I need your suggestions on my grid-tie inverter design

[hkBattousai]

Hello.

I have been working on a grid-tie inverter circuit. I studied a lot of other similar circuits that I found online. I asked many questions on several forums. And finally I end up with a design like this.

Please criticize my design, make suggestion and corrections, and find bugs in it. This is my biggest design ever, and I'm not very confident whether it will work or not. I need experienced engineers' confirm before I realize a physical circuit out of it.

If I can make this circuit work, next, I'm planning to buy solar panels and use them with it. I will research if I need any official permission for connecting a circuit like this to the grid in my region. I will try to take a lisence if I have to.

Here is my schematic:

(Higher resolution versions (PNG and PDF) are in the attachment.)

The point that worries me most is any possible too large voltage spikes on the MOSFETs (SPA17N80C3) that switch the current to the grid. I know, in theory, I can solve this problem by simply putty large enough capacitors parallel to the grid before the MOSFETs and after the ferrite transformer. But in practice, there is no cheap capacitor which can handle that much of ripple voltage. Please make comments also on this issue.

Datasheets of critical components are in the attachment.

 

[4pyros]

The power company should never let you hook up a home brew converter to the grid.
It is too costly for an individual to get the necessary approvals to tie to the grid.
Do you even know the specifications for hooking up to your grid?
Can your power company provide a grid tie inverter for you to connect to?

 

[tcmtech]

Why are you using mosfets for the grid connection instead of triacs or reverse parallel SCR's or even relays?

 

[hkBattousai]

Why are you using mosfets for the grid connection instead of triacs or reverse parallel SCR's or even relays?

I'm supplying current to the grid via a ferrite core transformer. Its secondary windings has a very low inductance. If something happens and primary side current stops/fails, the secondary windings will literaly be short-circuited across the grid. I did the calculations once but I don't remember the exact numbers now, at worst case, if the secondary windings stay short-circuited for 10 ms, a lot of heat will be dissipated on the circuit. This may harm some components if it happens several times in a short time.
The MOSFETs turn the current off in much less time.

 

[madhuhegde]

hello .. what happened to the next .. about this project .. is it worked ... iam also very much interested to this ...

madhu.

 

[hkBattousai]

I couldn't find time to realize this project. It is like I abandoned this. I would like to hear if someone implements it, tries it out, and post to outcome here though.