Expensive to defrost with electric furnace

by Michael
(Peterborough Ontario, Canada)

Carrier 25VNAO36A00300

Amount of KW used to defrost with the electric furnace seems excessive but Carrier says it is normal. Example over an 8 hour period at roughly - 5 C the heatpump used 18 KW and the electric defrost used 12 KW.
Second question is the fact at low humidity and - 10 C weather the heatpump on its own can heat my 2000 sq ft home but at -2 C and high humidity it cannot. I think I get it a bit with the extra condensation on the coils.