Page 98 - A Comprehensive Guide to Solar Energy Systems

Chapter 5 • Sustainable Solar Energy Collection and Storage 93

progress toward the establishment of appropriate reverse logistics systems for the collection
of end-of-life modules, and the engagement of companies involved in all stages of PV product
lifecycles to establish reverse supply chains. Appropriate legislation, incorporating extend-
ed producer responsibility to finance end-of-life costs of PV systems may spark progress in
eco-design of modules for easy disassembly for recycling. detachable frames and glass allow
panels to be disassembled for reuse, and using thermoplastics to seal panels in place of EVA
plastic allows wafers to be recovered by melting plastics rather than crushing modules [32].
African nations now have a window of opportunity to put in place measures to enable
circular economy around the large volumes of c-Si PV and associated system components
which will be deployed across the continent in the near future. Organizations such as
Mobisol, who offer affordable solar energy solutions in East Africa, have recognized this
challenge and opportunity and established a project team to explore recycling of solar
components, and already offer a battery recycling service.

5.5 Energy, and Energy Storage, Needs of Households
in Rural Africa

To give a basis for discussion, we first need to define the energy needs to be met. In recent
−1
years, in South Africa, energy suppliers introduced a scheme to provide 50 kW h month
‘free basic electricity’ to grid-connected households, with a plan to develop off-grid solar
−1
powered systems providing 50 kW h month to rural households [33]. We have used this
−1
50 kW h month as an initial target to achieve with a simple off-grid system comprising
−1
−1
of PV panels, a battery, and a charge controller. 50 kW h month is ∼1.67 kW h day ,
significantly lower than the average daily consumption of South African homes with grid
−1
electricity access (∼8 kW h day ), but sufficient for basic commodities such as lighting, TV,
radio, cell phone charging, washing, and possibly refrigeration. Table 5.1 provides typical
daily energy consumption values (dC appliances are considered to avoid the additional
cost of an inverter).
If 90% of this energy was required overnight, then ∼1.5 kW h energy storage is needed.
−1
Allowing for an annual load growth of 2% year over the 20 year lifetime of the PV system
requires ∼2.1 kW h of battery storage. (We note that increase in electricity demand is
such that this year, 2017, the proposed on-grid ‘free electricity’ allocation in durban is

Table 5.1 Example Daily Energy Consumption for Small Domestic Appliances
Item Usage/h Energy Consumption/kW h day −1
TV (32 in. LCD) 5 0.35
Small DC fridge (50 W) 24 1.2
Compact fluorescent light (one 14 W bulb) 5 0.07
Cell phone charger (5 W) 3 0.01
Washing machine (500 W) 1 0.5
Total energy consumption 2.13