I'm debating between installing a solar water heater vs. a heat pump for supplying hot water to my house. The house is in Bangalore, India - we have about 300 days of sunshine in a year. My estimate is that we'll need about 150litres of hot water a day, mostly between 6:30AM and 8AM (just after sunrise). Whichever system is selected would be installed in the terrace and exposed to sunlight.
A few things I'm concerned about:
- Availability of hot water on cloudy days and early in the morning - is the insulation of the typical solar water heater good enough to keep the water hot overnight?
- Power consumption - with solar water heaters, the power consumption is pretty much zero. What kind of power consumption can I expect with heat pumps for heating up 150litres of water a day?
- Reliability: what kind of life can I expect for a solar water heater vs a heat pump. Intuitively it feels like solar water heaters should be more reliable since it has less electronic parts. What should I consider when installing these in the terrace to protect them from damage?
- How do these compare on maintenance cost and effort?
Since these will be installed in the terrace and there will be about 30ft length of pipe to bring the water down, I'm concerned about the water in the pipe cooling down and the cold water having to be drained before the hot water from solar heater/heat pump in the terrace comes out through the taps. This could mean a lot of water being wasted. Is there any way around this: for example, are insulated pipes available/a good idea in this case?