CommunityGeneralPopulationSocietyVillage Development

How To Build Your Own Portable Microgrid

Daimen Hardie & Sebastian Manchester of – 7/01/2015


First light – residents of Kokota islet enjoy first night with electric light provided by portable microgrid (Photo: Jeff Schnurr)

The problem . . .

The rise of renewable energy has to be one of the most inspiring revolutions of our time. It offers hope for transitioning to a low-carbon future – a future in which humanity rises out of the smog of fossil fuel dependence to put out a centuriesold fire that is now cooking our planet.

Rapid increases in the efficiency of renewable technologies such as solar combined with their plummeting costs is making this hopeful future increasingly possible. But as wealthy, progressive countries such as Germany lead the charge, proving that indeed the technology to address climate change exists and is feasible on a large scale, other barriers to a worldwide clean energy revolution are turning up. These barriers are largely social and economic, they’re about power of another kind, and they’re keeping clean energy out of the hands of the people who need it most.

Solar power is great, but how do you make this clean energy accessible to an impoverished, isolated community in the middle of the Indian Ocean? How do you deliver energy where there is no grid, where homes are not even wired for electricity? These are questions which inspired the team of Tanzanian and Canadian innovators at Community Forests International to develop the ‘portable
microgrid’ – a DIY solution to community energy production, sharing, and distribution that promises to bring vulnerable communities, and the world, one step closer to clean energy equity.

If you or your community faces similar obstacles, or if you’re just interested in all things renewable energy related, read on to learn how the portable microgrid works.


Remote power – the portable microgrid is a clean energy solution well suited to isolated communities such as Kokota islet, located in Tanzania’s Zanzibar archipelago. (Photo: Jeff Schnurr)

The solution . . .

Just a quick disclaimer before we start though – there is no one-size-fits-all microgrid solution for communities interested in generating and sharing their own energy. Many things need to be considered, such as the available renewable energy resources, access to materials, existing infrastructure, energy demand, and the particular types of desired electrical loads. This how-to is framed around the design process that we followed to build a microgrid for a remote island community called Kokota, which is part of the Zanzibar archipelago located off the east coast of Tanzania, and its based on what was locally available and in demand. You’ll have to adapt your own microgrid accordingly!

We set out to design an electricity system for Kokota that would span the entire island and empower every single inhabitant. This meant providing electricity to over 80 homes and three public buildings. The technical limitations associated with a conventional hardwired grid (cost, safety, and efficiency) forced us to come up with an entirely new way of delivering household electricity.

With no previous access to electricity, Kokota’s energy demands were simple; people wanted electric lighting so they wouldn’t have to keep buying and burning kerosene, and they wanted a way to charge their mobile phones. After some head scratching, we calculated that a week’s worth of energy to meet basic demands for a single household could be stored in a small motorcycle battery.
The batteries are locally available and very cheap (~$15). They’re also very portable. This, we realized, held the key to freeing Kokota from the limitations of a hardwired grid. The community could generate renewable energy collectively at a central location and then distribute it via a fleet of small carry-home batteries – a ‘portable’ microgrid.

How-to . . .


Portable power – a 12 V motorcycle battery, LED fixture, and wiring for household use. (Photo: Jeff Schnurr)

Every household on Kokota was given an identical home lighting system which consists of a 12 V motorcycle battery with a capacity of 7 Ah and an LED lighting fixture. The fixtures were low cost and assembled from readily available materials: 12 V LED light bulbs, a switch, 16 gauge wiring, and a connector that mates with an identical connector hardwired to the battery. The connectors ensure the polarity of the system cannot be reversed and the battery cannot be shorted. The LED bulbs have an output of 3 W, which is sufficient to illuminate a small room.

When the battery is discharged, it is brought to the central charging station where it is recharged using solar energy. This shared energy hub is housed in the Kokota school, located in the middle of the island and easily accessed by the whole community. The system that powers battery charging also provides power to the school itself, to a communal rainwater pumping and purification system, and to a public mobile phone charging station.


Harvesting the sun –Kokota’s portable microgrid is powered by a shared 700 W photovoltaic (PV) array. (Photo: Jeff Schnurr)

The source of electricity for Kokota’s portable microgrid is a 700 W array of solar photovoltaic (PV) modules. There are seven 100 W modules which are wired in series to minimize losses due to Joule heating. A 150 V / 70 A MPPT chargecontroller maximizes the power output from the PV modules and uses it to charge a central, “stationary” battery bank. Four large 12 V / 165 Ah valveregulated lead-acid batteries (aka “sealed batteries” or “gel batteries”) make up this stationary battery bank and are used to store excess solar energy and dispatch it as needed. The PV system and battery bank capacity were sized such that they can maintain enough energy to charge 20 portable household batteries per day and provide power to the school, rainwater system, and the mobile phone charging station for several days of overcast weather.


