September 10, 2023 Friends & Family Letter


Results from RVB's longest visit to Malawi so far

Dear Friends, Family and Compatriots:

  Well, I am just now concluding my longest visit to Malawi in the last eight years. On this trip, I have been in Malawi for a little over three months, with a one-week side trip to France to meet a potential funder.

  There have been two HUGE accomplishments on this trip. 

  The first organizational victory is that we have distributed 750 of our 900 solar pumping systems. This distribution has included about 150 kilowatts of solar panels purchased by and distributed to the solar pump users. The last 150 solar pumping systems will be distributed over the next few weeks. We estimate that these 750 pumping systems will each generate somewhere between $100 and $1000 per year of extra income for each customer over the next several years. This means that we have essentially taken about $100,000 in grants and donations and turned it into $0.5 million to $5 million worth of economic benefit to thousands of rural Malawians over the next several years.

  THANK YOU! This is great. We should do this again next year. Right? (If you agree: click HERE)

  The second huge advance is that we have finished the assembly and deployment of about 20 prototype forever batteries with the latest, greatest controller board and programming. This latest version monitors and records current and voltage  (and hence power) every 10 seconds and has software that protects against short circuits in either the wires to the solar panel, or the wires going to the load. We have also tested encasing the battery in clear epoxy, and that seems to work great so far.

  If over the next year we can measure the capacity change of the battery, and if the capacity changes are on a trend line that indicates that the battery should last 10 years, then this will be a huge victory for Access to Solar Electricity in rural Africa. We still have a couple more design iterations to go before we perfect the various aspects of battery operation and data recording, but so far it is looking like we should be able to commercially distribute the batteries to customers by about next June. With batteries that last 10 to 20 years, this will make an absolutely huge impact for rural Malawians who then will be able to switch from no electricity access to 10 to 20 years of electricity access for a cost of only $100 to $200.

Rachel & Christina: The dynamic duo of solar pump distribution

  You never know what impact small actions might have 5 to 10 years later. Back in 2017, a friend and African organizing colleague, Lesia W, came to Malawi, went to a village where we had a little collaboration going and trained a group of about a dozen village women in the art and practice of making solar lighting systems. The best solderer in that group was a woman named Rachel who eventually decided to come to the workshop in Blantyre and become a technician. Her friend Christina who was also trained by Lesia decided to join her.

  Fast forward five years, and last summer Lesia came to Malawi again with her friend Evelyn, and the four of them went to rural villages to promote the idea of solar pumps for women's gardening groups. That summer we started setting up women's solar shops and distributed 130 solar pumping systems.

  Then this year, we decided to increase our solar pump distribution by more than 6X to almost 900 solar pumps this last summer. Could we do it?

  With the continuing mentoring of Lesia and Evelyn, Rachel and Christina set up a small distribution company and expanded the network of village solar shops to more than 10 and in late May started distributing solar pumping systems to the shops as sales blossomed.

  The deal that we had with the shops is that if the customers covered the cost of the solar panels, they would get the pump and 50 meters of irrigation hose for free (because the pump and hose were already paid for last January by donors that read these friends and family letters). In addition, each of the women's groups that operate the shops earn a 10% commission on any sales happening at their shop.

  So Rachel and Christina set up a routine. First they would call the shops and see how many new customers each shop had. Then they would sit down and plan a distribution trip. Donors funds provided a few thousand dollars of operating capital. Rachel and Christina would take this operating capital and buy solar panels for 30 to 60 systems. They then hire a truck and visit the villages that have customers who were ready to pay. During the visit, they collect the sales money, and deposit the sales money in the bank to replenish the operating capital. The operating capital is then used again for buying the next round of solar panels for 30 to 60 systems.

  This way, Rachel and Christina used about $5000 of operating capital to organize the sale of $70,000 worth of solar panels for about 750 solar pumping systems over the course of three months. And they have more or less the same operating capital now that they started with in May/June.

  I don't know about you, but I consider this pretty amazing. Nobody turns over their operating capital once per week generating $14 in sales for every $1 of capital over the course of 14 weeks. Now of course the donor subsidies of the pumps and hoses made this possible, but this is an extremely efficient use of very limited resources to take care of the 50% solar pumping system cost that is covered by the customers.

Solar pump impacts: About $3 to $5 of increased income per year created for every $1 of donation.

  One of the key things we did in August is interview about 20 beneficiaries of the solar pumping distribution to try to get a more quantitative idea of how much the pumps increase rural household incomes.

  Both me and a friend who visited Malawi for a month (John W), spent a few days doing interviews. John did fairly thorough interviews, I did short and sweet interviews in order to see a more cursory view of a larger variety of customers to get an idea a wider range of impacts.

  I wound up seeing about 13 customers.  Keep in mind that the rainy season in Malawi is from about December to April, and the dry season is from June to October. Everybody grows food during the rainy season, and during the dry season, you pretty much cannot grow any food unless you irrigate.

