Solar Powered Water Systems in Humanitarian Context II - Q&A
This page documents the questions that were asked during the webinar: Solar Powered Water Systems in Humanitarian Context - Making Sense of SPWS Expansion.
This page is currently being updated!!
Questions to All
Which are the preferable solar water pumping systems that would eliminate the use of generators in the long run. We have challenges with solar systems in South Sudan refugee camps. Use of generators still takes about 60% of water pumping
when converting from diesel generator operation, the full details of the system (as being explained by Jeff) need to be known so that the right PV size can be designed to supply the required amount. Where solar cannot meet the requirements, a hybrid operation is then chosen
Regarding daily demand and solar, what sizing consideration do you do for consecutive cloudy days?
Usually, SWP sizing is based on the worst-case i.e. design is based on the season or days when you expect the least irradiation. So it should be ensured that the design is able to meet the demand when you have the least sunshine.
We realised one more factor important in design - slope and direction
In case you are referring to the tilt angle/orientation of the solar panels, then indeed you are right as the tilt angle and orientation impact the power output from the solar modules.
While there seems to be little or no support for using batteries in solar water pumping scheme could it not be feasible someday since the cost of battery storage is plummeting (as PVs did making PV water pumping much more feasible) would it not be possible to find batteries useful in some applications such as a situation where well capacity is weak and a longer pumping cycle would be needed to meet demand. This could be more efficient than opting for a solar-diesel hybrid system, no?
You are right. Battery technology is indeed evolving into batteries that have 15-20 years life as opposed to the current technology which has a short life (3-6 years) which has been the biggest deterrent for using batteries in SWP. However, the long-life batteries (lithium-ion etc) are very expensive prohibiting their wider use. Perhaps we will see this change in the coming years.
Questions to Jeff
I wonder how do you make solar systems like in Puerto Rico hurricane-resistant?
In a humanitarian context, how would you go about establishing the dynamic water level (where this information has not been established prior, but where there is anecdotal evidence of seasonal fluctuations and/or lowering groundwater levels?
Questions to Rick
Sometimes after geological survey, wells later start drying Not because of the aquifer condition but because of weather changes, what could be done to address such issues.
Questions to Alberto
using the LCCA is great for comparing between the generator, hybrid and solar systems. But how can you use it to calculate what potential user fees would be to cover costs for the system? Given that it uses present worth as its basis rather than looking at inflation, I know that this has caused some confusion when looking at what real-time costs will need to be paid.
Usually, the exact cost of equipment, maintenance and repair costs are lucking in developing country so how you exactly calculated LCC or you take the estimate.
We were able to find national based contractors supplying good quality solar equipment and pumps in every country we visited (including places like South Sudan or Somalia). We got the prices from these contractors and from the organizations working in the area (NGOs and the like); so the capital costs of equipment we used for the economic analysis were based in real prices of products in the country. For maintenance and repair, we based our calculation in conservative estimations provided by manufacturers (you can find those within the Cost analysis tool at https://thesolarhub.org/resources/cost-analysis-generator-vs-solar/
How do we integrate financing of Solar powered water systems especially to Sub- Saharan African Countries?
That is a good question with a difficult answer. We have come across different financing depending on context and other variables: basically either a donor provide full capital costs and users/owners of the system take care of O&M or the capital costs are offered to a subsidized costs to the users. When solar pumping is meant for productive activities (eg irrigation) farmers might have the option to pay after the harvest or in small monthly or quarterly payments. In some facilities, it exists the option of paying for water as a service (rather than paying for the solar equipment, with a private contractor paying and maintaining the equipment and collecting the fees). In theory and looking at the comparison in costs of a generator based water scheme vs solar, it would be many times wise that community of users save and pay for a solar system but in reality this is hard to find in low income countries.
What is the life time for solar pump system invertor?
It depends on the quality of the invertor. A good quality one design and manufactured for solar pumping applications (eg Grundfos, Lorentz, Franklin etc) might last 6 to 7 years if well maintained, according to manufacturers.
Yes, we will post them in www.thesolarweb.org
Did you consider the maintenance cost of systems knowing that in remote areas people do not have the skills? How do you manage that because it could help to increase the lifespan of systems and empower local communities especially youth?
There are different kind of maintenance that a solar water pumping system requires. The routine maintenance (eg cleaning the panels regularly and others) can be easily done by the users if briefly trained cause it needs little skills. Other more specialized maintenance (preventive and repairs) have to be done by specialized technicians as it requires skills that can not be provided with a short training to community members without proper and solid technical background. Having those technicians (normally based at capital level) have a cost that we did estimate and include in the cost analysis.
When it comes to the maintenance of a generator, we based our calculation in conservative estimations provided by manufacturers (you can find those within the Cost analysis tool at https://thesolarhub.org/resources/cost-analysis-generator-vs-solar/
You can find more on maintenance in chapter 11 or this book at https://thesolarhub.org/resources/solar-pumping-for-water-supply-harnessing-the-power-of-the-sun/
What the justification on the difference on the break even period for different countries? why is just 1 year in Uganda and 5.1 years in Iraq?
These analysis depend on the size of systems, the number of pumping hours and the like and not all systems analyzed in different countries were of the same size. You can find those details in our country visit reports at https://thesolarhub.org/category/case-study/
The case of Iraq (the largest breakdown of those shown in the webinar) is largely influenced by the fact that the price of diesel is one of the lowest in the world and grid access was present in some locations, a big difference with Uganda (expensive diesel and off grid areas).
Is drilling of borehole included in the calculation?
Economic analysis were made with the aim to compare technology costs (solar vs diesel) rather than having total costs. That’s why in order to simplify the analysis, we decided to eliminate all the costs that were common for both technologies. The cost of drilling a borehole will be the same, whether we install a generator or a solar system to power the pump, and therefore won’t have influence in the comparisons of both technologies. All the common costs (fencing of water point, salary of operator etc) were eliminated for the same reason.
Why did you choose a solar stand alone and not a hybrid system solar with grid?
I’m not sure to which case you are referring to. Most of our visits happened in off-grid areas, so a hybrid solar-grid configuration was simply not an option. In grid covered areas, you could certainly connect the grid in addition to solar to give more security to the system although this would increase the cost of the installation.
