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My planned solar system upgrade

Technology has improved and prices have dropped in the past decade, making an upgrade just about impossible to resist.
The first step for those thinking about going off-grid is to reduce electricity consumption. Image: Shutterstock

After nearly 10 years living off-grid and some 240 months not paying the municipality or Eskom a cent for electricity, not to mention the pleasure of not having to deal with load shedding, the time has come for me to upgrade my solar system and replace some components with more modern equipment.

The main reason is winter; the shorter days and days-long cloudy weather and rain along the Garden Route are making an upgrade unavoidable, or I will have the same power disruptions the rest of the country experiences. A secondary reason is that there is much better stuff available now.

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The only problem after 10 years is that my batteries are shot. I had to disconnect two for draining power out of the other two, and the remaining two aren’t coping.

A decade on a battery bank of only four batteries isn’t bad, considering that the batteries were second-hand golf cart batteries to start off with.

The thinking 10 years ago was that golf cart batteries are probably the best batteries one can get, because rich golf players don’t want to get stuck on the 16th fairway.

Golfers also replace their batteries regularly, again because they don’t want to get stuck without wheels.

Despite their much easier job of running a small solar system, however, even these good batteries eventually wore out. Still, they were a good investment at the price of R2 000 each 10 years ago. (I also didn’t have to pay the municipality R80 000 to install a transformer and run 200 metres of cable to my house back then.)

The other pieces of my system are still working well, but some are going to go too because there is much better equipment available now.

Solar panels

Solar panels last for years, the exact lifespan dependent on who you ask and the specific installation. In essence, as long as they work, they work. A quick test with an electrician’s multimeter will quickly pick up any problem.

Of more importance is to have enough solar panels, which isn’t a problem considering that prices of solar panels have nearly halved in the past decade.

Ryan Oliver, general manager of operations and procurement at Specialised Solar Systems, does however warn that solar panel prices have started to increase lately. “Prices of raw materials to manufacture panels have been increasing steadily, while freight charges have increased sharply.

“It looks like prices have reached a turning point,” says Oliver.

He notes that demand for solar systems is steady, with a bit of a spike in standby systems whenever load shedding becomes worse.

A small system with eight 100-watt panels can easily produce 4.8 kilowatt hours (kWh) of electricity a day, even in winter, based on the general assumption of six hours of good exposure to sunlight every day and the panels being correctly angled.

Experience has shown that longer summer days deliver much more electricity, even without adjusting the angle of the solar panels.

Charge controllers, measurement and inverters

Newer equipment combines charge controllers and measurement systems with the inverter in smaller residential systems. Previously, a charge controller was necessary to regulate the electric current flowing to the battery bank and another (optional) little box to measure what’s coming in, the state of the batteries, and electricity consumption.

An inverter – converting 12V, 24V or 48V direct current (DC) to 220 alternating current (AC) to power household appliances – is now truly the heart of the system, incorporating a charge controller and power management system. Several models link to a computer programme or a cellphone app for off-site management.

Today, mid-range inverters (costing around R5 000 to R15 000, depending on the output) include the better MPPT (maximum power point tracking) charge controllers and a management system.

Thus, my basic charge controller, voltage meter and older 1 200W inverter will all be replaced by a single 3kW inverter that combines all the functions in one unit. It is more than big enough, given its surge capacity of 6kW to allow for the electrical surge when an electric device switches on.

Prickly subject

A bone of contention in the solar industry – and among existing and prospective solar users – remains municipalities’ or Eskom’s reluctance to allow house owners to use the national electricity network as a ‘battery’.

This would be done by delivering electricity into the national grid while the sun is shining, and withdrawing it at night when needed.

If this was allowed, combined with reasonable rates, rooftop solar systems would become more affordable because half the cost of an installation – buying expensive batteries – disappears.


Batteries are expensive. Huge technological advances have made for a better product, and the choice of maintenance-free lead acid batteries, gel batteries and the newer (and expensive) lithium batteries.

Unfortunately, the cost of batteries still amounts to nearly 50% of an solar installation’s total cost.

