Hot Water Heater Hacked To Run On Solar Juice

September 6, 2024 by Lewin Day 41 Comments

It’s 2024, and there’s no getting around it. Grid energy is expensive. [Darrell] realized that a lot of his money was going on water heating, and he came up with a neat solution. What if he could hack in some solar power to slash his bills at a minimum of fuss? It worked so well for him, he’s whipped up a calculator to help others do the same.

[Darrell]’s idea was simple enough. He hooked up solar panels to just the bottom heating element of his hot water heater. This cut his power bill in half. His calculator is now up at pvh20.com, and it’s designed to help you figure out if it’s feasible for you. It takes into account your location, local power prices, and the amount of sun your area tends to get on a regular basis. It also takes into account the solar panels you intend to use and your water heater to determine how many panels you’ll need for properly hot water. Key all that in, and you’re well on your way to speccing a decent solar hot water setup. From there you’ll just need to buy the right stuff and wire it all up properly.

If you live in an area where the sun shines freely and the power is more expensive than printer ink, this could be a project well worth pursuing. Cheaper hot water is a grand thing, after all. [Darrell’s] calculator is really only the first step, and it doesn’t deal with the practicalities of installation, but that’s half the fun of a good project, right? Happy hacking!

A Smarter Solar Water Heater

February 25, 2024 by Bryan Cockfield 81 Comments

Installing solar power at a home is a great way to reduce electricity bills, especially as the cost of solar panels and their associated electronics continue to plummet. Not every utility allows selling solar back to the grid, though, so if you’re like [Rogan] who lives in South Africa you’ll need to come up with some clever tricks to use the solar energy each day while it’s available to keep from wasting any. He’s devised this system for his water heater that takes care of some of this excess incoming energy.

A normal water heater, at least one based on electric resistive heaters, attempts to maintain a small range of temperatures within the insulated tank. If the temperature drops due to use or loss to the environment, the heaters turn on to bring the temperature back up. This automation system does essentially the same thing, but allows a much wider range of temperatures depending on the time of day. Essentially, it allows the water heater to get much hotter during times when solar energy is available, and lets it drop to lower values before running the heater on utility electricity during times when it isn’t. Using a combination ESP32 and ATtiny to both control the heater and report its temperature, all that’s left is to program Home Assistant to get the new system to interact with the solar system’s battery charge state and available incoming solar energy.

While it’s an elegantly simple system that also affords ample hot water for morning showers, large efficiency gains like this can be low-hanging fruit to even more home energy savings than solar alone provides on paper. Effectively the water heater becomes another type of battery in [Rogan]’s home, capable of storing energy at least for the day in the form of hot water. There are a few other ways of storing excess renewable energy as well, although they might require more resources than are typically available at home.

Rocket Stove Efficiently Heats Water

August 4, 2023 by Bryan Cockfield 19 Comments

Rocket stoves are an interesting, if often overlooked, method for cooking or for generating heat. Designed to use biomass that might otherwise be wasted, such as wood, twigs, or other agricultural byproducts, they are remarkably efficient and perform relatively complete combustion due to their design, meaning that there are fewer air quality issues caused when using these stoves than other methods. When integrated with a little bit of plumbing, they can also be used to provide a large amount of hot water to something like an off-grid home as well.

[Little Aussie Rockets] starts off the build by fabricating the feed point for the fuel out of steel, and attaching it to a chimney section. This is the fundamental part of a rocket stove, which sucks air in past the fuel, burns it, and exhausts it up the chimney. A few sections of pipe are welded into the chimney section to heat the water as it passes through, and then an enclosure is made for the stove to provide insulation and improve its efficiency. The rocket stove was able to effortlessly heat 80 liters of water to 70°C in a little over an hour using a few scraps of wood.

The metalworking skills of [Little Aussie Rockets] are also on full display here, which makes the video well worth watching on its own. Rocket stoves themselves can be remarkably simple for how well they work, and can even be built in miniature to take on camping trips as a lightweight alternative to needing to carry gas canisters, since they can use small twigs for fuel very easily. We’ve also seen much larger, more complex versions designed for cooking huge amounts of food.

