Beat loadshedding on a budget: take your tech solar for R1 271

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Like it or not, loadshedding is here to stay. The latest reports suggest that maintenance at Koeberg nuclear power station will be ongoing until May at least, and that we remain at risk of rolling blackouts until then.

There are two possible responses to this news. Go apoplectic with rage over the incompetence of Eskom, and end up giving yourself an aneurysm, or embrace the punk rock, DIY make mindset and come up with a contingency plan of your own (even better, why not work one out with your neighbours?).

And by contingency plan, we don’t mean dusting off the board games and buying candles. Now’s the time to work out how to keep your tech turned on, so you can carry on enjoying HD Netflix while all around is dark.

If you’ve got a couple of hundred thousand rand to spare, you could go completely off the grid, and for less than R10 000 you can pick up a decent petrol generator which will keep your essentials up and running during hours of darkness.

But we’ve found someone who’s got a much better – and cheaper – plan than either of those solutions. A DIY solar set-up gives you a modicum of energy independence for now and the foreseeable future, and will keep the essentials running at a fraction of the price. Less than R1 300 in fact.

Here’s how one Gauteng hacker beats loadshedding and reduces their reliance on the grid. Engineer, entrepreneur and coder extraordinaire, Toby Kurien invited us to his home/office to see the set-up he’s built for himself.

First off, a warning. Playing around with electric equipment is dangerous to yourself and your gear. As most of the following is based on 12V gear, the chances of a deadly shock are low. But get the set-up wrong and you may fry sensitive electronics in your TV or laptop, hurting your wallet if not your heart.

Our thoughts on a standard UPS

The easiest and most convenient way around loadshedding is to buy a bunch of Uninterruptable Power Supplies (UPS). These are basically big batteries which plug into the mains power, and have a power socket on the back. The battery is constantly charging, so that when the mains goes off whatever is plugged into the front carries on working without a blip.

The problem with UPSs, however, is that they’re expensive – starting at around R1 500 – and only tend to last for an hour or so. As most loadshedding periods are four hours long, they aren’t especially practical.

Kurien adds that in his experience, many UPS boxes are badly made and don’t maintain the battery properly, so they need replacing after a year or so (and this mirrors our own experience).

So what does the budget minded geek do? Hacks their own solution, of course. Kurien says that originally, he started playing with small solar panels and batteries because he works from home in an area notorious for lightning strikes. His thinking was that if he could put his network connection and laptop on an independent power supply, he’d be able to keep working even if everything in the house was unplugged.

And what he’s built is essential a bunch of low cost, reliable UPS systems which run entirely off of solar power, keeping his laptop, modem, router and even gate motor up and running all day, every day.

For less than the cost of the cheapest UPS we could find in South Africa, Kurien has a neat system which keeps his essentials running all day and night long.

The fact that it isolates him from loadshedding is merely an added bonus.

[su_box title=”Cost for basic solar backup” box_color=”#41AD49″]

Total R1271.58

*You can get away with a 30W panel at half the price if you’re not running a laptop from itAs mentioned in the comments, you’re also going to need a few lengths of cable, and whatever connectors you need for your modem/laptop/router etc. You can find a massive selection of DC connectors here at Communica from R5 a pop – the difficult part is figuring out which one you need based on measuring yourexisting one.  [/su_box]

Picking the panel

The core of the system is a solar panel, it’s where the energy comes from and – during the day – what provides direct power to Kurien’s gear. At home, he says, his laptop and gate motor have been running smoothly on solar power, with battery back-up for when it gets dark.

In addition, he runs a WiFi router, an iBurst router, a Telkom LTE router and a Raspberry Pi media centre (with USB storage) from two panels and batteries.

Fortunately there’s a huge number of cheap solar panels out there, many designed for camping and 4×4 enthusiasts. They’re simple sheets of photovoltaic circuitry, with two cables coming out of the back. They provide direct current (DC) electricity at a rate dependent on the panel size, the amount of sun and the conversion efficiency.

The challenge, says Kurien, is in the latter. Most panels are less than 20% efficient, so go for one as big as you can. If your laptop draws 20W at peak, get a 50W panel. You won’t regret over-provisioning for the sake of a hundred rand.

A portable panel means you can move it around, so you can work in the garden or take it on holiday.
A portable panel means you can move it around, so you can work in the garden or take it on holiday.

Getting the position right

Much has been said about where to place solar panels for maximum efficiency, and how to keep them pointing at the sun. Some roof mounts include motors that keep shifting the panel to its optimal angle. Kurien’s advice, though, is to put a bracket on the wall at about shoulder height – that way you can move the panel easily if you want to use it elsewhere, and adjust the angle as you need too. Plus, it makes it easy to clean – and a clean panel is a more efficient one.

[su_box title=”How much power do I need?” box_color=”#41AD49″]Almost every electrical device in your home will have its power requirements written next to the plug in very small print. This should tell you how many amps it draws and the voltage requirements. These will usually be slightly exaggerated – the requirement should be a maximum, not the average draw.

