“The electrical system was without a doubt the most daunting task of our DIY camper van conversion. Our goal was to design and build an off-the-grid electrical system that’s safe, reliable, simple, and intuitive (yet no compromises on functionality). After over 4 years of full-time VanLife, we’re happy to report that our system is working flawlessly, nice!”

“Designing and building an electrical system isn’t really straightforward, there are so many concepts to grasp: solar power, alternator charging, shore power, 12 volts, 120 volts, inverter, battery bank, etc. But with our background as engineers and full-time vanlifers, we’re in a good position to make this intimidating task within your reach and help you put the pieces together with the following guide!”

Read more: Electrical System Guide for DIY Van Conversion.

“In 1909, inventor George Cove posed in front of an early rooftop solar panel of his own design for a photograph. One hundred and ten years later, the resulting image was reprinted in the official journal of the US’ most prestigious research institute – but Cove was nowhere to be seen.

Using a range of sources such as newspaper archives and historic city maps, Bellingcat sought to establish the seeming mystery of Cove’s ‘disappearance’ from the photograph. This analysis of archival material from the pioneering days of solar energy tells a cautionary tale about the ease of misattributing historic photos.”

Read more: Untangling the Mystery of the World’s First Rooftop Solar Panel. Foeke Postma, Bellingcat, August 2023. Image by Bellingcat.

“Solar energy often appears a technology without a history, perpetually new and oriented towards the future. This sense of perennial novelty has gone unchallenged by historians, who have generally neglected renewable energy outside the rich world and all but ignored solar energy everywhere. Left to industry professionals, solar history is typically narrated as a triumphalist tale of technical innovation centered in the global North. Such accounts often conflate solar energy with solar photovoltaics (PV) for direct electricity generation… It is tempting to draw a straight line from this innovation to the huge solar PV installations of the twenty-first century; India’s largest, Rajasthan’s US$1.4 billion Bhadla Solar
Park, sprawls across an area the size of Manhattan.”

“Rejecting the eschatology of climate change, such huge mega-projects have reignited the high-modernist idea of progress. They fuse an optimism about the possibilities of science, technology, and human innovation to deliver sustained improvements in economic production and the satisfaction of human needs. In this bright new age, endless rows of solar panels promise to square the circle of economic growth and environmental preservation by providing virtually infinite amounts of clean power for all—and empowerment for women to boot. These utopian ideas, the environmental humanists Imre Szeman and Darin Barney suggest, are coalescing into ‘one of the sharpest and most powerful of ideologies’ today…”

“After the oil shocks of the 1970s, activists in the rich world saw in the sun’s dispersed rays a revolutionary path towards a decentralized ‘energy democracy’, emancipating newly self-reliant citizens from the authoritarian infrastructure of the fossil-fuel-fired electric grid via rooftop solar panels or designer solar homes. Before this point, though, solar energy was more often pigeonholed as something much drabber. A postwar generation of experts cast solar as the ‘poor man’s energy’, to quote a phrase from the period’s best-known international advocate, arguing that the diffuse and intermittent quality of sunlight made it a second-best energy source suited to the scattered rural populations of ‘underdeveloped’ nations… Together these experts imagined solar not as a post-carbon energy source, but a pre-carbon parallel track for those left outside the modern energy economy—a substitute for firewood and dung rather than the abundant and flexible energy of fossil fuels and grid electricity…”

“In the contemporary rich world, going off-grid is framed as a choice. As this earlier episode suggests, though, for much of its history solar energy did not signify the empowerment of the high-tech ‘prosumer’, but spartan compromise with a low-energy past. The physical characteristics of solar energy—available in immense quantity, but diffuse, intermittent, difficult and land-intensive to capture—shaped expert assumptions about its appropriate deployment. In and for the arid tropics, it was seen less as a substitute for fossil fuels than a way to circumvent the expensive expansion of electric grids, marking an admission of the postcolonial state’s inability to deliver public power to the rural majority. Even after independence delivered regimes committed to rapid industrialization, research into solar technologies continued along a low-modernist parallel track. Not simply energy modernization but energy dualism was the pragmatic prescription of the day: large infrastructures for industry and cities, cheap and simple devices for the vast hinterlands of the rural poor. The result was a two-tier energy system, structured by hierarchies of town and country, class, race, and the traditionally gendered division of household labour.”

