You already have a pretty good regulator in the inverter. The problem is once the dump load turns on you don't have anymore power for it. Think about 95 volts and 4 ohms - 2200 watts from a windmill rated at 1000.
The best you can do with your system is to use the largest resistor you can that keeps everything together and set the trip point for the dump load as high as you safely can. The larger resistor should have produced less heat. (p=I^2R).
You will have the same problem with the bigger inverter. It will just happen when the wind is blowing harder.
Actualy your wrong !
Even a very small wind turbine can produce far in exess of its rated power for a split seccond. There is a certain amount of inertia in the rotating blades. When the dump load is first connected its job is to quickley reduce the speed of the blades. In that brief moment the current levels can be very high indeed !.. To give you an idea of how high, the solid state relay I have controling the dump load has to be rated at 80 amps !. It is entierly possible that for just a brief moment the power within that circuit could exeed 3Kw. Think about it P=V/RxV !. So the current in the circuit = 110v / 4 Ohms x 110v = 3025w. But this IS what we want it to do, this is how the braking system works. In fact the manufacturers of the turbine have suggested I use a 2 Ohm load !. If the resistance was too large more of the power would end up in the dump load and less of it in the inverter.
A modern family car may only have a 95Kw engine and takes 10 secconds to accelerate to 60mph. But the 4 large disc brakes usualy fitted to a modern car are capable of absorbing energy at a rate which 4 or 5 times the output power of the engine. Which is why it only takes 2-3 secconds to stop from that speed. However the heat dissipation ability of car brakes is poor. If you fitted less agressive drum brakes they would be in-effective. If you continued to drive the car in the normal way, braking just as if you had disc brakes fitted, the drums would get very hot and most likely catch fire.
My dump load will absorb large amounts of power for very short periods, such as strong wind gusts. Its low impedance ensures that it will slow the turbine rapidly. Thankfully strong wind gusts are not constant, so the heat dissipation ability of the dump load is not requied to be huge. Thus its 400w rating is more than enough. If I were to increase the value of the dump load resistors, it would have the same effect as fitting old drum brakes to your car. It would be in-effective at reducing the turbine speed and would likely overheat, possbly catching fire too.
The same problem will NOT occur with a larger inverter, because there is a point where the turbine simply cannot produce any more power, no matter how hard the wind blows. If I make the inverter larger it will absorbe all the available power when the turbine is running and the dump load will be redundant. However it will still need a dump load, to restrain the turbine incase of inverter failure.