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250 watt grid tie inverter build


New Member
I have a small query ,suppose i have sync the inverter(i.e freq,voltage) output with the grid ..in this case line voltage and generated voltage become same then how will i identified which is input voltage and which is generated voltage..
Thanks in advance


New Member
Thank you so much for the the info..and im sorry for being stupid :sorry:
Hi all!
Try update topic.
I build this inverter test version (on a table as a Barbe), my mechanic power meter show - it really work!
Electronic power meter (it cant show direction, becoase use both) show max 120 W (primary from PV 17V, 8A).
But! C1 (I use 680u*50V) very hot:eek: One pcs shooted:arghh::banghead:

What are ideas?


Most Helpful Member
The ESR (Equivalent Series Resistance) of a capacitor has a lot to do with how much they will heat up in use and where C1 is located in the circuit it's handling a very high ripple voltage which means it's also handling a very high average current in and out of it as I stated in post 3 "The Capacitor" description.

If you can not find a suitable capacitor in the specified range, ~5uF per input amp, that has a low ESR value you can cheat by going up to a higher working voltage rating, as I referenced to using s 250 volt rated unit in a 12 volt system, or use multiple smaller value capacitors in parallel.

On my larger higher voltage GTI units I have used nonpolar AC rated motor run type capacitors being they are specifically designed to work in very high ripple current applications.

So given that if you are using a 680 uF 50 volt capacitor on a 17 volt 8 amp input I can totally see why it blows up. The uF value is way way too big (17X) and the voltage rating is way too low( .2x).

This and re-reading the instructions should help you out considerably on C1 overheat issues. ;)
Last edited:
Hello sire
I try to make one grid inverter but the main problem is how to eliminate the one of the output not to be live . because both wires are live. I did not try yours disign.
Thank you
Thrasos christou


Most Helpful Member
If you try my design make sure you follow the numbers reasonably close. As you may have red, if you go too far outside of the recommended values you will have odd problems with the design.

Also if you have not already seen here on the forum there are other threads related to the design and construction of my units that have more information than just what is presented here.

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