What size generator do I need for a construction site in Saudi Arabia?

Add up the nameplate ratings of everything that will be connected, apply a demand factor of about 0.5–0.8 depending on how much runs at once, convert kW to kVA by dividing by a power factor of about 0.8, add 20–25% headroom, then check that the set can also absorb the starting surge of your largest motor. Round up to the next standard class. A small villa site often lands between 40 and 60 kVA; a mid-rise site with a tower crane, site offices, and welding bays usually lands between 150 and 250 kVA.

What is the difference between kW and kVA?

kW is real power — the work actually done. kVA is apparent power — what the alternator and cables have to carry. They are linked by power factor: kVA = kW ÷ PF. Diesel generator sets are almost always rated at a power factor of 0.8, so a 100 kVA set delivers 80 kW. Generators are sold in kVA because the alternator is limited by current, not by useful work, and an inductive load draws more current for the same output.

Why does motor starting current matter so much when sizing a generator?

A motor started direct-on-line draws about 6–7 times its running current for a few seconds at a poor power factor. On a grid connection that surge is absorbed by the network; on a generator it has to come from one engine and one alternator. If the set is too small the voltage dips, contactors drop out, protection trips, and the site stops. Soft starters typically cut the surge to around 2–3 times running current and variable frequency drives reduce it further, which often lets you rent a smaller, cheaper set.

How much does it cost to rent a generator in Saudi Arabia by kVA class?

Typical market rates start from around SAR 800/day for small portable units (20–100 kVA), around SAR 2,500/day for medium sets (100–500 kVA), around SAR 5,000/day for large industrial sets (500–1500 kVA), and around SAR 8,000/day for mega power sets (1500–3000+ kVA). Monthly contracts typically work out cheaper per day. Fuel, maintenance, and insurance terms are agreed with the owner, and the final quote comes from the owner.

Is it bad to rent a generator that is too big?

Yes. A diesel set that runs for long periods below about 30% of its rating suffers from wet stacking — unburnt fuel and soot accumulate in the exhaust, cylinder bores glaze, and efficiency falls. You also pay a higher day rate, burn more fuel at idle, and pay more to transport a heavier machine. Aim for an average loading of roughly 50–70% of the prime rating, and if the load genuinely is that light for now, rent the smaller class and revisit it when the site scales up.

How much output does a generator lose in Saudi summer heat?

Generator sets are rated at ISO reference conditions of roughly 25°C near sea level, so a 45–50°C site is well outside the reference and both engine and alternator lose output. The exact loss is model-specific and commonly falls in the 5–15% range at those temperatures, with additional altitude derating in higher cities such as Taif and Abha. Ask the owner for the manufacturer's derate curve for the specific model and confirm the set has a high-ambient radiator, then base your headroom on the derated figure.

Should I rent one large generator or two smaller ones?

Two smaller sets give you redundancy and let you shut one down during light periods so the running set stays in a healthy load band — useful when day and night loads differ sharply, or when a stoppage is expensive. One large set is simpler to fuel, connect, and supervise, and usually costs less per kVA. If you split the load, either keep the circuits separate or use sets and controllers designed for paralleling; do not connect two generators together without a proper synchronising panel.

What information should I send when asking for a generator quote?

Send the kVA class you calculated, the largest motor and how it is started (direct-on-line, soft starter, or VFD), the city and site address, the rental duration, whether you need a soundproofed canopy, the voltage and phase you need, and who will supply fuel. That is enough for an owner to come back with a real quote instead of a range. Delivery is arranged with the owner when you book, and the documents the owner holds for the machine are collected before the rental is confirmed.

What size generator do I need?

A practical kVA sizing method for Saudi sites — add your connected loads, allow for motor starting current, apply power factor and high-ambient derating, then pick the next standard class — with typical market day rates from around SAR 800/day.