Solar Powered Water Systems in Humanitarian Context - Q&A

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

Contact Information of Lorentz and Grundfos

Overview Questions about SPWS Technology

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).

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.

What is the reason for the power limitation of a DC system?

Please listen to the webinar recording.

Which type of motors is cost-effective, normal pumps, or pumps designed for solar power system?

The same pumps you might use with a diesel generator or the electrical grid, can now be solarized, so no real difference. DC pumps (normally small pumps of up to 4kW of motor power) have higher efficiency than AC pumps (than have larger power).

Can we combine a solar water pumping system with a solar home system? If not, why?

The two systems cannot be combined because the solar pumping controller/inverter is designed to power a single pump motor, and no other load should be connected to it.

I am not an expert in conversion units, but just wish to find out what parameters do we need to put in place to combine horizontal friction of pump and vertical in making decisions of where to install a pump and distribution tank to assure proper gravity flow to all in a community

Detailed calculation of the total dynamic head (TDH) should be done to determine the total system head required to deliver water to the tank. For groundwater, the parameters of TDH are dynamic water level, static head [ground elevation + overhead tank height] and friction losses. The gravity pressure needs (tank height) for distribution to users should be determined based on the rate of water use by users, distance to the users, the pipe size to be used for distribution (friction), and flow velocity required

Is it possible to have a solar solution for a pumping head of 150m and a horizontal distance of 1.5km?

Yes, it is possible, SPWS computer design software from Lorentz and Grundfos can be used to make an appropriate design. Other system parameters are however required to be able to make the design.

Would like to know also if there is an output advantage for solar panel system placed at heights?

Raising the panels gives no power output advantage, but can enhance the security of the panels from theft and vandalism.

One of the challenges to install power solar water system is the availability of products in the market and it takes a longer time up to 6 months to import products from China/EU to Ethiopia, so it is one of the challenges to use the products in Emergency and Humanitarian responses

Ethiopia has unique conditions of the supply chain, sometimes also linked to the availability of foreign currency. Recurrent emergencies (eg droughts) and protracted ones (eg refugees) are contexts where some ahead planning could solve those problems. For rapid onset emergencies, prepositioning of stocks might be the most realistic way forward.  You can find some info on emergency solar pumping kits for rapid deployment: Solar Pumping Toolkit - Technical Design.

We’re just in the process to plan a new solar-powered irrigation project. We thought it was important to also take the water availability aspect into consideration. Do you also address the risk of overusing water resources in the long run? Monitoring water level was mentioned in the context of avoiding damage to the pump/ no damage to groundwater availability. This is the hydrology side. But there is also the awareness side with regard to appropriate application/ use of the pump/ water. Is this being addressed? Successfully? UNHCR mentions environmental factors - seems to mainly focus mainly on CO2 reduction aspect. Proper planning and design roughly mentioned as well though

The issue of over-pumping groundwater and monitoring water levels will be addressed in webinar 2.

What are the technical solutions for multi-purpose use of SWP considering lighting, charging of electronics, etc

Use a separate independent solar system for other power applications. Our recommendation is that the SWP system should never be connected to auxiliary loads such as lighting because this might reduce the water output and affect make the water system underperform. However, some manufacturer products come with auxiliary output for charging phones, so reference should be made to the product instructions.

How many pumps are installed in yearly in Africa?

We don’t have that kind of mapping or data, apologies.

Pump Sizing

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 the way to size your water pump for your borehole is similar to the way if using other power sources.

What is available from Lorentz and Grundfos to provide solutions for deep boreholes ?

As explained during the webinar, you can solarize their submersible pumps of up to 100kW (Lorentz) with TDH 450m and 250kW (Grundfos) with even higher TDHs.

Use of Batteries

What about the use of Batteries?

It is technically feasible but they are costly, might need maintenance and introduce high 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.

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.

Hybrid Systems

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.

How much does it cost to install a hybrid system to a borehole with 25m3/h capacity (22Kw control panel) and to supply water for 12 hrs per day

There are several other details needed to be able to provide an answer to that question. We will talk more about costs and finances in webinar2 in January.

Which motor type is used in a hybrid system?

The motor can either be a DC motor or an AC motor. Both can be operated in a hybrid configuration

I see a larger percentage of solar pumping installations are hybrid compared to purely solar installations. Why is this the case in your opinion?

It is a combination of factors: Genuine need to meet demand, lack of proper needs assessment to know demand vs supply to be pumped leading to unnecessary buying of generators, lack of insight into collection patterns vs storage sizing (unnecessary operation of Genset).


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 and look in the appendix for an example on how to size a generator.

Why you did not add a power bank to save the power to use it at the night to avoid using a generator?

While that is a technically viable solution, power banks are costly, might need regular maintenance, introduce high inefficiencies and are prone to theft. We have found very few examples of that configuration in the field. As much as possible, storing extra water in elevated tanks (a way to store energy in itself) is a preferred option.