Read more: Chatterjee, Elizabeth. “The poor woman’s energy: Low-modernist solar technologies and international development, 1878–1966.” Journal of Global History (2023): 1-22.

“You hand pump seawater or polluted water into a bowl. Throughout the day the energy from the sun heats up this water and, instead of evaporating into the atmosphere, it gets trapped in the top section. All the fresh water will then trickle down into this bottom basin and all the impurities of the salt and polluted water stay behind. You’re going to have a left-over salt brine which is going to be a waste resource, but instead of throwing it away, this salt brine goes into the series of seawater batteries around the perimeter that can light a LED strip during the night. At night you can turn on the light and you get an energy source through the salt batteries. And during the day, this is like a skylight, bringing natural light to the interiors.”

“The power of the sun is amazing, and I was trying to copy this hydrological cycle. It can kill 99% of dangerous pathogens, remove salt brine and reduce the need of having to boil your water. I am not necessarily reinventing the wheel; solar distillers have been around for a long time, but a lot of these systems are heavy, expensive to make and with very complicated designs. I wanted to think about one which could potentially be portable and simple to construct, made out of local materials and able to Achieve a higher yield of water.”

“This new design was exactly the same but at a large scale. We created a recipe book that is a step-by-step guide on how you can create this same design using bamboo and local work. It could be flat packed into a bag and deployed very simply and quickly and then attached to a bamboo structure which allows structural rigidity but also a community shaded spot, where you can produce around 18 liters of purified water everyday.”

Read more: Low-Tech Solutions for Complex Demands: An Interview with Architect Henry Glogau, ArchDaily. Image by Henry Glogau. Hat tip to Michael.

“Although this boom has aided in extending electricity access to many energy-poor households and businesses, an emerging concern is the short (three to four years) working life that these off-grid solar products typically have. This has led to a growing issue of solar e-waste. Here we examine how the structure of the off-grid solar sector results in substantial barriers to addressing solar e-waste in the Global South. We consider how practices of repair might contribute to addressing the issue, and set out a research agenda to facilitate new approaches to the issues of solar e-waste.”

Read more: Munro, Paul G., et al. “Towards a repair research agenda for off-grid solar e-waste in the Global South.” Nature Energy (2022): 1-6.

Jelle Seegers set out to design a production line that drastically lowers our footprint, using nothing but the sun, wind, or muscle power as its energy source. The ‘Solar Metal Smelter’ is his pièce the résistance: this huge magnifying glass creates a powerful focal point that, on a sunny day, makes metal melt. Cast in a sand mould, the hot substance is transformed into machine parts for a foot-driven grinder in an off-grid practice.

More:

• https://www.designacademy.nl/p/study-at-dae/graduation-show/graduation-projects/jelle-seegers
• https://jelleseegers.com

“This research indicates the technical capabilities of using a 40 cm2 Fresnel lens to heat, melt and vitrify a variety of materials and suggests future applications of this technology including the ability to digitise the process. This material processing technique offers an alternative to heat matter and is significant in geographical locations with ample sunlight, offering a cost-effective option to traditional heating methods and allows directional heating, which local craftspeople can exploit to their creative advantage.”

“A Fresnel lens was proven to be an accessible and affordable tool to heat and melt materials reaching temperatures over 1200 degrees C using
natural sunlight as the energy source. Building on the literature, this solar craft process was proven to melt sand, a variety of glass, metals and burn wood and fabric in a controlled manner.”

“The results from this research reintroduce ancient craft methods and build on the techniques discussed and developed in the works of Kayser (2018) and Jordan (2014), yet solar enamelling on metal is something not seen before, presenting a new area of practice to expand upon… In the sunniest locations on the planet where solar ovens are already used, this practice could be adopted and automated; solar processing technologies could also be integrated into solar farms to process materials.”

“Moreover, whilst this research explored solar craft in outdoor and greenhouse conditions in Scotland, it is also possible to create a safe indoor workspace designed for solar craft practices in a location with consistent, high intensity sunlight, such as Portugal, where there is an indoor solar laser lab, to increase the reliability of this craft method.”

“This study melted materials between 600 and 1200 degrees C which suggests that it may be easier to alter materials at lower melting points. Developing environmentally safe methods to recycle materials like aluminium and plastics through solar concentration may offer alternatives to a discipline which would benefit from innovative solutions that contribute to sustainable development.”

