As I said in a previous blog, with the publication of the report, I have had many emails asking if induction hobs are the way forward. I had yet another ‘induction’ email this morning from a colleague. Once again the suggestion was attached to the efficiency
savings of induction stoves.
So in this blog I would like to outline some of what we know about the major components and document where we might save energy and make system efficiency improvements.
PV array – there will of course be ongoing improvements in Solar Photovoltaic panels, and the price will come down. That was the start of the proposition. The Solar PV panels are likely to take up about 20% of the system cost, depending of course on how you size them. Do you size them so the system works every day of the year, or do you size them so that ‘during the rains’ the charcoal fire gets reinstated. This of course would have implications on health, and half a year of charcoal cooking is probably enough to cause the same respiratory failures that a full year does. In the words of ESMAP -no significant improvement in health.
Leach and Oduro 2015 point out that on a full system cost discounted over its lifetime, half year operation is almost as expensive as full year operation – so probably better to size for the full year.
Then we are left with the question; do you size so it works every day, or ‘most’ days. That is an important question because it affects the size of the battery, and the battery is the major cost (greater than 60% of total cost). Are the family going to discharge the battery (to its safe minimum) every night with their cooking, or could the battery have a surplus that carried over to the next morning? Making the battery so large it has a surplus likely means the PV panels could be smaller since they would be sized for their cumulative effect not their daily effect. However given that the battery is the expensive bit, probably better to have slightly bigger set of panels to cover cloudy days.
Finally, the panels could be part of a home systems, or part of a nano, micro or mini grid. Indeed the system could be part of a greater whole or stand alone. In either case, sizing of the panels to match the needs of the users will be a fairly key issue. We don’t want people to regularly get the charcoal stove out (although matching the system with LPG might be a healthy way forward).
- What do we know? That we need to model the outputs of solar panels, and that a solar systems design engineer needs to produce some guidelines on system sizing.
Charge controller – there are no issues as far as we know. Lithium Iron Phosphate needs a different charger from Lead Acid so it doesn’t over heat, but as long as the solar panels are wired up to a sensible charge controller, everything should be fine. We are not charging ‘rapidly’ so the idea that the battery may overheat when charging should not be an issue.
- What do we know? That the link between solar panels and batteries is well established and as long as manufacturers follow the accepted norm for charge controllers there should be no issues.
to be continued……