I have hellebores planted against the north side of my home in full shade and they grow and bloom well. I also have some planted where they get sun in the winter and they seem to grow faster (it's hard for me to say because my plants in the sun have manure worked into the soil so of course they grow faster).

Maybe you can find a place under the south side of some evergreens where it will be in shade in the summer but the low sun will reach it in the winter?

These are not full shade plants. They prefer some shelter from midday sun, but will grow tall and devoid of flower if grown in too much shade.

If you have no choice but full sun then make sure they have ample summer moisture, not waterlogged ever. They will take full sun reasonably provided they have the moisture.

Ideal conditions include a good rich deep soil, full exposure in winter, and light shade in summer, ie under a high canopy of deciduous trees in humous rich soil.

I grow in a variety of conditions and provided they do not bake dry, full sun is almost as good as light shade. I get summer temperatured of 20-27C.

Cheers Greenmanplants
Hampshire England Zone 8-9