---
title: "Solar output in winter: what's normal in Gauteng"
description: Why solar output changes through the year in Gauteng, what a normal winter dip looks like, and when lower production means a fault.
image: https://cleanvolts.co.za/hubfs/solar-output-winter-gauteng-featured.png
---

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![Solar panels on a Gauteng home on a clear Highveld winter morning with dry grass and low sun](https://cleanvolts.co.za/hs-fs/hubfs/solar-output-winter-gauteng-featured.png?width=1200&height=630&name=solar-output-winter-gauteng-featured.png)

# Solar output in winter: what's normal in Gauteng

![Tony Lopes](https://cleanvolts.co.za/hs-fs/hubfs/clean%20volts%20launch%20post.png?width=48&height=48&name=clean%20volts%20launch%20post.png)

 Tony Lopes

November 6, 2026

**Short answer:** Gauteng winters are dry and mostly cloudless, so output drops mainly because the sun is lower and the days are shorter, not because of cloud. A typical north-facing system makes roughly 15% to 30% less per day in June and July than in its best months. A drop well beyond that, on clear days, points to a fault.

*Last updated November 2026.*

Many owners notice their solar app showing lower numbers from May and worry something has broken. Usually it's the season. This guide explains the yearly pattern on the Highveld and how to tell a normal dip from a problem worth a [Solar Health Check](https://cleanvolts.co.za/health-check).

## **How much less do solar panels produce in winter in Gauteng?**

| Season | What happens | Typical daily output |
| --- | --- | --- |
| **Spring (Sep to Oct)** | Clear skies, longer days, cool panels. | Often the best months of the year. |
| **Summer (Nov to Feb)** | Long days, but afternoon thunderstorms and hot panels. | High on clear days; storm days can be much lower. |
| **Autumn (Mar to Apr)** | Clearing skies, sun dropping lower. | Steady, slowly falling. |
| **Winter (May to Aug)** | Dry and clear, but a low sun and short days. | Lowest in June and July, roughly 15% to 30% below the best months for north-facing roofs. |

Roof direction and tilt change this pattern. Low-pitched east or west roofs lose more in winter; steeper north-facing roofs lose less.

## **Do solar panels work on cloudy days?**

Yes, but far less. On a heavily overcast day output can fall to 10% to 30% of a clear day. In Gauteng, cloudy days are mostly a summer feature, which is why summer output can be patchier than winter's.

## **Why is summer output sometimes lower?**

Heat and storms. Panels lose efficiency as they get hotter, roughly 0.3% to 0.4% for every degree above 25°C at the cell, and summer afternoon storms cut production. Dust after a dry winter also lowers output until the first rains or a clean. See [when to clean your solar panels](https://cleanvolts.co.za/guides/when-to-clean-solar-panels).

## **When does lower output mean a fault?**

- **Compare with the same month last year,** not with summer. A drop of more than 10% to 15% on similar clear days is worth a look.
- **Watch for sudden steps** rather than gradual change. A string or connector failing shows up as a sharp, lasting drop.
- **Check for new shade.** In winter the low sun casts long shadows from trees, walls and neighbouring buildings that miss the panels in summer.

Our guides to [an underperforming solar system](https://cleanvolts.co.za/guides/is-my-solar-system-underperforming) and [reading your inverter app](https://cleanvolts.co.za/guides/how-to-read-solar-app) go further.

## **Frequently Asked Questions**

### **Do solar panels work on cloudy days?**

Yes, at a fraction of normal output, often 10% to 30% of a clear day under heavy cloud.

### **Which months produce the most?**

In Gauteng, usually September and October: clear skies, longer days and cool panels.

### **Why is summer output sometimes lower?**

Hot panels lose efficiency, and afternoon thunderstorms cut production.

## **Where We Fit In**

If your output has dropped more than the season explains, CleanVolts arranges a Solar Health Check with a registered [CleanVolts Approved](https://cleanvolts.co.za/cleanvolts-approved) installer, who contracts with you directly and does the work. If the installer pays us a referral fee, we tell you up front.

[**Book a Health Check**](https://cleanvolts.co.za/book-an-audit)

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## Keep reading

### [![Homeowner checking a solar monitoring app next to a wall-mounted hybrid inverter](https://cleanvolts.co.za/hs-fs/hubfs/how-to-read-solar-app-featured.png?width=1200&height=630&name=how-to-read-solar-app-featured.png) How to read your inverter app](https://cleanvolts.co.za/guides/how-to-read-solar-app)

### [![Aluminium solar mounting rails fixed to a concrete-tile roof of a South African house](https://cleanvolts.co.za/hs-fs/hubfs/roof-types-and-solar-featured.png?width=1200&height=630&name=roof-types-and-solar-featured.png) Roof types and solar: tile, IBR, slate and flat roofs](https://cleanvolts.co.za/guides/roof-types-and-solar)

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