at least 14 to 15V for charging a 12V batt.

  26. Thank u sir for helping me …i am planing to connect a 12v DC to 24DC converter for charging the battery of 12v 7.5ah. Sir is it possible…
    First i will connect 12v solar panel to converter circuit then the output will be 24v , again this 24v i will connect it to battery of 12v…. sir is it possible
    Thank u sir…me bhanu

  27. 3) You have given a formula for calculating resistance value that is 0.6/charging current ,, in the place of charging current can i use this formula to get the the resistance value easily i.e 1/10th of battery Ah value. the battery is 7Ah so 7/10=0.07ohm then 0.07*1000=70 kohm is this correct formula…
    4)Sir i am previously i have about color code of 14v zenor diode,, according to your suggestion i have searched online but i could not get a satisfied answer so can i use 15v zenor in place of 14v zenor
    Thank u sir….me "bhanu"

  28. Yes sir thanks …. me bhanu
    1) but sir got a good circuit from your site it is used for charging battery form solar panel where LM338 or LM317 is used link is (http://homemadecircuitsandschematics).
    From this circuit i can get a variable DC supply which will be helpful for me… is it be possible for me….
    2) First i will generate 24 volt from LM338 & then this 24v i will connect to the input of solar MPPT charger for getting required voltage for charging battery….is it possible….

    3) You have given a formula for calculating resistance value that is 0.6/charging current ,, in the place of charging current can i use this formula to get the the resistance value easily i.e 1/10th of battery Ah value. the battery is 7Ah so 7/10=0.7 Amp then 0.6/0.7= 0.857 Ohm 0.857*1000= 857 kohmbut is this correct formula…or I will use simply 0.6/battery Ah
    4)Sir i am previously i have about color code of 14v zenor diode,, according to your suggestion i have searched online but i could not get a satisfied answer so can i use 15v zenor in place of 14v zenor
    I am doing this in my project i have assembled all the components have some doubt …Thank u sir…

    • amps handling capacity is solely dependent on the mosfet…no other component is involved with amps and load.
      so it's all about modifying the mosfet as per the required output specs

  29. Sir me bhanu
    1)Sir why 2.7v zenor is connected to base of the transistor and again why the transistor is used there. I know that pin 7 is discharge pin why the transistor is used in IC2 only.
    2)why sir the transistor is used between mosfet and the diode of solar panel..
    3)Why the 14v zenor is used in the output of pin5 only in IC2.
    4)What are the functions of ceramic capacitor in the circuit…….
    Please sir help me β€˜β€™Thank you’’

    • BC557 and 2.7v zener are for current limiting so that the 555 pwms do not falter during voltage fluctuations.
      pin5 zener is for restricting the voltage within the 555 supply voltage otherwise the pwms will get clipped.

      capacitors are for determining relevant frequencies.

  30. Great job, yet again. SO I hven't been able to build your inverter from the other circuit because these transformers aren't popular in my area still looking though. But I went and got a 500 watt inverter for $20 works well, i power everything, downside it's modified sinewave so my sensitive appliances hum πŸ™ so I don't use it on them just incase.

    my question for this circuit is the wiring, if the tracks are joining to another track is that what the big black joins are for and some tracks have gaps to indicate not touching passing tracks but the tracks that pass and dont have the big black dots are they still joining when they crossover another track? like the 2 IC555 and the 4 capacitors see that track that just comes straight through them to the zener diode. also what voltage are the 4 capacitors?

    • Yes in the diagram enclosed above, the lower section indicates the black dots as the joints while the plain intersection as "not connected" meaning only the intersections that have black dots are joint other are NOT.

      In the upper section, the "not connected" intersections are simply shown as broken line intersections.

      As a rule of thumb capacitors should have a voltage rating that may be twice of the supply voltage, if it's greater there's no harm.

  31. Hi Mr.Swagatam, i want to ask you about that PWM like MPPT circuit. there is a 2.7V zener series with 470 Ohm after 12V regulator. is that make all of Vcc to be 2.7V or it's just for the IC1 (Wave generator) only? i'm afraid it can work as well. because the IC was running on 4v minimal i think. so thank you for your explanation.
    i want to make this one for my off grid 20Wp PV and 45AH 12V Battery.
    regard. Dhyaksa Hada.

    • okay i have tried to make this one yesterday, but i simulate the input from 16,5V Power Supply to 45AH Battery. but i think there is a malfunction on my circuit. now i try to make a simple one. just ordinary NE555 Fix frequency PWM and the Output from Pin 3 is drive a Gate mosfet (P-Mosfet) with series 100 Ohm resistor. try to turn it on, and it's charge the Battery. but i had my Mosfet and Blocking Diode was very HOT (like 70'C and up with my analog thermometer). how i can make the right one without any HOT devices?
      thanks a lot Mr.Swagatam.

