At the start of my solar journey, I had a very basic question to answer, would I be able to generate enough power from a single 100w solar panel to power my computer whilst working in the office. Whilst only a fraction of my total energy usage, my computer is a key part of my daily life, so it seemed like a great place to start.
I'd often plug in my screen, so really I wanted to know could I power a computer and screen at the same time and what would I need to do it.
I started off with a 100w solar panel, in strong sunlight it would generate around 4amps of current, and around 18volts of power. I decided to opt for a lithium battery, 24amh, as my calculations suggested that this would give me enough power to last through a full day in the office.
My calculations were as follows
- Laptop power adapter - 12v @ 3amps
- 24" LCD Screen - 14v @ 2.5amps
Total consumption - 5.5amps at 12v.
The really inefficient thing about all our modern technology is that they are all generally really low voltage, so most appliances take 240v then bring it back down to a save voltage of 12v, before powering a device. The solar setup I had, was taking 12v, convening it up to 240v through the use of an inverter, and then the transformer at the screen was converting this back down to 14v again. There are now more and more appliances that will run on a direct 12v supply, saving you all the valuable energy.
So I'd worked out my peak consumption was 5.5amps, that would drain my battery in around 4-5 hours, but once my laptop battery was full, my consumption would drop to only around 2.5amps, on just the screen, my battery would last for almost 10 hours, plenty of time to do my solar calcs !
And this is all before, you take the input from the sun, on a great day you'd get between 6-8 hours of energy generation, on average 2-3 amps per hour, so around 20amps of power, and I'd only be depleting the battery by around 5amps per day.
Connected up to my 12v battery, I've installed a Victron BMS system, which gives me all the right sort of data on how much charge I've got left, how many amps I'm using or putting into the battery, and what state the battery is in. It will also turn off my setup once the battery is almost depleted ensuring that I don't discharge the battery past a point its happy with. A key point with BMS systems is always to connect all negative loads through the BMS so it can give an accurate voltage of consumption or energy harvesting.
I ran all my connections through a basic buzz bar, to give me flexibility to interchange batteries and panels and chargers freely, although a direct connection would suffice.
I opted for a smart Victron charge controller, this helped me manage my flows as I could view all the content from my handheld device (phone/tablet). It also allows you to fine tune how battery is charged, with lots of additional settings and features inside the app.
From my BMS system and battery, I then had a direct connection to a 1000w inverter. This was far higher than my requirements which were only around 70-100w, but its one I had around the workshop, so was perfect to use, and allowed me to grow my setup in the future. This type of inverter is pure sine wave which allows for a smooth and clean power delivery.
I've been able to power my computer and screen throughout the summer with ease, off grid. Whilst I'm enjoying a weekend away from the office, I enjoy knowing that my battery and solar setup are getting ready for the week ahead.
If you have any questions on your own solar setup, feel free to reach out and I'll be sure to help in aiding you setup your own home/office solution.