An inverter changes one power type to the other. In off-grid solar we regularly talk about off-grid inverters. These convert the DC power of a battery power store into 230w AC power so that you can use your appliances. They are an essential component of any off-grid solar system as without it, all that potential energy stored in your batteries cannot be used to power your property.

Victron MultiPlus Pure Sine Wave Inverter Charger 3000w


Inverter/chargers do the same job as an inverter. The charger part adds an extra input that allows power to be fed into the system to pass through to the plug sockets and/or charge the batteries at the same time. Effectively, an input from a mains power supply or generator that charges the batteries and power the devices directly, possibly at a higher power capacity than the inverter itself. It charges the batteries at the same time.

When the input is not active it works as a singular inverter and powers the devices from the battery power.

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Types of Inverter/Charger

Inverter/chargers come in many types and with many phrases attached. Phrases such as Pure Sine Wave, Quasi Sine Wave and Modified Sine Wave. We tend to recommend Pure Sine Wave for systems that will provide power 24-hours a day and Modified Sine Wave inverters for leisure purposes such as caravans, boats and campers.

Pure Sine Wave inverters are more expensive than Modified Sine Wave but produce cleaner energy suitable for home use. Modified Sine Wave energy is referred to as ‘dirty’ as the voltage is provides isn’t as refined. This is partly down to lower quality construction which is reflected in its lower price.

If cost isn’t an issue, we would recommend using Pure Sine Wave inverters wherever possible. Where budget constraints require efficiencies, Modified Sine Wave inverters are suitable for leisure use or where dirty power won’t be a factor.

Sizing an Off-grid Inverter

It is essential that you have a large enough capacity inverter to power the largest power requirement of your solar power system. You need to exceed the maximum requirement of your system so as not to stress the inverter and shorten its operating life.

For example:

In a camper you may want an inverter to run an electric bike charger which is 200w. so a 250w inverter would be ideal.

In a home you may have an oven, fridge, lights and appliances so you need to add them up and make sure that the worst-case scenario is covered by the available power the inverter can output. If you ask more from the inverter than it is designed for will be an overload and overheat shutdown to protect itself.

Refer to ‘How to size an off-grid solar power system’ for more guidance on the power requirements of a solar power system.

Selecting Your Off-grid Solar Inverter

Inverters typically come in 12v, 24v and 48v sizes. The lower the voltage, the higher the efficiency. You should always try to keep the current as low as possible to keep the efficiency up. Anything over 30A DC for example, you should then look to see if the next battery voltage can work.

Caravans, campers and motorhomes are typically 12v so it is difficult to upgrade to a 24v or 48v system. Off grid homes however can easily use 48v systems. This reduces the Amps and current at DC level by 4x.

Ensure that the cable size meets manufacturers guidelines. These tend to be very large to handle the power. Also ensure that fuses are used where needed to protect any cables from potential shorting out and short circuits.

Most of the inverter we supply are from Victron which is a renowned brand for quality. At the price point they are at the leading edge of communication and technology and have outstanding backup and support, they are a very good option. Manufacturers such as Studer and SMA are perhaps the best known for ultra-high quality and reliability.

Contact Sunstore with any questions or issues you have with planning your off-grid solar power installation. We would be more than happy to help!

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