Making a Transformerless Solar Inverter

Sun is a major and an unlimited source of raw power which is available on our planet absolutely free. This power is fundamentally in the form of heat, however humans have discovered methods of exploiting the light  also from this huge source for manufacturing electrical power.


Today electricity has become the life line of all cities and even the rural areas. With depleting fossil fuel, sun light promises to be one of the major renewable source of energy that can be accessed directly from anywhere and under all circumstances on this planet, free of cost. Let's learn one of the methods of converting solar energy into electricity for our personal benefits.

In one of my previous posts I have discussed a solar inverter circuit which rather had a simple approach and incorporated an ordinary inverter topology using a transformer.

Transformers as we all know are bulky, heavy and may become quite inconvenient for some applications.
In the present design I have tried to eliminate the use of a transformer by incorporating  high voltage mosfets and by stepping up the voltage through series connection of solar panels. Let's study the whole configuration the with the help of the following points:

How it Works

Looking at the below shown solar based transformerless inverter circuit diagram, we can see that it basically consists of three main stages, viz. the oscillator stage made up of the versatile IC 555, the output stage consisting of a couple of high voltage power mosfets and the power delivering stage which employs the solar panel bank, which is fed at B1 and B2.

Circuit Diagram

220v, 120v transformerless solar inverter circuit

Since the IC cannot operate with at voltages more than 15V, it is well guarded through a dropping resistor and a zener diode. The zener diode limits the high voltage from the solar panel at the connected 15V zener voltage.

However the mosfets are allowed to be operated with the full solar output voltage, which may lie anywhere between 200 to 260 volts. On overcast conditions the voltage might drop to well below 170V, So probably a voltage stabilizer may be used at the output for regulating the output voltage under such situations.

The mosfets are N and P types which form a pair for implementing the push pull actions and for generating the required AC.

The mosfets arenot specified in the diagram, ideally they must be rated at 450V and 5 amps, you will come across many variants, if you google a bit over the net.

The used solar panels should strictly have an open circuit voltage of around 24V at full sunlight and around 17V during bright dusk periods.

How to Connect the Solar Panels

Parts List

R1 = 6K8
R2 = 140K
C1 = 0.1uF
Diodes = are 1N4148
R3 = 10K, 10 watts,
R4, R5 = 100 Ohms, 1/4 watt
B1 and B2 = from solar panel
Z1 = 5.1V 1 watt

Use these formulas for calculating R1, R2, C1....


The above 555 IC design may not be so reliable and efficient, a much reliable design can be seen below in the form of a full H-bridge inverter circuit. This design can be expected  of providing much better results than the above 555 IC circuit

Warning: Please connect the SD pin#5 of the IC with the ground line, otherwise the IC will not initiate.

Another advantage of using the above circuit is that you won't require a dual solar panel arrangement, rather a single series connected solar supply would be enough to operate the above circuit for achieving a 220V transformerless inverter output.

Need Help? Please send your queries through Comments for quick replies!


Lee said…
Can you replace the solar power with a dc motor?
freqiancy said…
Not working. :(
Abid Ali said…
sir please guide me how i make a high power jamer circut for electronic circut jaming please
Swagatam said…
what frequency do you want to jam....
Qamar Khan said…
Dear Swagatam ji,
I want make a 500 watt transformer less inverter what can change in this circuit please give diagram I am a beganer .

Swagatam said…
Dear Qamar, if you have the required source for the high voltages (dual), then you can try the above design for your purpose without changing anything.
Mohamad Saqre said…
can i use on sollar cell instead of the two battery
if i can how to replace the two deffernt positions of batterys with it
and thanks
Swagatam said…
yes you can do it...there's even a better design than the above which all can try, it's given below:
Sonal Kachare said…
Hello sir, I want make transformer less photovoltaic inverter any help will be great thank you
Swagatam said…
Hello Sonal, please provide voltage and wattage specifications of the inverter
Sonal Kachare said…
Sir i m also curious will the above circuit can run a single phase ac motor and if not what changes are required!
Thank you
Swagatam said…
Sonal, yes you can do it using the new updated circuit above.

