Van Buskirk Correspondence

April 16, 2018
Ok. We will pick some time in June for me to drop by. But the latter half of the month, I will need to go to Malawi again through China to gather parts for a pilot distribution scale-up if we can get some basic system to work on the present trip.

I am hoping we can sell at least 100 systems with voltage-control cookers by the end of the summer.
When I come in May, I will bring samples of the first set of designs that we test with customers. I expect the first customer tests starting at the end of next week.
I am not sure that I mentioned it, but our Malawi operations actually have a stock of solar cells, so we can make some not-so-durable solar panels for less than $0.50/watt. So we can actually distribute a fair number of test systems with different panel configurations to customers without burning through very much cash.
April 18, 2018
Hey Pete:
FYI: hey are voltage control (not temp control) cookers. Which will act like virtual batteries during the day.
Just got to Malawi.
Went over stuff with staff. They seems to be echoing my excitement.
We think we can buy 100 watt panels for $70. We think we can build an “indoor grade” plywood 100 watt panel and sell those for $35.
We can hook up an inverter for $20. We can sell the pot for about $20. We can add a 40 Wh battery pack for about $25. Basically we can do a system that cooks, provides lights, charges cell phones and has enough power for radio and a small TV for $100 in total.
What your team can do to support is replicate our prototypes, and then do performance measurements for the replicated prototypes and different variants.
Your work and documentation then can provide a basis for trying smart design variants and raising finance foe expansion. Investors/funders are going to believe a research team at Cal Poly a lot more than a retired freelancer organizing ad-hoc in Malawi. We organize production, distribution and sales: you do performance testing and optimization and technical documentation.
I expect that we will have a couple systems together by the weekend.
We will send pictures and documentation via whatsapp.
Perhaps you can remind me who the whatsapp contact is going to be on your team.
Things are moving…

April 18, 2018
Good news back at you. Matt ran 50 A through a 3 A diode directly immersed in boiling water yesterday – the copper leads were glowing. Hard to believe, so we will follow this up with more tests. Thermally grounding the diodes seems important.Pete

April 20, 2018
And more good news: we can now get 100W panels on the local market for slightly less than $60.

And they are really high quality and actually output 100W in full sun here.

The pots with the diodes on glued on the outside are running at only 50% efficiency. So immersion you suggested...will probably give us nearly a 2X improvement on water heating efficiency.

So I made an immersion heater today. If it tests at >80% efficiency as I expect, we will convert to those. I think we have enough parts to make 50 to 100 such systems.

The system works great with the $15 inverters that are sold here. But we have lots of partly cloudy days here, and power drops off rather precipitously when a cloud passes, so I am going to add about somewhere between 30 to 100 Wh of battery capacity to see if this creates a system with reasonably reliable daytime AC electricity. with full cloud, I am only getting about 10W out of the panel.
If you could give me more details on you immersion heater construction methods that would be great.

And the students can start thinking long and hard about immersion heater design. There are lots of options there.


April 23, 2018
FYI: I added a mention of our collaboration on the Kuyere USA facebook page:

-Robert VB

April 24, 2018
Dear Pete:
As you can see from below, I have cultivated Kunyang New Energy (KoyoSolar) as a potential producer and distributor of our slow cooker.
They have a version at:
Which is a small rice cooker that runs off 12V DC.
And it looks like 12V DC rice cookers are available on Amazon. For example:
Perhaps we should get a 12V rice cooker and check-out how it operates?
I could see someone like KoyoSolar selling hundreds of thousands of units per year in Africa in a few years at about $20 each.
This is not so interesting to a US business, because a hundred thousand units at $20 each is only $2 million/year of revenue. Much of thiswould go to expenses, so perhaps they would clear $500,000/year in operating profit which would support only a few employees.
The same operating profit in China would support dozens of additional employees. So making such a product for Africa for them is much more interesting.
-Robert VB

May 1, 2018

I am not feeling secretive at the moment, so sounds fine
[to share our proposal with the class].

I did a consumption and impact survey of 17 households. Data and report attached.
And I attach a slightly outdated list of the villages we have served so far. They can look up Karonga, MChinji, and Machinga districts on the Internet.

If they look up my videos on youtube:
They will see lots of interviews with villagers, where they will get a good feeling for the demographics and economics.

Note, we don't commit to a community and do integrated, multi-faceted development, we introduce solar gradually (bit by bit) to many communities at a time spread over large areas.

Robert VB

May 8, 2018, Robert and I talk about including a Television (??) in the solar cooking package

Hey Pete:

If all goes well, we will be selling the Cooker system with the TV at a profit starting next week in the Machinga District of Malawi.

