Vicaya GlobalCalculator · Solar · orientation optimizer
What is your roof angle actually costing you?
Every tilt and every compass bearing, simulated separately and shown at once. Not "what will my roof produce" — that is the output calculator — but how far your roof sits from the best one available at this latitude.
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.
If your roof is pitched between 10° and 50° and faces anywhere within 60° of south, there is a 52% chance it is already within 5% of the best orientation available here.
Across the whole chart that share is only 11%, because the chart includes north-facing walls that nobody would choose. That gap is the point. Orientation is not a dial to be tuned — it is a cliff to be avoided. The worst orientation shown loses 55% against the best, but almost all of that loss is concentrated in orientations you would never propose. Once a roof is roughly right, the exact angle stops being what limits the system.
The whole surface
Show the surface as a table
| Tilt | 0° | 30° | 60° | 90° | 120° | 150° | 180° | 210° | 240° | 270° | 300° | 330° |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0° | 91% | 91% | 91% | 91% | 91% | 91% | 91% | 91% | 91% | 91% | 91% | 91% |
| 10° | 85% | 86% | 88% | 91% | 93% | 95% | 96% | 95% | 93% | 91% | 88% | 86% |
| 20° | 79% | 80% | 84% | 89% | 94% | 98% | 99% | 98% | 94% | 89% | 84% | 80% |
| 30° | 72% | 74% | 79% | 86% | 93% | 98% | 100% | 98% | 93% | 86% | 79% | 74% |
| 40° | 66% | 68% | 74% | 82% | 90% | 97% | 99% | 97% | 90% | 82% | 74% | 68% |
| 50° | 60% | 63% | 69% | 78% | 87% | 94% | 96% | 94% | 87% | 78% | 69% | 63% |
| 60° | 55% | 58% | 64% | 73% | 82% | 89% | 92% | 89% | 82% | 73% | 64% | 58% |
| 70° | 52% | 54% | 60% | 67% | 76% | 83% | 86% | 83% | 76% | 67% | 60% | 54% |
| 80° | 49% | 50% | 55% | 62% | 69% | 76% | 78% | 76% | 69% | 62% | 55% | 50% |
| 90° | 45% | 46% | 50% | 55% | 62% | 68% | 70% | 68% | 62% | 55% | 50% | 46% |
How to read this
The dark band across the middle of the chart is the plateau. Anywhere inside it, orientation is not what limits the system — panel count, shading and budget are. The pale region is the cliff: the worst orientation here collects 55% less than the best, and no amount of extra panel efficiency recovers that. Read the chart to find out which side of that edge you are on, not to shave a degree off the top.
Two things this surface does not know about your roof. It assumes nothing shades it, and a single obstruction can outweigh every difference shown here. And it ranks orientations by annual total, which is the right measure when exports pay well and the wrong one when they do not — if you are paid little for what you export, a west-facing array that generates into the evening while you are home can be worth more than a south-facing one that produces more in total.
Frequently asked questions
What is the optimal solar panel angle?
Roughly your latitude gives the best annual total, but the honest answer is that it depends on what you are optimising for. This tool shows every tilt and bearing at once as a yield surface, so you can see the cost of the roof you actually have rather than chasing one ideal number.
As a solar panel tilt angle calculator it also shows how much output you give up at the angle and direction your roof already has.
Which direction (azimuth) should solar panels face?
Toward the equator — south in the northern hemisphere, north in the southern — gives the most annual energy, though an east–west split can suit self-use better. The optimizer shows the yield for every bearing so the trade-off is visible instead of assumed.
Do solar panels have to face south?
No. South is best for total output, but east or west typically loses only a modest amount and can line up better with when you use power. The tool gives the exact figure for your latitude, so you can see what your own roof costs.