Vicaya GlobalCalculator · Solar · trackers
Is a solar tracker worth it where you are?
A tracker follows the sun, which sounds like it must always win. Whether it does depends almost entirely on your latitude — and at some of them, a fixed frame beats it outright.
What do kWp and kWh mean?
- kWh — kilowatt-hour
- A unit of energy, and the thing your electricity bill charges you for. A 1,000-watt heater running for one hour uses one kWh. A typical home uses somewhere between 2,000 and 10,000 kWh a year depending on where it is and how it heats.
- kWp — kilowatt-peak
- A unit of capacity — how big the solar array is, not how much it makes. It is the output the panels would produce under standard test conditions: bright, cold and perfectly aimed. Real roofs rarely see those conditions, which is why a 4 kWp array does not generate 4 kW for most of the day. One modern panel is roughly 0.4 kWp, so 4 kWp is about ten panels.
- Putting them together
- kWp is the size of the system; kWh is what it produces over time. The ratio between them — kWh generated per kWp installed, per year — is the honest way to compare locations, because it strips out how big the system happens to be. It runs from roughly 700 in cloudy high latitudes to over 1,800 in sunny deserts.
20 × 450 W at 21% is 2.14 m² per panel — about 43 m² of roof.
At London, United Kingdom, a single-axis tracker changes output by -0.5% — and on cost, the best choice here is fixed frame.
A tracker is compared against a well-oriented fixed frame here, which is the only honest comparison and the one that makes trackers look worst. Set the fixed frame flat, or point it the wrong way, and the tracker's advantage grows — but the money saved by fixing the frame's orientation costs nothing at all.
All three, on your array
| Mounting | Annual output | Against fixed | Extra cost | Upkeep a year | Net a year | Premium repaid in |
|---|---|---|---|---|---|---|
| Fixed frame — best value | 9,125 kWh | — | — | — | — | — |
| Single-axis tracker | 9,078 kWh | -0.5% | £2,340 | £108 | −£117 | never |
| Dual-axis tracker | 9,875 kWh | +8.2% | £6,300 | £108 | £42 | beyond 60 years |
When a tracker wins, and when it loses
| Month | % |
|---|---|
| Jan | -22.6 |
| Feb | -16.1 |
| Mar | -8.9 |
| Apr | 1.7 |
| May | 7.1 |
| Jun | 10.3 |
| Jul | 10.1 |
| Aug | 5.0 |
| Sep | -5.2 |
| Oct | -15.9 |
| Nov | -25.3 |
| Dec | -24.8 |
Tracking gain is mostly a question of latitude
The same 9.0 kWp array on the same 35° fixed frame, moved around the world and given the same trackers. Sorted by distance from the equator.
| Site | Latitude | Fixed kWh/kWp | Single-axis | Dual-axis |
|---|---|---|---|---|
| Nairobi, Kenya | 1.3° | 1,402 | +32.8% | +35.1% |
| Chennai, India | 13.1° | 1,478 | +16.0% | +19.3% |
| Phoenix, United States | 33.5° | 1,914 | +12.0% | +26.1% |
| Santiago, Chile | 33.5° | 1,860 | +14.8% | +25.9% |
| Denver, United States | 39.7° | 1,738 | +6.0% | +22.1% |
| London, United Kingdom | 51.5° | 1,014 | -0.5% | +8.2% |
| Oslo, Norway | 59.9° | 911 | -0.7% | +10.5% |
| Tromso, Norway | 69.7° | 719 | -3.4% | +11.0% |
Nairobi, Kenya sits closest to the equator and gains 32.8% from a single axis alone — nearly everything a dual-axis tracker would add, for a fraction of the hardware. Tromso, Norway is the furthest from it and loses 3.4%.
The reason is geometry. A horizontal north–south axis rotates east to west and nothing else, so it can follow the sun's daily arc but never lean towards the equator for the winter. On the equator there is no winter lean to give up and the daily arc is everything, so the match is perfect. At high latitude the sun stays low, most of the light arrives as diffuse from the whole sky rather than as a beam worth chasing, and a fixed frame tilted towards the equator beats a tracker lying flatter than it should be. Trackers built for those latitudes use a tilted axis, which this page does not model.
What this does not model
- Horizontal north–south axis only. Tilted-axis, east–west-axis and azimuth-only trackers all exist and all behave differently. A tilted-axis tracker would recover much of what the high-latitude rows above give up.
- One row, with nothing behind it. Real tracker fields shade each other at low sun and run backtracking algorithms to manage it, which costs output the single-row figures here never lose. Gains for a multi-row field are therefore overstated.
- No downtime, no wind stow, no drive failures. A fixed frame has nothing to break. The upkeep field is the only place that difference appears, and it is a number you set rather than one this page knows.
- No clipping. These runs are the 288-interval representative year, which cannot see clipping — and a tracker's flattened, broader output curve interacts with an inverter ceiling in ways the clipping calculator is the right tool for.
- Prices are per kWp and linear. Tracker economics are dominated by scale; a twenty-panel garden array and a twenty-megawatt field are not on the same cost curve.
Frequently asked questions
Are solar trackers worth it?
The extra energy is mostly a question of latitude. Single-axis tracking can add a useful amount in sunny mid-latitudes and very little — sometimes negative once you allow for the losses and cost — elsewhere. This tool compares single- and dual-axis against a well-aimed fixed frame for YOUR location, rather than quoting a best case.
That is the solar tracker efficiency calculation that matters: the extra energy a tracker would give at your site compared with a fixed frame.
How much more energy does a solar tracker produce?
The gain grows with clear-sky sun and shrinks toward the equator and in cloudy climates, so the marketing figure rarely matches a specific site. The calculator computes the uplift for your latitude and climate against a fixed array.
Single-axis vs dual-axis — is dual worth the extra?
Dual-axis adds a smaller increment on top of single-axis for a good deal more mechanism and maintenance. The tool shows both against a fixed frame so you can see whether the second axis ever pays for itself where you are.