Hey Everyone,
I'm done picking out all of the parts for my PC, but had a thought about making it completely off grid. Purchasing solar panels and configuring the solar array to power a battery pack that would in turn send power to the PC via a converter.
Has anyone done this? If so, how did you size the battery? Does anyone know of any good calculators out there to help me size the solar installation and battery for this kind of use?
Theres not a whole lot to it. You need to figure your KWh of your computer. How long you plan on using it. Whether or not you care if the solar panels can charge the battery AND power your system. Do you want lead acids or are you going to use 18650s?
The hard part is figuring your actual load, sizing the system is fairly straight forward after that.
my uncle uses solar to power his garage and second home. he uses 2 13ft wide solar panels and an array of 110 car batteries. if he does not get any sun for 3 days then its trouble time for his batteries. considering your needs i would say 1 13ft panel and around 20 used ( still in decent shape ) car batteries should be able to keep you up and running for a few days.
If you want to keep it off-grid, get a laptop. PC's suck ridiculously much power having one off the grid only makes sense if you live next to a dam.
Used a 12v to 110v converter in a truck once. That was with a 486 and a 15" crt screen.
It was single player campaign only 
This. When I lived off the grid I could power my Alienware M15x for about 2-3 hours off a single 15Ah SLA battery. It also helps that laptops have their own included battery backup in case your battery bank voltage drops and won't power the laptop. Gives time to save the game and shut it down.
Its not THAT bad. A modestly spec'd machine would maybe use 250w under full load. Definitely doable with solar. Though a powerful laptop would really only need a single 100w panel, so it would be much easier and cheaper to build for.
It definitely depends on power usage. My HTPC can be powered by my solar panel because it is undervolted and draws 30-40 watts. I currently have a N3150 Celeron and my N3700 laptop powered by my solar panel, along with running lights and charging boost packs for powering my phone and Bluetooth earpiece.
Solar panels are very affordable, so it doesn't make much sense to spec it out and get the bare minimum. Just making up fictitious numbers here, but if you found you needed just over 200 watts of power for a typical day, I wouldn't just get one panel ~250 or two that add up to that. I would get 2 x 150 watt or 3 x 100 watt panels. Maybe more if I could afford it.
You would have to go outside and survey where the sun lands and what obstacles might be in the way, also noting what may grow into the way in the future. You need to be able to survive cloudy weather on the winter solstice. As long as you can survive that then you won't have any problems. Cloudy days still give some power. My batteries are full now even with days of rain because my load on it isn't that high. I probably get almost as much energy on a mostly cloudy day in June than a mostly sunny day in December.
There are lots of options for batteries. Shipping can kill an otherwise affordable deal. Amazon has a few things, or you can hunt around locally. I've heard of places dumping old UPS's with big batteries that can be salvaged. Sometimes people make setups of a similar size as what you need and can buy the whole thing for a reasonable price. I have a pair of 50AH batteries from a wheelchair. It isn't perfect since they were used gel-cells, but free and still taking a charge over 4 years later.
I would avoid the Harbor Freight Panels or the long rolls made for roofing. They are amorphous and only last around 10 year vs mono- or polycrystaline panels which usually are warrantied for 75% to 90% of rated power after 25 years, depending on manufacturer. Also the manufacturer of those amorphous roof rolls went out of business, plus I think they are 24V.
That could be an important point. The voltage of the panels and the charge controller have to be compatible. Going with a higher voltage setup means there will be a larger difference in voltage between the battery bank and the computer, which means lower efficiency. It would likely be best to stick with 12V or maybe 24V.
Then of course if you expect to run an overclocked high end CPU with a modern high end video card then good luck finding a power supply. In that case you might have to get an inverter. This means more inefficiency. The same rule about battery voltage applies to inverters. A 12V bank converting all the way up to 120V would be less efficient than using a 48V bank, and that would be less efficient than a 96V bank, assuming you can find an affordable inverter that accepts the voltage you want to use.
