Beat loadshedding on a budget: take your tech solar for R1 271 - htxt.africa

edited February 2015 in Site discussion

imageBeat loadshedding on a budget: take your tech solar for R1 271 - htxt.africa

How to hack your home and take your essential tech off the grid.

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  • bluntblunt Cape Town
    Any chance of getting a proper laundry list of items required for the basic setup? I see you have a list but no specifics on what connectors you will need.
  • @blunt Connectors are going to depend on your setup - the only one that's critical is the one to connect the DC-DC converter to your modem, for example, which is a few rand from communica (mentioned further down). But that's going to be specific to your router.

    You could - although I wouldn't recommend it - use the connector from the wallwart. Just cut through the existing cable low enough down and wire it into the DC-DC output. I wouldn't recommend it as you'll probably want to hold on to the wallwart, just in case and all that.

    The charge controller and DC-DC converter have terminals built in - you just screw the bare ends of the wires in - and I guess you can use crocodile clips for the battery, or get a pair of flat connectors for it. Or - with the smaller alarm batteries (not the one pictured) just wrap the wire around the terminals.

    Same for the cigarette lighter adapter. You can wire in to it with flat connectors (again, a trivial cost from Communica or RS) or simply solder directly onto it. Then everything you need is in the car charging kit.
  • @blunt Direct link to that Communica page is here. You might also be able to find what you want at rs-online.co.za.
  • There is some rather inaccurate and potentially dangerous information presented here.
    This is my first comment here so I tried to say that as gently as possible.
  • edited February 2015
    @fluffy Really? It's all based on a working system and is tried and tested. If there is anything that's potentially dangerous please do tell me so I can investigate and correct if necessary.
  • How can I communicate with you privately so I don't pollute your excellent effort.
  • Sounds good, but not sure the numbers are up to too much:
    = 7.2Ah battery with 20W laptop == will last you 4 hours and be completely dead. I'm not sure about where you are, but here the "running all day and night long" includes more than 4 hours of darkness.
    (Good choice of battery other than that, it's a good robust 100% dischargeable one)
    [50W peak at 4-5 hours of good sunlight = 250Wh = 20Ah possible charge... so you could get a bigger one and still be able to charge it, as long as it's a sunny day (and you stay outside all day!?)]

    Just wondering: why you can't just attach the solar panel straight into the laptop? It's already got a charge controller and battery; but I guess this at least adds something of an additional buffer for you.
  • @fluffy If you want to reply in private you can either PM me through the comments system or I'm adam at htxt dot co dot za - either way is fine.

    @richjdavies Yeah - reading that I should probably have shown my thinking a bit more clearly here. So a couple of things:

    - The mistake I've made, I think, is that I'm thinking of a fairly modern, low powered laptop drawing 20W peak - most of the time that number's going to be around 10W or even less (my old Levovo Sandy Bridge machine ticks over at about 11W) but it's spiky depending on the task in hand. Tweetdeck, funnily enough, is one of the primary offenders, but obviously video editing, code compiling, anything that puts a load onto the CPU is where the battery killing problems come from.

    But what I've not considered is a budget laptop that doesn't have a decent mobile processor or efficient screen is going to be a lot worse.

    - The 4 hours figure is the length of time loadshedding is /supposed/ to happen in an area. Again, should have made it clearer that that's not always going to be the case.

    - The other factor, though, is that the laptop has its own battery. There's an underlying assumption that you'll be able to (and probably prefer to) draw on that rather than the standalone battery in hours of darkness. Certainly between the two batteries the assumption is that it'll keep you working for a good time.

    - Size of battery = bigger is always better, and again, should possibly have been clear that this is what we'd consider the bare minimum setup. Ideally, I think, you'd double everything and have a separate rig purely for the routers and modems.

    - In terms of cabling directly in to the laptop, you could but there's a couple of things we were thinking of. Firstly, that the laptop battery itself might not be enough to work all night (see above), and secondly it means you lose a lot of flexibility with the system. With a separate charge controller and battery you can add on and do the routers etc too. Also, given that the laptop is the most expensive piece of kit here I think for my own piece of mind I'd want to go through an extra layer of protection for it :)

    I guess if you were going to go straight into the laptop, I'd probably recommend doing it via the car charging kit option, have to look into that a bit more though.
  • Hi, I like this post of yours! It is creative and easy. I have done something similar last night. Basically - I installed by camping equipment in the house. It is Saturday morning and I am on remote standby for a rather complex data centre...ready for the power to fail but my old 4x4 Varta 75AH battery and 300W TES inverter are both ready for action. I run the ADSL, laptop and Samsung S27C750 screen from it. Yes, sure - there are MANY losses in this setup. I will loose significant energy on the inverter and again on the laptop transformer and the ADSL transformer. But, I don't care too much. Efficient energy transfer is a specialized field for electrical engineers which I respect and leave to them. I am an electronic engineer - so my rule is : over supply and everything will be fine (that is what Eskom used to believe in).

