Choose a direction that matches your savings goals. Model annual output and bill credits quickly. Get clear angles, losses, and cashflow for decisions smarter.
| Hemisphere | Goal | Roof azimuth | Recommended | Deviation | Loss | Adj. annual kWh |
|---|---|---|---|---|---|---|
| Northern | Maximize annual | 210° | 180° | 30° | 2.00% | 7,220 |
| Northern | Favor afternoons | 240° | 205° | 35° | 2.72% | 7,160 |
| Southern | Favor mornings | 30° | 25° | 5° | 0.06% | 7,360 |
Δ = min(|A−R|, 360−|A−R|)loss% = clamp(18 × (Δ/90)², 0, 25)E₀ = kW × PSH × 365 × PRE = E₀ × (1 − loss%/100)v = s×retail + (1−s)×export, where s is self‑consumption fraction.V₁ = E × v − O&MNPV = −Capex + Σ( (Vᵧ)/(1+r)ᵧ ), with yearly degradation applied to E.Azimuth sets the compass direction your modules face, and it changes when production peaks. The best direction matches your consumption pattern, tariffs, and roof limits. A shift toward morning can reduce evening imports, while a westward shift can support later loads. This calculator compares those tradeoffs in a single framework.
Use true‑north bearings where possible: 0° points north, 90° east, 180° south, and 270° west. If you know a magnetic bearing, correct it with local declination before entering it. Confirm roof orientation with a compass app, satellite imagery, or a site plan. Accurate bearings matter because a few degrees can move modeled loss and cashflow.
The recommendation starts from the hemisphere baseline and applies a goal offset. Deviation is the shortest angular distance between your selected azimuth and the recommended azimuth. The model applies a conservative loss curve that grows with the square of deviation, capped to avoid extreme assumptions. The Plotly chart shows adjusted annual energy across azimuth angles so you see the best zone.
Annual energy is estimated from system size, peak sun hours, and a performance ratio that captures typical losses. Financial value uses a blended rate: self‑consumed energy is valued at the retail rate, and exported energy is valued at the export credit. Subtract annual operations and maintenance to estimate net year‑one value. By changing self‑consumption, rates, or costs, you can stress‑test scenarios. Include O&M and check incentives, because they can materially change returns today.
Long‑term planning needs time value of money and output degradation. NPV discounts each year’s net value using your chosen discount rate and reduces energy using an annual degradation factor. A positive NPV suggests the project meets your hurdle rate, while simple payback offers an intuitive timeline. Use both together, and revisit assumptions when tariffs or usage patterns change.
For maximum yearly energy, panels usually face about 180° (true south). If your roof forces another direction, enter the roof azimuth and compare the modeled loss and financial metrics.
Azimuth is measured from true north. 0° is north, 90° is east, 180° is south, and 270° is west. Keep values between 0 and 359 degrees.
Loss reflects how far your selected azimuth deviates from the recommended azimuth. The model uses a conservative, capped curve to help planning, not to replace detailed site simulation.
Estimate the share of solar energy you will use on-site, based on daytime loads and any storage. Higher self-consumption increases the blended value rate when retail rates exceed export credits.
Installed cost, retail and export rates, peak sun hours, performance ratio, discount rate, and degradation typically dominate NPV. Adjust these first when running scenarios to understand risk.
Yes. Simple payback divides installed cost by year‑one net value. Use it as a quick check, then rely on NPV and IRR for a fuller view over the entire project life.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.