Going solar makes sense
According to the South African Department of Energy, ‘most areas in South Africa average more than 2500 hours of sunshine per year, and average solar-radiation levels range between 4.5 and 6.5kWh/m² in one day’.
‘This makes South Africa’s local resource one of the highest in the world’.
So, we have the sunshine and more and more businesses are coming on board to manufacture and import the various components.
How do solar panels work?
Without getting into too much detail, a solar panel comprises an array of photovoltaic cells – also known as PV cells – that use sunlight to generate electricity by a process known as the photovoltaic effect. Each cell comprises two, possibly more semi-conductive materials, such as silicon. One has a positive charge and the other is negative.
When exposed to sunlight some particles of light are absorbed by the negative semiconductor atoms (at the bottom), knocking electrons off atoms on the lower (negative) material. These free electrons can then flow (if connected to an electrical load to create an electrical circuit) back to the positive semiconductor (at the top). This type of flow is known as direct current (DC).
Each cell generates only a tiny amount of electricity, so they are connected together to form an array, mounted on a panel.
In short, the more panels that are connected, the more energy can be generated.
On-grid, off-grid… what’s the difference?
Terms you will come across when considering solar power are on-grid (also sometimes referred to as grid-tied, grid-connect and grid-direct) and off-grid.
On-grid solar power means that the system is connected to your electricity supplier and has the advantage that if your solar system isn’t producing enough energy, for example on an overcast day, then the extra power you need is drawn from the grid. As a result, an on-grid system does not have to produce all the energy you require. However, bear in mind that an on-grid system will not protect you from power outages, because when the grid goes down, its systems stop working and stay off until switched on again – for example if a power line has been cut or a sub-station developed a fault. No power – including that from your solar system – goes though so that the repair crews can fix the faults without the fear of electrocution.
- A system to monitor the production and transfer of electricity.
- Electrical safety components such as circuit breakers and fuses.
- One or more inverters.
- PV panels – as mentioned above, the number will vary according to how much electricity you want the system to generate. The higher the requirement, the more panels that will be needed.
Off-grid solar power is totally independent of the grid, so you would have to have sufficient PV panels to provide what is required – even on overcast days. As it is not connected to the grid, you might therefore need to have a back-up generator and as the system generates electric power only during the hours of daylight, you would need batteries to provide sufficient power at night.
These systems are more complex than the on-grid type and are less flexible than the latter.
- A system to monitor and balance consumption of energy with production.
- Charge controller that regulates output and stops the battery being overcharged.
- Electrical safety gear such as circuit breakers and fuses.
- One or more batteries.
- One or more inverters.
- PV panels – again, the number will vary according to how much electricity you want the system to generate.
This is basically an on-grid system that to which has been added a battery backup. So it works like an on-grid system, but you are free of suffering power outages… when one occurs, the system switches over either manually or automatically to the batteries for an uninterrupted power supply, or at worst, a very short outage.
The components required for a hybrid system are basically the same as those required for an on-grid system, but with a suitable battery backup added.
Naturally, as an adjunct to installing a solar system of whatever type, you need to go for low energy consumption appliances and lighting – for example LED lighting throughout.
The pros and cons of solar power
As with everything, there are pros and cons to solar power and when deciding whether or not to install it in your home, you need to consider a number of factors.
- Using sun power to generate electricity for your home will lower your electricity bills, which, as mentioned above, are going to simply carry on rising. Solar power can reduce your electricity bills by as much as 50-75%, though that does of course depend on how big a system you have installed.
- A substantial increase in the value of your home.
- Lower carbon footprint.
- Depending on the system you install, anything from a partial to a complete freedom from power outages.
- The initial cost.. Like all things, the bigger you go, the greater your costs, so it is impossible to state an accurate cost for a particular system, but there is little point in investing too little in a system that does not actually provide the amount of power you need, or still leave you victim to power outages etc. You also have to bear in mind that the larger your home, the bigger the system you will need, if you are to enjoy its benefits throughout the home.
- On-grid systems can range from around R12,000 for a 1kW system to around R30,000 for a 3kW system, but note that this may vary greatly from supplier to supplier depending on whether the components have been imported (cost depends on the strength of the rand) and so on. Also add to the above installation costs, connection fees and so on.
- Off-grid systems can start at around R6,000 for a 300W system to as much as R12,000 or a great deal more for a system supplying 12kWh or more of power. For a very large house you could be looking at R24,000 or more. Again, you need to include extra costs as mentioned above. (There is a case of one individual who went totally off the grid for a cost of around R350,000, to which he has to add replacing the batteries every 10 years or so at a cost of R150,000 or so a time – even then he still used gas for cooking and wood for heating water. So, in all, a great deal of money, but he can laugh when there is a power outage.)
Hence the initial cost installing the system can take as long as seven years or longer to ‘pay off’. However, you also need to look at the other benefits of not being subjected to blackouts, which are not only an inconvenience, but can also be detrimental in other ways as well – for example, food spoiling, loss of internet communications and so on.
- A roof might not be suitable to fit the panels, depending on its material – for example, slate tiles – or large enough to house the number of panels required to provide the desired power.
- Any system requires maintenance, and a solar power system is no exception – and that will cost you in terms of cleaning, repairs, replacement of any components that develop a fault, and you would need to insure the system as well.
So there are pros and cons, and you need to consider the issues and costs carefully before committing yourself.