All systems go – Kokota’s portable microgrid charging station. (Photo: Jeff Schnurr)

Two 800 W inverters convert the 12 V DC power from the batteries and solar modules to 220 V AC power. The motorcycle battery charging system requires AC power and is made up of two individual 12 V battery chargers. Each is capable of charging up to 8 motorcycle batteries at a time, a process which takes approximately 4 hours total. The public mobile phone charging station also uses
220 V AC power to charge up to 18 phones at a time. All of the power electronics and solar equipment was purchased in Dar Es Salaam, on mainland Tanzania, and transported to Kokota islet by dhow sailboats with the help of the community.

The future . . .

According to the Rocky Mountain Institute, small scale renewables now provide close a quarter of the world’s electricity1. Mircogrids are gaining ground too, and there are now over 388 remote microgrid projects worldwide2. Community Forests International plans to add to both of these scores by bringing its pilot project up to scale and building portable microgrids in another 18 rural island communities in Tanzania over the next 5 years. Open source sharing of our ‘how-to’ will hopefully inspire even more widespread adoption, helping needy communities around the world to leap-frog convention into a decentralized, renewable energy future.


Sharing innovation – Community Forests International plans to build 18 microgrids in rural Tanzanian communities over the next 5 years. (Photo: Jeff Schnurr)

This sort of equalizing technological shift isn’t unprecedented – it just happened with cellphones after all. To make it happen with renewable energy technology we need solutions that address not only technical constraints but also the unique social and economic barriers of marginalized and isolated communities. The portable microgrid is an innovation inspired by those very limits, and successfully piloted by one of the most vulnerable communities on earth. You know what they say – necessity is the mother of all invention.

What other hopeful innovations could communities living on the front lines of scarcity and climate change offer to the world? To learn more about Community Forests International and it’s fledgling Rural Innovation Campus on the island of Pemba, Tanzania please visit:





  1. A very nice system. It is similar to models we at the Alternative Technology Association ( considered in Timor Leste as part of our Solar Power program. Ultimately, we chose not to implement this kind of system because it didn’t fit with the local conditions (as the Author explains in the article). I would be very interested in getting an update on the performance of the system after 6 months or 1 year. Based on the figures cited in the article and our own experience I have reservations about performance of the lighting systems and the lifetime of the batteries. Under the conditions specified I would be surprised if the batteries lasted more than 6 months as they are being pushed way past their specifications.

  2. Green technology or a new industrial revolution? Solution or problem? Alternative energy is a pr term for new industrial revolution. Lead batteries aren’t “renewable” and last only 5 years if well cared for. My grandmother said the car was the environmental solution to horses in cities. I don’t want to detract people’s efforts to make things better and appreciate people’s intentions to help “poor” people. But I would like to open up the conversation about what alternative energy sustains…In my perspective–privilege which Something these people don’t have and the common way to get it is to leave the village and move to the city. I cannot help but think of missionaries spreading the good word to help people only to destroy their traditional cultures. Perhaps the best way to make the world better is by starting in our backyard. Sorry if I’m coming off like a hater, but I am afraid we have been fooled about “alternative energy” and have become unpaid salespeople promoting something that is extremely destructive and unhealthy. Areas where materials are mined leave the native people landless and destitute, solar panel factory workers are more likely to get silicosis, and lead is a major bioaccumulative toxin. I guess we are living in the matrix.

    1. I can assure you that the author is doing this in his own backyard as well! Your points on the weakness of alternative energy are valid and something that needs work – however these people want to live on their island but their traditional ways are being thwarted by climate change. Fisheries are collapsing. They want to have access to power just like the rest of us – and this is a solution for energy sovereignty even if in 5 years they have to purchase new batteries (which can be purchased on the mainland by them). I would also note they know how to set up these systems and thus fix these systems themselves (through capacity building/knowledge transfer) – all materials to do so are available on the mainland (which they have access to with boats). However, I understand the dilemma with alternative energy can be environmentally destructive. But so is the computer you own (and they don’t) and the power you used to make it run (which they definitely don’t have).

      1. I’m wondering how many of the people decided they “needed” this electricity, or were they talked into needing it? I’m not faulting your organization for this. The convincing of need came long before your group. The biggest threat to our planet it all of those folks in the “West” who think they “need” all of the electrical conveniences that they have, myself included. Society in the U.S. is set up in such a way that we are almost forced to “need” massive amounts of power just to get by each day. Personally, I would prefer to live with the environmental problems of solar power to the damages caused by huge commercial generating plants any day. We over-consumers must take a good look at our own lifestyles and make an effort to change them so that we stop overtaxing the capacity of our planet. We must also find ways to minimize the problem of poisoning from lead and other toxic metals and chemicals. We must also lobby in more effective ways to counter the corporate culture that insists on profit over planetary health.

