At Okra we’ve been running theoretical calculations for a while, and they all seem to suggest that a smart connected network of solar panels & batteries are almost always going to be more efficient in providing off-grid electrification than standalone solar home systems. That’s because it’s hard to predict exactly how much power a household will consume day to day, add to that the intermittency of sunshine and the fact that batteries, the most expensive part of the system can only hold a finite amount of power before becoming full. This combination of factors means a standalone solar home system usually has to be oversized to guarantee sufficient power and there’s usually a non-trivial amount of power that’s wasted when there’s nowhere to store it.

We decided to back up our calculations with some empirical evidence so we went to Prey Pdao in Takeo Province, Cambodia and installed 5 solar home systems for the community. The Levelised Cost of Electricity in Cambodia from charging batteries with diesel is approximately $4.5/KWh, so we decided to charge households $1/kWh of electricity consumed, very steep compared to what we’re used to in urban areas, but still a fraction of the cost these households were paying. With the help of our implementation partners NRG Solutions and Camsolar, we installed 150Wp solar home systems with a 100Ah battery in each of the 5 households – which turns out was self-extended by the community to serve 7 households (will get to that later).

Our objectives were to let these households connect their old or new DC appliances to these systems, and observe the energy consumption behaviour, and importantly find out if there was any excess generation that could potentially be utilised in a smart connected microgrid network.

The pre-pilot was running since the start of August and the results are really encouraging (at least in terms of opportunities to improve!)