Solar and water from air sound like a perfect match: free sunshine making free water. It works, but there is a catch most people miss. Water generators produce the most at night, when the air is most humid and your panels produce nothing.

Step 1: how much energy the unit uses

The compressor cycles on and off, so real daily use is often lower than running flat out. These are the upper planning figures.

Step 2: why the night matters

Relative humidity is usually highest between late evening and early morning, and lowest in the mid-afternoon. A generator therefore makes much of its water overnight. If it only runs on direct solar, it works mainly in the driest part of the day and production drops sharply. To get the full benefit, plan for battery storage that covers the night-time hours, or a grid or generator connection for night running.

Step 3: rough system sizes

As a planning rule, a solar panel in South Africa produces roughly 4.5–5.5 kWh per day for each kWp installed, depending on location and season. Divide the daily energy by that figure, then add margin for cloudy days and losses.

These are rough planning figures, not a design. A qualified solar installer should size your system from your site, roof or ground space, inverter and load profile, and issue the electrical Certificate of Compliance.

Practical tips

• Three-phase inverters are needed for the 1000L and 5000L.
• Several 1000L units are easier on solar than one 5000L, because you can switch units on one by one as power allows.
• Load-shedding: units pause in an outage and resume afterwards, and stored water stays available (see load-shedding guide).
• Use surplus daytime solar to run the unit in purification mode, filtering tap or borehole water, while generation is weaker.

Working with an installer

SkyTap supplies the water generators and the technical data your installer needs: power draw, supply type and expected running hours. For larger projects we can introduce you to an experienced commercial solar installer, so the water and power sides are designed together.

Questions

Can a water generator run on solar power?

Yes. Size the solar for the unit's daily energy use and add battery storage for night-time running, when humidity, and therefore output, is highest.

How many solar panels does a 1000 litre water generator need?

Roughly 45–55 kWp of panels and about 120–150 kWh of battery storage to run at full production around the clock, depending on site. A qualified installer should design the system.

Will a 20L water generator work on my home solar?

Usually yes. It draws about 970 W while running, similar to a kettle on a low setting, so it fits on most home systems with batteries.

Sources and assumptions. Output and power figures are the manufacturer's tested values for SkyTap units (1000L: about 1,000 L/day at 30°C and 80% RH, 600 L/day at 27°C and 60% RH, 135 L/day at 25°C and 30% RH, 8.7 kW). Electricity costs and solar yields are planning assumptions stated in the text, not quotes. Prices are SkyTap's published unit prices at the time of writing and are confirmed in a written quotation.

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