13 units over 24 hours averages out at around 540W.
If we assume the major consumer of juice is the A/C then 540/2000 would put it running at about 27% which is pretty ok for this time of year.
Add on your fridge/freezer (which will also be working harder) and I don't think that's entirely unreasonable.
For a (not very good) comparison: -
Over the weekend when we have family visiting (so 3x12,000 BTU A/C running only at night) we will swallow >50 units in 24 hours.
On a weekday when it's just myself and Madam (1x12,000 BTU A/C again only at night) our consumption is around 32 units in 24 hours.
But our biggest single consumer of energy is Madam's ruddy 15,000 litre koi pond. Pumps, UV, air pump - The load isn't massive but it's 24/7/365.
Cooling isn't cheap! Have you got that fan yet?