To Go Solar Electric – Now or Later?
- We of course are huge believers in rooftop solar electric generation (PV), but in the domestic home unless you have spare cash to invest, or being ‘off’ the grid is the only option, or you really hate Eskom, or you need to help save the environment, it is still too early.
Solar PV, Inverters, Batteries Technology
Can you use the electricity generated during daylight?
- Solar electric generation using solar PV panels and inverters/ controllers to convert direct current (DC) into 220V alternating current (AC), and using that electricity as it is generated makes economic sense, as the cost over buying mains power per kWh is less. As a general guide, the cost of the system can be paid off over 5-7 years (assuming the electricity is used every day).
Batteries are Still Expensive
- The big problem with solar electricity generation is the cost of batteries to store power. Although the price of lithium batteries continues to fall, and the number of cycles they can provide increases, they are still very expensive. Lead acid, or gel batteries although much cheaper than lithium, are not falling in price, and due to demand have actually increased in price over the last couple of years.
More Expensive than Eskom?
- The result is that when using power from batteries for appliances and lighting at night, taking into account the cost of the battery and the number of cycles they can provide, the replacement cost of the batteries at the end of their useful life (between 5 and 15 years), the actual cost of the electricity can be double the cost of buying the same kWh from Eskom or the municipal reseller.
The Economic Realities
7 Day a Week Businesses
- From an economic perspective, solar PV with minimal storage is ideal for supermarkets, shopping malls, showrooms, and businesses that operate 365 days a year. They can be cash flow positive from day 1, even when financed and pay off the system in 5-7 years (depending on their tariff).
- For offices working on a 5-day week, (rather than 7) the payback period is pushed out by a couple of years.
- For homes that don’t use much power in the day, the economics change as battery storage is required. Payback is likely to be 12-15 years, and with finance as much as 19 years.
- Additional consideration needs to be given to splitting power demands, so that heavy use items such as kettles, electric geysers, washing machines, tumble dryers work off the mains, and low consumption items such as TV’s computers, DSTV boxes, LED lighting runs on the PV and battery systems.
- Unfortunately, there are very limited opportunities for feeding surplus home generated power into the grid. Until that changes, unlikely to be any time soon as Eskom have a surplus of power, solar electric generation has to stand on the return on investment calculations of each individual’s circumstances.
Outlook and Be Aware
- As the price of electricity continues its path progressively higher, and at the same time the price of PV panels, inverters /controllers fall (they are already much cheaper than only a few years back), and most importantly the price of battery technology falls, the time will arrive when it will be cheaper for everyone to generate and store their own electricity.
Checks Before Investing
- Before investing in solar PV, do the economics carefully, get at least 3 quotations from suppliers (there are many unscrupulous dealers out there), and understand your time of use and consumption demands.