Studer Xtender XTM 3500-24
Studer Xtender XTM 3500-24
Xtender Inverter/Chargers provide a seamless supply of AC power, acting as battery chargers when there is a source of mains, or inverters when there isn't. The Smart-Boost function enables inverter power to be added to either shore-power or generator. Fully programmable with adjustable charger output.
Convenience and Ease of Installation
Inverters produce an AC mains output from a battery bank DC supply. In many cases this is used as a back-up in case a grid supply fails. Once the grid comes back on line, the inverter is no longer needed, but we need to replenish the energy consumed from the battery bank. So, we could simply attach a battery charger to the battery bank and now, supplied by the restored mains power, it will charge the batteries ready for the next outage. Alternatively, if the relationship between the amount of inverter power needed and the charge rate to replenish the batteries afterwards is a commonly used one, then we can use an all-in-one inverter charger unit. With fewer connections and a smaller unit size overall - it is a neat solution.
Game Changing Functionality
Early units simply combined the two functions of inverter and charger, switching between these functions automatically. Today, the more advanced inverter-chargers have an added function; they can add inverter power to the mains power being supplied. When required, the inverter function will connect seamlessly to the supply power and give a boost to a low power supply when demand temporarily peaks above what is available (such as from a weak grid or small generator). When the demand drops back down below the level of supply from the mains input, the charger function uses the some mains power to recharge the batteries - putting back the energy used, until next time. This ability to 'parallel' inverter power with a mains supply has profound implications for the design of modern power management systems in terms of maximising efficiency.
New property development
In developed countries there are places we may wish to build a new house but the grid supply is too low. If the property has a peak power demand which is higher than is available, there may be the option to have the utility supplier provide more power by upgrading the supply, such as converting to 3-phase or similar. But, even if possible, this can be expensive. The better solution is to use a Studer Xtender system to provide that extra boost when needed. If the development is also going to have a solar installation, on the roof for instance, then we can begin to build a hybrid system. This will enable the property to benefit in more than one way; it will have protection against overloading the weak grid supply and it will have grid failure back-up (anti-blackout). If grid-feeding is part of the desired outcome (to benefit from Feed-in-Tariffs), then the Xtender can be programmed to work with grid connected inverters and grid-feeding in conjunction with a suitable anti-islanding protection system (G83 or G59).
Reducing the size of generator needed
For a fully off-grid or standby power system, it is common to use, as a source of power, a diesel generator. Traditionally, to ensure we can meet the needs of all consumers, it would be necessary to choose a large generator which then spends the majority of its operating life running at relatively low levels of power. This is not efficient in terms of fuel consumed and will cause premature wear to the engine. It is better for diesel generators to operate as close to their optimum power level for as much of their life as possible. The use of inverter chargers such as the Studer Xtender with a mains boost function, allows us to select a smaller generator; one which is sized to meet the 'average' load demanded and then let the inverter charger take care of any additional, temporary, periodic power demands.
The Hybrid Power System
The ability of a Studer Xtender to work with a source of mains and use a battery bank as a 'reservoir' of energy, leads us to consider the battery bank as a focal point of energy storage and it becomes more important than just for short term 'back-up'. The battery bank can now be fed with as much energy from renewables as is practical such as from solar, wind turbines or water turbines. In the case of solar, an Xtender can use the output from AC coupled inverters as well as making use of energy supplied via DC coupled MPPT charge controllers. Direct AC from a grid inverter output of solar panels can be 'back-fed' through an Xtender to charge up the batteries, used directly or even sent back to the grid (with the addition of an anti-islanding device to comply with local regulations). We now have the tools for a sophisticated power management system which combines all the resources available to us in one automated package - the heart of which is the modern inverter/charger. See the Applications page for more information.