Understanding the path electricity takes through a solar system explains most of the questions people have about it — including why a 5kW system almost never produces 5kW, and why that is entirely normal rather than a fault.
How it works
Sunlight strikes the module and frees electrons in the silicon, producing direct current. That DC travels through cabling to the inverter, which converts it to alternating current at grid voltage and frequency. The AC feeds your distribution board, where it is consumed by whatever is running. Anything you are not consuming flows out through the meter to the grid. When the sun is down or your load exceeds generation, the flow simply reverses and you draw from the grid as before.
| Stage | Typical loss | Why |
|---|---|---|
| Temperature | 8-15% | Modules lose efficiency as they heat above test conditions |
| Soiling | 2-6% | Dust and grime on the glass, worse in dry months |
| Inverter conversion | 2-4% | DC to AC conversion is efficient but not lossless |
| Cabling and connections | 1-3% | Resistance over cable runs, more on long routes |
| Mismatch and shading | 2-8% | Modules in a string perform to the weakest one |
Indicative loss ranges for typical rooftop installations. Actual figures depend on site conditions, layout quality, and equipment. Together these are why a system's real output is meaningfully below the sum of its module ratings.
The engineering view
Module ratings are measured under Standard Test Conditions — 1000 W/m2 irradiance at 25C cell temperature. Indian rooftops rarely meet those conditions during generating hours, because a module sitting in Bengaluru sun runs far hotter than 25C. This is why a well-built system typically delivers around 75 to 80 percent of its nameplate rating at peak, and why installers speak in expected annual units rather than in kilowatts.
What this means in Karnataka
Karnataka receives roughly 4 to 5 peak sun hours on average across the year, which is favourable by global standards. The pattern is not flat: the pre-monsoon months are the strongest, and the monsoon months are noticeably weaker. Any generation estimate you are given should be an annual figure, because judging a system on a single monsoon month will always look disappointing.
Common mistakes to avoid
Misreadings that cause unnecessary worry after commissioning:
- Expecting a 5kW system to produce 5kW at midday
- Judging performance on a monsoon month rather than an annual total
- Assuming a drop in output means a fault when soiling is the usual cause
- Comparing your output against a neighbour's without accounting for orientation and shading
- Ignoring that a single shaded module can pull down a whole string
What we recommend
Ask for an expected annual generation figure with the assumptions stated, not a peak kW number. Then compare your monitoring against that annual expectation month by month, and treat a sustained gap rather than a single bad day as the signal worth investigating.
Common questions
- Why does my system never hit its rated output?
- Ratings are measured at 25C cell temperature, which rooftop modules rarely reach while generating. Combined with soiling and conversion losses, 75 to 80 percent of nameplate at peak is normal.
- Does the system work on cloudy days?
- Yes, at reduced output. Diffuse light still generates, typically a fraction of clear-sky production depending on cloud density.
- Does one shaded panel matter?
- In a series string, yes, considerably. Modules in a string perform close to the weakest one, which is why shade analysis during design matters more than most buyers expect.
- What happens to surplus generation?
- It flows out through the bidirectional meter to the grid and is credited under net metering, offsetting units you import later.
- Do panels lose efficiency over time?
- Gradually. Around half a percent a year is typical, which is why performance warranties are quoted at 25 years rather than as a fixed output.
Talk to our engineering team for a solar assessment.
We will review your consumption, roof, and site constraints before recommending any capacity.