  The vast majority of the customers that I met said that were watering their gardens using watering cans the previous year, and as a consequence of the solar pumps they currently had gardens that were about twice as big this year compared to last year. Making the gardens are so much easier to irrigate with the pumps allowed people to more or less double the size of their gardens. People's gardens this year were typically about half an acre, and typically people were growing corn. 

  Corn is THE staple food in Malawi, and it's price fluctuates over the course of the year, with peak prices of  $0.60/kg occurring around January/February, and with prices that are about half that in May when the harvest from the rainy season comes in.

   Typically people harvest about two  tons of corn per acre (see: This corresponds to $1200 in gross revenues per acre. Since most customers are growing about half an acre, with about half of this being new acreage, then their increase in gross farm income ranges is about $1200/4 =  $300 per irrigated harvest. Many farmers will try to do two irrigated harvests (albeit at a 20% lower price), so let's say a typical gross income increase is about $500/year when customers can use the pump for the entire irrigation season.

  We found that inputs (i.e. fertilizer and pesticide) had a significant cost but were less than half of gross income. So perhaps $300/year is a good estimate of the typical net income increase from the solar pump.

  I should note here that this $300 of annual income increase is about 500,000 Malawi Kwacha (MWK) in the local currency. Now in Malawi, there are two exchange rates: (A) a cash exchange rate where the dollar has a higher value (i.e. more than 1600 MWK per USD), and (B) A bank transaction rate where the dollar has a lower value (i.e. about 1000 MWK per USD). At the bank exchange rate, every $1 in donor dollars is creating about $5/year of additional income. 

  By what percentage do the solar pumps increase the cash income of the beneficiary households? In my interviews, I found household monthly spending ranging from $30/month to $120/month (at the cash exchange rate), or between $360/year to $1,440/year, so this $300 increase in net income represents a 20% to 80% increase in net household cash income. This is a pretty huge poverty reduction impact: i.e. we are increasing household cash income by about 50% for potentially several years for a household of 3 to 7 people with one $100 investment by philanthropic donors.  Pretty huge.

  John did his own estimates of solar pump benefits which might be quite a bit higher than mine. But at this point, I prefer to report the lower, more conservative estimates so that it is easier to make and measure improvements over time as we improve both our solar pump implementation and data collection.  My hope is that next year, we will be able to report something like $5 to $10 of added income per year for each $1 donated to subsidize solar pumps. 

  Wish us luck!

Forever Batteries with built-in data logger: The Holy Grail of off-grid solar electrification in Africa

  Everywhere that you go in rural Malawi there are some houses with solar panels, and two out of three times, when you go inside, what you see is a dead, or barely working lead acid battery and an AC/DC inverter. The lead acid battery probably cost about $50 to $100 and probably lasted 3 to 6 months.

  Now, for the past few years, our projects have been blessed with the technical assistance of an Electrical Engineering Ph.D. student, Skyler S. Initially he helped us evaluate supercapacitors that we were using for small lighting systems, and later Skyler helped us make the strategic decision to move to "forever solar lights" and "forever batteries" that are based on a new battery chemistry called "Lithium Titanate" (LTO). LTO has a theoretical cycle life that is 10 times longer than Lithium ion batteries.  So theoretically they can last 10 to 20 years (or even longer!).

  But to make an LTO battery live up to its full potential of lasting 10 to 20 years, it is necessary to connect five 2.4V cells in series to create a battery with 2.4V x 5 = 12V battery, and then add some electronics to make sure that the battery cells stay in their ideal operating range so they can last a really long time.

  Consider this: a 100Wh forever battery costs between $50 to $100. If this battery cycles once per day, then this battery is helping provide the following:

100Wh/day x 365 days/yr x 10 years = 365 kWh of electricity.

  Thus the cost of battery regulation when using a forever battery is ($50 to $100)/365kWh which is $0.14 to $0.27  per kWh. 

  Compare this to a Lead-acid battery that lasts 6 months, which perhaps delivers equivalent electricity, but which lasts only a couple of hundred cycles because is it consistently gets overcharged or over-discharged. Even though the lead acid battery is initially much less expensive per unit battery capacity, that cheap capacity gets used much less efficiently. Because the battery lasts such a short time, the per kWh cost of the lead acid battery electricity is actually much, much more expensive of the long term. Even worse, after the battery dies. The left over lead is discarded near the home, and kids get slowly poisoned when and if they play around with the discarded battery lead.

  Obviously, our LTO forever battery is much, much better.

  We are currently testing just a few batteries in the field, yet already, after hearing about what we are doing, customers are showing up saying that they are ready and eager to buy them, today!

  Thus, when we are ready to start producing and distributing forever batteries, demand will effectively be unlimited. 

Next letter: Cookers, solar cars, and effective altruism students.

  Well, this email letter is certainly long enough for now. In the next letter, I will try to give an update on our work with off-grid solar-electric cookers, solar cars, and working with students who are learning the geeky philanthropic philosophy called "Effective Altruism."


In love and struggle,

Robert VB