        1. Here is a great book about energy use by the venerable Alfred Crosby called Children of the Sun: A History of Humanity’s Unappeasable Appetite for
          Talk about a catch 22! Using electricity and computers to figure out how messed up it the tech is. As far as I can tell, the entire “alternative” energy industry is only possible because of/and dependent on the other electricity sources such as coal in China to make solar panels. How are these products created? mining, deforestation to mine things like rare earth minerals, removal of native/local people to clear the forest and mine, extraction of fossil fuels for electricity to manufacture/distribute. The list goes on and on. Most of us are born into this crazy world, doing the best we can with the tools at our disposal.

        2. Curt – I suggest you try getting through school studying with a kerosene light, or walking or taking a boat into town every few days to charge your phone, or spending a couple of hours walking home because your phone is flat and you can’t call ahead and check the person you are meeting is there. Or going to bed at 6pm because its dark and you can’t afford more kerosene.

          Basic electricity – even as little as 10Watts – provides many of the needs that we take for granted. 1.4 billion people don’t even have the luxury of lighting their homes. If you’ve spent any time in villages I think you’ll realize like me that its western arrogance to think that other people don’t have a right to it, rather than western imposition of a “need”.

  3. I’m interested in your costing for the grid ? Of the three broad classes of solution (pole&wires; individual home SHS and battery charging) we’ve never seen battery-charging come out most affordable, largely because of hte double-battery costs, i.e. you need batteries at the central site to store enough energy to charge the portable batteries, so each unit of energy consumed has to be stored twice – and batteries are becoming the largest cost.

    Our PAYG technology (at Lumeter) works just fine with any of these 3 solutions, so we really aren’t biased. We are interested in seeing scalable solutions – so cost is really important, once you get away from cross-subsidies by aid organisations so we are really interested in what your cost analysis was that came to the conclusion that battery charging was best.