In my case, four new 150 amp hour (AH) batteries will be enough to power everything. The total cost of improvements comes to R18 000, most of which will be spent on the new batteries at R12 000 (R3 000 each).

A very desirable 48 volt lithium battery with a 20-year lifespan will (unfortunately) cost around R30 000.

Little installation is needed as the panels are already up and all the wiring is in place. The system will produce at least 4kWh units of electricity per day, even in winter, and will be able to power 3kW worth of electric appliances at the same time.

This shows that a (small) off-grid solar system is not suitable for everybody, considering that a decent coffee machine pulls 4kW, even if only used for five or 10 minutes at a time.

A hair dryer will also stress a small inverter –and would even stress a bigger one if several refrigerators, a tumble dryer, vacuum cleaner and air conditioner are running too.

Oliver says that bigger solar systems to run a household are not always an option because of the higher cost and upfront capital outlay. “Houses in municipal suburbs are still paying reasonable rates for electricity, making total off-grid systems too expensive to consider,” he says.


While hybrid systems (systems tied to the national grid or grid-tied systems) are good alternatives, regulatory changes and new policies at municipal level will be necessary.

Rural residences and commercial farms find it increasingly viable to move to solar as electricity charges rise, especially due to municipalities’ move to increase fixed charges.

Ray Nolan, project manager at Specialised Solar Systems, cites the example of an installation on a smallholding, where the owners were paying in excess of R2 000 per month in fixed ‘availability’ charges and only a few hundred per month for electricity itself.

“It makes total sense in this case. In fact, Eskom is effectively paying for the installation,” says Nolan.

First step

He says the first step in going off-grid is to reduce electricity consumption. “You can save 70% of your electricity consumption by changing over to a gas geyser and gas stove, reducing the size of the solar system required,” he says.

Businesses, including commercial enterprises with massive roofs, and commercial farms are at the forefront of moving towards solar power. Not a week goes by without a corporate or large farm announcing a new solar installation. Investors are demanding it, and an improvement in the return on investment allows it.

The problem is that municipalities and Eskom are losing their best-paying customers – those who can afford R100 000 to take their house off the grid, and businesses than can afford upwards of R500 000 to do so.

A comment by a Moneyweb reader on an article about the troubles at Eskom a few weeks ago summed it up. AP wrote: “Biggest risk to Eskom would be a breakthrough in solar/renewable energy technology making it affordable to the masses. I [believe] this day is not too far away.”

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Interesting article. Although it may be a little early in the life cycle of residential solar power systems it would be good to hear more users experiences.

Agree but 3kW inverter and 4 batteries sound way to light to run a house with fridges etc.

My 4 kW inverter copes but it takes some creativity. As long as the dishwasher and laundry machine don’t run at the same time the heat pump comes on everything is fine.

It is however not an ideal setup, I’m also looking to upgrade.

The drought in CPT taught us all to appreciate the water infrastructure. Everyone was surprised to discover that their brand new JoJo tank delivers no water pressure, and that it carries only enough water to last a week despite occupying the whole of what was once the back garden. It’s the same with electricity.

Obviously you live where pumps and boreholes haven’t yet been invented. Bottle store free Pinelands?

I rather suspect that this is a zero sum game. As municipalities, SOE’s and government (well, the oaficials) don’t get there cut from inefficient utilities they will try other ways to recover the income – rates and taxes.

Strongly suggest that when you upgrade to go for a 5kW – 48V system as it offers a whole lot more flexibility!!

“A small system with eight 100-watt panels can easily produce 4.8 kilowatt hours (kWh)”

From my experience that generation seem a little generous, a good year round average I always use is 3.5x sun hours.
So a 800W array would generate 2.8kWh on average throughout the year.
But yes on a cool summers day that around could generate 0.8KW x 6 = ~4.8kWh

That comment is a LOT more than generous 🙂

800W of panels won’t get deliver 4.8kWh in winter. There are some websites that will give you irradiance but month by location.

In a sunny place in SA you can expect around 1550 hours per year for a grid connected system. If you are putting the energy into batteries and then drawing it at night you can reduce that by about 20% for round trip losses.