Found a 19 inch, 12V TV on the local market today for $90, I think in a week, we will have the cost down to $84. Needs an Antennae and decoder box, which is another $32. So it is $122 for the TV equipment. The 100W panel is $60, and we plan to charge $20 for the cooking pot (which should require less than $10 in parts). Retail distribution fee is $15. Production and wholesale distribution management is $15, and short-term financing fee is $20. This totals $252. Batteries for 3-4 hours of nighttime TV will probably be in the range of $30 – $50 the total close to $300. Assuming a total of $300, $122 is TV, $60 is panel, $40 is battery, $10 is pot parts, $10 + $15 + $15 = $40 is assembly and distribution labor, $20 is capital financing, and $48 is battery.

Subtracting the TV equipment costs, this is $178 for a system that should provide 200 Wh/day. If we can convince people to buy another panel for $60 to help cook faster and to add an inverter for $15, then this would be a 400 Wh/day system for $253 which is about $0.63/Wh/day. If the 200Wp system is used well for 6 years, this is $0.31/kWh solar electricity. If the system lasts 12 years and is utilized well, this is $0.16/kWh solar electricity and we have gotten solar electricity in rural Africa as cheap as regular grid electricity in the US.

TV draws 0.75 Amps at 12V. Decoder box draws about 0.35 Amps at 12V. So even if people watch TV all day, on sunny days there is enough energy for cooking. On cloudy days, the panels put out enough energy to still pretty much run the TV without batteries, using the cooking pot voltage controller.

I should probably bring cooking pots, a TV and decoder box back to the US so that we can rebuild and evaluate the system for your class.

Note, this way, the TV purchase pays for the solar panel, and the cooking pot is cheap, so we make it feasible, right now, without subsidy to sell ISECs as part of an integrated cooking/TV system. And yes, tomorrow, I will try to add lights and cell phone charging. Can do that for only $10.

In the Africa solar electrification effort,

Robert VB

Pete Responds:

As being someone without a TV, I am a little conflicted about providing to the poor, what I find the worst of our society. However, I recognize each person’s right to make this decision. And I certainly do believe that this product is what most people do want. However, affordability is a question. I also applaud your efforts to continue to innovate. It’s good that you can make these modular – a person could buy the cooking/light/cellphone charger system much cheaper and buy a TV later if they way, no?

Yes, please do bring some stuff home for us to work on.


Robert Responds:
Yeah, I hate TV too. But over my life I have watched a lot of it.

What I am finding, is that some people will pay 10 times more for a TV system then they will pay for a lights and cell-phone system. And they won't pay much for a cooker system. So what we are doing is getting the cooker developed on the back of the solar TV system which people some people are demanding rather insistently.

We probably won't give them a choice...if you get a TV, you get a cooker.

People will spend $300 for a TV system, but we can't get them to spend $80 for a cooker system.

The way that some people can afford it in Machinga district, is that they are rice farmers. They sell a 50 kg bag of rice for $15. Maybe they harvest 50 to 100 bags of rice, and decide to make the TV purchase as their big ticket item that they invest in this year. They harvest their rice in June/July/August. And some people will save up for Christmas. So we figure our seasonal sales window for the expensive TV systems is June through December, with very few purchases from June to May.

What is their next best alternative for a TV? The electric company charges $200 for a connection to the grid: and on top of that people get billed monthly about $10 to $20, especially if they do some cooking. A TV will cost another $100 to $200 for them (They can't get the TV at the price we can because we have access to the wholesale markets in the big city. The villagers don't have such access, so they have to pay about 1.5 times to twice as much as we do for the TVs).

So over the course of the year, if they were to get TV, lights, and a little electric cooking with the Electric company, it would cost them $150 + $150 + $15 * 24 months = $300 + $360 = $660. So their current next best alternative is more than twice as expensive as the solution we are providing. The district has about 70,000 households. If just one out of every 70 people want to get the least-cost TV solution for their home this year, that is more than 1000 customers at $300 each. It is a small fraction of the population, but a relatively big market (i.e. potentially $300,000 in sales) for us. And it potentially provides a profitable way to conceivably get 1000 cookers out into the market this year, which otherwise we might not do.

Yes, these systems are going to richer households. The median household can afford to invest only about $20 to $30 for a solar system. So the median customer has to be subsidized. The cooker/lighting system is going to cost at least $100 at present, so we would need at least $70/household of subsidy money. I have limited subsidy money, so if I have to decide between subsidizing 3.5 houses for lights and cell phone, or 1 house for lights, cell phone and cooker, I will prefer to subsidize the 3.5 houses. Later, when the cooker, lights and cell phone system cost is down at $60 to $70, I think we will able to distribute them to the poorer households. In the meantime, I have to have the solar TV purchasers subsidize the in-Malawi development of the solar cooker design, development and production, until we can get further cost reductions (such as getting $0.30/Watt panels to Malawi) which will allow us to get the cooker to a much wider range of customers.


