Mike
it is folks like you that make groups like this such a great place!
now that i have a better understanding of your needs, and capabilities
here is some more unsolicited advice to use as you like, or disregard if you like.
i would go with the turbine build, and drive an alternator to do dc charging of a battery bank, the bank need not be large, just needs to be a buffer.
i would go with a 48volt system, and i would use the 110-555jho leece neville/prestolite alternator with a standard regulator with a sense wire.
(if you want to know more about this scheme contact me by pm)
actually if you have enough capacity, i would drive two of the aforementioned alternators, which would get you very close to your 10kw goal.
figure on driving them at ~6500rpm and gear accordingly.
then it is a simple matter of an inverter system large enough to do the job. i would strongly suggest looking for a surplus exeltech mx series system. the mx is not grid tie, nor would i want it to be. these inverter systems come up with some regularity on ebay and are usually one hell of a buy in my opinion. exeltech will repair any of their products for a flat fee of 100 bucks provided it is repairable and not a molten puddle after a lightening strike or fire.
the exeltech can take a very wide range of input dc voltage, much wider than most other consumer grade inverters. they are the cleanest sinewave inverters made too, which might be of concern to you with your wifes health issues.
if you can get that far, then you will have a very robust system, capable of up to 10kw output (if you can get that much from the water source and your turbine of course) and also have approx a 22 kw surge capability for starting heavy loads.
then you get to where you have to switch loads, or divide loads between your resource and that of the utility. that in my opinion is a much easier proposition. if you put the batteries, inverters, and all switchgear, and control systems within a separate building (powershed) that is not habitated by man or beast you have no concerns with the NEC, just build all into a metal container and lock it up. feed the utility to the power shed and also feed the hydro to the power shed, and then take the resulting power from the shed to the house.
sounds like a really fun project
btw, there will be those that will suggest an aircore pm alternator, i would recommend against such because of issues relating to the ease of regulation and control of the power coming off the the pm generator.
the use of the 555alternator at 48volts nominal will return a respectable efficiency of around 80% with a field draw of less than 1% of generated capacity (approx 7amps total field excitation at 10volts for both alternators, ~3.5amps each)
the 555 alternator is pound for pound, amp for amp, the best bang for the buck on the market today, this allows one to keep a spare on the shelf should something happen and you need it, without breaking the bank.
with careful shopping and not including the hydro turbine, i think one could source all the parts to do this system for less money than one gridtie inverter in the 10kw class.
fwiw
bob g