When does necro soloing become "worth it"?

[bwe]

I have a level 21 necro on green and I've never played one before. I tried killing the hermit in South Karana at level 20 and could mostly handle it (even con, occasional fear/darkness resists led to me having to feign and pet dying) but even with the two minute respawn timer I felt like I was getting more exp per hour in a full group in Unrest due to the ZEM. Killing yellow or red mobs solo leads to more resists but killing low blues seems to take too much mana for the amount of xp I get.

I have a spyglass for GCD reset.

My general strategy is

Pull with darkness
Send pet in
Fear
Heat Blood
Siphon Life if needed
Reapply Fear as needed

This usually leaves me with ~30-40% mana remaining which I regen back by the time the hermit respawns.

Am I maybe not doing 51% damage? Is the pet eating too much xp?