Pete Responds:


Yes, Excellent. I think that having a cooker doesn’t add to the price of the TV system anyway because the cooker is the voltage controller, no?

In the process of selling the more expensive TV systems to richer families, you are in fact getting the word out for cookers anyway. It’s a great idea in my opinion.


Robert responds about how the rich determine the game in energy by making the GRID the important thing… it doesn’t have to be that way.

Yes, it is the overvoltage control.
More specifically, because panels are far cheaper per watt-hour per day than batteries, increasing the reliability of TV power supply given variable solar input leads to oversizing the panel. If you don’t oversize the panel, then you are wasting the money you spent on the TV, because you bought a TV, that you can’t use as much as you want. If you oversize the the battery instead you are mako.g the system too expensive.
The cooker takes the electricity from the oversized panel and converts it to something flexible and useful for the household.
As panels get cheaper, and wood and charcoal get more expensive, eventually the cookers will justify themselves, and then because the cookers require much more electricity than other uses, the electricity for everything else will be reliable amd cheap because the cookers absorb the fluctuations in supply, and the large cooker load kustifies economies of scale in the system design. Households will no longer need grids or microgrids for cheap reliable electricity.
This will allow households to have reliable, cheap solar electricity for their homes because they won’t need grid connections, which are expensive because the grids are economically optimized to serve much richer people in the cities, because those people provide the majority of utility revenue.
For any grid, a key expense is the right to move electricity over public land. The price of land and land rights scales with the income of people who can buy land. Which is usually higher then the incomes of the poor majority, so this expense is high for really poor people.
But now the low income solar owners have their own, cheap energy and can now negotiate with the utility. If the richer people on the grid want access to the poor people’s cheap electricity, they can negotiate a deal that is perhaps in their mutual self-interest. Since it is now the richer people that rationally would want access to the cheap electricity at the poor persons house, the right of transmission now rationally gets paid by the richer people, who are the ones driving the relatively high price of transmission (and other infrastructure) on the grid.
The above scenario is a much more rational negotiation in my mind, than the current state of affairs where poor people are asked to pay a richer person’s price of electricity, or do without. The current state of affairs leaves poorer people with no negotiating power in the economic negotiation for electricity access. So poor people lose out.
That is the real reason in my mind that half a billion people don’t have access to electricity in Africa: because the richer people and business that control the politics have no real motivation to give them access to their grid. So they keep the grid for themselves, that is how the priorities play out.
And the reason aid does not solve the problem is that aid folks talk to the college educated richer people in the countries that are more like them. So they agree through political pragmatism that the grid has to serve the people with money first because the utility has to balance its books. So they take the money, use it for the richer people’s grid, and then argue that it will trickle-down to poor people through economic growth (that is how Obama’s Power Africa worked in practice). But Power Africa’s trickle down works about as well as Reagan’s trickle-down. It becomes a very small trickle at the end of the day.
May 13, Robert describes preliminary success in distributing Solar Cooking/TV systems:


People in the village LOVE the TV system, and they will use the pot if it cooks well and conveniently. We are going to do a couple more design variations to make it easier for people to use.
They are happy to take the panel out every day and point it at the morning, noon, and evening sun.
But they like leaving the TV on, so to have enough electricity for cooking we need a bigger panel, 150 or 200 watts.
The system price is very high compared to their income. We set the proce so it absorbs the cost of the pot, but cannot get the price high enough to cover the cost of a panel larger than 100 watts..
A good exercise for your class that would be helpful, is if they could calculate the carbon value of the increased panel assuming that 50% of the additional energy is used for cooking, and that the cooking with the pot displaces charcoal.
We need a subsidy of about $0.7/watt of increased capacity. Under what conditions might such a subsidy be justified?
You might also think of the health benefits of the decreased indoor air pollution measured in DALY. Those can probably be valued at their opportunity cost of $20 to $50 per DALY avoided.
Pete Responds:


I’m simultaneously inspired and concerned about this news. Spreading solar cooking and 24-7 TV to rural communities… I’m personally conflicted as I regard TV as the worst that industrialized technology has to offer. I remember in Guatemala, the TV is often constantly on and the kids just sit in front of it and watch the sex, sexism, and violence that is offered by the local stations. Is it the sound that people enjoy during their daily routine? Would music be equally accepted? I recognize that this may not be for me to determine for someone else, but it is up to me to decide where I put my efforts… I suppose the answer is to study and learn.
When you come in a week and a half (!!), you will speak with the class and also meet with students and groups individually. Would you also like to hold a university seminar while you are here, or should we invite “outsiders” to the class presentation?
Great hearing from you.

