A typical solar mini-grid supplies about 30 KW to 60 KW of power. 30 KW is a typical module for a 200-household village to meet most energy needs at the household level.
Solar mini-grids: Electrifying rural households, businesses, and communitiesElectrification
Solar mini-grids offer the most widely applicable and viable mechanism to provide electricity for under-served rural areas of South Asia and Sub-Saharan Africa, where sunlight is abundant through most of the year. First, the policy environment in many countries has been increasingly supportive of renewable energy. Simultaneously, in the last decade, both the cost and availability of solar photovoltaic (PV) technology has been steadily improving, and unlike a few years ago, solar power systems now are modular and scalable based on the needs of the users. Countries like India have many manufacturers who are capable of producing the necessary components at scale.
Unfortunately, a number of critical hurdles are still keeping solar mini-grids from being a truly viable solution. Despite the positive trends with PV costs steadily declining, the capital costs of constructing mini-grids are still too high, especially in light of what most low-income rural households can pay. Lead acid batteries—the current standard for storage—notoriously underperform when subjected to high ambient temperatures, which are common throughout most of South Asia and Sub-Saharan Africa, deep discharge cycles, and remaining in a state of partial charge for extended periods of time. This, combined with the absence of standardized, affordable tools for metering and collections, poorly engineered components across the board, and weak system integration, creates a range of operational challenges, which make maintenance of mini-grids expensive and cumbersome. Lastly, the absence of affordable, energy-efficient appliances including refrigerators, TVs, fans, irrigation pumps and other mechanized tools that people can use to increase their incomes, severely limits the demand for electricity.
To overcome these challenges, we have launched a broad-based project focused on the following innovations:
We have identified a shortlist of emerging battery technologies that can serve as a short-/medium-term solution until Lithium-ion batteries, the likely long-term solution over the course of 10-15 years, become affordable. These include advanced lead-acid batteries, which overcome the aforementioned problems, sodium-ion (a promising new battery chemistry), and a hybrid system which combines existing lead-acid batteries with Lithium-ion in order to balance affordability and reliability.
System integration: a “utility in a box”
Currently, construction of mini-grids involves procurement of a broad range of non-standard and sub-standard components from a number of vendors who have no incentive to ensure their components work well with others’. This increases the overall cost of the system, while also reducing performance. Through “productization” and much better system integration, we are building a “utility-in-a-box” which will reduce the overall cost of the mini-grid, improve ease of installation, and also improve performance.
Targeted appliances: refrigeration and brushless DC motors
Refrigeration is an essential tool for storing and transporting perishable food. Sadly, it is not an option for most low-income households and businesses. We are developing a low-cost, energy-efficient refrigeration solution using an innovative thermal geometry.
The second group of appliances we are developing, are based on brushless DC (BLDC) motors. While BLDC motors are much more energy-efficient than the more commonly used AC induction motors, they are considerably more expensive (in part because they are used so sparsely that companies using them tend to be sub-scale). We are exploring pathways to reduce their cost, and then building appliances around them. Importantly, we are not just exploring technology innovations, but also bulk procurement and large-scale manufacturing as economic levers for driving down costs.
This project is currently based in India, and our partners are Tata Power – DDL, the Rockefeller Foundation, and the Development Alternatives Group.
A big challenge in rural areas is demand from households, which forces companies to seek anchor clients like telecom towers to be able to generate a retrun on investment.
Lead-acid batteries like these are currently the only cost effective option for energy storage in solar mini-grids.