India’s peak summer temperatures often reach 45 – 50 °C, exposing rooftop solar systems to intense heat. While solar panels may still generate strong output, most solar inverters used today are based on silicon IGBT technology, which reduces their power when temperatures exceed optimal limits to protect internal components.
This reduction in output is known as thermal derating. To understand derating in detail, refer to our earlier article: Thermal Derating
Most Indian cities receive between 5 and 7 peak sun hours per day during summer. In practical terms, this means a solar system operating at full capacity for six hours should, in theory, deliver the following output:
Example: 3.3 kW Solar Inverter
3.3 kW × 6 hours = 19.8 units per day
At ₹8 per unit, that translates to ₹158 worth of electricity generated every sunny summer day. That is the theoretical maximum. Now let us examine real-world performance.
At ambient temperatures around 48°C, a conservative 20% output reduction is entirely consistent with documented field performance for silicon-based inverters.
With 20% derating applied:
3.3 kW × 0.80 × 6 hours = 15.8 units per day
Units lost: ~4 units
Revenue lost: ~₹32 per day
On the surface, ₹32 may not seem significant. But the cumulative effect tells a different story.
One peak summer (April to July, ~120 days):
4 units × 120 days × ₹8 = ₹3,840 in lost value
Over four summers:
₹3,840 × 4 = ₹15,360 in unrealized savings