you may have to connect a capacitor/coil across the load to reduce noise.
Sonal Kachare said…
Thank you so much for ur time sir!
i m definately gonna try that circuit and will let u know about the outcome!
thank you for promt reply
Swagatam said…
you are welcome Sonal!
Sonal Kachare said…
hello sir, thank you for the response!
But i am not able to find the IRS2453(1)D is there any other replacement for that and how will i convert that square wave(output) in sine wave for ac motor without using transformer.
Swagatam said…
Hello Sonal,

this IC will be required, there's no other option you can order it from an online store also.

you will need a 300V solar panel either by connecting many panels in series or through a single unit for operating the last circuit above.

other options may involve heavy transformers or complex SMPS designs.
Sonal Kachare said…
OK. I will try to get the same IC. So this what i understand strictly following your article, 300V dc is applied across the +/- AC rectified lines using the solar panels (i understand the connection becoz of the above article thanks to you again). But i m still confused at output part, the load is shown in the circuit diagram so should i connect ac motor(single phase) as a that it OR the output has to be modified to run the motor if yes how?
sorry for too much doubts!
hope to get your reply thank you!!!
Swagatam said…
yes that's correct.

the motor can be directly connected across the points marked as "load" but since the output here is square wave could cause some noise in the motor...which could be eliminated to some extent by adding a calculated LC network across these points.
Sonal Kachare said…
OK, thank you sir........i will work on it!!!
Sonal Kachare said…
Also, if you come across any online sites from where i can order the IC plzzz mention it!
I m searching tooo
Swagatam said…
you can try digikey, radioshack, mouser, onsemi, etc all these are reputed online part suppliers
Sonal Kachare said…
Sir, can you help me with CT & RT what values should i go with. I know it has to be done by trial and error for 50Hz........but i m confused with what values should i start!
Swagatam said…
you can use a 0.22uF for Ct and a 100k pot for the Rt and then check and confirm the frequency at the output by varying this pot
Sonal Kachare said…
ok sir thank you!
I didn't find the IC anywhere (in local electronics stores).
I also tried to use yours mentioned suppliers, but they deliver in bulk and the import cost and duties are there so it is pretty costly. Also the delivery time long.
Sonal Kachare said…
Hope you can understand! Can you give me another circuit which can i use for my application (transformer less inverter to run a single phase ac motor)
Swagatam said…
you can try the following circuit:

put the load in place of the motor.....the high voltage from the panel should be connected across the load upper wire and the mosfet source.

the 555 circuit will require a 12V for operating correctly.
Swagatam said…
the frequency can be set by adjusting the value of C1, and the RMS by adjusting the pot.
Sonal Kachare said…
Thank you sir again for helping me here really appreciate.
From the circuit diagram in the mentioned link i understand, the drain will connect with the (-) of the ac motor, the motor (+) will connect with the (+) of the 300 V dc supply, the (-) of the 300 dc V will become common with the source of fet. But then (-) of the 12V supply is grounded or connected with 300v (-),

As you mentioned in comments of that blog, for replacing ac motor in place of dc motor,
fet will not rectify both the halves of the AC, you can try using a triac instead and it will work. so should i replace fet with triac if yes how and which one for 300v dc.
and please tell me the device configuration i understand the ic 555 part but the other part is bit confusing.
Thank you for helping me.
Swagatam said…
Sonal, the panel voltage is DC so the device should be a transistor, a triac cannot be used here.

the (-) of the mosfet/panel and the circuit will need to be made common for proper functioning of the circuit.