Now we are going to state the obvious, but it pays to think about the following points:
- Ask around, take time to speak to nearby homeowners who have solar power installed. Ask all the questions like the cost, who did the installation, what the system produces and what the owner can operate on it, whether there have there been any problems with it, the maintenance costs and, what sort of saving have they achieved.
- Once you have the answers, you will have a better idea of who is out there, what the costs are – initial and on-running costs such as maintenance – what sort of output/size of system you will require for your needs and so on.
- Speak to your financial institution holding your bond – they too should be able to provide you with useful advice on the way forward – for example, accredited contractors you can use, any changes to your home insurance rates and so on.
- Contact your local authority to ensure that whatever you have installed is within regulations. (There appears to be a move afoot on the part of local authorities to require all homes with independent power sources to be registered – cynics might be forgiven for thinking this is more to do with future taxation rather than simply keeping track of who has what, but in any event, ensure that you comply with local regulations.)
- Contact at least three contractors, staff at your local Mica may be able to point you to a few, but remember that at the end of the day it is YOUR decision as to which contractor you take on.
- Tell them precisely what you want in terms of power output, whether on-grid, off-grid or hybrid. You have to be precise; if what you get is not sufficient for your needs, you will have only yourself to blame.
- Once you decide on a contractor, ensure that you obtain a very detailed quote detailing exactly what is to be installed, the cost of every component, the labour costs, and any other costs such as registration costs, cost of any verification checks and so on.
Your hot-water geyser is generally the article in the home that consumes the most power, so it makes sense to look at using solar power to heat your water using free power from the sun.
- Heat exchange system
- Reservoir or storage tank
- Solar collector
Hence it is plain that a solar water system is far less complex than a solar system using PV panels, batteries and so on, and that means you can also generally assume that installing a solar water heating system will not be as costly as its PV cousin, but again, it all depends on the size of the system you want, and other factors.
Bear in mind that you will need to have such a system installed by a qualified and registered contractor, and all the points regarding selecting the right system, financing, selecting a contract or and on apply as mentioned in the section on energy-generating systems mentioned in the first part of this article.
Generally, there are few factors that militate against solar water heaters.
- According to some experts, it will generally pay itself off within anything from 4-8 years.
- Boost to the value of the home.
- Easy to maintain.
- Hot water even when the power goes out (generally, provided the power outage doesn’t coincide with an overcast day).
- Lower carbon footprint.
- Savings on your electricity bills.
- You are using clean, infinite energy.
- Although manufacturers do try to make their panels as aesthetically pleasing as possible, solar water heaters do rather stand out more than do PV panels on a roof.
- As with its electricity-generating cousin, some roofs might not lend themselves to having a panel or panels installed on them.
A word of caution
As you can see from the above, solar power is here to stay and can be a very good choice of supplementary or even total independence when it comes to your electricity and hot-water needs.
However, unless you are yourself a qualified, registered electrician and/or plumber, installing such systems is for the professionals. They should not be considered a DIY project, except in its simplest form – for example putting free-standing solar powered lights around the garden or solar-powered security lights over garage doors and so on.
Mica stores usually carry a range of these lights ranging from a low of a couple of hundred rands or less, to R800, or more. Ask at your local Mica for their range of solar-powered lights and light up your garden at night (and protect vulnerable areas). These free-standing, independent solar-powered garden and/or security lights are well within the capabilities of the average homeowner to install.
However, if you try to install the far larger systems mentioned in this article and you make a mistake, you could cause a lot of damage to your home, which would have ramifications for your home insurance and any payout you might get for damage caused (very likely, little or no compensation). You could also cause damage to the incoming supply systems, which would then be trouble with your local authority. And finally, and most important, an incorrectly installed system could cause injuries – or worse.
So, no matter how good you think you are, get in the professionals for any system that will be connected to either your home’s electrical or plumbing system – sometimes both.
There are electrically powered pool heaters available but they use extra electricity to heat pool water. Most people therefore go for the solar version, in which water from the pool is pumped up through thin tubing where it is heated by the sun and returned to the pool.
An array of solar PV panels on a roof. Note that in South Africa, the north-facing slope of the roof is chosen to house these arrays (and any other solar heater, panel or whatever) and nearby trees that shade these fixtures need to be cut back or removed, uninterrupted sunlight is the aim – always!
A solar water heater mounted on a flat roof – so it is angled to expose as much of its surface as it can to the sun’s rays at an angle as close as possible to 90°. Some very sophisticated systems allow the units – be they water heaters as here or PV panels – to track the sun as it passes over for maximum efficiency.
A free-standing solar-powered garden light that can be angled as desired. Note that garden lights do not generally provide very bright illumination… they’re closer to mood lighting than they are to brighter lighting.
A solar-powered ceiling light with a remote control. The panel is fitted where it will collect the maximum amount of the sun’s energy. Such a unit could be a good choice for a patio or veranda, for instance.
Another example of garden lights, and a jar that is a very effective night light or can be used to provide some light when there’s a blackout.
An example of a motion-sensor-operated solar-powered security light mounted over a garage door and powered by a small PV panel.
Another example of a motion-sensor-operated solar-powered security light. In this case the PV panel is far larger and is mounted on a bracket so that it can be angled for optimum performance. This also has a hand-held remote control.
Simple and secure. This very small unit, also motion-sensor-operated and solar-powered provides a lot of light and costs about R200 per unit. It is attached to the wall with one screw.