When purchasing a generator, the biggest consideration is size. Assessing your power requirements is integral to choosing a generator that will align with your immediate and long-term needs.
Whether you’re purchasing a generator for your home, office, or an industrial site, it’s vital to calculate the total wattage of appliances and equipment, then you’ll need to factor in additional energy consumption.
Get it wrong, and you could be left with a generator that either doesn’t meet your needs or is too powerful for your home or business.
Discover which size diesel generator you need with Solent Power.
When determining which size generator you need, the first step is to assess your needs. For example, if you’re powering a small house, you won’t need a large generator, but businesses often have lots of equipment.
Think about which appliances and equipment you’ll use the generator to power.
For example, if it’s a residential generator, it will probably power the fridge, freezer, lighting, and cooking equipment.
Commercial businesses may need the generator for IT equipment and lighting, while industrial companies have machines and equipment.
Remember, you should think about which items you’ll actually use the generator to power.
For example, some homes may choose to keep the essentials running in a power outage, while commercial and industrial businesses often need to ensure all equipment has access to electricity.
Electrical products list their wattage on either the product label or informational manual. If you can’t find a listing in watts, check for volts (V) and amps (A).
You can turn amps and volts into watts using this formula:
Watts = Amps × Volts
Some electrical appliances and equipment have different power requirements from starting up to running. You’ll need to factor this in when calculating total wattage and split the list:
Add the running wattage of each device you’ll be powering when the generator is in use. Once you have a list, it’s best to identify the highest running wattage and add it to the total.
Not only does this ensure your generator can reach peak power requirements, but it also gives you some wiggle room if you invest in more equipment.
Most diesel generators are rated in kilo-volt-amperes (kVA), while appliances use kilowatts (kW). So, when choosing a diesel generator size, you’ll need to convert the total wattage.
The difference between kVA and kW is simple:
However, generators aren’t designed to work at their full capacity, so a percentage of the apparent power converts into kW (usable power).
When converting kVA to kW, you’ll need to include the Power Factor, which is usually 80% of the generator’s capacity (0.8).
kVA = kW ÷ Power Factor
So, if you worked out your total load to be 20 kW and the power factor is 0.8, you’ll need a generator with a capacity of at least 25 kVA.
Please take a look at our comprehensive guide to discover the differences between kVA and kW.
Once you know your total wattage, you can find the right generator capacity for your needs. However, it’s always a good idea to choose a model with sufficient output, as this will ensure you have extra power when needed.
Adding a safety margin to the calculation ensures that your generator can deal with peak loads and adapt to your changing needs. For example, adding a 10-20% is beneficial, but increasing the margin can give you long-term peace of mind.
Diesel generators come in various sizes, but you can also select models based on your needs. Understanding what you’ll be using the generator for can help you when it comes to choosing the right size, power type and model.
As an authorised distributor, Solent Power offers a range of generators for all purposes. Our experts are also able to help you with the installation process, ensuring a smooth transition for your home or business.
While choosing a generator can seem complicated, once you invest in the right one, it will last for years. So, to make sure you select the right size for your needs, it’s also important to consider the following factors.
As mentioned before, the power factor determines the generator’s efficiency when converting kVA into kW. While the majority of generators have a 0.8 power factor, it can vary especially in industrial environments.
Equipment, including inductive loads and multiple motors, might decrease efficiency ratings, and you may need to invest in a larger generator.
Learn more about power factors.
When working out the required size of your generator using kWm (mechanical engine power output), alternator efficiency matters.
The alternator creates electrical energy from mechanical energy, and most have a 90-95% efficiency rating. To replace this lost power, you should apply a conversion factor.
As we mentioned before, adding a 10-20% additional capacity buffer enables you to add new equipment or appliances, and ensure your home or business benefits from power when there are spikes.
You don’t need to go overboard, but choosing a higher capacity means your generator will be a long-term solution for the future.
There are different types of fuel for generators, and the type you choose will impact maintenance, running costs, and efficiency:
Learn more about generator fuel types.
Generator noise can be a significant issue especially if you’re in a residential area or build up commercial location. Thanks to technology, silent and low noise generators run under 60 dB, ensuring they don’t cause significant disruptions.
View our range of silent generators.
To run a house, you’ll usually need a generator that runs at 5,000 to 10,000 W – but larger properties may need a higher output. Consider the following factors when sizing a generator for your home:
To run a house with three bedrooms, you’ll usually need a generator that ranges from 3 kW to 20 kW. This depends on whether you’re powering essential items or have more extensive power requirements.
The ideal size for a construction site depends on several factors, including the project’s scope, the number of workers involved, and the type of equipment needed. Generally, the site should be large enough to accommodate all necessary equipment, materials, and personnel, while also ensuring sufficient space for safe working practices and compliance with regulations
Working out a generator size for a construction site can be challenging, as your equipment needs may change. However, choosing a generator that can supply power to all of your on-site equipment is essential while ensuring a safe and productive environment.
To run power tools, a generator with a minimum running power of 2-3 kW is best. However, if you’re running tools simultaneously, it’s best to find generators in the 5-7.5 kW range or above. This prevents overloading and ensures stability.
Determine the amount of appliances or equipment you’ll need to run simultaneously, then add a buffer to ensure that they have enough power. Then, use the formulas mentioned above to calculate the generator size.
If you experience frequent power outages, make sure you invest in a modern generator that provides seamless backup support.
Again, the size of your generator for business and commercial applications depends on the amount of equipment you’ll run at once and how many watts it consumes. Small offices may be able to use a small diesel generator, but larger businesses often require something more powerful.
The average size is 25 kVA, but larger commercial and industrial businesses will require a higher capacity.
We understand that finding the right generator size can be challenging, but that’s where we’re here to help.
Solent Power provides a variety of diesel generators for all applications. Whether you’re powering a home, commercial business, construction site, or industrial business, you’ll find the right generator with us.
Please get in touch with our generator sales team today for guidance. We also offer installation support and generator maintenance services.
Solent Power Ltd (Company Number 12622565) is a company registered in England and Wales. Our registered office is located at Station yard, Bowes Hill, Rowlands Castle PO9 6BP. VAT No. 363504018