“Expanding this material research to trial using solar concentration to fire locally-sourced clays, preserving wood with ‘shou sugi ban’, a Japanese technique which charrs wood surfaces with fire, and exploring solar lampwork may hold craft potential.”

Read more (open access): Westland, Karen. “Solar Concentration for Craft Practice and Sustainable Development: Fusing Ancient and Modern Methods.” Journal of Jewellery Research 5 (2022): 18-33.

Previously: The bright future of solar powered factories.

In 2020, our solar powered website obtained an uptime of 95%, meaning that it was offline for 444 hours or 20 days. Unsurprisingly, most of the downtime is concentrated in the winter months.

The graph above (click to enlarge) shows battery storage capacity in relation to the weather in Barcelona from January to December 2020. Yellow is sunny, grey is cloudy, blue is rain. From May to November, we were online without interruption for almost 6 months.

The data were collected and visualised by Roel Roscam Abbing and David Benqué.

During a global catastrophe such as a nuclear winter, in which sunlight and temperatures are reduced across every latitude, to maintain global agricultural output it is necessary to grow some crops under structures.

Either a small regional nuclear war, such as India vs. Pakistan or a minor one-sided nuclear assault on population centers could catalyze a global nuclear autumn, which would starve millions of people.

This study designs a method for scaling up crop production in low-tech greenhouses to contribute to global food sustainability during global catastrophic conditions. Constructing low-tech greenhouses would obviate growing crops using more expensive and energy intensive artificial light. To significantly contribute to world-wide food demand, these greenhouses must be constructed quickly, cost-effectively, and in extreme quantity.

The greenhouse structures are designed to utilize global markets of timber, polymer film, construction aggregates, and steel nails. The limiting market that determines the growth rate of the greenhouses is the rate at which polymer film and sheet are currently extruded.

In an event that causes sunlight and temperatures to decrease over the entirety of earth, most crops would be too frost sensitive to be grown outside the tropics, and even the tropics would require an alternative method to growing crops than simply conventional growth outdoors. Conditions under low-tech greenhouses in the tropics would feasibly accommodate the production of nearly all crops. Some supplemental lighting would be required for long day crops.

The analysis shows that the added cost of low-tech greenhouses is about two orders of magnitude lower than the added cost of artificial light growth. The retail cost of food from these low-tech greenhouses will be ~2.30 USD/kg dry food higher than current costs; for instance, a 160% retail cost increase for rice. According to the proposed scaling method, the greenhouses will provide 36% of food requirements for everyone by the end of the first year, and feed everyone after 30 months. (Population is considered constant at currrent values).

Source: Alvarado, Kyle A., et al. “Scaling of greenhouse crop production in low sunlight scenarios.” Science of The Total Environment (2019): 136012. Open access.

Joey Hess has designed, built and tested an off-grid, solar powered fridge, with no battery bank. Using an inexpensive chest freezer with a few modifications, the fridge retains cold overnight and through rainy periods. The set-up consists of a standard chest freezer, an added thermal mass, an inverter, and computer control. He writes:

The battery bank is a large part of the cost of a typical off-grid fridge installation. It needs to be sized to run the fridge overnight, as well as for several days of poor weather. Cheaper batteries only last 3-5 years, and longer lasting batteries are correspondingly expensive; either way a battery bank for an off-grid fridge is extremely expensive over the lifetime of the fridge. By storing solar power in the form of cold, I can avoid the battery bank expense and environmental footprint. The only battery power it needs is enough to turn it off cleanly when the solar panels stop producing — a few minutes of power instead of days — and a small amount for its computer control.

Joey’s off-grid, solar powered, zero-battery-use fridge has successfully made it through spring, summer, fall, and winter:

I’ve proven that it works. I’ve not gotten food poisoning, though I did lose half a gallon of milk on one super rainy week. I have piles of data, and a whole wiki documenting how I built it. I’ve developed 3 thousand lines of control software. It purrs along without any assistance.

Read more:

• Fridge 0.1
• Fridge 0.2
• Fridge data
• Fridge Wiki

Related:

• “Daylight Drive” DC Solar Power at the Living Energy Farm

Thanks to Roel Roscam Abbing.