Stealing/Vandalism of Panels

Is stealing the pannels a problem? If yes what are the solutions?

In our trips to 8 different countries, we found stealing of pannels a much smaller problem than what it used to be. There are a number of measures that field NGOs take to minimize the problem, please write us through Ask and Expert at and we will share some document on this. (This question was also addressed during the webinar, Please listen to the webinar recording).

How many of these installations are equipped with water treatment disinfection systems before storage

I don't know how many of those presented in the webinar but it is not uncommon to find different online chlorinators solutions in solar pumping systems.

Cleaning of Panels

What's the percentage loss in PV generation due to dust?

Depends how dirty the panels get and how often (or not) they are cleaned...we have seen clean systems just losing 1 to 3% of total power to systems that don't work as too much energy is lost to dust and therefore, not enough to start the pump.

What's the recommended frequency to undertake routine PV module washing?

Depending on how dusty your environment is, and what season (dry or rainy) you are in. Typically we have seen communities cleaning panels every 3 or 4 days to every some week.

Is there any effort to making self-maintaining solar panels by the manufacturers, self-cleaning for example on higher grounds?

There is a technology for self-cleaning but it might get expensive, and needs maintenance, making sense mostly for large utility-scale solar plants for electricity supply. We have seen more local solutions where a pipe with holes is placed on top of the panels so that by opening a valve, panels get somehow cleaned.

Grid Electricity

During the webinar, almost all speakers discuss fossil fuels and generator, is there any problem with the system connecting to grid electricity? I mean the effects on the system that creates a problem by connecting through the electricity grid?

Water pumps can be connected and run on electricity grids. The problem in many contexts where humanitarian operations take place is that grids are unstable and/or there are frequent blackouts, making the water supply unpredictable and damaging pumps over time. But if you are working in a place with a stable and predictable electrical grip supply, that would probably be a good solution for your water supply project.

Operation and Maintenance

In Somalia from field experience, I have noticed most of the solar projects installed by Humanitarian partners are abandoned, due to either lack of poor rural village communities’ economic power for replacements of parts in case of breakdown, or to lack of technical capacities of the local community for the operation and maintenance (O&M), how can this be addressed? - Thanks Eng. Abdiaziz A. Haroon - IMC Somalia mission.

More thought needs to be given to O&M from the onset o prevent such issues. Measures for O&M should be incorporated in the project design as mentioned in the webinar: community ownership, links to government agencies for support/oversight, link to the private sector for aftersales support (including service agreements).

Case Studies

Do we have a case study of using Solar powered water pumping in the small-scale mining artisanal underground mining?

I haven't seen any for that application but not saying there might be something out there

What is the experience with maintenance and sustainability of larger (but also smaller systems) in a humanitarian setting? Who does what, ownership of the technology? What happens when the security situation worsens and becomes complicated to access camps?

Please listen to the webinar recording.

I am working in the mining industry. lots of pumps are used for water withdraw. is it possible to install a solar pumping system in u/g mine?

Solar panels must be placed in sunny places, if you can do that, your water pump in the mining place can very likely be solarised.

Any experience a/o suggestions to use the payment system when cattle troughs is implemented?

Sorry, we don’t have any case study or example for that kind of situation.

Resources (software, links...)

Can you share the design template in excel form?

Design for SPWS is done using computer software provided by manufacturers. If interested in those, please contact us through

Is it possible to have a support tool to facilitate the rapid sizing of solar systems in the context of humanitarian interventions?

Computer design software from SPWS manufacturers allows quick and easy sizing.

Also refer to a selection of emergency kits under resources: Solar Pumping Toolkit - Technical Design.

If there is excel spreadsheet for SPW systems sizing and design for water pumping systems?

Computer design software from SPWS manufacturers allows quick and easy sizing.Also refer to a selection of emergency kits under resources: Solar Pumping Toolkit - Technical Design.

Is the Oxfam solar pump kit available in the supply catalog?

Yes, it is and you can find the two types here:

Do we have any computer-based software that helps calculate the length of water reticulation networks versus pressure at the tapping point?

EPANET is a popular choice, with tutorials and software available for free online.

Questions asked to Lorentz

Do you have a prepaid card method to speed up revenue collection in the community water supply set up

Please listen to the webinar recording.

Is there any representative for LORENTZ in Turkey or any local company you are working with?

Yes we have a distributor and several sales and service partners in Turkey. You can find a list of LORENTZ partners here

Do they have a list of countries where they have a distributor?

Yes, please see this list, choose your continent and country for a list .

How many water tanks/floaters can you control from one single electrical board?

When filling multiple tanks from one pump we would normally do this by pressure control rather than multiple float switches. We use a combination of pressure switching software functions and constant flow functions to achieve this. You can see how this is done here (about 20 mins in)

Can we have rough prices on smarttaps?

