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!

One of the most troubling trends of almost every modern consumer product that uses electricity is that the software that controls the product is likely to be proprietary and closed-source, which could be doing (or not doing) any number of things that its owner has no control over. Whether it’s a computer, kitchen appliance, or even a device that handles the electricity directly, it’s fairly rare to find something with software that’s open and customizable. That’s why [Traditional-Code9728] is working on a power bank with an open-source firmware.

From a hardware perspective the power bank is fairly open as well, with a number of options for connecting this device to anything else that might need power. It sports a bidirectional USB-C port as well as a DC barrel plug, either of which can either charge other devices or receive energy to charge its own battery. These ports can also accept energy from a solar panel and have MPPT built in. There’s also dual USB-A ports which can provide anywhere from five to 12 volts at 25 watts, and a color screen which shows the current status of the device.

While this is a prototype device, it’s still actively being worked on. Some future planned upgrades to the power bank include a slimmer design, charge limiting features to improve battery life, and more fine-tuned control of the output voltage and current on the USB-C port. With all of the software being open-source, as well as the circuit diagram and 3D printing files, it could find itself in plenty of applications as well. This power bank also stays under the energy limits for flying on most commercial airlines as well, but if you don’t plan on taking your power bank on an airplane then you might want to try out this 2000-watt monster instead.

Here’s a hypothetical situation. You decide to build your own steam generator plant and connect it to the electric grid. No matter where you live, you’d probably have to meet a ton of requirements from whoever controls your electric power, almost surely backed by your government. Yet, according to a recent post by [Bert], a version of this is going on in Europe and, probably, in many more places: unregulated solar power inverters driving the grid.

If you have just a few solar panels hanging around, that probably isn’t a problem. But there are a sizeable number of panels feeding power — and that number seems to grow daily — having control of the inverters could potentially allow you to limit the grid’s capacity or — if the inverters allowed it — possibly take the grid down by feeding power incorrectly back into the grid.

According to [Burt], a small number of companies control most of the inverters in his country — the Netherlands — and there is virtually no regulation about how they operate. While we don’t think he’s suggesting they would act maliciously, you don’t have to search the news very much to find cases where companies have been hacked or made a mistake that caused major impacts to important systems.

Apparently, inverters in the Netherlands do have to meet certain technical standards, but the post since that’s widely unenforced. But the real point is that the companies managing the switches are not regulated or managed. [Burt] thinks that EU-wide legislation is needed to forestall some future disaster.

You might think this isn’t a realistic scenario, but you just have to think about Crowdstrike to realize it could happen. Or other major network outages. We aren’t usually fans of more regulation, but [Burt] makes some interesting points. What do you think?

Australian grids have long run a two-tiered pricing scheme for electricity. In many jurisdictions, regular electricity was charged at a certain rate. Meanwhile, you could get cheaper electricity for certain applications if your home was set up with a “controlled load.” Typically, this involved high energy equipment like pool heaters or hot water heaters.

This scheme has long allowed Australians to save money while keeping their water piping-hot at the same time. However, the electrical grid has changed significantly in the last decade. These controlled loads are starting to look increasingly out of step with what the grid and the consumer needs. What is to be done?

Controlled What Now?

In Australia, the electricity grid has long relied on a system of “controlled loads” to manage the energy demand from high-consumption appliances, particularly electric hot water heaters. These controlled loads were designed to take advantage of periods when overall electricity demand was lower, traditionally at night. By scheduling energy-intensive activities like heating water during these off-peak hours, utilities could balance the load on the grid and reduce the need for additional power generation capacity during peak times. In turn, households would receive cheaper off-peak electricity rates for energy used by their controlled load.

This system was achieved quite simply. Households would have a special “controlled load” meter in their electrical box. This would measure energy use by the hot water heater, or whatever else the electrical authority had allowed to be hooked up in this manner. The controlled load meter would be set on a timer so the attached circuit would only be powered in the designated off-peak times. Meanwhile, the rest of the home’s electrical circuits would be connected to the main electrical meter which would provide power 24 hours a day.