Reader Goran Christiansson sends us a link to Living Energy Farm, a research and community project in Virginia, USA. Most notable is their use of “Daylight Drive” DC solar power without batteries for workshop tools — reminiscent of the ideas outlined in How to run the economy on the weather. Also of note is their choice for less efficient but more durable Nickel Iron batteries for lighting.

Below is an excerpt from the introduction page:

“The vision of Living Energy Farm (LEF) is envisioned to be a community that is food and energy self-sufficient. We are off-grid, and we are putting together the means to run our farm without fossil fuel. Our intent is for Living Energy Farm to operate on a modest, globally applicable, renewable energy budget. We have found that this global perspective differentiates us from most other projects working on sustainable technologies.”

All of LEF’s DC shop tools and most of our appliances run “daylight drive” straight from the solar electric (PV) panels. We run high-voltage industrial DC motors with no batteries, no inverters, no costly or fragile electronics whatsoever. This is a MUCH cheaper, simpler, and more durable way of utilizing solar energy.

“In starting Living Energy Farm, our plan was to pull together renewable energy technologies already in existence rather than “re-inventing the wheel.” We have found that we cannot buy a lot of what we need, and thus we are having to build some of the tools and machines we need. We live, day by day, off-grid and (mostly) without fossil fuel. We experience the benefits and limitations of our own ideas every day.”

“We have assembled a set of documents to explain how our unique, off-grid systems operate. We suggest you review “Longterm Integrated Village Energy (LIVE) — community energy systems that make centralized power grids unnecessary” before proceeding to the other documents. That will give you an overview of the design process at LEF.”

At Living Energy Farm, our conservationist design means we need very little stored electricity. We store electricity with nickel iron (NiFe) batteries, a very old, very durable battery technology. Nickel iron batteries tolerate tremedous swings of voltage input and discharge rates that would destroy any other kind of battery.

“We have been pleasantly surprised by how well our DC Microgrid has worked. We have found a much, much better way to live off-grid. The widespread adoption of the tools developed at LEF could widen access to energy services for people all over the world while radically decreasing our environmental footprint. We are trying to spread these tools far and wide, and looking for support in that work.”

Living Energy Farm. Overview of all technologies (pdf).

We are reaching an important milestone in the Testfield: the high-precision membrane mirror that we have been working on for the last two years, is standing. A team within the technology group has designed and built a prototype solar concentrator by innovating and developing the inflatable membrane mirror technology first introduced by father and son Hans and Jürgen Kleinwächter several decades ago. The present advances are the result of a dedicated team within Tamera working in cooperation with Jürgen Kleinwächter, SunOrbit (Germany) and supporters in India and Australia.

Our prototype mirror uses 0.1mm thick reflective polymer films inflated with air pressure, over a lightweight aluminium frame, achieving high optical precision cheaply and with very low embodied energy. It has an effective optical aperture of 4m2, concentration of over 1000 times, reaching over 1000 degrees Celsius, and has applications ranging from round-the-clock cooking with storage, through ceramics, metalwork and lime burning for waterproof clay buildings, to photo-catalytic fuel production from water and CO2. Future concentrators will undoubtedly take the technology further.

Many challenges in the components and sub-systems have been overcome over the last two years. Now we will start to see how the system really functions as a whole. We have progressed from unstable wooden experiments to a simple, lightweight aluminium framework, developed a deflectometric mirror analysis technique using computational photography, built a tool to weld flouropolymers together (basically welding Teflon to Teflon), designed and fabricated a dual-axis tracking construction, and invented a robust technique to evenly tension membrane films. We are looking forward to testing and tuning the complete system. System tests will start now, as we continue to complete the details.

Quoted from: High-precision Membrane Mirror Research in the SolarVillage Testfield of Tamera, August 2016.

Previously: The bright future of solar powered factories.

The SunSaluter is an ultra low-cost, passive, single-axis solar panel rotator (called a tracker) designed for the developing world. Using only the power of gravity and water, the SunSaluter enables a solar panel to follow the sun throughout the day, boosting efficiency by 30% and producing four liters of clean drinking water.

It is 30 times less expensive than conventional motorized solar panel rotators (which use complex electronics), much more reliable, and consumes no electricity itself. With improved efficiency, fewer solar panels are needed, and the overall cost per watt of solar energy is reduced.

