Physical goods is the least of Africas problems. Your clean water will literally drown in the sand until the leadership problem is solved.
"Ngango Cho'kto, 4 years, would like to eat. Won't you help? Your dollar can feed him for a year." Sounds oh so easy and compelling. Couldn't be further from the truth though. If it's just to clear your conscience, go right ahead. But don't misguide yourself into thinking that will solve anything or help anyone.
^^^ This!
OP, if you have NGO experience, you should know that raising the funding is never a major problem, getting someone to develop the software and configure the hardware needed is also relatively easy, but getting the funds distributed to their intended target is an impossible task in Africa.
Years ago, when the CPU mining was still feasible, I designed this cute Solar Miner. 125Wp panel + 3A MPPT + 1kWh lithium battery + 15W TDP Mobo + GPRS dongle = +/- $350, earning some $100-$150 per month in Bitcoins. I also had a solution for the Bitcoin to Cash conversion, easy and low-cost, the African way.
But what I could not solve is the comfort the NGOs needed in order to get involved with this. At the end, I had to abandon the idea, as I find it was not feasible, not in Africa.
After reading this OP I went and re-run the figures to see if my contraption will be feasible mining Litecoin today. And it sure was! Also, for little bit more, one could configure it to use BFL's 5GHs Miner instead of the Mobo, making this even more profitable that it was intended to be in the first place.
But I am still convinced that although technically one can create a mining solution for Africa, one should not do because is never worth it - at the end this will see everyone involved wasting their time and money while the local leaders enriching themselves again and Ngango Cho'kto, the proverbial 4 year old, will get nothing out of this, will probably die of hunger and some exotic diseases!