I'll have to check the numbers. The 6000W came from the stove's rating tag. It's a small stove that supplements an oil burner to make the living room and kitchen comfortable. The oil burner keeps the whole house warm enough to not burst the pipes.
I'm not sure where I read 1000W but it is for a square meter perpendicular to the sun's angle. Here in North East USA, solar installation folks say we get "3 hours" of direct sunlight per day in winter and 6 hours in the summer. I think that accounts for shorter days and weather.
Where, for how long and when? Certainly not when you need to regularly use a wood stove for heating, at least not around here in northern Europe. :)