Solar PV designed for heat, dust and the load it has to carry

Choosing on-grid, hybrid or off-grid

The three system types answer different questions. On-grid reduces the energy bought from the utility. Hybrid adds storage so that critical loads keep running through an outage. Off-grid supplies a point that has no mains at all.

The point most often missed: a plain on-grid system provides no backup. When mains fails, the inverter disconnects to protect people working on the network. If the goal includes keeping cameras or access control running, the design needs storage and a separate backed-up circuit, or a UPS alongside it.

On-grid and hybrid systems connected to the distribution network need approval from the utility before connection. We prepare the technical package for that application (single-line diagram, equipment data and protection settings), and the export connection is not energised until approval is given.

Designing for Saudi heat and dust

Module ratings are given at standard test conditions, with the cells at 25 °C. On a Saudi roof in summer the cells run far hotter than the air, often 70 °C or more. Crystalline silicon modules lose roughly 0.3–0.4 % of their power for every degree above 25 °C, so at peak summer temperatures output can be some 15 % below the nameplate before any other loss is counted.

Temperature also changes voltage, and that drives string design. Module voltage rises on cold mornings and falls in the heat. We size each string so that the open-circuit voltage at the coldest expected temperature stays below the inverter's maximum input voltage, and the operating voltage at the hottest stays inside its MPPT window.

Dust then reduces output further. How much depends on the site, the season and the tilt, and a single dust storm can cut output sharply in a day. We put a cleaning frequency into the yield estimate and the maintenance plan instead of assuming clean panels, and water supply and safe roof access for cleaning become design inputs.

• Inverters reduce their output when hot. We place them in shade with airflow, not on a sun-facing wall.
• DC cabling is sized for voltage drop and for derating at roof temperatures, with UV-resistant insulation and protected routes.
• Mounting structures are designed for the wind load and fixed without compromising the roof waterproofing.
• Protection: earthing, surge protection on the DC and AC sides, and clearly labelled DC isolation that maintenance staff and emergency responders can find.

Powering remote security points

A camera at the far end of a perimeter, a gatehouse or a barrier on an access road may be hundreds of metres from the nearest distribution board. Trenching, cable and a protected feeder can cost more than a small off-grid system. In those cases a pole-mounted array, a charge controller and a battery enclosure can run the device, while a wireless link or fibre carries the video.

Off-grid sizing works backwards from the worst day:

• Load: the device's real 24-hour consumption, including IR illuminators at night, heaters or fans and the radio link. Night loads matter most because they come entirely from the battery.
• Autonomy: how many days the point must run with little usable sun, through dust storms or with soiled panels. For security points this is typically two to three days, agreed with you.
• Battery: capacity for that autonomy at a usable depth of discharge, derated for temperature. Batteries go in a shaded, ventilated enclosure; in a sealed box in direct sun they age quickly.
• Array: sized for the lowest-yield month in soiled condition, with margin to recharge after a run of poor days.

We also design remote monitoring of battery voltage and charge state, so a failing point is visible before the camera goes dark.

We provide design, installation, commissioning and maintenance services. Panels, inverters, charge controllers and batteries are procured by you or your contractor against our specification.