    • which mosfet did you use? don't use a mosfet because mosfets are critical devices and require strict parameters….use a BJT instead…you can try a TIP122 but it may too require a large heatsink.

    • I use P-Channel MOSFET IRF-9540N for high switch… i don't know where is the problem. Ordinary NE555 that use 10k & 2.2nF for the Rt&Ct. Vin from Solar panel (I simulate it from Adj. Power Supply) 16.50V and Schottky diode + 100uF/25V Caps after Drain pin of Mosfet. or can you suggest me a simple one that completely working without any HOT mosfet? i'm very confuse with DC-DC Converter before. i have tried to built a lot but i still can't make it work well..

      thank for the advice Mr.Swagatam…

    • oh thank you so much for your help to me. πŸ™‚ because in my region now was very unpredictable for the mains supply. i'm afraid that can make a lot of electricity doing malfunction (like notebook,refrigrator, etc.) once again thank you so much..
      you can notify me by email or social networking like FB with my email account.

      thanks from Indonesia. πŸ™‚

    • If your requirement is a stepped down voltage with correspondingly increased current, then it's better to opt for a buck converter…..buck boost circuit can be employed but the process might require a lot of optimization and inconvenience.

    • KM, if your battery is 12V, then you won't require the above circuit, you can simply connect the panel through some diodes in series with your battery for getting maximum efficiency

  32. Thank you very much for your kind reply. I was also thinking like you. Cuz i need ad much efficiency i can get. I have modified an auto cut circuit for this pannel. I will connect it for full charging auto cut.

    Sir, i read you blog frequently since 2012. But it was my first comment on here. I need a 100% pure sine wave (similler to AC) inverter of good efficiency by Bulk type transformer (12-0-12/10A) and analog IC's. could you please design it for me. I have read all your blog but i would like to build a inverter like microcontroller inverter output (sine wave).

    I am seeking your help.

    • thank you KM,

      I have plenty of sine wave inverter designs in this blog, however none of them will produce an exact replica of the actual grid sine-waveform and it is not required also…all my designs are PWM based and can be safely used as sinewave equivalent inverters.

      just type sinewave in the search box given on the top of the page…and you'll be redirected to the relevant pages, from where you can choose the one you prefer.

  33. You are welcome!

    And yea, i have read all of your blog and the one you made with 4047 and 3 sets 555 ic , i preferred this one, cuz of review from other hobbyists you uploaded in the blog.

    Now i want to know if i can use General purpose NE555 ic insteed of 7555 ic . cuz 7555 ics are not found in the local market arrount the place i live. I have Ne555 available.

    Please reply.

    And another question, can i use this above MPPT circuit to make pwm charger by changing the solar pannel of 20 voltage with 24 volt 5 Amp bulk transformer to charge 12 volt 20 AH battery? Please tell me your openion.

    Waiting 4 your reply

    • any 555 variant can be used, that's not critical…all and any type of 555 will work.

      yes the above design can be used in the way you want, however since the peak voltage of the PWM pulse will be always equal to input voltage (24V) so I am not sure what consequence this may have for the battery in the long term.

  34. Hi Swagatam, I appreciate all the help you've been giving me lately. You're a great resource for my senior project.

    I'm trying to make sure I understand the functionality of the circuit correctly:

    It takes an input from the solar panel, which can vary depending on the sunlight. The circuit then adjusts the PWM's to the battery depending on the solar panel voltage. (Wider pulse for lower sunlight, thinner pulse for more sunlight). In order to keep the average voltage in the optimal charging range. Is this correct? Or am I missing something?

    Thank you!

    • Hi Austin,

      yes that's correct, however since a P-mosfet is used for processing the output results, we need the PWMs to follow the sunshine by decreasing the PWM width as the sun goes down and vice versa, so that the response is inverted by the p-mosfet for implementing the required opposite effect across the output.

  35. Hi Swag, u are too wonderful, answering everyone infact great works, sir im John pls since i can not get the answer to this too difficult Maths [ f=1/1.453*rt*ct ] so please help me with the high amps 48v dc smmp solar circuit or to convert this 280v-300v to high amps 48v dc for charging batteries because im having a number of solar panels that is giving me about 280v-300v please help me for circuit to convert it to 48v to charge my 4 batteries thanks.

  36. can you please provide me circuit for automatic dimming solar circuit. Like if we have 5Ah Lithium battery and having 50 watts panel. now this 5Ah solar should run 9w Led for 12 hours. using a dimming circuit.

  37. Hi,
    Dear Sawagatam,
    Thanks for your information. I am going to use a 5W-12V solar panel
    could you please tell me which kind of battery should I use to have a effective circuit? And also which type of voltage regulator and zener diode do I need. is the mosfet a enhancement mosfet . do I need to use 5 diode in parallel ?

    • Hi Farhad, the panel voltage will need to be always 5V higher than the battery voltage for ensuring proper functioning of the indicated circuit.

      The zener diodes will not need any kind of change…

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