Solar energy can't be used at night. In a solar efficient designed house, the building elements themselves store the energy in their thermal mass for night-time comfort and for cloudy days. Electricity from photovoltaics can be stored in batteries. Wind generators run day and night. Hydro power, derived from the solar evaporation of the oceans, can be used at any time, with water storage buffering the effect of river flow variations.
Solar energy is too expensive.
Solar water heaters would be even more attractive if you could get the same loan terms that the utility gets to build a power station. Remember, consumers don't have to pay for the power station when they buy their electric water heater. Current solar devices aren't effective a breakthrough is needed. While researchers continue to produce further improvement in a wide range of renewable energy technologies, the big breakthrough needed is equality of financing terms with conventional energy. There is 25 times the yearly energy needs of Australia and New Zealand falling on those land areas on an average day.