Posts in category "project"


  • DC Energy Measurement Using PZEM 017

    You might remember that I have been looking for an accurate DC current measuring device for a long time for my solar project. The hall effect sensors I have been using in my solar project was inaccurate. Basically the zero current point drifts quite a bit depending on the ambient temperature and power supply voltage. While a shunt would give more accurate zero cross overs, I did not want to modify my setup to use it. You see, the problem with shunt resistor based sensors was that they have to be inline with current. Which means I have to remove a bunch of wiring from my battery and UPS and insert these sensors inline. I was not willing to do that. However I recently came across another project which would be a good fit to test out these shunt resistor based sensors. So I tried a couple of them and what follows is my experience with one of them.

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  • Converting a USB printer into a WiFi Printer

    We have an old USB laser printer which was purchased in early 2012. It has been in fine working condition since then. I rarely use it because usually there is nothing much to print. We do the occasional flight ticket print outs. Once our daughter was born there was a little bit more printing. I changed the toner just twice in these 11 years. Anytime anyone in the family needed a printout, they would connect their laptop to the printer via USB and print. Although it wasn’t that much of a hassle, I wanted to make the printer a wireless one. This post is about how I achieved it. As you can imagine, it can get technical and if you are not into computers and software, it is better you skip this one :).

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  • Solar System Comparison with MKBHD

    Some of you may already know MKBHD, a popular youtuber in the tech world. He recently posted a video about the going completely solar and not having to pay an electricity bill for a whole year. It is a very well made video which explains how the solar panel system works with batteries (off grid) and with net metering (on grid). Although I don’t have net metering and I am not completely off grid, so mine is a hybrid approach. Still, if you watch the video it will help you understand how my setup works (sort of). My setup is closer to the hybrid system explained in another video. Anyway, I wanted to compare my puny setup with MKBHD’s setup and see how I compare. So here goes.

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  • Accessing My Home Network From Anywhere

    There are two kinds of apps that I build when I am working on my personal projects. They are either apps that are confined to my home network or ones that run on the web. Examples of apps that run on the web are my investment planning app or investment recommendation app. I can access them from anywhere. Examples of apps that only run in my home network include home automation, drip irrigation, solar power management, etc. These are apps that are running on android devices, linux PC or ESP8266 boards and are connected to my wifi. You cannot access them from outside the home network.

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  • Why I Cannot Add More Solar Panels

    You might know that we currently have a sole 320W solar panel. Initially I just wanted to check if it was worth buying a solar panel. While there is a lot of talk about the many benefits of solar panels, I was not so sure. Will the panels really last a long time like they claim. Will the efficiency reduce quickly as the panel ages. Will the panels really produce the rated power because they are tested in ideal laboratory conditions of 1000 W/m2 irradiance, but in real life I was not sure if we get so much sunlight etc. Well, after owning the panel for over 2 years now, I can tell you that most of my doubts have been clarified. So I was wondering if I should add another panel.

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  • Switched to NixOS

    After using Manjaro Linux for a really long time, I finally decided it was time to switch to NixOS. Manjaro has been quite good until recently. Then there were some changes because of which my GPU hardware acceleration broke. I don’t remember all the details because it has been some time since I switched over to NixOS. All I remember is that video encoding is not able to use GPU acceleration and that was a big bummer. I tried EndeavourOS and liked it. Everything was working as expected. Yet I switched to NixOS. The reasons and more follow in this post. This is one of those posts with too many technical details, so if you prefer, feel free to skip this one.

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  • How Much Money Did My Solar Panels Save? - 2023 Edition

    A long time ago I wrote a post on how much money my solar panel was saving me. In the post I promised to write another post in November 2022 with updates. Well, lots of things happened and I completely forgot about it until one reader reminded me requesting for an update. So here it goes. It has been more than 2 years since I installed a 320W solar panel and I have been diligently collecting data from my panel, our consumption and how much we are pulling from the grid. Very recently I finally finished my code to fetch the data, massage it and used some nice libraries to draw the graphs so I can analyze the data.

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  • Solar Panel Project Update - Part 5

    This is the final update in the solar panel project series for now. Hopefully by now you must be quite bored with the updates because I am sure no one is going to build a project that is exactly same as mine. But in case you are following along, you might have picked up some things that you did not know earlier or may be you found somethings that you could have done differently. The reason I am writing is to keep a journal of things. While I fixed most of the issues with my setup, I still had a couple of problem that don’t happen frequently which makes it difficult to debug. In this post I will discuss the problems and my solutions. May be there are better solutions, but these are ones that I could come up with. A reader was lamenting that my posts are too short so I let this post go as long as it needs to be. So enjoy :).

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  • Solar Panel Project Update - Part 4

    As I mentioned in my last post about solar panel setup, there still a few more issues with my sensors. One of them is temperature drift. When the weather is cool like early in the morning, the DC current sensors read one value and in the evening when the temperature is hot, they read a slightly different value. The difference is quite small but get magnified when doing the calculations. For example, in the night around 7 pm when there is no solar power, the sensor would read 2.5V which after all the transformations turns out to be 0 amps of current. All good. Then in the morning say around 5 am when there is still no sun, the sensor would read 2.52V. Not much of a difference, but it get magnified as I will soon show you.

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  • Solar Panel Project Update - Part 3

    In my previous post I explained how I improved the accuracy of my DC sensors using ADS1115. But there is one problem though. The ADS1115 gives accurate reading even when the supply voltage keeps changing. Yet, the sensor values will not be correct. The reason is that if the supply voltage is changing, the reading on the sensor will also change, but the accuracy of the reading will be stable because ADS1115 is independent of power supply voltage fluctuations. For example, let’s say the supply voltage is 2.5V, then when there is no current, the DC current sensor will read 2.5V, and in the code we assume the current is 0 at 2.5V. Now if the supply voltage drops to 4V then the sensor will read 2V, which is still the mid point and indicates 0 current. But in the code we have a hard coded number that 2.5V is the midpoint and we mistakenly assume that some current proportional to -0.5V is passing through the wires. That is the problem.

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