please click the diagram to enlarge, all the parts are clearly mentioned in the diagram, which part is confusing you? The diode across the mosfet could be a 6A4 diode.
Sonal Kachare said…
Hello Swagatam sir,
OK, sir i got the connection part, i m confused how will it work, just replacing dc motor with ac motor in the circuit and giving the ac 300v dc supply directly to ac motor.
plz just a little bit explanation will do.
which mosfet should i go with?
thank you sir
Swagatam said…
Sonal, this 555 IC is configured as a PWM controlled astable which will produce half wave square waves for the motors, which will operate the motor but not as efficiently as with the ICIRS2453. but the motor will work.
I have suggested this rather crude option since you could not get the H-bridge IC. you can connect a capacitor across the mosfet for improving the response of the motor.
Sonal Kachare said…
Hello Swagatam sir,
Thank you sir, i will work that i will get the components by monday and will start work.
sir which mosfet should i go with?
Now rest all is clear thanks sir!!
Swagatam said…
thanks sonal, you can try FQP6N70 or 2SK3878 mosfet
Sonal Kachare said…
Hello Sir,
Becoz of the exams the work got delayed but I have completed the circuit. I have properly soldered the circuit on general purpose PCB, and also I checked the connection failed for checking continuity and cross connection everything is fine.
All thanks to you
Sonal Kachare said…
Sir now I have to test it, but I m not getting the Motor as of now to test. Can u suggest any other load which I can use for eg. bulb or anything else and if yes how much voltage should I apply on the load side for the load u will mention. For ic 555 I m giving 15v
And I m using MOSFET irf 840.
Swagatam said…
hello Donal, you can try with a 100watt bulb, and check its illumination by varying the pot.

also to improve performance of the mosfet connect a 1K resistor across its gate and source....and make sure the gate of the mosfet is as close as possible to IC 555 output pin.
Sonal Kachare said…
Ok, sir i will the changes as u mention!
and i will give 120-150 dc voltage across the bulb and mosfet(source).
Thats ok right!
Swagatam said…
yes that will do!
Sonal Kachare said…
hello sir,
i checked the ic555 circuit it is working,
the bulb is not turning on, when i tried to turn it on.
what could be the issue. i used ac bulb 100 watt and applied 120 voltage dc approx.
Swagatam said…
Hello Sonal,

did you check whether or not it was generating PWMs in response to pot rotation?

and whether the drain of the mosfet was also doing the same at 120V??
Sir, how do I calculate Rt & Ct on the updated circuit diagram with using IC IRS24539(1)D ?
Swagatam said…
Fatai, please see the datasheet of the IC, the details are explained in the datasheet.
Sonal Kachare said…
Hello sir,
I checked the ic 555is not responding, also I m confused ic555 has output at pin3 then why pin 7 is given to mosfet gate. Also I connected source to the ground and gate to ic555 pin 7...and connected the drain to CRO but it didn't give any output.
Sonal Kachare said…
Hello sir
What if we apply only 30vdc to the 1st circuit in the above article with same configuration what will be the output.
Swagatam said…
Hello Sonal, confirm the output using an should be able to hear some kind of frequency in the earphone if the IC working correctly....

the shown configuration in the link is also correct, if you wish you can change it to the conventional astable mode with pin3 as the output
Swagatam said…
the CRO must show a square wave output at the output pin of the IC
Swagatam said…
It should be 30 + 30 V, the output will be 30V AC
sherif said…
Hi, my name is sherif , am having issues with that circuit ....
what did you mean by load?
how many kva is the inverter ?
Swagatam said…
Hi, the load refers to the appliance which you would want to run from the inverter.

the wattage will depend on the solar panel output wattage capacity or the battery capacity. this can be modified as per your performance simply by upgrading the supply input and the mosfet power ratings.
aditi said…
dear sir ,
Nice post what components MOSFET/ IGBT do I have to use, i have bias voltage +400v solar panel to run 1kv load
Swag said…
Thanks Aditi, you can try any 400V/30amp mosfet pair, your part dealer will be able to guide you better regarding the exact number for these devices.
aditi said…
Sir , Could you please provide the details of Rt and Ct as not mentioned in schematic
Swag said…
Aditi, the formula is furnished in the following article:

However I would recommend to confirm the results practically using a frequency meter...
conandrum said…
I saw your other page 12V DC to 220 AC Power Converters / Simplest Full Bridge Inverter but I cannot post comments there.
(You mention that the Mosfets can only handle 600V max.)
I have a circuit that fills up an 8KV capacitor. Is it possible to connect my capacitor to your inverter and get 240VAC 50Hz?
I appreciate your help.
Swag said…
I have enabled comments now, it was accidentally disabled.
Can you please show me where did I mention that mosfets can only handle depends on the specifications of the particular device, it can be 600V or 6kv depending on how the mosfet may is created by the manufacturer.

Your capacitor will get discharged within milliseconds after connecting it, so capacitors cannot be used with inverters for driving a load

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