We will look at the case for a purely diesel powered mini-grid where PV and storage is gradually added to eventually end up with PV as the single source of power (stand-alone). Adding a nearly standard grid-tied PV system to your mini-grid will achieve solar shares (i.e. diesel fuel savings) of up to ~40%. Up to ~50% are in reach if you also add a power smoothing storage system (“buffer”). By the way, at this point the power rating of your PV system might already exceed your peak load (“PV penetration rate >100%”). Please do not worry, this is a standard scenario; the rate needs to rise even more to reach our ultimate goal. Still, we are not yet able to switch off the diesel generator (not even for a limited time). It seems a paradox, but we first need to add another piece of equipment (battery inverter) that takes over the responsibility of the generator to “form the grid”. Combined with an increased storage size, the batteryinverter now lets us switch off the generator during the day. Add more storage and the generator will serve as a backup only, i.e. running occasionally to recharge storage with off-times spanning days or weeks. 

Our journey to get rid of the generator, having gradually increased PV size and storage capacity, means we can now cover up to 95% of our energy demand by solar. The PV penetration rate might have reached more than 200% by now. Let’s now go the extra mile and get rid of our generator completely: a bit more PV and storage? If only it was that easy! With no generator we lose our backup option. For PV and storage to take over this responsibility (under any weather condition!) a gradual increase of size is insufficient: it needs to be an exponential leap.

While the unit cost (LCOE) of our stand-alone PV-storage system might still be lower than that of the generator, CAPEX are definitely not. So, should you get rid of your diesel generator? Maybe start looking for alternative fuels first.

Free Live Webinar: You are invited to deepen the topic on an interactive level in the form of a free live webinar prepared by Renewables Academy Online. Register now to discuss the topic with the author and RENAC expert for solar energy and rural electrification, Lars Koerner.

Date & time: 04.09.2018 at 15:00-15:45 CEST (find your local time)

Six years ago, Studer Innotec built a distributed mini-grid pilot project in the Swiss Alps for a village at 1,700 m altitude called "Mayens sur le Scex". Over time this solution has proven to be robust and stable, receiving positive acclaim from the community as it has perfectly adapted itself to their needs. 

Sharing excess energy and reducing costs

Initially many of the 32 chalets were already equipped with individual PV systems with diesel generators as backup but their occupancy rate was low, the batteries often full and a lot of solar energy was lost. To address this situation an alternative mini-grid solution was developed taking in consideration the wishes of the local community. Among their demands were: the possibility to keep their energy independency, the flexibility to add power in the future if needed, reduce the cost of system infrastructure, and to avoid having one big central PV installation with solar panels in the landscape.

The technical concept

The novelty of the distributed mini-grid is combining several individual systems together to share their common benefits, maximizing the use of excess energy, and extending the individual battery life. The system is based on a central inverter which provides a reference voltage and uses variation in AC frequency for communication among system components. A low voltage AC distribution line is connected to every house.  Each house has its own individual system with PV panels, inverter/charger and battery bank. A set of energy management rules ensures smooth energy exchange and the successful operation of the mini-grid.

Adaptable solution

This is a highly flexible mini-grid solution, so it is possible to add additional distributed inverters, to use different battery technologies and to use AC-coupling with all sorts of energy resources such as solar, wind or hydro energy. If desired, it is also possible to add a smart metering function, where a tariff structure defines the quantity of electricity to be used among the mini-grid participants.

For more information, see the video on YouTube (https://youtu.be/4aGvNELr8aw) or download the whitepaper "Mini-grids with distributed energy generation and frequency control" from our website (www.studer-innotec.com/en/downloads/).

Often mini-grids nowadays are still combined with a “dispatchable” power generation technology, however, with the sharp decline in storage technologies the path is paved for 100%-renewable systems. What would such a system look like? To simplify things let’s only consider the two renewable-energy sources that are available on every location on this earth: solar and wind power.

Resource maps guide the way

The Energy Sector Management Assistance Program (ESMAP) of the World Bank has done a great job in mapping the global wind and solar resource data and making them publicly available in interactive maps.

At first sight the two resources seem to complement each other quite well: wind is abundant at higher latitudes while the irradiance levels increase towards the equator. Also, the sun shines the brightest at higher altitudes while the wind blows the hardest near the coast lines. 

It’s the COE, stupid!

To dig deeper we ran a bunch of HOMER simulations with the same system configuration providing power to a typical village load (250kW peak, 2MWh/day electricity demand).