    The other thing (which is not mentioned here) is that you need to use 'deep cycle' batteries. They can be pulled dead without being damaged. So I actually prefer the Deltec 105AH. These deep cycle batteries are about R1500.

    My thinking is - why bother with a solar panel if I can just charge the battery under my desk with a normal car charger - which I am doing now.

    I have a 60W solar panel. I used it once in Botswana in a town where there is no electricity. The only aim was to drive a camping fridge (National Luna - which works without brushes and is very energy efficient). The solar panel could not keep the batteries charged. That was full sun all day in the desert. This means that tracking the sun with a solar panel is actually very important. The 60W means : I will get 60 watt, in the middle of a sunny day in full sunlight on the equator at a 0 degree angle to the sun.The solar control unit is also something that should not be taken lightly. The solar controlling unit (I don't really understand what it does - but the best on the market is R3500 - and the people that sell it (at Voetspore in Woodlands in Pretoria) will tell you exactly why. I believe them but I am not going to pay it. My plan is to take some of the LED lights in the house "off the grid" - but it only really is to play with the idea.

    I realised that the only really useful solar application is to put in a solar geyser. But, it costs (after the Eskom rebate) about R14 000 per geyser; you pay that many back fairly quickly...unless this : I had a simple timer switch (R300) installed in my DB board that allows the geyser to switch on for 90 minutes a day. I cut my electricity use in half by doing that. So, I will basically never make the money back if I sell my house in 10 years.

    My advice : buy a decent deep cycle battery, a 500Watt inverter and a charger. This setup will drive the TV (120 Watt, DVD player - 120Watt) and the laptop and ADSL).

    This converstation has to go on - because eventually people are just moving the load to a different timeslot and it will not help Eskom. Going solar has to happen.

    A more important problem though is water. We can easily make a plan for electricity to keep all the non essential things like tv's and laptops running.(unless you are dependant on an oxygen machine or a dialyses machine- I know people like that). But, when the water goes off - then we have a problem right after the next toilet flush. I live in a estate and I resolved to go and pee in the garden when the water is off. Unfortunately I don't only pee...and my wife does not know this and she will not do this. I don't have a very big garden..so sooner or later my dogs and neighbors wont like it either. Luckily we have not had too many water problems. I have (at least once) went with a bucket to steal water from the estate's swimming pool to flush the toilet. When I camp (like Bear Grills does - with no comfort) then I use a 2l coke bottle with luke warm water - heated on a fire-and some holes in the cap to shower with. It is actually enough to clean myself. (Although I cannot really relax in my hand shower for hours). i have not done this at home...but I have at least went for a swim in the toilet water supply place aka pool to counter the coke bottle method. The solution to this is to install a small Jojo tank at home. The problem with this is that the water does not break frequently enough (yet) to keep the water flowing through the tank. Storing water is difficult because stuff lives in it. So I thought of putting a water tank in series with one of the toilet's water supply. This means that the water will regularly flow through the tank and I dont have to worry about adding chlorine etc. But, I found that to steal water from the pool is easier than this as I will have to think about adding a valve to the intake that allows water to come out if the water supply is off (there will be a vacume in the tank)..the other thing is- if I dont use rain water, will the tank take the pressure of the municipality. I dont want ot have a potential water bomb attached to the house.

    back to my life for now.
    Abraham











  • Hi Abraham, thanks for the great reply and advice. I think it's a really good point you're making, which to me boils down to the fact that every household should have its own energy strategy now, or be pkanning it, based on three things. Current usage costs, loadshedding survival and future price rises from Eskom.

    For me I'd also throw in a desire to move to renewable energy, but that's not going to be everyone's goal.

    The advantage of putting bigger panels or solar geysers etc on the roof for me is that your payback time reduces the higher e;ectricity costs go - and that's not a hypothetical here. We know Eskom wants a 25% increase this year already. Of course, by the time big cost increases come,renewables may have dropped further, etc.

    Surviving loadshedding I don't think is about recouping costs agains electricity bills, though. It's about keeping essentials up and running for as little as possible, and what you consider essentials may be different to me. So I'm happy to watch video on a tablet when the power goes off - someone else may feel the Xbox & plasma is a must-have.

    If you're after a chunky deepcycle battery kit, I can't recommend Netsheild enough for their system they've developed using a lot of local engineering. Also, if you want to get maximum efficiency out of your existing panel and feel like you're up for a challenge, Google some instructions for building your own tracker - a couple of stepper motors, an Arduino board and a home made gimball will move your panel to keep it in line with the sun. Could be fun - I'm going to try it and write it up as soon as I can :)

    Quick point on the batteries - the advantage of the lead crystal batteries is that you don't need to deep cycle them. The disadvantage is that if you want a big enough system to - say - run a TV, they get pricy (although even this is a balancing act. you don't need the supersophisticated charger).

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