The list price of the smartTAP is USD1000 including the PV module to power it. It is designed for wide scale deployment and so priced accordingly. The local prices may change depending on duty, taxes, transport etc. Deploying systems at scale will reduce prices as the project overheads (mobilization) are reduced.

What are some examples of places/regions where the Lorentz hybrid pumps, and water dispensers are installed?

The first PSk2 hybrid solutions were installed in 2015. Since then they have been installed in many countries (>50). SmartTAPs were first installed in 2018, they are installed in about 20 countries, projects go from one smartTAP to 1000 smartTAPs in a single project.

Which motor type is used in hybrid system?

A 3 phase AC motor is used in the hybrid systems

When can we expect detail training on Smart Tap system?

These two webinars will provide more information:

Planning smartTAP implementation, sizing and commercial planning

Quick intro and example use cases from small to large

Would like to enquire whether solar Hybrid system for LORENTZ is available in Mogadishu Somalia local supply companies ?

What is the lifetime of solar pumps nowadays?

Lifetime is always difficult to predict. LORENTZ controllers are IP68, designed for outdoor installation and with intelligent temperature management so electronics are very robust. Motors typically have a long life and have good protection by the controller. Water quality (high sand levels) will effect the life of a pump end. Good quality solar pumps will last at least as long as good quality non solar pumps.

Do you have full package of surface pump that float on the running river including the floater to support the pump. if you have experience in floating surface pump how you manage it during raining seasons flooding in case of River

LORENTZ has a full range of surface solar pumps. The floating solutions are usually built locally to meet site requirements with advice from our engineering team. Here are some examples –

Hybrid floating pump:

Wheeled pump with floating suction:

For the development context: SDG6 is water on premises! Apposed to public smart taps - do you have any household water meter product in your portfolio, development or for recommendation?

My understanding of SDG6 is that it is not specific to water on premises but to equitable access to water for all. When designing smartTAP networks we would locate them so that there are short distances to travel (<100 m) it can be shown that this encourages multiple visits, keeps water fresher. Shared water facilities are much more economical to install and have much lower operating costs. In house metering is a logical extension of the solution, we have been testing different solutions in this area but we have no announcements on this at the moment.

Does the payment system work also in the community for the regular water supply system?

The smartTAPs can be deployed on any piped water source, from the “water grid” or a standalone solar pump. We have customers who use them on a water kiosk to provide service 24 hours per day and water utilities using them on piped city water.

Questions asked to Grundfos

1. Do they have a list of countries where they have a distributor?

We don’t have a global list, please use the website: to contact your local/nearest Grundfos office and they will help you.

You can also email and you will be forwarded to the local Grundfos office.

What is the advantage of SQFlex over other options? Has it been adapted specifically for humanitarian contexts?

It is an all in one solution that have been made for easy installation, and only configure the amount of solar panels to match the needs.

It is used in many refugee camps and remote locations with success

Is it true that sqflex can be tracked after it have been stolen?

No, there are no tracking device on it, it has an unique serial number. (It is not possible/easy to track something that is submerged in water.)

Average price of SQflex of Grundfos product for shallow well of max depth 45 m?

List prices for our products are shown, when using the website: you’ll need to select the country in settings to see prices.

What does the RSI stand for?

RSI= Renewable Solar Inverter

Is Grundfos RSI compatible with SP that are not Grundfos

Yes, it works with other brands, it will then be the customer that is responsible to ensure the product can work with VFD’s and the water output.

Is Generator sizing factored in the Grundfos online sizing platform?

No, this is something that is typically depending of the manufacture of generators specifications, we can give some general advice, but it is the specific generator that sets the sizing

What is the lifetime of the AQPure units?

Depends on the installation and usage, but expected 10 years

Do you have a full package of surface pump that float on the running river including the floater to support the pump. if you have experience in floating surface pump how you manage it during raining seasons flooding in case of River

We don’t have a package for that, in a river there are some additional concerns and I think a submersible pump in a flow sleeve, attached to a float is a better solution.

I cannot find good information on Grundfos' hybrid concept "PowerAdapt". Can you send us links to the technical specifications?

See the attached documents.

About the Water kiosks: have they been tested in the initial phase of emergencies, like refugee settings?

I’m not aware of that it has been used in the initial phase, but it is used widely in refuge settings and host communities.

About the Water kiosks: can the cards be charged automatically, say weekly/daily water allowance for a family.

Yes, they can.

Can the card/tags be used for other types of contactless uses (distribution cards/e-cash distribution?

No, they can only be used for AQtap systems

Can they be installed in places with no/limited connectivity?

Yes, they can be charged with credit, at the local AQtap with a “Vendor” card.

From your presentation is it possible to have a solar solution for a pumping head of 150m and a horizontal distance of 1.5km?

Yes, we have that, both in SQFlex and with RSI+SP range, it depends on the required flow per day, it can be sized at choose Solar Water solutions for sizing.