Solar Water, Electricity & Rainwater Catchment for Developing Communities
I live in Florida. Our pool is heated year-round by black, tubular solar panels sitting on the roof of my home. The only cost is a nominal amount of electricity required to pump water from the pool to circulate through the roof solar panels 10 meters above the pool. The number of hours per day required to pump varies by amount of sunshine per day throughout the year. In some years, we’ve been able to enjoy the pool every day of the year. This is, without argument, a luxury. Millions around the world don’t have access to a regular supply of household water, let alone hot water. While communities continue to solve access to household water in a variety of ways, reliable and consistent hot water, on demand, is not prevalent in most cases, without significant effort, expense and opportunity cost.
I’m been privileged to travel in many parts of the world, and one thing I have observed over the years in many developing countries, is that access to hot water is uncommon and expensive. I realize that access to water itself is even less common, not to mention clean, potable water. I recognize this and while not diminishing that critical need, that’s a topic for perhaps a different article. This article focuses on an idea that came to me, as they often do, on a flight back from overseas travel. Those long periods of time trapped in an aluminum tube at 35,000' have generated some of my most exciting ideas over the years. This was no different.
I began considering all the ways developing communities could benefit from a consistent, low (no) cost supply of hot water. From increased sanitation in washing dishes, as well as personal hygiene for both bathing and toilet hand-washing, food preparation and laundry, these use-cases are real, every day situations that western communities too often take for granted. Sure, developing communities can produce hot water, but the fuel (often firewood, charcoal or other combustible materials) are expensive to obtain, and costly to the local environment as well as the health (smoke inhalation) to the immediate users, and releases more carbon into the atmosphere than is really necessary. (yes, it’s true, humans contribute to climate change). There’s also an opportunity cost to obtaining fuel for a fire to heat water, and to keeping that fire going throughout the day and night as needed. Individuals, predominantly women, are often tied to the chore of keeping a fire going and to gathering fuel for that fire if hot water is needed. This time could be better spent.
How can a consistent supply of hot water be provided to millions of homes around the world using the same technology we enjoy to heat our swimming pool year-round? How would that impact and change lives, at a very personal level? How can several traditional problems be overcome in a single, affordable package, and how can that be made available at industrial scale?
I’ll confess right now, this is not necessarily a radical new idea and is short on many technical details. It was also, in part, inspired by Nokero, which I discovered a number of years ago at an international aid event in Washington, DC. I also took inspiration from Solar Source, and if you spend some time on their website, you’ll see why.
What is perhaps new or different, is the idea of pre-configuring or prefabrication of kits, much like ShelterBox does with their humanitarian mission. This is how to scale beyond a few thousand “early adopters” in developing communities. It’s not trivial and it’s not easy to do properly.
So, here’s a list, a conceptual “what’s the box” that will cover a vast majority of residential use-cases irrespective of geography. (you knew that word would eventually be used, right?)
a) black, tubular solar panels for rooftop installation
b) rainwater catchment system & tank
c) insulated hot water storage tank
d) solar cell for electricity generation
e) batteries for storage of surplus, solar-generated electricity
f) solar powered water pump
g) durable, extended-life, all weather tubular piping
I probably should invest in creating a graphical mockup of a typical (conceptual) installation configuration, but I’m not very talented in that department, but if any readers are so inclined, I’ll gladly insert the graphic and provide proper credit (hint, hint). So, sans schematics, at least in my mind, it’s set up like this.
The solar panel (or panels, given the size and estimated water consumption needs of the individual residence) are installed on rooftop with maximum annual solar exposure. These are very durable, black plastic tubular panels that assemble quickly and easily, and are interlocking with one another, and that are easily affixed to any roof surface, pitched or flat. Ideally, these panels would have integrated solar cells for electrical generation as well, but the energy generated from these would only be used for pumping operations and any surplus electricity would be stored in batteries for overnight needs or during periods when the sun’s solar rays are obscured by clouds or inclement weather.
As close to the panels as possible, an insulated hot water storage tank / reservoir would also be installed, typically with a capacity of of 200–400 liters. This could be elevated at the same height as the panels to allow maximum leverage of gravity to circulate hot water throughout the residence or property. This would reduce or eliminate the need for additional pumping, (and corresponding electricity requirements) but storing 400+ liters of water at any elevation off the ground requires reinforced infrastructure, which may not always be available and in earthquake prone areas, may not be advisable or practical for safety concerns. So, alternate configurations that allow hot water generated by the panels to be fed to the storage tank at lower elevation on a continuous basis, and then when hot water is needed above ground elevation, a solar-powered water pump will be required to circulate the hot water throughout the structure.
Whenever the hot water is not actively being consumed, the storage tank is constantly being replenished and the desired temperature maintained. Some residences may opt for a larger capacity hot water storage tank or multiple tanks to maximize the solar availability. This could result in peer sharing or even surplus hot water transactions among neighboring residences. Entirely possible if not probable.
In some communities, this may not be possible for every property or residence. In this case, I envision a communal location where one entrepreneurial person would implement an installation and then open it up to the local community for a nominal amount of money in a transaction based micro-economy. There is ample precedence here in many communities, specifically regarding telecommunications — before cellular networks and even before landlines reached many individual residences or even communities, there would typically be one “public” phone that was often owned by a village business, and made available to anyone for a fee at the time of use. In this case, for hot water, this may work well in areas where a village water source or well is a community property, and the addition of abundant hot water could be apportioned based on custom or community rules.
Integrating a rainwater catchment & storage system could provide all the necessary water, hot and cold, that a residential community may ever need without imposing additional burdens on watersheds, aquifers or existing electrical grids. Where there is an ample annual rainfall total, a portion of this supply could be pumped to the solar panels for heating and storage, and a non-hot water storage tank could provide the balance of the water supply needs.
Should be lightweight, durable, easy to install and adapt to infinite installation configurations, various pricing levels and packages, certified service and maintenance & repair, franchise potential, manufacturing and sourcing.
High efficiency, high capacity batteries for electrical storage would be constantly charged during solar exposure periods, and then as needed, overnight or during other periods of need, the stored energy can be used to pump and circulate the hot water. In some environments, there would be enough stored energy to power household lighting (for example, from Nokero as mentioned above or other LED type fixtures) or other appliances, but in this concept, the focus is on providing hot water on demand for hand washing and other sanitation needs, dish washing, laundry and bathing. The frequency of each of the above is, in reality, often minimized due to the stark experience of using cold, often frigid, water.
Having nearly unlimited (in a practical sense) access to hot water would ultimately alter patterns of behavior, open up opportunities that have been held back and decrease the risk of health and sanitation issues, and provide a better quality of life for the end-users.