I personally believe in using cheap charge controllers for small scale solar and buying an extra solar panel vs buying a massively expensive MPPT charge controller, unless you are not stationary. The increased efficiency just isn't enough to cover the massive cost increase for a good MPPT controller. It's cheaper to just grab another 100 watt panel or whatever you are using and end up with more power, not to mention the panel will last much longer than even the best charge controllers that I have seen. I'd also really like to see a side by side comparison of both setups in low light conditions, as I think having more panel surface area could be better at collecting light (energy) in that instance. For mobile uses you need the smallest and lightest setup possible, so monocrystalline panels and MPPT would be better.
If you just want to offset your energy usage and lower your power bill then just getting panels and a grid-tie power inverter would be much cheaper and easier. With the relatively cheap cost of panels you can make back all of your investment in a handful of years or less.
Hey Everyone,
Thanks for replying and giving me your feedback! I really appreciate it. What I'm looking to do is eventually get my entire house off of Grid - but starting with something small that I can grow on.
As I'm looking at replacing my aging PC, this seemed like a good time to get moving on deploying solar as well. Haven't found the batteries that I would use as of yet - and have seen a few 100w solar panels and kits on amazon.
Thanks again!
If you are going to mess around with solar and you live in the United States of America, better check to see if you can go off grid, some states in America require you to attach your solar panels to the local power company, meaning the power generated by the solar panels makes your meter run backwards, meaning you are not completely off grid. I know Ohio was one State that required solar panels to connect into the local power grid some how.
This is very popular in the carribean countries. I remember in the late 90's early 00's going for a week and a half without Power due to storms during my stay in the carribean. Many business run off of generators and solar panels
Thanks - I'll have to look into that.
My PC with an i5 over clocked and a classified 980 overclocked only use a total of 360watts on full load, playing the witcher 3
I run my PC completely off-grid in my van. Its a Chevy express extended 6.6L v8 diesel that I plan on converting to run biodiesel. I've got a solar rack on top of the van comprised of four 150-watt renogy solar panels all going to a solar charge controller that shows me the rate of charge and battery bank capacity. It then goes to my battery bank comprised of 4 marine deep cycle lead-acid batteries, in a battery box underneath the bed in the back of the van. My PC is set up in the kitchen area in front of the bed, behind the front seats with my 1440p Korean monitor on a swivel mount. My PC consumes 360-watts under full load tested running the witcher 3 (i5 4670k @4.5Ghz, 980 running custom overclock bios). It would take approximately 11 hours of full load for my PC to drain my battery bank from full capacity. My solar rack manages to charge my battery bank to 100% on sunny days, so its a matter of managing my PC time. I travel a lot so when the bank needs to be charged I just drive somewhere for a bit. I've also got a backup set of battery cables in the back of my van from the factory, that were meant for an extra engine battery hookup. If I connect it to my battery bank, I can effectively drive around and charge the battery bank at the same time with the engine using my alternator. However I don't want to wear the alternator out because its a bitch to swap out. I currently tether my oneplus one to my PC through USB for internet with my tmobile unlimited plan. I usually get around 70 average ping on my games which is tolerable. I've had to call them a few times for data throttling but they always lift the restriction after I threaten to switch providers lol.
Be sure to get a pure signwave inverter. Modified signwave inverters are cheaper to make which is why they're more popular but they'll fuck up your delicate electronics like phones and computers over time. Things like electric burners, blenders, and kitchen tools run fine on modified.
Speaking of pure sinewave..
I plan on going off grid once I own my home in a year and half or so..Really I plan on building another house out of a quonset hut and off griding it..And living in it instead of this small crappy two bedroom house I have now..
Figure I will use this I bought it for $125 on sale..
I get micro outages here anywhere from a few seconds to 20 minutes at worst a few hours..Was tired of the BS outages so this fixed that problem..
I was looking at a build your own solar panel kit at amazon..
This was $75 new..But it looks like right now they only have a used one..
I was also looking at these
And maybe a turgo generator for my spring in the back yard..Just not sure yet what I should use to generate electricity with my water..My spring is kinda small..
Oh and hydronics to cool the building since my spring has nice cold water
Things to factor in:
-asume that your solar system will only put out 80% of its rated output on an average day.
-your hole house usage (hot water is a big one).
-never drain a deep cycle battery below 50% of its rated capacity and 70% for car batters, anless you only what a couple of years out of them.