If projections is what will make you feel more confident i will be willing to take time and do the math but it really all is speculation beyond the next difficulty change so i cant promise my projections would be accurate over a period of ten years.
I wasn't talking at all about bitcoin mining costs, but the costs of your solar electricity.
The running cost for solar may be free, but the upfront capital outlay is huge compared to mains power. Most larger mains-connected photovoltaic systems require government subsidies to be viable. A battery system is even more expensive.
The calculation/estimate would go some like this:
Average hours of sun per day (various solar website can give a good indication for this, remembering that early morning and late afternoon won't generate as much power). Units: hours.
Average power generation: Units: Watts/kW.
Length of operability of system. Panels can last 25 years, but inverters generally 10, and batteries probably less. Also, if mining becomes unprofitable sooner, you will need to depreciate your equipment faster. Units: Years. Convert to days by multiplying value in years by 365.
Cost of system. Units: $.
Thus:
Cost estimate per kWh = {cost of system} / {kWh generated over useful life}
= {cost of system} / ({Ave hours sun per day} x {Ave power generation} x {operating lifetime in days})
= $??/kWh