See what's happening - users can see their consumption, statistics and credit balance on their smartphone, on the Internet or on a wall terminal in their apartment at any time. Administrations and organisations have a configurable and powerful interface via the PayU Manager, which enables, among other things, the monitoring, evaluation and administration of users, budgets and credit balances. Thus, a sensible use of monitoring and prepaid systems for water kiosks for the fair distribution of water is possible, up to the extensive management of individual dispensing points or many apartments in properties. Based on the budgeted dispensing of water, electricity and heat.

In our iSAtech PayU Cloud, all data for processing converges. According to the requirements of the application, data is collected from different sources, stored and processed. The connection of third party systems to process the data or to record transactions, such as credit top-ups, is easily possible. The PayU-Cloud is thus the central interface for the sensible use of data from the field, the extensive and transparent evaluation as well as the budgeting, billing and control/release of the levy.

The dispensing and consumption data can be collected via different systems in the field. For example, by means of the iSAtech prepaid dispensing systems that are connected by radio or cable. Alternatively, the data can also be collected via field buses such as MBUS, radio (LoRa) or via interfaces to other systems. The active control of dispensers, e.g. the activation and deactivation of the water/power supply, can be realised with the iSAtech GLT control unit.

Pay as you use

The user loads up a credit and can use it directly, e.g. for water or electricity. They only pay for what they actually use. A tariff system allows different billing of user groups as well as time-related volumes. If the system is operated with online credit, the user can also purchase and use credit directly with his mobile phone. He has a full overview of his costs at all times.

Budget system

The user is provided with a budget for one year, for example. All consumption, whether water, electricity or heat, is charged. The user can check his residual budget and consumption at any time. If the budget has been used up, credit can simply be purchased.

Scalability and reliability

In order to achieve high reliability and good scalability, the prepaid dispensing system was developed as a cloud-edge software system in cooperation with the Fraunhofer Institute for Open Communication Systems. For this purpose, the aspects of data security were also specifically taken into account. High-performance communication protocols and a distribution of data streams and computing load enable a robust and well-scalable operation of the system.

NFC cards offline and online

The iSAtech Prepaid Meter System can be used offline and online with NFC cards. The user tops up credit either via the iSAtech PayU Manager app, via the internet or by mobile phone. The user is assigned to a tariff that defines how much water, electricity, etc. he gets for his credit. The credit can be used at any time at a dispensing unit, e.g. at a public water dispensing point such as the Public Water Taps (Water-ATM). The user draws the water he needs, and the credit is reduced accordingly. If he loads the credit onto a dispensing system in his own house/apartment, e.g. via a STS token, he can draw electricity permanently until the credit is used up.

System integration

The dispensing system was designed for easy integration into existing infrastructures. The online system can connect to various payment and billing systems via multiple interfaces. The system can also be connected to existing administration and online systems and flexibly customized. The connection of existing smart meter systems is also possible, as integration into existing network infrastructures.

System architecture

iSAtech PayU Manager Cloud
Technical overview iSAtech PayU Manager Cloud

Data collection

Consumption data, whether water, heat, or electricity, can be collected by the iSAtech prepaid control unit. For this purpose, the control unit is connected to the meter's pulse output. Alternatively, meters can also be connected via wMBUS using the iSAtech gateway, or already installed smart electricity and water meters can be connected via web services. This makes it easy to set up new installations as well as to integrate existing systems into the iSAtech Prepaid Metering Cloud quickly and without significant effort.

Control of the dispensing

The control of the water, electricity or heat supply can be realised via any actuators such as contactors, valves, or ball valves. The actuators are connected directly to the iSAtech prepaid metering control unit. A battery can power the control unit. If online communication is required, the online connection occurs via cable or radio (LoRa) to the iSAtech gateway.

Alternatively, credit tokens can be generated according to the STS(Standard Transfer Specification) and sent or provided with SMS.

Integration into infrastructure

For the integration and extension of the iSAtech Prepaid Metering System, additional systems can be connected via various web services REST-API interfaces. This allows the iSAtech Prepaid Management System to be extended as desired or also integrated into existing infrastructures. Particular values can be published on websites, or billing data can be transferred directly to accounting.

