Solar Powered Water Systems in Humanitarian Context - Q&A

This page documents the questions that were asked during the webinar: Solar Powered Water Systems in Humanitarian Context

'Please note that this page is a work in progress and will be updated with all the questions asked during the webinar'

Contact Information of Lorentz and Grundfos

• https://www.lorentz.de/partners/
• https://www.grundfos.com/za/where-to-buy

Q1. How can we install solar-powered pumps to replace an existing hand pump installed borehole in a rural context?

this is technically possible, depending on the parameters of your system. Typically the borehole diameter (normally 3 inches or less) is a limiting factor for replacing handpumps with solar pumps...If your borehole diameter is a bit bigger (4 or more inches) this can be done without a problem).

Q2. Which solar pumps are best for different depths ? surface pumps and submersibles

you can literally solarize any electrical submersible pump and many surface pumps, like the ones used with diesel generators or connected to the grid....so the way to size your water pump for your borehole is similar to the way if using other power sources.

Q3. What about the use of Batteries?

It is technically feasible but they are costly, might need maintenance and introduce high inefficiencies...it is normally a better option to oversize your solar panel array, since the cost of panels is low, and store water in an elevated water tank, which is a way to store energy, so that water can be made available at any time by gravity.

Q4. How do we address the high initial capital costs of solar water supply systems?

There are various means of financing, similar to when you use another power source... depending on the size of your system, solar pumping options might not be that initially costly as you may think, as prices of panels have dropped by 80% in the last 10 years. Having said this, what really helps in financing is to look at the cost over the lifetime of the equipment, which almost always brings to light the savings incurred over time when using solar pumping. We will talk about this in-depth during Webinar 2 in January.

Q5. Can we store the solar energy in batteries for night use instead of the hybrid system requiring a generator?

Yes, you can do that. It might be more expensive and inefficient than other options but technically feasible.

Q6. How can you make sure the Genset is running within its boundaries? meaning a 30KVA Genset cannot supply 5kW power, or it risks to be in underload, correct?

There is a way to size a generator so that it works within an efficient range for a given pump. A 30kVA can provide 5kW, but as you say, it will be underloaded and therefore more inefficient and perhaps influencing in a shorter lifespan for the Genset. Please, download the book from www.thesolarhub.org and look in the appendix for an example on how to size a generator.

Q7. What are the water quality considerations while designing hybrid solar pumps?

The pump technology will be the same, whether your pump is powered with solar, hybrid, generator, or grid, so there are no specific water quality considerations linked to the use of solar panels.

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