The solar power sun is rising
There was little warning of the impending power cuts (called load shedding here). Just a notice from the government owned utility, ZETDC, in the press and the next day we were cut off for 8 hours. That was 10 days ago and they have been very regular since then – alternating mornings and afternoons.
The first one coincided with the demise of a set of lead-acid batteries we’d bought of a local manufacturer in February for our solar system. They’d just been returned under warranty and we’d decided to go upmarket and more reliable. After a lot of reading up and phoning around and being promised all manner of quality and prices I visited a supplier whom I’ve dealt with in the past and who I know supplies quality equipment. He also knows what he’s talking about. An hour later and he’d convinced me that lithium batteries were the way to go with their 10 year warranty and superior charging characteristics (3 hours under bright sunlight). Initial outlay is high but lead acid batteries only have a one year warranty for most types.
We duly dug into our savings and paid up. Much to his embarrassment the supplier then discovered he didn’t have any lithium batteries in stock so lent us a set of lead-acid gel batteries that were to be returned to the factory for some minor defect. Going back to the outlet today to get some further information on the new lithium battery one of the senior staff confided that ZETDC had told them that the power cuts were going to get MUCH worse. It was not just sales talk.
Zimbabwe most of its power from Lake Kariba on the Zambezi River on the country’s north-west boundary with Zambia. Both countries have been over-utilizing this water resource for some years now and the lake has fluctuated far more in recent years than in the past. Add to this the fluctuating rainfall and we are into dangerous territory. It should be said that a large proportion of the water that flows into the lake comes from northern Angola and central Zambia which has more reliable rainfall than Zimbabwe.
The dam was finished in 1960 and since then the turbines have been upgraded and the power stations on both banks of the Zambezi River have been expanded. It is the largest man made lake by volume on the planet and such is the mass of water that it is not unusual for the residents in the area to experience minor earthquakes. Such is the volume of water that can be released from the floodgates that it was feared the vibration could cause damage to the wall and it is very rare for more than 4 of the six floodgates to be opened at any one time. The plunge pool, where the spilling water falls, has undercut the foundations of the wall beyond permissible limits and has to be stabilized along with overdue maintenance on the floodgates. This means that the dam should not be allowed to spill until the work is complete so this last rainy season substantial water was allowed to flow from the dam before the flood waters come down from the upper Zambezi, usually in April. It seems that someone got the maths wrong, let out too much water before checking how much rain the catchment had received which was less than normal, and now there is barely enough head of pressure to keep the turbines going. Add to this the fact that one of the turbines at Hwange, the large thermal power plant in the west of the country, is out of commission and we have a power supply crisis. Alternative development projects, such as solar, have failed to come to fruition due to the dismal credit rating of the country.
This of course is not bad news for the sellers of alternative power systems. Whilst it is certainly cheaper to buy and fuel a generator than a solar system in the short term there is also the added complication that we have a fuel supply crisis. This has been ongoing for some months now and is driven by a lack of hard currency to pay for the imported fuel. Fuel queues are long and ubiquitous if one wants to pay in the local currency (now just referred to as ZWL). For those who have hard currency there is no queue and fuel is always available.
One could be forgiven for thinking that this is the death knell for the local currency and it may be, but the vast majority of Zimbabweans just do not have access to hard currency (usually the $US). The country is not earning much hard cash from limited exports and already the government has reneged on it’s promise to pay tobacco farmers at least a portion of their earnings (the majority of the crop is exported) in US dollars. Appeals to South Africa to sell us power is likely to be refused; they too are inflicting load shedding on their population due to a lack of power capacity. In their case, the local power authority – Eskom, is guilty of lack of development to meet increasing demand and corrupt dealings and over-paying senior management. Anyway, they would demand hard currency which we don’t have.
Downstream of Lake Kariba, in Mozambique, is Lake Cahora Bassa. It too is a large lake built to generate hydroelectric power which is mostly sold to South Africa. Not surprisingly it is full thanks to the outflow from Kariba and I’ve heard speculation that Mozambique will be approached to supply us power. Once again, we don’t have the money to buy it. It’s not looking good at all until at least April next year when the flood waters from the upper Zambezi reach Lake Kariba assuming the rains will be good in the catchment area. The government has promised not to cut power to the vital mining sector but its track record on promises is poor.
Meanwhile the local currency is under severe devaluation pressure. Just this last week the unofficial rate (what it can actually be bought for vs the “official” rate as quoted by the central bank) has fallen from 5 to the US dollar to 7. The official rate of 3.5:1 US dollar exists only on paper. Many outlets have stopped quoting goods in local prices and some, such as the accounting firm that holds my company documents, is demanding only US dollars. The ZETDC power utility is owed millions in unpaid accounts and our electricity price has remained at 14c (local) per unit for years despite the falling value of the currency. It has appealed to the government to raise tariffs but the last application was rejected – the government doesn’t want to foment unrest. They may have missed the bolting horse. Today I was shown and anonymously authored WhatsApp message announcing a mass stay-away. Details were sketchy, deliberately I think, but the message was clear; we’ve had enough.
