Most power projects that go wrong were mis-specified, not mis-built. The good news is that the inputs that decide a project are few, and knowable in advance.
Before anyone can size a generator, choose a fuel or price a plant, five questions have to be answered. You do not need engineering training to answer them, and you do not need exact figures to start — good estimates are enough to move. But the more precisely you can answer these five, the more accurate the design and the quote will be, and the smaller the chance of an expensive surprise at commissioning.
1 How much power do you really need?
"How many megawatts?" is the obvious question and the one most often answered too simply. A generator is not sized to a single number but to the shape of your load. Three figures matter: the peak load the plant must cover, the continuous or base load it actually runs at most of the time, and the start-up load — the surge when a large motor starts. That last one catches people out: the inrush from starting a big pump or compressor can size the alternator more than the steady load does.
2 What duty — and how much backup?
The same engine is rated differently depending on how it will be used. Prime or continuous power (the plant is your main supply, running most hours) is a different rating from standby (it only runs when the grid fails) or peak shaving. Duty determines the allowable output and the maintenance regime. Tied to this is reliability: if downtime is costly, the plant needs redundancy — typically N+1, one more unit than the load strictly requires, so a fault or a service interval never stops production.
3 What electrical form do you need?
Power has to arrive in the right shape. That means frequency (50 or 60 Hz), voltage — low voltage such as 400–480 V, or medium voltage into the kilovolt range — and phases. It also means deciding how the plant relates to any existing supply: does it run off-grid in island mode, or does it need to synchronize in parallel with the grid or with other sets? These choices decide the alternator, the switchgear and whether paralleling and synchronization equipment is required.
4 What fuel makes sense?
Fuel is usually the largest operating cost, so the right choice is as much about logistics as engineering. Gas gives the lowest running cost and emissions where a supply — pipeline, wellhead or associated gas — is available. Diesel is dependable, fast-starting and needs no gas connection. Heavy fuel oil can be the cheapest per kWh for large, continuous baseload where it is economically supplied. Where gas flow is variable, a dual-fuel configuration keeps power up on diesel backup. The deciding factor is often simply what fuel you can reliably get to site.
5 Where will the plant live?
A generator's rating is quoted at reference conditions, and real sites are rarely reference conditions. Altitude, ambient temperature and humidity all reduce real output through derating — a decisive factor in the high Andes and the hot, humid Caribbean and Amazon. Site also covers the practical envelope: space and access for delivery, indoor or outdoor installation, and any noise limits. These shape not just the sizing but the enclosure, the cooling and how the plant is delivered.
The sixth question, really
There is an implicit final question behind all five: who works this out with you? Answered together, these inputs turn into a specification, a sized plant and a firm quote. Answered in isolation — or assumed — they turn into an over- or under-built plant. This is exactly why our assessment is built around these same five points: give us the shape of your load, your duty, your electrical form, your fuel and your site, and we will design to it and price it.
Ready to answer the five?
Our power-assessment form walks through each one — fill in what you know and our engineers will handle the rest.
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