PowerOptimal Elon 100 Case Studies
Solar PV array size: 1.575 kWp Family size: 4 people Solar Fraction achieved: 52% of energy from the sun
When & Where: Pretoria, May 2017 (Winter)
Comments: With a system of only 1.5 kWp for four people, over 50% of the family’s water heating energy was obtained from the sun in winter time.
Solar PV array size: 1.5 kWp Family size: 2 people Solar Fraction achieved: 65% of energy from the sun
When & Where: Johannesburg, November to December 2017 (Summer)
Comments: Approximately two-thirds of this family’s water heating energy need was obtained from the sun.
The size of the solar PV array (in other words, the number of solar PV modules on the roof) will directly impact the performance of the Elon 100. Additionally, time of year and location will also have a substantial impact on system performance. Click here for a PDF with more information.
As can be seen from the graph below, payback period decreases as number of solar panels increases, and is also different for Johannesburg, Cape Town and Durban .
The reason that payback period improves (decreases) as number of solar panels increases, is because there are some fixed costs (such as engineering design & safety components) and some costs that do not scale linearly with array size (such as labour, wiring, mounting kit costs, etc.).
 Calculations based on actual Elon performance, assuming a 20% reduction due to non-optimal user behaviour, an initial electricity tariff of R2.15/kWh (which is the 2019/2020 average residential tariff across the 4 major metropolitan areas Johannesburg, Cape Town, Tshwane and eThekwini) and an annual electricity price increase of 8%.