Investment costs of solar, wind and storage are deemed to be representative of today’s total installed cost at remote locations (respectively 1.2$/W, 2.5$/W and 500$/kWh) but are obviously not considering the large local variations that may exist due to temporary market shifts and/or incentive schemes. Also, these costs are not for MW-scale power plants but for wind turbines and solar arrays in the tens to hundreds of kW’s.

The HOMER Optimizer then does the job of finding the lowest-cost system comparing all the feasible system configurations. In Chilean Patagonia the lowest-cost-of-electricity system (COE) would consist of 135kWp PV, 300kW wind and a 1.3MWh battery and deliver electricity at 25cents/kWh.  While in eastern Ethiopia, an LCOE of 22cents/kWh is obtained with 420kWp PV, 100kW wind and a 1.3MWh battery. 

The graph below shows the reduction in LCOE obtained when adding wind power to the mini-grid system.

Conclusion

Adding wind to the mix can bring the LCOE down significantly: a 10% reduction is already achieved at wind speeds of 6m/s, and up to 25% can be achieved at higher wind speeds. So, what had been proven in larger interconnected systems, also holds for Mini-grids: wind and solar are better together.

Thanks to their complimentary in diurnal and season patterns, wind and solar together can always match the load better than alone and the necessary amount of storage can be reduced.

So, include wind in system-sizing calculations, otherwise you’ll never know what COE you could have got !

With our long-term experience and vast expertise in the design of hybrid power systems integrating high shares of renewables, conventional power sources and storage technologies within isolated or grid connected applications, our team at Fraunhofer ISE took part in the design and planning phase of the power system for SKA Low1, which will supply more than 130,000 antennas and required data processing.

Due to the magnitude of this scientific equipment, which will cover more than 100,000 hectares at MRO area in West Australia, its power consumption is comparable to that of a town, a small city, or an island. Expected energy consumption is 25,000 MWh/year at average power of about 3 MW.

In our assessment, especial attention was put to site topology, renewable energy potential (solar, wind), to specific system requirements, and to the particular economic and financing environments.

Storage is well known as key element for enabling high penetration of renewables in power systems, but it is also (still) generally the most expensive component of such. Therefore, detailed lithium-ion market projections were adopted and incorporated to our complex battery performance and degradation models.          

Following a design spiral methodology, a simulation model was set to optimize both size of PV-diesel-battery components and its spatial distribution, comparing a centralized concept, with reticulated transmission lines, to a decentralized power supply where the farthest antennas are fed from local power plants.

Importantly, optimal renewable penetration was found to surpass 95% at this site and for this application, favored by high diesel prices and O&M costs. Optimized system configuration was obtained to consist of a total of 19 MW solar PV, 45 MWh lithium-ion ESS, and 3.5 MW diesel back-up.

Regarding spatial distribution, our study showed that a central power station covering up to 90% of the total power budget was economically preferable, with transmission lines covering up to 20 km of radial distance from the Central Processing Facility. Antennas at longer distances should be powered from local power stations.

The levelized cost of electricity, LCOE, was estimated at 0.28 €/kWh, and sensitivity analyses were presented to observe how changes in most influencing variables could affect project costs.

Independent engineering and quality assurance offered from Fraunhofer ISE, such as the study presented here, can minimize risks to customers, project developers and investors, facilitating or enabling its bankability and insurability.

SNV believes that Integrated Decentralised Energisation in Africa (IDEA) is an effective way to dramatically increase energy access, reaching communities who need it the most. We are now looking for partners to help develop, fund and implement this new IDEA.

IDEA: a bottom-up approach to meet local customer needs

There have been many initiatives in SSA to facilitate energy access for rural communities - from household stand-alone systems to multi-village mini grids. But these have generally taken a siloed approach that considers only one type of energy delivery. This fails to recognise that a mix of energisation options is most cost effective, using appropriate and innovative business models to make this option affordable.

Energy for agricultural production

For many rural African communities, access to household electricity simply isn’t enough - the use of energy for agricultural production is crucial.  Supporting farmers and SMEs to grow their businesses raises income levels and enables investment - increasing the electricity demand and therefore making the connection more cost-effective.

An example of this integrated approach in action is the Mashaba mini-grid in Zimbabwe - a project supported by SNV.  Here, the mini-grid provides household energy, and energy for local businesses, the local school and a health clinic. It pumps water to irrigate local farmers’ fields so that yields are increased by 50%. More profit means greater demand and reliable payment for the operation of the mini-grid.

