Archive for the ‘Solar’ Category

C-Cell Mobile Phone Charging in Ghana

Jun 24, 2009 Africa, Ghana, Innovation, Mobile, Power, Solar

Nana Owusu Acheampongs C-Cell Cell Phone Charger

Nana Owusu Acheampong's C-Cell Phone Charger

Kevin Rehak, an MBA Student at Columbia University that I am working with, recently sent me this photo of an innovative approach to cell phone charging in Ghana.  Using a charging system he made himself, Mr. Acheampong, one of the Abusuapanin Community Leader’s in Bonsaaso village, use’s 4 C dry cell batteries to charge mobile phones.  The four 1.5V batteries in series adds up to 6V which is similar to the 5.5V that most cell phones require (amperage varies). The set of batteries cost 1 Ghana Cedi and he is able to charge four phones before needing to replace the batteries.  This compares to the 1 Cedi cost of charging a phone at the local cell tower.

Obviously, for a number of reasons this solution is not ideal.  The phones charge very quickly (~10 minutes) but are probably receiving too high of a current which damages batteries.  From an environmental standpoint, this method is particularly wasteful.  All this is to highlight both the huge demand for cell phone charging in rural areas in Africa and a general lack of cheap and efficient technologies available for entrepreneurs like Mr. Acheampong.

Tough Stuff Solar Panel

Tough Stuff Solar Panel

Luckily, a lot of new products are beginning to enter the market that should help change this.  The Tough Stuff Solar Panel a 1W (5.6V, 174mA) highly robust, amorphous panel that is ideal for charging individual cell phones is a particularly exciting example of this.  More important then spec, the Tough Stuff Panel (with cell connectors) comes in at about €10 or less per panel retail.  The retail price will obviously have to be a bit more but if you consider existing charging practices (see above) even a $20 price-point seems very viable.

Also see related post on 12V Cell Phone Charging Practices in Mali

Rethinking the term “Solar Systems”

Jun 15, 2009 ICT4D, Solar, Technology

Off-Grid Component Costs over Time

I had a really interesting discussion at work with my boss Vijay Modi and some colleagues about the real costs of an off-grid “solar” systems.  The perception is often that solar panels make up the bulk of the cost of an off-grid system.  The reality, however, with any time horizon over three years is that the cost of batteries will be the biggest determining factor of cost over time.  It is for this reason, that Mark Hankin’s argues that off-grid system should not be called “solar systems” but rather battery-based systems.

If you consider that most off-grid systems in Africa fail after three years, this term is unfortunately even more appropriate.

Off-Grid Solar Calculator

May 3, 2009 Africa, Power, Resource, Solar

Part of my job over the past couple of years has entailed doing energy sizing for off-grid photo voltaic (PV) solar systems.  To help with this I have relied largely on an excel-based solar calculator that I created.  I thought it might be useful to share.

  • Solar Toolkit - excel based solar calculator. Last updated 05.03.09. Please see instructions for proper usage.
  • Solar Radiation Chart - useful for estimating peak solar of your location (# hours of day of strong sunlight)
  • Solar Radiation Chart 2 - includes optimal PV inclination angles for facing the sun

Please note: this is NOT intended to replace getting a detailed power estimate from a local solar expert who can best take in account the local conditions. This is more intended to help you with estimates when you are looking to bring a project off-grid. Please use at your own risk.

Solar Costing

A common question relating to PV systems is what does it cost?  A technique commonly used is to estimate the cost at $10-per-watt. This includes the cost of the panels, batteries, charge controller and wiring - installed.  A 100W system, for example, would cost you around $1,000.   You can begin to see why we tend to get so nutty about power efficiency! =)

Note: In Africa we’ve found this price to vary widely from $10 to over $15 due to different policies on import taxation, transport costs and varying levels of local competition.  Also, $10-per-watt is for the initial setup of a PV system only.  To consider issues of sustainability, it is important to take in account that batteries will need to be replaced every 2-3 years and the charge controller ever five.  If you wish to factor in replacement costs, to keep the system operational,  $15-per-watt should be used.