The Bushlight India Project
	Hardware

Bushlight India Village Solar Energy Systems are a standardised technology package that utilise a number of project specific hardware which provide both centralised as well as decentralised load management functionality. The systems are comprised of a solar PV array that feeds to a central Power Conditioning Unit (PCU – a single unit combining an inverter, charge controllers and battery charger), which manages the charging of the centralised battery bank and outputs high quality 50Hz, 230V AC electricity to a main System Control Board (SCB). The SCB doubles as an AC distribution board and directly feeds power onto the main distribution system with dedicated lines for the different load types in the community (households, community and commercial buildings, streetlights and the powerhouse). Each building is connected via an Urja Bandhu, a load controlling device. Bushlight India systems also have the capacity to accept direct input from an alternative source (eg generator).

The aim of the Bushlight India Project was to develop an optimised model for remote village electrification using renewable energy. Given India's long history of renewable energy technology development and the significant differences between remote Aboriginal communities and India's remote villages, a collaborative approach to the development of the model was needed. The process adopted involved an initial series of workshops and ongoing review and communication that effectively brough together the skills and experiences of the Bushlight Project in Australia, with those of a range of organisations and individuals working in the rural energy sector in India including grassroots community organisations, technical companies and agencies and government organisations.

One of the most important initial discussions centred around the identification of major lacunae in current models and approaches to remote village electrification through decentralised generation systems. Three of the major issues identified during these discussions which it was decided the model should try and address were: equity, reliability and safety.

• Equity related to being able to ensure that each and every user connected to a system could reliably access a known amount of energy for which they would pay a fixed cost. Most DG systems operate for only a fixed number of hours every day (evening) with no control over actual energy use at a household level, meaning tariffs were not reflective of actual energy use and availability usually dependent on others usage. 
• Reliability related to the importance of being able to ensure access to energy every day, with quality of power also a major factor. Energy, specifically electricity, is a major enabler of livelihoods, however, people are unable to effectively plan or develop electricity dependant livelihood activities without a reliable supply; reliability of access being more important than the actual quantum of energy accessible.
• Safety related to both personal safety as well as safety of supply. Power theft is a common problem even in small centralised DG power systems so deterring 'hooking' was a major issue that needed to be addressed as was ensuring the safety of the power system itself from theft.

These needs were duly incorporated into the Bushlight India Model as it was developed and resulted in the development of a number of technical responses. The issue of safety was principally managed through the use of materials readily available in the market (insulated and armoured cables, cable piercing clamps, security bolts and secure compound fencing and lighting). Addressing the issues of equity and reliability however led to the development of two pieces of project specific hardware. Although unexpected at first, these now look to have significant potential impact on all such future work in the country.

Urja Bandhu

The Urja Bandhu or "Energy Friend" is a adaption of the Energy Management Unit (EMU) developed and used by the Bushlight Project in Australia, with most of the complexity and additional functionaility removed. In essence, the Urja Bandhu is a display and control unit which displays the current availability of the programmed daily budget through its five indicator lights, and cuts off power if this budget is exceeded during a 24 hour period. Each unit is remotely programmed by a handheld, universal programmer, with values for the internal clock, energy budget and budget reset time. The programmer can read and programme values into any Urja Bandhu.

With an Urja Bandhu installed in all buildings connected to the system, the maximum total daily demand (in kWh) becomes fixed: it is the total of all daily energy budgets programmed into each Urja Bandhu, plus streetlighting loads (either on a timer or dusk-to-dawn switch). This effectively eliminates the risk of the system battery bank being over discharged while at the same time ensuring every consumer can access their daily energy budget whenever they want. With the energy budgeting activity of the Village Energy Planning process involving every household determining their daily energy budget themselves, this maximum total then becomes a known limit essentially set by the people themselves; an important part of the process of educating people about the limitations of a solar PV system and building community ownership over the system.

The Urja Bandhu was designed by CAT Projects and engineered and manufactured by Mansi Technologies in Ahmadabad. The units installed in the two demonstration systems established as part of the Bushlight India Project included a custom made switchboard installed below the Urja Bandhu, with the whole unit mounted on a standalone steel post fixed into the floor. The total cost of this unit was a little over Rs 3000. 

System Control Board (SCB)

The SCB is a ‘smart’ central distribution board with four individually monitored and controlled outgoing feeder lines through which the different load types within the community are segregated. This allows a high degree of definition for monitoring power usage (including any power theft) and identifiying faults. The SCB also incorporates an automated battery voltage based load-shedding system whereby power is disconnected on a prioritised and programmable basis to different load types during extended periods of low sunlight, thereby avoiding the need for total system shutdown. An intuitive, image based interface fixed over the SCB provides easy to read information about the status of the system and allows operators to easily monitor system performance and identify any faults..

The SCB was designed by CAT Projects and engineered and manufactured by OPSI in Kolkata, the same company who supplied the PCUs for the demonstration systems. The SCBs are installed next to the PCUs on a raised platform in the main control room of the powerhouse and are designed to be the main 'point of contact' for the system operator, providing all the information they need to know about the status of the system.

The Urja Bandhu and System Control Board are the major technical components of the demand side management strategy of the Bushlight India Model, which along with the information and education components of the VEP, and the user training delivered post-installation, work together to ensure that systems are protected from damaging overuse, while ensuring that people have reliable daily access to the amount of energy identified and planned for during the VEP.