Getting the private sector on board

To engage private investors, an attractive financial model is needed. The private sector is often deterred by the uncertainty of local conditions. This risk can be mitigated by using public funds to offset the initial capital requirement – justified on the basis that energy supply is a basic public service. In turn, this support will attract private investment for the operational costs (a practice that isn’t yet commonly used by suppliers).

SNV’s Integrated Decentralised Energy for Africa

Supporting local agriculture businesses to increase electricity demand and create a viable market is the motivation behind SNV’s IDEA concept. This approach will demonstrate different business models, involving different types of finance in communities across a number of countries including - Zimbabwe, Zambia, Burkina Faso, Benin, Rwanda and Ethiopia. SNV will work with local governments to ensure that the necessary frameworks are in place, and use our country offices to implement sustainable, local business approaches. 

If you would like to learn more about IDEA please contact Dean Cooper, SNV Market Development Manager at dcooper@snv.org.

The project which is funded by UNHCR was completed in July. It serves a local school, health centre, police post, welding shop and market stalls among other socio-economic needs. 40 solar street lights were also installed in the settlement. 

The system consists of 112 pieces of 265 watt polycrystalline panels with an installed capacity of 38kWp and 48 pieces of OPzS maintenance free sunlight batteries (192 KWh). It was designed to ensure that this capacity can handle the current load and at least 40% expected growth in the next 5 years. It has a 40 KVA diesel generator back-up. The system is the first of its kind in Somalia with a smart metering capability and makes Farjano the first community in the nation to receive 100% of its energy needs from a solar system.  

Somalia faces a major challenge in the access to affordable and reliable electricity service. Over 10 million Somalis lack access to basic electricity, 2.1 million live in the margins of food security and 1.1 million are internally displaced (World Bank, 2018). The Horn of Africa nation has no grid connection and suffers one of the highest electricity tariffs in the world at a cost of $ 1/KWh. This makes it difficult for the average citizen to afford electricity. The SolarGen developed mini-grid will provide electricity at a cost of between $ 0.40 and 0.60/KWh. 

SolarGen, a leading locally-owned renewable energy company that specializes in the design, installation and distribution of high quality solar products, prides itself as a development partner for communities in some of the toughest locations. While implementing the Farjano mini-grid, it faced several challenges including the lack of skilled local work-force and had to maximize on its team of engineers and technicians to ensure the successful and timely completion of the project. The company is currently training two Farjano community members who will be employed as the system operators.  For the next six months, SolarGen will handle maintenance of the mini-grid as it works closely with the Farjano Energy Cooperative - established to manage collections from the mini-grid. The revenue will be used for the O&M of the system.

Until recently, practitioners at a clinic in the Ethiopian village of Ashoka had to ration the use of their scanner to preserve battery life and minimize recharging treks to the nearest town connected to the grid. And at a larger clinic 15 kilometers away, where as many as 30 babies a day are born, there is connection to a grid—but even its electricity sometimes fails. Until recently, there were times where, at night, staff used cellphone flashlights during deliveries and to check patient charts. 

Today, both facilities are on their own reliable micro-grids powered by a new, reliable technology—hybrid distributed power (HDP). There’s now electricity for scanners and baby warmers; fans have been installed; and the comfort level for staff, mothers and newborns has improved considerably. One clinic has even taken on the role as an impromptu community center where people gather at night to socialize and take advantage of the light, saving on precious kerosene. This clinic is the only places perhaps within a 20- or 25-kilometer radius of the village that has consistent electricity.

Talk about transformative change: This is technology that can create healthier communities in regions where many people still live without electricity. And the promise is exciting for GE as well: With a long history of innovative solutions in the power sector, we’re now looking to collaborate with companies who can partner with us to bring these life-changing solutions to populations around the globe. From licensees to marketing partners, my team and I see tremendous opportunity in teaming up to illuminate more villages and create stronger, healthier, upwardly mobile communities in developing markets around the world.

GE can deploy a number of different business models—ranging from power island supplier to technology licensor—to help our partners build, sell and install the physical power islands that produce the electricity, which allows for mass, rapid scaling.

