With load-shedding back in circulation, residents are looking for alternative ways to survive this winter without electricity and others are seeking long-term options.
GCN spoke to Paul Straussner from a local solar solutions business about the cost of powering your home with solar power.
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Cost
Straussner said when considering solar, the important facts one should know are that solar systems have three main components, namely PV panels, inverters and batteries.
“Solar solutions can only generate an average of about five hours of its full-rated capacity per day. If you have a solution that can generate a maximum of 5kW/units of power per hour, you will only get about 25kW/units of power from the system a day,” said Straussner.
He said if one is planning on going solar to reduce their reliance on grid power, they need to have a detailed profile of their power consumption.
“How much and when this power is being consumed to correctly size the system. Solar prices depend on brand and type of solar solution and can vary considerably, depending on the client’s current power consumption and their expectation from a solar solution,” said Straussner.
He said the size of the system is determined by the size of the home.
“A small off-grid system from as little as R15 000 small home backup system with solar from around R60 000 and full hybrid systems averaging between R135 000 and R155 000 for an average home with four people,” said Straussner.
He said a typical four-bedroom house uses between 25 and 30kW/units on average per day, but this can vary significantly depending on lifestyle.
“Typically, a 5kW hybrid solution would greatly reduce or even eliminate your reliance on the grid. A fully off-grid system for a four-bedroom house would require more batteries and a bigger inverter system, 10kWs or more to cover heavier loads with enough panels to power the house and keep the batteries charged,” said Straussner.
Type of products
He advised that before deciding on using solar power, one needs to know the kind of products available.
“There are essentially three main solar solutions for residential: grid-tied, off-grid and hybrid systems.”
The grid-tied system is connected to the grid and does not have battery storage.
These systems are typically used to reduce your grid power consumption.
Grid-tied solutions are generally not suited for residential installations in South Africa and would only be used in a situation where the majority of the power is used during the day and in peak production times.
Businesses that have a high consumption rate can benefit from grid-tied solutions. These systems also shut down when there is a power outage.
Residential grid-tied systems are more common in parts of the world where PV-generated power can be exported to the grid and one is credited for the power exported.
Off-grid systems are mostly used in cases where there is no grid power or as a backup solution for a grid-powered house.
Off-grid residential systems rely on a larger battery storage capacity to power the household at night and during bad weather days with little to no solar power generation from the panels, generally making full off-grid solutions more expensive than grid-tied and hybrid systems.
The systems used as a backup system for load-shedding or power failures work well for this purpose but generally don’t significantly reduce your electricity bill, as they only power the essential loads, which are normally small appliances and lights, and not heavy-load appliances like geysers, ovens and stoves.
Hybrid solar power systems are generally best suited to the South African residential solar market as they combine the best of both worlds with grid-tied and off-grid.
Hybrid systems can use the battery as backup or self-consumption or a combination of both.
The system is also able to supplement or power the household’s heavy loads with the option to export power to the grid when allowed in SA.
He said with enough options to choose from, it is possible to run totally off the grid.
“It is possible to run totally off the grid. The main factor here is that the more power you use the bigger the system needs to be and the more expensive it will be. A household can run totally on PV-generated power with both an off-grid and hybrid system if they are sized correctly,” explained Straussner.
The pros of solar energy
• You are generating clean power, reducing your carbon footprint.
• Your power generated is free when your system is paid for.
• You are not affected by load-shedding or general power failures.
The cons of solar energy
• The initial cost of solar, although it has gotten more affordable over the years, is still a substantial investment.
• Storage of solar energy is expensive.
Straussner said even though it’s a substantial investment, it’s once-off and thereafter it requires maintenance.
“The main component of a solar system that would need to be replaced is the battery. All batteries have a cycle life. Acid batteries have the shortest life cycle and would need to be replaced more often than lithium batteries.
“Lead-acid batteries typically have less than 1 000 cycles, lithium on average now has 6 000 cycles and would last longer than 10 years. The overall life of batteries can also be affected by temperature and incorrect usage. There are new technologies like super capacitor batteries that have 1 000 000 cycles and a design life of 45 years,” shared Straussner.
He said solar panels are generally a component that won’t need to be replaced in most cases, but they do deteriorate over time.
Most panel manufactures will guarantee a minimum power output of over 25 years.
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