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IoT Solar Pool Heating

July 14, 2018 by Dan Maloney 10 Comments

A backyard swimming pool can be a great place to take a refreshing dip on a summer’s day. It can also be a place to freeze your giblets off if the sun has been hiding for even a few hours. That can make pools an iffy proposition unless they’re heated, and that starts to get really expensive in terms of upfront costs and ongoing charges for fuel or power. Unless you put the sun and the IoT to work for pool-heating needs.

Preferences vary, of course, but [Martin Harizanov] and his family clearly like their swims on the warm side. With nobody using the pool when it was below 25°C (77°F), [Martin] picked up a few bits to harness the sun to warm the water. Loops of PVC lawn irrigation tubing were tossed onto a shed roof with a favorable solar aspect and connected to the pool with a length of garden hose. The black thin-wall tubing is perfect for capturing the sun’s energy, and 200 meters of the stuff can really heat things up fast. A small pump is controlled by a microcontroller — it’s not explicitly stated but we suspect it’s a Raspberry Pi — with a pair of temperature sensors to sample the water in the pool and in the heating loop. Metrics are gathered and logged by Emoncms, an open source energy monitoring app. [Martin] says he’s harvesting about 10 kW from the sun on a good day, and that the ~~pool~~ water in the heating loop has gotten up to a steamy 55°C (131°F) without any other energy inputs other than the pump.

Plenty of others have made the leap to solar for pool season extension, with designs from the simple to the more complex. And if you live where the sun doesn’t shine, there’s always a compost water heater.

Water Softener Level Detector Keeps You Out Of Trouble With Wife

October 29, 2014 by Rich Bremer 81 Comments

Some households have water supplies that contain higher than desired levels of minerals. This condition is called hard water. There is nothing harmful about hard water but it does leave mineral deposits on pipes and appliances and makes cleaning a little bit more difficult. The solution is to have a water softener system which is basically a tank filled with salt that the household water passes through. This tank has to be refilled about every month and [David] was catching a little flak from his wife because he kept forgetting to fill it. He then set out to do what any great husband would do and built a Water Softener Monitor that reports the quantity of salt in the basement tank up to the living quarters.

[David] started thinking that he should test the salinity of the water to determine if salt needed to be added but after thinking about it for a while decided against it because any metal in that salty water would surely corrode. A non-contact approach would be to use an IR distance sensor mounted to the top of the tank and measure the distance to the pile of salt that slowly lowers as it dissolves into the water. In this case, he used a Sharp GP2D12 that can measure accurately from 10 to 80cm.

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DIY Solar Collector Boost Your Hot Water System

May 24, 2012 by Mike Szczys 23 Comments

This home is heated by a wood stove in the winter, which also produces hot water. But the other three seasons it’s an electric water heater that does the work. This latest hack is a solar collector meant to take over the hot water production work for the house. it uses basic building materials and rudimentary construction skills, making it much more approachable than trying to make electricity from the sun.

It’s really just a wood box with a glass lid. The inside has been painted black, and the black tubing that snakes through it holds the water. A three-way valve lets the homeowner patch into the hot water reservoir. The collector is lower than the reservoir, so the heated water makes its way back into the tank as cooler water takes its place. Not bad for an entirely passive system!

[Thanks Minde]

Composting To Create Hot Water

May 23, 2010 by Mike Szczys 33 Comments

Want nature to supply you with 130-150 degree hot water? [Onestraw] shows you how to get just that by building a compost heap that heats water. Finding himself the proud owner of a dump truck of green wood chips [Onestraw] went about building his own version of Jean Pain’s thermal compost pile. The idea is to produce and store methane generated from the compost pile but in order to do so, the temperature must be kept fairly low. The microorganisms in the compost generate a lot of heat trying to break down that matter and running water through the system will keep the temperature low enough for the methane-producers to be happy. The side effect of this cooling system is hot water coming out the other end. [Onestraw] even has plans to use salvaged car radiators to turn the hot water into a heating system for his home. Granted you’re not going to add this to your apartment, but if you have space and waste plant matter and need hot water this is a great way to get it.

[Thanks Joel]