The SunSaluter features an adjustable design which allows it to integrate with any solar panel – no special tools needed. The solar panels are mounted on the rotating frame, a weight is suspended from one end, and a special waterclock is suspended from the other. As the water empties and the container gets lighter, the panel slowly rotates. The user can set the rate at which the waterclock empties, which controls the SunSaluter’s rate of rotation.

The SunSaluter also contains a water purifier so that each day it produces four liters of clean drinking water. By combining energy and water collection into one simple device, the SunSaluter improves consistent usage of the purifier, which is the Achilles heel of clean water programs. SunSaluters are available for purchase anywhere in the world as a DIY-kit, or in India as prefabricated systems.

More information: SunSaluter. Via Makeshift, who made a video about the technology.

“Graining cereal crops is a basic, century old business and it will continue to be as important as ever before for centuries to come. Before the age of oil grain milling was entirely based on renewable energy. It was either done by wind energy, hydropower, animals or manpower. For the last century the traditional grain milling has been mainly replaced by electricity and fuel driven milling.”

“The Solar PV Grain Mill works to the same principle like any conventional, electrically driven mill. The mill has a very efficient 3-phase AC motor which is directly coupled to the graining system. The main invention of the system is, and that makes it unique among PV systems, that it is a “direct drive system” without the need of batteries. The Solar PV generator converts solar radiation into electricity, and the generated electricity is directly feeding the motor drive. There are no additional conversion losses, such as energy storage losses in batteries, battery maintenance or replacement costs, which are a common problem in conventional Solar PV off-grid systems.”

Read More: Solar Milling. Via Engineering for Change.

I would like to add that the direct drive system also eliminates the high energy use caused by the production of the batteries, which can make solar PV off-grid systems everything but sustainable. Therefore, storing work instead of energy — the solar mill only operates when the sun shines — is a very interesting strategy in sunny regions.

Related:

• The Bright Future of Solar Thermal Powered Factories
• Back to Basics: Direct Hydropower
• Wind Powered Factories: History (and Future) of Industrial Windmills
• Pedal Powered Farms and Factories: The Forgotten Future of the Stationary Bicycle

Build-It-Solar blog writes:

Kotaro Nishiki built a passively cooled home in Leyte Philippines at 11 degs north latitude that incorporates a number of unique cooling features that allow the home to be cooled passively and without electricity…

In this area, most homes are constructed of concrete, and the concrete structures tend to absorb solar heat during the daytime, and then retain that heat through the night making the homes uncomfortable.

Kotaro’s design is centered on eliminating these daytime solar gains. He keeps the whole house shaded using these techniques:

• The south facing single slope roof has on overhang on the south that keeps the south wall in shade most of the day.
• The north side of the house is shaded by an roof extension sloped down to the north that shades the north side of the house most of the day.
• The roof is double layered with airflow between the well spaced layers.  This greatly reduces solar heat gain through the roof.
• The east and west walls of the house are double wall construction with a couple feet between the walls.  The shading that the outer wall offers plus airflow between the double walls keep the wall temperatures low.
• In addition, he has worked out ways to take advantage of the night
  temperature drop and to use thermal mass on the basement to provide some
  cooling.

More: A unique, passively cooled home in the Tropics (Build-It-Solar), Passive Solar House in Tropical Areas (Kotaro Nishiki). Build-It-Solar has more examples of passively cooled houses.

If anyone has more information, comments are open.

“The solar kiln described was designed, constructed, and tested at Virginia Tech. This design is based on 25 years of research and development on the solar drying of lumber in the United States and foreign countries. Drawings for two versions of this kiln are available; one for 800-1,000 bd ft and the other for 1,500-2,000 board feet of lumber. Both kilns will dry a load of lumber in approximately one month of moderately sunny weather at its location in Blacksburg, VA.”

“Drying lumber can be a complex process where accelerating drying without having quality loss often requires extensive knowledge and experience. The design of the Virginia Tech solar kiln is such that extensive knowledge, experience and control are not required. The size of the collector keeps the kiln from over-heating and causing checking and splitting of the wood. The kiln is simple to construct and utilizes a passive solar collector, four insulated walls and an insulated floor. The roof is made of clear, greenhouse rated, corrugated polyethylene.”

Virginia Tech Solar Kiln. Via Build It Solar.