Ultra low power home DC electrical system - 4th iteration

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The problem

Nowadays, installing solar photovoltaic panels on big city buildings is limited to the roof area of the building. This means little power generation capabilities for energy savings when considering each individual apartment.

The idea

The idea of this "Smart Home Solar Power Management" Project is to develop simple components and accessories that enable easy, "for dummies" kind of installation of solar photovoltaic cells. For that to happen is required installation of additional wiring in the apartment electrical network. Staring with a 5V DC wire, suitable for most small home appliances such as vacuum cleaners, smartphones, tablets, and any other smart device or technology. And another with 12V DC suited for computers, gaming consoles, and OLED TV displays. This can be achieved by installing "power delivery" technologies, common in USB-C power solutions.

Energy storage methodology follows a decentralized architecture of installation, where each individual room or compartment has its own "independent" battery storage upwards 40.000mAh. All connected to a Smart Home device I made available on my Github.

The solar panels can be assembled in a Lego-style kind of way. Due to the reduced size of the photovoltaic solar cells, can be assembled into any shape or area. For instance glass door windows and doors. For instance in a terrasse or a terrasse exterior wall regardless of floor area shape..

3rd Iteration of my Power Wall

The current iteration of my test "power wall" has the ability to charge batteries during the night. For that I'm using a regular 16A Tuya WiFi EU Smart Plug Outlet Power Monitor where I connect a regular USB fast charge power brick. This means I can use my illumination at night and not be connected to the main 220V power lines and save on the higher cost the utilities company charges on those hours of the evening and night. The setup, is made in such a way to charge during the day from the solar panels I installed on my windows (see previous articles ) and during late night it charges batteries to full, so on the next day I have available a fully charged power wall.

On the photo above is already possible to see, above the power outlet, the enclosure for a Smart Distributes Power management Device to replace the current power management setup (the Tuya smart outlet and the USB power brick)

4th iteration of the Power Wall

Now that all 20,000mA power banks, with quick charge, have arrived from AliExpress, the hardware electronics on my test Power Wall was simplified to the maximum and has now a storage capacity of 60A. It now looks like in the photo below.

Hardware electronics is now much more simplified requiring only a USB-C fast charge decoy trigger module, one for each power bank, and my solar panel array I have installed on my kitchen window is now connected to one of the power banks using a 6V 3A Solar Power Manager Module. This module utilizes the CN3791 IC and has MQTT tracking capabilities. For now, charging is made and happens using regular, commercially available power chargers with fast charge capabilities connected directly to a Tuya Smart Outlet, which I have setup and configured to power ON during late night, from 1H30 AM to 8H AM,

Combined and connected to my low powered DC wiring I installed at home, this Power Wall serves now the purpose to power, during all day, all my 5V to 12V devices I have a home:

• Smartphones
• Tablets
• Handheld Vacuum Cleaner
• Shaver
• Headphones, earbuds and bone conduction phones
• all other smart devices that run on 5V to 12V DC.

without the need to use electricity from the main power utility company. It also powers all my indoors micro LED illumination I installed on all rooms and compartments of my home combined with a remote control for LED lights.

Preliminary Electricity Savings

The first results are now (02-10-2023) available for savings on the electricity monthly cost, a total of -20kWh saved last month of September with this setup for my test "power wall". And there's still much it can be done to improve savings.

Energy savings were not just because of savings from charging during the night. I also change room illumination to micro LED (with a dimmer) powered only by the power wall (see photo above). This means in the evenings, and at night, I'm not using electricity from the local utility company. So overall, the savings for the month of September when compared with the previous month were around minus 20kW.

It is worth referring to the number of sunshine hours before this installation was fully operational. For the month of August is around 200h/mo and compare it to the number of hours for the months of September, 140h/mo and October, 115h/mo. Another important metric for this analysis in savings is the number of daylight time (hours). In August, is 435h, in September that value is reduced to 377h/mo, and in October is reduced again to 318h/mo. This means evenings at the end of the day starts sooner and thus requiring me to turn on the indoor illumination earlier as winter approaches (see change column in the table below;

In the beginning of November, I've done the same to both of my 2x 13 inch Laptops powering them from a 36V 60,000mA battery pack I bought on AliExpress, and since then, I've been using it all day long, evenings and night running solely on battery power. Now that December is here, the monthly savings for November show my energy expenditure was roughly the same as in September and I had less 110h of daylight (see figure and table above). To better understand that number, is the equivalent of me saying I'm living in July, in the solar maximum and height of summer.

I'll be writing an article just for the micro LED illumination setup . Stay tuned.

Visit the GitHub repository for this smart device here:https://github.com/aeonSolutions/AeonLabs-Distributed-Power-Somainlutions-Smart-Distributed-DC-Power-Management

Next Iteration

In the 5th iteration for this project I'll be CNC machining a piece of wood made to fit my existing balcony window wood frame, where I will assemble the solar cells into four solar arrays, each for a maximum output of 5V 5.2A DC.

https://www.hackster.io/mtpsilva/low-power-home-dc-electrical-system-5th-iteration-f90f3f

one final note about the author
The PCB Design Files I provide on GitHub for anyone to use are free. If you like this Smart Device or use it, please consider buying me a cup of coffee, a slice of pizza or a book to help me study, eat and think to work on new PCB design files.

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