PV Solar Water Heating

The Elon 100 Solar PV Water Heating unit with 2 x solar panels or 3 x solar panels depending on size of geyser and people using hot water.

·        Competitive capital cost, no maintenance costs and a long lifetime.

·        Converts a standard electric geyser into a solar PV water heater. No element change and no inverter or batteries needed.

·        Easy compliance with SANS 10400-XA2 and can help achieve EDGE certification. The Elon® uses advanced proprietary switching technology to allow for direct provision of DC (Direct Current)

power from solar PV (photovoltaic) modules to electric geyser and optimised solar power use in a single

compact unit. The system can be connected to the grid (AC mains) as well, and intelligently switches between AC

and solar power supply. The system requires no inverter and no battery, and can be connected to standard AC

geyser heating elements and AC thermostats, which translates into the most cost-effective solar water heating

option today.

How can solar PV water heating be more cost-effective than solar thermal? Isn’t solar thermal efficiency

much better than solar PV?

It is true that solar thermal collectors are currently more efficient per square meter (area) than solar PV modules

in collecting solar energy. However, overall efficiency must also take into consideration factors such as heat loss

in piping (especially in winter) and energy use of solar thermal circulation pumps.

Solar thermal system lifetimes range from about 7 years (for cheap imports) to about 15 years for high quality

(and more expensive) systems. (In a comprehensive analysis, Sandia National Laboratories found that about 50%

of solar thermal systems fail within a 10-year period.) Solar PV modules are routinely guaranteed at 80%

performance after 25 years, and the US National Renewable Energy Laboratory uses a lifetime of 33 years in its

solar PV system calculations.

Solar PV module costs have dropped dramatically – by over 80% in the past 5 years – and the trend is continuing.

This has changed the paradigm. Whilst solar PV systems will continue to require more roof space than solar

thermal in the short term, the key issue is not roof space, but cost. Solar PV systems have become costcompetitive

to solar thermal, and the much longer lifetimes and lower maintenance translate into a lower

lifetime cost per kWh.