Remember that in a DC circuit, there’s a straightforward calculation that Watts = Volts x Amps, also known as Ohm’s Law. So if you are connecting a router directly to a battery (or via a DC-DC converter, see below) and are missing one of the numbers, you can work out amps by taking the rated power (Watts) and dividing it by 12V. It’s equally important to remember that Ohm’s Law doesn’t work for AC gear, so if you’re running a TV through an inverter (see below), you’ll need to physically measure the power draw of the TV yourself, but do it safely, with something like this. [/su_box]

Controlling the charge

The second piece of kit, the charge controller, isn’t absolutely necessary if you really know what you’re doing, but it is a good idea all the same. These generally have three sets of terminals to wire in to. The first goes to the positive and negative terminals on the solar panel, and takes energy in. The third goes out to the kit you want to power.

The middle terminals here lead to the battery, and either divert energy to charging the battery or draw power back when the panel switches off.

Kurien says that if you are going to use a charge controller, get a good one. Cheap ones don’t regulate the charge to the battery correctly and either end up running the cells too flat or over charging them. Both of those things shorten the lifespan of lead acid batteries enormously. Less than 50% charge will see a build up of lead sulphate on the electrodes that’s almost impossible to remove, for example, and they can be expensive to replace.

A good quality charge controller isn’t expensive, he says, and will make your battery last for years to come.

Don’t skimp on the battery!

There’s no shortage of big 12V batteries capable of charging from a solar panel and discharging into your gear – but as with everything beware false economies. Car batteries, for example, are big and heavy and not designed for the kind of deep discharge you need to keep your router up for a long time.

What you’re looking for is the kind of battery designed for a burglar alarm. These are small and portable but carry enough charge to keep electronics going for plenty of time – exactly how much charge will be written on the side and expressed in amp hours (Ah) or milliamp hours (mAh). If you want to do the maths, you can work out how many amps each piece of kit draws and therefore how many Ah you need in storage. One amp hour is equivalent to connecting a piece of kit that draws one amp for sixty minutes. So a 0.7A router connected to a 7Ah battery should last 10 hours.

Kurien says that he swears by Lead Crystal batteries from Bushpower. These are slightly more expensive than traditional lead acid batteries, but they are far more reliable and will last years longer. A 12V, 7.2Ah Lead Crystal battery – enough to keep most of your electronics going by itself – costs R296, compared to R165 for a comparable lead acid one.

Of course, if you want more capacity, lead crystal might get prohibitively expensive quickly.

[su_box title=”Don’t forget your laptop has a battery!” box_color=”#41AD49″]When the sun goes down or the power goes off, remember to unplug your laptop from the solar system and let it run on its own battery. It’s not essential, but it means you save more of your bulk storage staying online. [/su_box]

The inverter adds an extra load, and will eventually drain the battery even if your gear is off.
The inverter adds an extra load, and will eventually drain the battery even if your gear is off.

Inverter or no?

An inverter will take the low voltage DC power supplied by the solar panel and battery and convert it into high voltage AC power required by anything that plugs into the mains. The problem is, says Kurien, that almost all mains-powered electronics have a built in rectifier – which does exactly the same job in reverse. The internal workings of your LED TV, for example, are all DC-powered.

Converting AC to DC (or vice versa) is a tremendously inefficient process, so plugging a laptop charger into an inverter is likely to lose you around 50% of your hard earned energy coming in from the solar panel.

You can increase the efficiency by investing in a “pure sine wave” inverter, but they do cost more than “modified sine wave” ones.

Luckily, most gear can be run without an inverter. For anything that has a USB charging port or cameras or laptops, see if you can find a car charging kit. A cigarette lighter adapter that can wire onto a battery via a DC-DC converter (see below) will cost you R37 from Communica.

The joys of USB charging, straight off of a high capacity battery.
The joys of USB charging, straight off of a high capacity battery.

It’s all in the cable

There’s more good news for gear like your modem or router. Anything that relies on a wallwart for power can probably be run directly from the battery. The wallwart is just a small rectifier and transformer designed to take mains electricity and turn it into low voltage DC power for whatever piece of kit is on the end of it, so you bypass this, and Communica also sells a wide variety of male plug ends, one of which will almost certainly fit the size and shape of the power in socket on your technology.

Be careful though – attaching this straight to the battery will almost certainly cause some damage. Get a variable step down transformer (aka DC-DC converter) that will convert the 12V out of the battery into exactly the right voltage and current flow for your gear first.

The bigger stuff

Theoretically, you can run your TV, pool pump and fridges from a similar system, but you’ll need to do the maths. In our tests, a 42inch LED TV drew 48W peak power at 0.7A, and a 24inch computer monitor pulled 27W at 0.3A. Both of these, however require 240V mains power – even though modern screens are pretty energy efficient, you’ve got to factor in loss of power by running through an inverter to your capacity calculations.

Basically, unless you’ve got a really big battery, you’re not going to keep them up and running for four hours, although as modern TVs are so energy efficient you might get two hours from a standard car battery. You’ll get more if you’re brave enough to rewire the insides and go directly from solar to the monitor bypassing the inverter, but you’ll also run the risk of destroying your TV and voiding the warranty. So it may be inefficient, but unless you know what you’re doing, just use an inverter. It’s the simple way.

Going further…

One of the benefits of hacking together your own system like this is that you don’t have to do it all at once. Unlike a massive rooftop installation, you can add extra batteries and panels as you need or can afford. Kurien says that his next big plan is to switch out his mains powered light bulbs at home for 12V LED ones, and get all of his domestic lighting onto solar, for example.



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