  4. Thanks for the insightful “lesson”,however, in the name of freedom of speech i feel obliged to offer a critical, if not informative response to this well meaning rant.
    The artikel and the design of this system are an embarrassment to the college education of its author and system designer.(and for the benefit of people who might copy your “invention” please remove it immediately from the internet…or change the title to “how NOT to build a microgrid” or “how to build a batterykiller”…its shockingly shortsighted)
    Regarding the preaching self promoting authors text,…clever banter and bad design is the last thing fellow aid agencies,donors or their recipients need….and “poor” people doesnt = “dumb” people- in fact,they need REAL value and REAL innovation more than anyone- think of a renewable energy “solution” as planting a tree or creating a permaculture design -think long term,dont rush,get informed and use empathy…it’s the best medicine for creativity
    A few factoids;-
    -this is NOT a microgrid, its a battery charging station,and battery swap systems are nothing new,they are common place from the early 1900’s onwards – amongst others for electric cars (chicago and boston among other)
    -photovoltaics are nothing new cells produced in the 1950’s are still working and installations in the arizona desert from the 1960’s are still producing over 65% of their original capacity – the biggest deal with PV is that its been becoming increasingly affordable since 10 years , leading to many new “discoveries” amongst enthusiasts.
    The design;-
    -NEVER use start batteries for designing a long term energie storage system,…these “cheap” $15 motorcycle batteries MIGHT last for 30 cycles.
    options;- a $30 DEEP CYCLE lead battery MIGHT get 100 cycles in the HOT african climate,combined with the intended application for this particular system
    -a $50 lifepo4 battery of almost half the size will provide MORE power for between 1200+ to 2000+ cycles….it will weigh 20% of lead and be unaffected by hot weather,charge MUCH faster (about 1 hour) …the avoided “recycling problem”also doesnt need to be “solved”.
    lifepo4 can also lead to greater innovations in a thoughtful plug and play system;-does the community need an ebike ambulance of small boat emotor for emergencies?
    CHARGING efficiency;-
    -a solar panel DC regulator directly charging a lithium battery will be more than 95%
    -the artikels design has the following losses;-
    big lead battery charges at about 83% (lead are less efficient-lifepo4 about 99% )
    battery to 220 volt AC inverter efficiency about 85%
    AC inverter to AC battery charger about 80%
    and again the small lead battery…about 83%
    ….Therefore,if we calculate the efficiency losses through electronics and the lead storage batteries, the cheap motorcycle battery will supply about 47% of the power supplied by the solar panel ….and a 100w solar panel in hot africa supplies about 65% of its “laboratory specs” which means a total efficiency of 30 watts of power from the 100 watt solar panel in a round trip.
    Just by way of comparison, a lithium battery of half the size with a DC controller and a 50 watt solar panel would charge much faster,give more power and last about 60 times longer than the motorcycle battery.(or 10 to 20 times longer than a small deep cycle lead battery)
    Phone charging efficiency;-
    -here it gets even worse, cheap AC phone chargers are notorious for poor efficiency-try 65%…you can even feel it – hot electronics = power loss,or 29 watts power from the 100 watt solar panel in the baking african sun.
    -A simple DC phone charger set up connected to the LOAD side of a Solar controller gives about double the efficiency,or 60 watts of bang from the 100 watt solar panel compared to 29 watts for an AC charger….and would require no battery or inverter.
    -System sizing and reserve based on cloudy days?
    -the cloudy seasons on this coast coincide with reliable seasonal winds..remember its one of the best kite sailing areas on the planet…small wind generator?
    -the community is used to oil lamps…why throw them away in case of emergency? The potential to grow organic oil is logical, think coconut oil,croton oil, jatropha oil – it has the added potential of introducing faecophobic communities (its actually called “najis” in islam,and many muslims find its adherence very important) to the advantages of urine separation and recycling on “non food crops”…it may even help desensitise an unfortunate taboo and simplify sanitation practices.
    -Consider converting an old bycicle into a “cloudy day” generator…great punishment for misbehaving schoolchildren or overweight loungelizards.( talented artisans,such as the “Wonder Workshops” disabled welders can make anything)
    Search hard for energy related innovation, theres alot to be found;-
    -Alfredo Moses “bottle of light” invention
    -The genially pragmatic “BURRO” micro charging concept in Ghana, -SAHA global has a well documented community project with such a system (a small,cheap and economical led headlamp is unbeatable for reading,nightwalking or working in the dark-its actually quite liberating to have a handsfree lamp that moves with your head…ideal for midnight gardening)
    -besides BURRO there are quite a few organisations/products such as Solar aid, Sunny Money,or Sun King offering highly pragmatic solutions and,perhaps just as important… thoughtful micro financing models
    -Saving the best for last is “the barefoot academy”, this college teaches illiterate grandmothers how to design, install and maintain renewable installations…they even build their own electronic solar controllers (check out Madagascars solar grannies on the WWF’s website)….maybe they’re open to paying western students?
    -can be highly dysfunctional if taken too literally, as priveledged westerners its our obligation to research,promote, import and educate best long term practices….like why cant the “local guy” import the clever stuff?We in the west import alot of our best technology…so whats the difference?
    -for an eye opening,easy to follow selection of cutting edge renewables and storage products try checking out, they design and test their own lithium based off grid solutions (and for others) their pricing and service is friendly,highly knowledgable and no nonsense …and if looks count for anything the owner looks like a cave man.
    They are currently testing and developing 10-20,000 cycle LTO batteries (lithium titanate oxide)
    Conventional cheap and cheerful doesnt work with off grid renewables,but profound design inspired by knowledge can do much more with much less for much longer ..while providing pleasure and affordability.
    Sounds like permaculture, not?
    My advice to the “headscratching,innovative engineers” STOP,and before “designing” any more installations-please do more research into what others are doing – gain more insight into the actual recipients and their environment/lifestyle/culture-patience leads to understanding,understanding leads to creativity.

    so thats todays rant, and to quote one of einsteins eternal fountain of one liners;-
    “…our species is not going to solve its problems by using the same thinking that creates them”
    and keep things in context
    “any intelligent fool can make things bigger,more complex and more wasteful – but it takes a touch of genius and alot of courage to take things in the opposite direction”
    …..he would have loved permaculture

  5. Hey – this projects looks very good. A lot of people in the world do not need this excess energy like we do. Mostly light, charging mobiles and radio or TV sets have to be supplied with electricity.
    In countries with bad infrastruture I’m afraid about the recycling of the batteries because. I have seen the way people in poorer handle old batteries caused by the small knowledge about ecological effects. So it is good to give electricity to the people but perfection is only given if the recycling of the devices is also included.

  6. Why is it that p.v. Solar practioners consistently reach for systems specs that replicate our current wrong headed device powering approach?

    I open with a reflexive question to make one simple point. “Low wattage/low voltage” systems thinking makes imminently better sense, as everyone who ever uses a “wall wart” to charge their phone should understand.

    Why would you convert up to 120/240v, only to down-convert back to 3-to-12 volts instead? Think for a second about the virtue of USB! A single platform that can do several things without all that extra hardware, or more importantly, with out all the extra heat sinks.

    Conventional AC grids function over great distances by transporting high voltages and down converting at the load. The spec looses viability when the load is say, one 7watt string of LED Christmas lights. Essentially, a 12/24/48v systems approach would work miracles in the outback, where the total line-load per sub-system might be 1kw at peak.

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