RVB responds

I know the concern and share it.
There are about 19 channels available in rural Malawi. They are pretty wholesome by US standards.

About 3 or 4 are religious channels, one Islamic and several christian. They also are pretty mild. There are two or three music channels. Again, folks are pretty covered up on these. A couple foreignish channels and a couple of regular local channels (Malawian and Zambian). But I did not do a detailed catalog of channels

We are going to distribute radios too ($7 each).
I would be happy to not distribute TVs, but if I am to grow business in Malawi, for Malawians, I have to be accountable to what they want, and create a piece of my operation that is profitable.
If we find someone to give us a grant, I would be very very happy to distribute solar system sans TV. But we can’t ask a family of five, earning less than $80/month to pay $100 for a cooking pot when they can gather wood for free.
Right now, I have solar lighting systems that help families that are getting one to several scorpions stings per week get free from scorpions stings. And I can’t get $4 per person donated so that they can stop being stung by scorpions once per month per person (which is the consequence of the solar lights for them). I have thousands of such households that need subsidized lights.
In my assessment, when push comes to shove, the rich world doesn’t care very much about the well being of Malawians, or the system is such that much money gets used up before it gets to Malawian Beneficiaries (which is sort of the sealer thing) . So unfortunately, if I want to help Malawians, help each other, I and my Malawian partners are going to have to produce some products that the richer Malawians like, so that we can share the profits with poorer Malawians that need the bare basics.
Alternatively, if you help organize subsidies, I can allocate those to solar systems without TVs. Happy to do that. Subsidy per household will probably have to increase to about $0.9/watt of panel capacity because I don’t have the cross-subsidy from the TV purchaser.
One thing that informs my attitude is that my family wasn’t rich, and I watched a lot of TV as a kid, and fought over the TV with my brothers and sister. In many ways the kids here remind me of us as little kids. I know that if I was them, I would want the chance to watch TV. Again, the density we are talking about is about one TV for every ten houses. But, if we are successful at raising standards of living over ten years, most houses will have a TV in 10 to 20 years. How do you feel about that?
I think that one thing that the Gates foundation does is that It makes people healthier without raising their income. It means that millions remain in poverty with very limited choices. It seems pretty patriarchal and undemocratic to me.
I think rich country poverty reduction is clearly conditional. That conditionality is an exercise of power. I would hope that you exercise of you conditionalities are conscious of that power dynamic.
I have my conditionalities too, and one way that I try to hold them accountable is by taking time to talk to the villagers. I pushed to introduce the TVs when I did a batch of villager interviews in the Machinga area and more than half said we should continue and introduce bigger systems. This was said by both rich and poor. So I consider that if I am going to represent their interests, I have to be responsive to what they ask for. And they clearly want access to TV as part of the following priority order for services: (1) lights (2) cell phone charging, (3) radios (4) TV.
I am trying to get cookers and/or fans inserted next in priority after TVs.
But I hear you, it would be nice to bump the cookers ahead of TVs, but to do that I need subsidy money. Low prices (I. E. Money) talks.

May 14, on how we can stabilize voltage drop across diodes
Dear Pete and Matt:

Some ideas on the cook pot as I practice using it in my room here in Blantyre, Malawi.

What happens is that the number of diodes for maximum power to the pot varies with the temperature of the diodes and the input current from the panel.

The other thing that happens is that there is always some resistance in the wires from the Panel to the Pot, and this modifies the voltage of the maximum power point at the pot.

It is easy for us to add a voltage display to the pot, and add multiple leads that go to different voltages in the diode string.

My idea is that we make a standard piece of equipment that we can put in the lines which is a little dial switch that can pick the different voltage settings. So that users can pick the setting that optimize the operation and outputs of the cookpot, based on a reasonable heuristic like: “pick the setting that keeps the voltage for the pot between 14 and 17 volts.” This setting may be different for conditions with more or less sun.

It is pretty easy for us to educate the users and explain that the cook pot voltage should be 15 volts when the sun is shining. We could also have a similar dial for the phone charger want to set the phone charger voltage to between 5 and 6 volts when you are charging your phone.

Note by placing Schottkey diodes in sections of the voltage string, we can adjust voltages by increments of 0.3 to 0.5 volts if we want to. This should allow us to really fine tune the efficiency of cookpot operations under varied conditions, really cheaply.

This will also allow people to use the same cookpot at close to optimum conditions for different sizes of panels even if users don’t use the dial much. Because the voltage across the diodes varies with current, the optimum number of diodes needed for peak power voltage and utilization changes with panel size and panel wire resistance. Even if the user does not adjust the dial, the installer can adjust the dial at installation and then tape it up to fix it in position.

Hope this suggestion/idea is useful.

-Robert VB