Bills in Kerala rarely rise in a straight line. When summer pushes consumption past a slab boundary, every extra unit costs more, so a 20% rise in use can mean a 40% rise in the bill.
Why solar helps most in summer
March to May is also when the sun is strongest and the days are longest. Solar output peaks just when the air-conditioner is running, so the units that would have been charged at the highest slab are the ones your roof covers first.
A quick example
A household using 350 units a month in winter and 550 in summer usually sees the summer bill more than double. A 3–4 kW system that generates 360–480 units a month removes most of the expensive slab units.
What to do
- Look at your last six bills and note the peak month, not the average.
- Size for daytime consumption; see the savings worked examples.
- Try the calculator with your peak-month bill to see the ceiling, and your average bill to see the floor.
