Solar home

As I write, our neighbourhood is wrapped in darkness. At Stage 6 national load shedding, electricity cuts out several times a day. But we hardly notice. We enjoy the benefits of energy that shines down from the sky, for free, every day.

In August we installed a solar power system. After fretting for a while over the cost, we saved up and just did it, knowing that this investment will pay itself back in a few years. After that, electricity will be free.

Installed and pumping electricity!

Best of all, we reduced our family’s carbon footprint, making a major contribution from our side towards solving the climate change crisis.

The best location for solar panels was the garage roof, as it is the most nearly North-facing, with the least shade.

The solar panels convert sunlight into electricity. This power is variable, and it comes in as DC (direct current) while the home uses AC (alternating current). So the current has to go through an inverter.

The inverter receives electricity (from the panels, from the grid or from a battery), converts it as required, and sends it as required to the home or the battery or exports it to the grid. Beware: the inverter is noisy.

Batteries supply power at night. Without them electricity would only be available during daylight hours. They act as a storage tank, ensuring a steady supply while power production peaks and dips. The inverter also needs a battery to start up during power outages (it is a computer after all). This took me a while to understand. Without electricity from the grid or from a battery, the inverter cannot power up in the morning, and the solar panels are useless.

The Watt ratings on the panels indicate the maximum power produced per square meter. I don’t know if one ever reaches that maximum, but today at lunch time (a blazing sunny spring day) our panels produced 85% of their total rating.

An online app records and makes pretty graphs of everything – the energy being harvested from the sun, our electricity usage, how much we import and export from and to the grid, even an estimate of total savings – in Rands (our monthly electricity bill) and in carbon dioxide (1.8 tons in under 3 months, or more than half a ton of coal). Wow!

Electricity production (green area) depends on the weather, the length of the day, and other factors.

At this time of year the weather is extremely variable, swinging from blazing hot sunny days to grey fog and drizzle, and back. Despite this, our solar system has supplied our needs, on average. On some days we import from the grid, on others we export. Even on the darkest days with heavy cloud cover, the panels produce at least enough electricity to keep the fridge and freezer going 24/7 (with two batteries). But this is good to know.

Back to question of money: these past few years the cost of solar power has come DOWN, to the point where it is now getting cheaper than electricity from fossil fuels (like coal power stations). At current electricity prices our system (which we paid for cash) would take about 10-11 years to pay off.

But electricity prices in South Africa have gone UP, faster than inflation (15% annual increase on average since 2008, which is 3x faster than inflation). If this trend continues (very likely) we will get our money back in about 7 years, after that, profit. So this is an investment that makes business sense. No wonder more and more businesses are installing solar power. In theory one can start small and add more over time.

I just discovered that 13 October was International Day for Disaster Reduction. On 11 October 50% of Durban city was without power after an explosion at a major substation. Half a large city! The Durban flooding disaster damaged electricity infrastructure and caused major power outages. Sometimes we lose power for several days due to local faults. And have I mentioned the load shedding?

In every way solar power makes sense. It makes sense for today, it makes sense for the future, it makes sense financially, it makes sense for disaster readiness and for peace of mind.

by Marlies Craig