Mosfets FB11N50A ,12NM50,13N50 - Compatible?

Thank you for the help. The GA is the least I can give,

When I try to get data sheets, I always get links to pay sites. I ordered already.

The inverters are some cheap (but good) grid tie 300 Watts Power Jack PSWGT-300.

Paid about $90.00 and the first one lasted more than a year and will cost now 4 Mosfets and one 5 amp fuse to repair it. Normally only 1 dies but I want to go with your proposed type.

It saved me $230.00 in power bills over a year in use. ( because here $.42/kWh)

The issue with batteries and this inverter: the inverter starts backfeeding at 14,4 volts, a difficult voltage to keep the batteries (12 V) from drying out.

I ordered a big one (5 kilowatt - 170 lbs) in China and after messing up my back with installing it I figured out that it doesn't work on 60 Hz. So I need to buy 2 times. Sending it back to China costs me more than 1 Grand.

I wonder if I better buy plenty lighter versions (like 500 Watts) instead of 1 bigger one. I live rather isolated on an island and the smaller ones I can repair by myself.

Again, thank you for helping me out.

Are you letting the original MOSFETs overheat? They need to be kept reasonably cool. Well away from the sun and for your application, very oversize cooling fins and maybe a few tiny ventilators.....from Intel CPUs maybe.....th3ey are cheap and use only a few milliamps and usually run on 12 volts.

Furthermore, what do you mean by "back-feeding"?

By the way, 14.4 volts will charge the batteries fully (If that is what you are referring to), but will not let them give their maximum life span. Less is better. If you charge to around 70% only, they will last longer that you will!!!!

If you need further infos on those points, just ask. Many here can help.

I actually did a non favorable thing repeatedly:

These inverters come with a cord that fits in an outlet. Connecting them is not a big problem, but disconnecting is.

I did not disconnect the 250 Watts panel's DC before I pulled the plug. Since the inverter has a MPPT device, the phase could have been terribly messed up, so that a possible reverse voltage had built up (120 Volts + 0-120 Volts from the inverter).

I noticed a reasonable big spark while unplugging the plug.

I used Back feeding to mention that I send the 120 Volts back in the grid, spinning the meter wheel less forward or even backwards.

The mosfets are assembled and fixed on the extruded alumin(i)um box and thermostatically cooled with a small Papst fan. This fan runs 20% of the time.

The first inverter worked well for months. The second one had been squatted by a lizard. Thank you for the help. D

A good cooling suggestion from Andy Germany. Have you considered failures might be due to overvoltage? Those solar panels do not have much regulation!