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 shortly 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

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.

1.    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.

1.    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 grid....so 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 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.

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.

1.    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).

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

1.    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 www.thesolarhub.org 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

1.    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.

1.    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 solarquery@iom.int

1.    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.

1.    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:

• https://supplycentre.oxfam.org.uk/pump-kit-solar-submersible-4-655-p.asp
  
• https://supplycentre.oxfam.org.uk/pump-kit-solar-submersible-3-low-yield-654-p.asp
  

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

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.