For a solar tower you..
Convection tower performance is very poor and the convection tower portion of the SHPEGS system accounts for less than 10% of the system output. It is still clean renewable power, but the convection tower wind turbine output is trivial. The chimney is there to allow a large volume of air to move across the heat exchangers efficiently and the wind turbine takes a slight advantage of the effect, but it isn't significant.
I wonder how this would be for growing winter crops as well
The thermal storage would be deep enough to not interact with the surface or shallow groundwater. The Drake Landing project has some information. This is another research document on thermal storage.
There is a lot of potential for integrating bio-methane which requires a very constant temperature as well as this Solar Hydrogen from methane production system. Algae farming also has a potential integration with the solar thermal storage.
Thanks. I'm looking for a number though.
I don't mean to avoid the efficiency question. Again, in an arid location with the majority of electrical usage for AC, Solar PV or Solar Thermal is simpler and probably more suitable. The cost/m2 of collectors is substantially cheaper in a thermal system, so I'm not sure what you are comparing. Marginal and poor land that isn't suitable for crop production or the roof of a Walmart isn't the cost factor, the solar collector is. The MIT group was able to get 1kW from 14m2 of trough collectors on a straight thermal system and the SHPEGS additions should improve on that.
There are also 2 heat sources in the SHPEGS system, solar and hot summer air along with two power generation systems, thermal and the wind turbine. In theory, the absorption system should improve not degrade the straight solar thermal system, so I would expect something better than 10% efficiency on the solar portion if you include the additional heat from the air. The conversion efficiency of the heat being extracted from the air is difficult to calculate. The energy cost is the energy going into the solution pump to pressurize the aqueous ammonia and there isn't the same direct cost in the volume of air being moved, in fact the more air that is moved the better the output of the wind turbine portion.
I used 5% thermal to electrical efficiency for the calculations to be conservative, and generally 10% is used for binary geothermal plants
If you are comparing Solar PV, you need to account for battery cost and cut all the numbers by at least 50% to account for the daytime only output. Regardless of what is used for electrical storage, there are 3 months of the winter in Canada and the northern US where Solar PV isn't going to put out anything substantial and seasonal electrical storage isn't feasible.
The Toronto Exhibition Palace Live Solar PV Stats
page has some historical data on Solar PV in winter in Canada.