Inverters provide a source of AC power from a battery, when none is available from the grid or a generator. They are available in different sizes, so you simply choose the unit which will be able to supply the total load you may demand at any point in time. They can be very small if they only need to supply enough power for remote monitoring or a back-up to a security system and they can be large, capable of providing full domestic consumer loads. The length of time an inverter can deliver its rated power and also the maximum amount of power an inverter can deliver is a function of the size of the battery bank; small loads for short periods would only need a small battery bank and large loads for long periods would need a large battery bank.

Pure Sine Wave or Modified Sine Wave

The first issue to address is whether to choose pure sine wave or modified (quasi-) sine wave. Pure sine wave inverters use battery energy more efficiently and produce an output which properly reflects the mains. As such, all AC consumers will work perfectly with pure sine wave inverters. Modified (or quasi-) sine wave inverters are less efficient when converting battery energy into AC and also, they produce a 'lumpy' output such that it is not suitable for some electrical consumers (they either don't work or, work badly with modified sine wave). Today, pure sine wave technology is very common and available in low priced inverters, so there is little to justify investing your time or money buying and fitting cheap modifed sine wave inverters.

Are all pure sine wave inverters the same?

No. Pure sine wave inverters can be made in two different ways, the most common is to use high frequency technology in both the inverter stage and transformer stage. This produces a lighter, smaller and cheaper unit - but the efficiency only reaches its peak at the upper end of the load range (so for most of the time they are in service they may only be 50-60% efficient), they have poor overload capability and they are sensitive to inductive loads (eg powering electric motors). Studer AJ inverters use a high frequency inverter stage but low frequency transformer process.  This results in a slightly heavier and larger inverter - but it is extremely efficient all the away from very low loads up to full load (so for most of the time the average efficiency is likely to be in excess of 90%). This technology is very robust and reliable, copes well with inductive loads and they tolerate higher overload capacity.  When stand-by or off-grid systems rely on stored battery energy, efficiency is everything; the inverter must not waste any energy unnecessarily.



Standby Power Consumption

When an inverter is not supplying a load it still requires power to be ready to deliver a load when it is demanded. A good inverter has very low 'No Load' power consumption. Better still, the best inverters have a 'Stand-By' function which reduces their power draw still further when not delivering loads (the unit goes to sleep), until they are 'activated' by demand. Many don't have this and will drain a battery bank rapidly even when they are doing nothing. Inverters which have a high 'No Load' power consumption and worse still no 'Stand-By' function, are not suitable for off-grid back-up systems powered by small solar panels with small battery banks. The Studer AJ family of inverters have extremely low 'No Load' power consumption and all have 'Stand-By' function to reduce power draw even further.

Built-in Solar Regulator

If the inverter is being used to convert solar generated battery energy, then for a simpler installation, Studer inverters can be purchased with the option of a built in solar regulator.

Battery Lifetime Optimisation

Repeated heavy depletion of the battery bank without properly recharging of the batteries afterwards will ultimately result in a ruined battery bank. So, when the Studer AJ inverter detects this behaviour, it adjusts the low voltage shutdown parameter automatically to switch off earlier and prompt recharging sooner, resulting in better recharging of the battery bank.


Victron Inverters

We can also provide a range of Victron inverters. Please contact us for more information.


AJ Inverter Range

To view Datasheets & Manuals, click on the Downloads tab above.

Model Inverter Power VA (30 min) Inverter Peak Power VA (5 sec) Voltage
275-12 275 450 12
500-12 500 1000 12
1000-12 1000 2200 12
2100-12 2100 5000 12
350-24 350 650 24
600-24 600 1200 24
1300-24 1300 2800 24
2400-24 2400 5200 24
400-48 400 1000 48
700-48 700 1400 48

All AJ series power inverters are also available in 120 VAC / 60 Hz - use (-01) suffix.



Click on the links below - the document will open in a new window and can then be saved or printed.

Studer - All Products

Studer Catalogue

Studer Inverters

Studer AJ Series Datasheet
Studer AJ Series User Manual

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