Sun G has already indicated that the mosfet used will be upgraded but I am in agreement with you that I do not necessarily think it was a manufactuer design flaw but more on how or where the customers are using them. Larry, over the past two years Of our testing we have bought and shared from the same shipments. Four of mine faltered and yours remained working. We imitated the same set ups yet something is different ,, what is it ? We both doubled up on our amount of inverters or used over rated inverters so ad not to use battery clamping , not to experience over volt and not to experience dump load ! Now through conversations we find out that you have installed the surge protection and I didn't . This leads us to why I should ave them installed because I believe this is where our difference is, I seem to have much heavier more constant winds than your location. My winds are also more turbulent due to violent storms. Quite frequently during heavy storms in my section of Manitoba it is not uncommon that our grid service provider has power spikes / outages that last from 2-3 seconds up to 10 hrs. When it is the 2-3 seconds this can repeat up too 4-6 times in a few minutes. It also disrupts other electrical appliances in our area such as satelight television receivers. I think this has been the major problem for my inverters and why the mosfets are not holding up. This also concerns me because even if it is a 2 sec grid failure or a 10 hr grid failure the inverter should be treating both the same with it's Island protection ! Under normal circumstances the inverters function well But our different locations are no where close to being normal and all the crazy ass set ups we are trying to force them into are our Own Failings . Larry thanks again on the heads up for the surge protection, will talk to you more on what to purchase and how to install.