Mass stay-aways in the past have had limited success but have clearly rattled the government which has responded with shutting down the internet and crushing any demonstrations with a very heavy hand. The WhatsApp circular advised people to remain peaceful and stock up on essential supplies. Sound advice for those who can afford to pay for them – a forever diminishing proportion of the population.
Zimbabwe Absurdity 
Taming the voltage
1 05 2026It became evident soon after we installed the solar panels and inverter that we were going to have to do something about the terrible power quality. Most of Zimbabwe has erratic power supplies. Called “load shedding” it’s really just a statement about the government’s ineptitude in supplying power to the nation. The national supplier, ZETDC (Zimbabwe Electricity Transmission and Distribution Company) is a subsidiary of Zimbabwe Electricity Supply Authority (ZESA) and is the sole distributor of power. Other subsidiaries, also government companies, are responsible for sourcing power. It’s a mess and a major driver of the private sector embracing solar power. We have a friend who works for a company that installs industrial sized solar systems and she tells us that they cannot keep up.
Our problem is not power supply per se, but a wildly fluctuating voltage. We have been told that we are on the same part of the power grid as a “person of influence”, i.e. a political fat cat, so we don’t often get intentional power cuts though faults are not uncommon especially during the rainy season.
We installed the voltage protection unit (VPU) pictured above to protect the solar inverter from the voltage which we have seen anywhere from 280 volts down to 160 volts. It simply disconnects the supply outside of the safe range of 190 volts to 240 volts. During the day the supply is often above this range and at night it falls below. We can hear the VPU switching on and off in the evening and the lights flicking as the inverter takes over. Most of the time it is merely tedious but on occasion the voltage goes low for so long that the solar battery goes flat and the lights go off. Especially in cloudy weather when the solar battery never fully charges.
Over the years I have acquired a reasonable collection of woodworking and other power tools. These are in the spare garage next to the cottage in the garden and most can run off the cottage solar system. The planer/thicknesser and it’s accompanying dust collector cannot as they draw too much power so must run off the mains supply and the voltage fluctuations would destroy the motors very quickly. The planer is a very useful machine and because I am so dependent on it very little happens in the woodworking sphere these days.
Whilst I knew that voltage regulation units (VRUs) that supply a constant voltage existed, I had researched them on the internet and found that they tended to be large and very expensive. I asked my friend Barry, who is a professional carpenter, what his solution would be. He has liquidated his company he has no large machines but I thought he might know someone who did. It turned out that he and his partner had just installed a relatively small VRU in a flat that they’d bought and were available locally for less than US$1,000. So I got hold of the company and started asking questions, lots of them.
Having ascertained that I would need a 15kVA regulator and that the warranty would be valid for a year they couldn’t give me a clear answer as to whether it would be valid, or what would happen to the unit, if the voltage went outside the maximum rated supply of 250 volts. Asking around led me to another hardware outlet but they were only interested in selling the VRU and had little backup and simply wouldn’t answer the voltage range issue. A chance conversation with one of my cousins and with an electrician that he knows led me to call Richard of ElectroTronics and he answered all my questions.
ElectroTronics is based in the Southerton industrial area of Harare. Once a bustling hub of industry it’s a lot quieter than I remembered (I had no reason to go there for quite a few years) but was surprisingly clean. The roads were mostly good though the one past ElectroTronics was in very poor shape.
Richard is a very trim man, not looking at all like his 70 years and he assured us that he’d been in the business nearly 50 years. His small warehouse was impressively well stocked, indicating an active business, and he happily gave of his time explaining the principles of VRUs. The one we’d opted for was essentially a variable transformer. “Of course they are made in China” he responded to my inevitable question. “I could sell you that Italian-made one for 18 times the price but these work just fine” he added (we paid $900). He has sold VRUs to all manner of customers including hospitals, laboratories and factories. The biggest was 1,000 kVA. “I back up and repair everything I sell and if it’s a genuine part failure I will honour it outside the warranty”.
Having got the AVR home my brother Duncan noticed some cosmetic damage to the case. I sent in pictures to Richard and asked if it would jeopardize the warranty. He apologized, said no, and the machine was replaced that afternoon. I was VERY impressed!
The AVR is installed in our kitchen (the only place where it can be easily placed to supply regulated/stabilized power to the whole property) and my woodworking machines work just fine! However, a VRU can obviously only work when there’s power and the next day there was none. Fortunately a WhatsApp message to the local faults department led to a prompt replacement of the problem fuse in the nearby sub-station. We’re back in business!
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Tags: ElectroTronics, renewable-energy, solar, solar power, Technology, travel, Volatage Stabilizer, voltage, Voltage Regulator Unit, ZESA, ZETDC
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