... There's been a trend in solar to "oversize" systems by 20-30%. By this i mean, if a customer is using 10,000 kWh/yr they may purchase a system that's generating between 12,000 and 13,000 kWh/yr.
... Over the course of a year the PV system overproduces 2,000 kWh of electricity. As opposed to selling that electricity back to the utility company at say $0.04/kWh it may be better to drop off a "bit coin rig" at the customers house that's capable of using up the extra 2,000 kWh in the course of say a week.
You are over-complicating it. As has been mentioned, Bitcoin miners are left running 24/7 to maximize ROI. Lower hash-rate miners will also be cheaper, and (hopefully) use less power when running.
2000 kWh/year works out to ~231 Watts of continuous load. One of the ASICminer cubes may fit the bill there (but are not very efficient (240W, 30Ghash/s+controlling computer needed)). If the reconciliation is done at year-end, it does not really matter if the load is present all year or not.
Many of the new miners draw as much power as possible. So you may want to look into modular ones. The popular
Antminer S1 draws about 360W.