Opinions?
Balloon of questionable origin detonates EMP. Although localized to a 500 mile radius, it begins a cascade failure of the entire US grid. Within 24 hours all store shelves and gas stations are empty. Most people wait for the Gov to come help. The powers that be are unable to do a black restart on the grid and within 3 weeks cannibalism overtakes all cities of over 10,000 population. 90% of US population dies within 12 months. People see your lights on. They come and barbeque you before you realize any profit on your system. Solar is not a good investment.
Watch the movie "The Road" (2009). A memorable experience to say the least. They kept their "food" alive in the basement until it was time for processing...
Also, in your scenario I highly recommend blackout shades and/or black plastic contractor bags taped on the inside of the windows.