A generator is a purchase for years, so it pays to choose it consciously rather than by price alone. In this guide we show step by step how to pick a generator for your needs — for your home, allotment, construction site or as backup power.
1. What do you need the generator for?
The purpose determines the power and features you need. The most common uses:
- Home backup power — keeping the boiler, fridge, lights and pump running during outages.
- Allotment and summer house — places without a permanent grid connection.
- Construction site and workshop — powering tools, a concrete mixer, saws.
- Outdoor events — catering, sound systems, lighting.
2. How to calculate the required power?
This is the most important step. Add up the power of the devices you want to run at the same time and remember two rules:
- Starting power — motor-driven devices (fridge, pump, compressor, power tools) draw 2–3 times more power at start-up than during operation.
- Power reserve — choose a generator with a 20–30% margin so it does not constantly run at maximum. This extends its lifespan.
As a rule of thumb: 2–3 kW is usually enough to keep home basics running (boiler, fridge, lights), 3–5 kW for an allotment and light tools, and 5 kW or more for construction and heavier loads.
3. Petrol or diesel?
Petrol generators are cheaper, lighter and quieter — a good fit for occasional and emergency use. Diesel is more expensive but more economical and durable for long, intensive operation. We compare both options in detail in a separate article: Petrol or diesel — which engine to choose?
4. Inverter or conventional generator?
An inverter generator produces "clean" power with stable parameters — safe for electronics: laptops, TVs, AV equipment and boiler controllers. A conventional generator is cheaper and more powerful for the same money, but better suited to less sensitive devices — lighting, heaters or power tools.
5. Single- or three-phase (230 V or 400 V)?
For a home and typical appliances a single-phase (230 V) unit is enough. Choose a three-phase (400 V) version only if you have three-phase equipment (e.g. some workshop machines). Don't buy three-phase "just in case" if you don't need it.
6. What else to look at
- AVR — automatic voltage regulation, protects connected equipment.
- Tank capacity and runtime — how many hours the generator runs on one tank.
- Electric start — more convenient than a pull cord, useful in winter.
- Noise level — important near the house and on an allotment.
- Protection and sockets — overload protection, number and type of sockets, 12 V output.
7. Which generator to choose — quick tips
- Home backup: inverter or conventional 2–3 kW with AVR.
- Allotment and power tools: petrol 3–5 kW.
- Construction / business: a powerful 5 kW+ model, diesel for long hours.
In our shop you will find proven generators from WEIMA and other trusted manufacturers. Not sure which model to pick? Give us a call — we will help you choose the right generator. More articles in our Guides.