Lighting up the dark night in bright sunny day world

I am reading an interview with Harish Hande , Phd in Energy Engineering from U Mass,Lowell on Sramana Mitra's blog and definitely recommend you to read it. Harish explains how Selco, he co founded with Neville williams is providing solar power to the rural parts in India & Sri Lanka. Countries with a strong sun light can really take advantage of this, esp countries between the tropics and right around the tropics. See the map to find where Solar energy can make a difference in lives. Is it already being used? Wake me up if I am sleeping. As I am reading this, I stopped for a second and asked myself which two tasks consume most energy resources among the households in US (a) Heating water (b) Laundry. I am thinking about the possible road blocks or hiccups we have to encounter to move in this direction to get maximum households on board. Climatic conditions? Storing required Solar energy? Maintenance issues? May be Harish/Neville can elaborate. Congress is doing its best to get us in this direction by providing tax benefits up to 30% of the equipment and more.