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.
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 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.
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.
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.”