For sure, winter it will be less than 2.8kWh and summer it would be 4+ that is why I said average 🙂

My daily production on a 1.65KW array ranges from 1.1kWh – 9.65kWh depending on the weather and the season.

I have 8 off 325 watt , facing north on a 25 deg roof … i generate on typical summer day 12 kwh, thus : 8 off x 325 watt x 6 hrs sun exposure = 15, 6 kwh calculated, thus my efficiency 12/15.6 = 77 % eff.

Batteries typically fully charged by 12h00 in summer, thus form 12h00 i give power away for free ( smart meters are an expensive option for low return )

Installed 2 batteries, LI-ION, 4.8 kw total ( normally flat by 23h00)

Most people do not grasp the importance of first reducing baseload , energy efficient fridges/freezer/solar water heating that revert to gas when cold ( automatically ) , proper ceilings and double glazing all part of the equation. BTW i have normal CFL globes, LED lights a waste IMO ( small gain vs cost)

Drumbeat , so how much do i use from eskom ….

My house designed and kitted for energy management, use total of 75 kwh/MONTH from eskom…..

Should eskom put up the prices more, or the city council try to rip me of more, i buy more batteries , threaten my and you can collect your cable.

But we must not conflate the issues. The substitution of gas for electric geysers / stoves / heating is irrelevant or even counter-productive to the argument for solar photovoltaic generation or going off-grid.

If I were to replace my geyser, stove and heating with gas, I would save maybe two-thirds of my consumption. But much of this saving would now go to gas. Hopefully there’s enough residual saving to justify the new appliances.

And sure, at this point I now have more modest electricity requirements and so smaller capital outlay for going off-grid, but given the fixed costs I’ve actually worsened the rate of return.

@GeneDeMurro there are other things to consider in that equation. e.g. that the costs of getting new appliances are one-off or very rarely recurring costs.

How often do you replace your stove/oven? I’ve had mine for 20 years.

How often do you replace a fridge? 20 years again

And so on.

One thing that is guaranteed, however, is that Eskom will getting worse in their supply due to ANC-driven incompetence, BEE corruption and general floundering, and as a result, will continue pumping up those prices while providing an even less stable electricity supply.

I have done my calculations and even with periodic replaceables like batteries, and eventually solar panels, I am more than happy to fork out the cash to know that while others are moaning about power cuts, increasing costs, and criminal risks in the darkness of load shedding, I am continuing blissfully unaware.

Most of us have regular situation : home has an existing connection, not facing ¼ million runts new cables and stuff.

Step 1 : check what size connection you are paying fixed fees for, and what size cinnection you need. That can save you R30k a year going by what the guy that built our house signed up for. I have a friend with a thatch roof which is always a bitch for solar and he stopped here.

Step 2: change hot water to solar and cooking to gas and lights to LED and rethink pool timer and seriously reconsider underfloor heating as a Neanderthal thing.

Step 3: figure what MUST run during loadshed and rejig that you can run those on batteries. You can survive 4 hours without aircon, tumble drier, pool pump and anything that has a motor.

After that you are a pig if you need more than about 2kW sustained and 5kW peak draw so call it 7 to 10 kWh battery.

Don’t believe the powerpoint sales pitches about future grid costs that would imply impossible (far more than running a bloody generator) energy costs. There are sharks out there

I learnt a lot from this article.. Thanks.
So, if more guys are going off grid, then eskom actually has less consumers of electricity, but still has load shedding…due to old equipment. But, they raize prices 15%. This SOE has 500billion debt. Nauseating…..

Bear in mind if you are going with lead acid you can’t get anywhere near the rated capacity, especially at high loads, if you want the battery to have reasonable service life. The more oversized the better.

Same goes to a lesser extent for lithium.

I like his suggestion of a combination of better power sources.

Gas + solar seems to be the simplest and best balance of cost Vs renewables Vs ease of running and maintaining.

Of course the total power consumption is a big factor. I mean he doesn’t even have a coffee machine? How does he live! :).

But it’s time more of us looked at this!

End of comments.





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