thanks for your replies, think it will be fine for what i need it for....
mneary, i'm pretty sure my calculations are right, but this is how i got to the inductance value....
I want to boost the output of a solar pv panel (17.7V) to 100V.
k = 1 - Vs/Vo = 0.823
switching at 20kHz Tp = 1/f = 50us
i want the ripple current Il to be 2% of the rated current of the pv panel (5.5A) so Il is 0.11A
rearranging V = L. dIl/dt gives L = Vs.dt/dIl
where dt = k.Tp = 41.15us therefore L = 6.6mH the nearest preferred value is 6.8mH.
Look right?