How does the technology work? Hybrid power leverages synergies between multiple generation sources. The HDP configuration electrifying the clinics in Ethiopia combines solar, storage (batteries) and diesel power into a self-contained unit roughly the size of a 20-foot-long shipping container. A smart box, controlled by software algorithms, switches between the three sources as needed and securely transmits data to the cloud via cellular networks for remote monitoring. The overriding intelligence of the system is geared toward maximizing solar production, with the diesel component kicking in and boosting efficiencies during rainy or cloudy weather.

It’s catching on. An HDP-powered mini-grid recently came online in northern Ethiopia, providing electricity to about 180 homes in a remote village some 180 kilometers from the capital city of Addis Ababa. GE Renewables is sponsoring the installation as a Corporate Social Responsibility project, in partnership with Ethiopia’s Ministry of Energy.

These efforts take “team.” Key technologies behind HDP originated within GE divisions that provide complex renewable energy systems to large utility customers. A group at GE’s global research center in Bangalore, India, fostered the idea of adapting GE’s expertise in renewables, storage and distribution at utility (megawatt) scale and shrinking it down to kilowatt scale to power micro-grids for rural electrification.  They envisioned a robust, hybrid offering for deployment in remote, hard-to-reach areas to provide reliable, continuous power that was cost-effective, easy to use and could be readily scaled as demand grew, without requiring customized add-on solutions.

We moved quickly: The concept went from a PowerPoint slide to an in-field pilot in nine months. GE Ventures’ licensing operation incubated the HDP offering and partnered with India’s Tata Power, a customer of GE Grid Solutions, on two pilot projects. At one site in Bihar, India, in addition to providing electricity to 150 homes the HDP solution is powering agricultural projects, including a rice mill. And in another village of 180 homes it’s powering a women’s school and a study center for children. The communities and Tata together decided how to deploy HDP, with Tata also setting up distribution links with usage metering to homes.

HDP exemplifies GE’s approach to managing technology licensing in the digital age that can learn, pivot and scale fast to solve big challenges and deliver immediate, powerful impact to people all over the world. It also represents a win on many fronts: for families, students and health care workers in off-the-grid communities; for GE’s partners; and for GE, where licensing impactful technologies to partners is, increasingly, a priority. We’re excited, too, about the potential for new partners who might join us in this area interested in helping power these villages and helping create more vibrant communities

Collaborating with creative entrepreneurs and forward-thinking partners around the world allows GE and its partners to unlock new opportunities and create value, while solving important problems, transforming industries and improving lives. This will, we hope, mean a brighter future for the estimated 1.2 billion people on the planet who still live without electricity.

Until the last decade, the grid was largely untouched by new technology. But a wave of innovation, the plummeting cost of solar and breakthroughs in storage have resulted in a revolution in distributed energy and the emergence of mini-grids -- small, localized power plants and distribution networks that serve remote communities.  

Tackling rural electrification by building smaller (often privately- or collectively-owned) grids is not new. According to the International Energy Agency (IEA), mini-grids are a USD 300 billion investment opportunity between now and 2030, and also the least cost option for almost half of the people who still need to be electrified.

The reason is simple: besides being deemed by IEA as the most affordable option, mini-grids also create more impact per dollar, are better at serving the needs of rural consumers, are faster to deploy, deliver power more reliably and with higher quality, and help create more vibrant local economies.

In India, Smart Power India, with support from the Rockefeller Foundation, is supporting the largest single cluster of private mini-grids so far -150 and counting -- showing significant impact on local communities, including new business creation, increased revenues for existing local enterprise and a rise in village per capita GDP.

Financing for mini-grids is also increasing. Two leading Indian mini-grid developers supported by Smart Power India, Husk Power Systems and OMC Power, recently netted a total of about USD 30 million in investment.

Unlocking greater financing can partly be accelerated through further innovation to standardize mini-grid design and drive down systems costs. Field testing already underway in India to develop a “Utility in a Box” -- a modular, scalable mini-grid -- has significantly reduced the capital expenditure of mini-grids.

Full and fair integration of mini-grids into national plans will help create a more level playing field. Currently, private utilities developing rural mini-grids are expected to deliver a service equal or better to the main grid, but most often without the public support that state utilities receive to prop up their operations. These force mini-grid developers to pass the costs on to the consumer, something state utilities in India can avoid, despite the fact that they have long been debt ridden. Government and donor support must be solution agnostic, and provide equivalent incentives to all sizes of grids, so rural communities get the solution best suited to their needs and we ensure that those still living without power do not wait decades more.