Let us assume for the moment that a 500Watt system is suitable for small households. The final system can have other components including M2M circuitry that interfaces with a SIM card for supply of usage data for lease holding, but our simple starting point has the following components:

• Panel
• Charge controller
• Battery
• Inverter?
• Hob

It does seem that even at todays (UK) retail prices, a system with these components could be brought together. One could have the panel, controller, inverter and battery for about $350, and run a 230V hob (which would add $50) – Total $400.

Alternatively one could keep to 12V but would have to design and get built a 12V 500W hob, giving a total system cost of around $300.

These prices have been estimated from data collected in June 2013, and based on retail online prices. It therefore seems more than possible that even at todays prices, a system could be mass produced with a $250 wholesale cost (conservatively).

We started our note by aiming at the year 2020. By then with the decrease of panel prices, and by ensuring a dedicated product design, it would seem more than reasonable to think that $180 retail (including market distribution costs and profit) is a viable target price.

To those of you reading this who cook on gas or electricity, at about 2KW or more, 500W may not sound much. Certainly you can find e-discussions and blogs by campers from developed countries complaining that it is “too slow”. However as a comparison with the standard Water Boiling Test for biomass stoves, 500W will heat the smaller standard pan (2.5 Litres with lid) in 30 minutes. This compares to say a charcoal cookstove  – from cold start around 55 minutes for improved stove, and 36 minutes for traditional stove, and 35 minutes for the hot start test on the improved, and 24 minutes for the traditional stove. I.e. 500W electric is fairly comparable to a charcoal stove. But is it enough for a family cooking?

Electric cooking is much more efficient, not just from the technical side but from the control for the cooking. Control of the process is far greater than a woodfuel or charcoal stove, where turning down the heat tends to mean taking the pot partially off the stove. A 500W stove is indeed on the borderline of being able to cook for a family of 5, and we must admit that perhaps it is suitable for only 1 Billion of the three Billion from a cultural cooking point of view. Still, 500W is a reasonable starting point.

Training and awareness on the limitations of the system might be necessary and this may decrease the rate of uptake in the early stages. These factors would need to be a part of the research. If we find (as we have done) that we can build a 500W system at todays retail prices then by the time we reach 2020, and prices halve again, we should be able to build a 1KW system for a similar system price, making the limitations more than manageable.