By and large, this system worked well. However, it did lead to more than a few larger families running out of hot water on the regular. For example, you might have had a 250 liter hot water heater. Hooked up as a controlled load, it would heat up overnight and switch off around 7 AM. Two or three showers later, the hot water heater would have delivered all its hot water, and you’d be stuck without any more until it switched back on at night.

Historically, most electric hot water heaters were set to run during the low-demand night period, typically after 10 PM. Historically, the demand for electricity was low at this time, while peak demand was in the day time. It made sense to take the huge load from everyone’s hot water system, and move all that demand to the otherwise quiet night period. This lowered the daytime peak, reducing demand on the grid, in turn slashing infrastructure and generation costs. It had the effect of keeping the demand curve flatter throughout the whole 24-hour period.

This strategy was particularly effective in a grid predominantly powered by coal-fired power stations, which operated most efficiently when running continuously at a stable output. By shifting the hot water heating load to nighttime, utilities could maintain a more consistent demand for electricity throughout the day and night, reducing the need for sudden increases in generation capacity during peak times.

Everything Changed

However, the energy landscape in Australia has undergone a significant transformation in recent years. This has been primarily driven by the rapid growth of renewable energy sources, particularly home solar generation. As a result, the dynamics of electricity supply and demand have changed, prompting a reevaluation of the traditional approach to controlled loads.

Renewable energy has completely changed the way supply and demand works in the Australian grid. These days, energy is abundant while the sun is up. During the middle of the day, wholesale energy prices routinely plummet below $0.10 / kWh as the sun bears down on thousands upon thousands of solar panels across the country. Energy becomes incredibly cheap. Meanwhile, at night, energy is now very expensive. The solar panels are all contributing nothing, and it becomes the job of coal and gas generators to carry the majority of the burden. Fossil fuels are increasingly expensive, and spikes in the wholesale price are not uncommon, at times exceeding $10 / kWh.

Solar power generation peaks are now so high that Australian cities often produce more electricity than is needed to meet demand. This excess solar energy has led to periods where electricity prices can be very low, or even negative, due to the abundance of renewable energy on the grid. As a result, there is a growing argument that it now makes more sense to shift controlled loads, such as hot water heaters, to run during the daytime rather than at night.

Shifting controlled loads to the daytime would help absorb the surplus solar energy. This would reduce the need for grid authorities to kick renewable generators off the grid in times of excess. It would also help mitigate the so-called “duck curve” effect, where the demand for electricity sharply increases in the late afternoon and early evening as solar generation declines, leading to a steep ramp-up in non-renewable generation. By using excess solar energy to power controlled loads during the day, the overall demand on the grid would be more balanced, and the reliance on fossil fuels during peak times could be reduced.

Implementing this shift would require adjustments to the current tariff structures and perhaps the installation of smart meters capable of dynamically managing when controlled loads are activated based on real-time grid conditions. In a blessed serendipity, some Australian states—like Victoria—have already achieved near-100% penetration of smart meters. Others are still in the process of rollout, aiming for near 100% coverage by 2030. While these changes would involve some initial investment, the long-term benefits, including greater integration of renewable energy, reduced carbon emissions, and potentially lower electricity costs for consumers, make it a compelling option.

Fundamentally, it makes no sense for controlled loads to continue running as they have done for decades. Millions of Australians are now paying to heat their water during higher-demand periods where energy is more expensive. This can be particularly punitive for those on regularly-updated live tariffs that change with the current wholesale energy price. Those customers will sit by, watching cheap solar energy effectively go to waste during a sunny day, before their water heater finally kicks at night when the coal generators are going their hardest.

While the traditional approach to controlled loads in Australia has served the grid well in the past, the rise of renewable energy has changed things. The abundance of solar generation necessitates a rethinking of when these loads are scheduled. By shifting the operation of controlled loads like hot water heaters to the daytime, Australia can make better use of its abundant renewable energy resources, improve grid stability, and move closer to its sustainability goals. It’s a simple idea that makes a lot of sense. Here’s waiting for the broader power authorities to step up and make the change.