Counter structures, user structures and account structures

The core of the PayU management system represents all connected meters in a virtual tree structure. This allows dependencies between meters as this is necessary for collecting and processing of e.g., tenant electricity installations or water supply infrastructures. The mapping of user groups, which can also be clustered, and the structured credit accounts enables the differentiated allocation and billing of services.

Accounts are topped up with credit via payment systems and budget systems. This can be done manually and automatically. Automatic recharging can take place cyclically with monthly, daily or annual budgets or depending on specified transactions. Furthermore, the recharge can be automated through connected payment systems.

Dependencies and rules

If required, rules and dependencies can be defined between meters, accounts, and users. This allows, among other things, the provision of credit on accounts to be defined as a function of payment transactions.

Both trader systems for the distribution and trading of water and tenant electricity models for the billing of electricity generation and electricity use can be realized in this way. The system also makes it possible to automatically manage reserve and maintenance accounts or to regulate the provision of water depending on availability.

Functionality of the water kiosk

iSAtech's prepaid metering system provides easy and secure access to clean potable water, electricity, heat, or gas. Credit is loaded onto an NFC card as prepaid credit or as a budget via the PayU-Manager app or accessed online via mobile phone and internet. The credit can be used to tap water and electricity, such as the Public Water Tap or in a home. The iSAtech prepaid metering system allows easy credit allocation, billing, and secure monitoring of all consumption and transactions.



A comprehensive management system is offered for the administration of the prepaid meter system, users and tariffs as well as for topping up the credit balance, which can be used both online and offline. With this system the dispensing units, user data, budgets and tariffs can be managed. The management system can be linked to existing online systems or operated alone. The scope of the management infrastructure can be flexibly adapted according to the complexity of the dispensing units.


All transactions at the dispensing units can be traced back to the time and user-specific. Using the management software and the iSAtech Cloud Service, the data can be viewed in real time and graphically analyzed.

Flexible pricing and budgeting

Flexible dispensing profiles can be defined with prepaid credits and budgets at different prices. On the basis of these profiles, utilities can provide fixed quantities of water and electricity and charge a flat rate. If the budget is not sufficient, you can make subsequent flexible payments.

The software: PayU Manager

The hardware: Control unit for outdoor installation or for building installation

Prepaid Meter Control Unit

iSAtech's prepaid metering system basically consists of a server cloud system and optionally of intelligent, networked dispensing systems for the prepaid or budgeted dispensing of water, electricity, heat and gas.

The prepaid meter control unit is the local control unit of the prepaid management system. Various water and electricity meters, valves, and contactors can connect to the prepaid meter systems. The credit is loaded from the NFC card or automatically transferred via the internet. Gateways are used to transfer the data between the control unit and the server cloud system. These gateways are connected to the internet via ethernet or radio (GSM/LTE/Wifi). The communication between the gateways and the control units in the field is realized by cable (bus system) or radio (LoRa).

The dispensing is effected by opening the valve or by the installation contactor during current dispensing. The connected meter measures the consumption. The Controller Unit calculates the consumption of credit based on the tariff and closes as soon as the credit is used up or as soon as the dispensing is stopped. The Controller Unit can be powered by a rechargeable battery or by an external power source (e.g. solar energy).

The dispensing system can be selected either in the form of a mounting variant for installation on a DIN rail or as a robust, remote control unit for outdoor installation.

Fields of application

Water kiosks with NFC credit cards

A water kiosk provides access to water at public places.

Water kiosks Online

iSAtech prepaid system for water kiosks. Credit is topped up online or by phone.

Prepaid water for industry and irrigation

Especially in remote areas, a tanker filling station with the prepaid meter simplifies the billing of bulk water customers.

Water and electricity quotas

The modern possibility to provide electricity, water and heat in properties transparently and without costly service charge billing.

Water and electricity for students

The modern and easy way to bill student apartments for electricity, water, heat and washing machines directly online via smartphone, securely and without administrative effort.