Check with the local Eaton Electric office. See if there is anyone that is savvy into the old IMPACC system. You could get a power/energy sentinel and connect it up to an old computer. IMPACC has a special modem that communicates to the devices. Data base is CSV, right down your alley. I have several of the setups running at different times for my customers.
I suggest this cause the company is not selling IMPACC anymore. They might give you a set up. Or know of a company in the neighborhood that upgraded to the current product. The power/energy sentinels are utility grade, depending on your rate structure. If your in Kalifornia with low peak, high peak, mid peak, etc. You need an better product.
E-mon has some simple meters that are good. So does PML
If your going to do it make sure that you keep the accuracy within 2-3% not much sense in going to all of the trouble and expense for a WAG.