FAQ – Solar Power Systems

What is a hybrid power system?

A hybrid power system combines a solar power system with backup power. A grid-tied solar power system is dependant on the power grid to operate. If there is a power failure the solar system stops working. But with a hybrid power system, the Batteries and battery inverter will simulate a “local grid” for the grid-tie inverter. Thus ensuring that there is always a grid available for the grid-tied inverter to work…

What is the benefits of a hybrid power system as supposed to just a backup power system of a grid-tied solar system?

Grid-tied solar systems depend on a grid being present for it to work. If there is no grid for example during load shedding the solar system also stops working. Having a backup power system in place, allows the solar system to continue working, even if there is a grid power failure. This is achieved by the backup power inverter simulating a local grid for the grid-tied inverter.

What is the advantages of Grid-tied systems

Grid-tie systems are most popular with businesses, or houses, where most of the power is consumed during the day. There is no energy storage in the form of batteries with a grid-tied system. This means as energy is generated from the solar system it needs to be used or exported to the grid. As there are no batteries involved, it makes the system very affordable and cost-effective.

Can I feed back into the Grid and what benefit does it really offer

Some municipalities do allow you to feedback into the Grid – although it is quite a bureaucratic process! For domestic users there is no limit at present as to how much you can feed back in (dependant on the municipal district); but for businesses, you are limited to your average monthly consumption over the past 12 months. You will get around 45c per kWh from your electricity supplier – which is currently cheaper than cycling a battery bank for reserve power.

What do you need to know in order to quote for a solar system

Every solar system is different, from our experience. In order to size up an applicable PV array, inverter and battery bank, we need to know: Your estimated peak consumption (a typical winter and summer month); Your daily, or monthly, consumption; as well as the make-up of the appliances you wish to operate. We usually start by attempting to reduce your consumption with energy-efficient lights and appliances, before we attempt to solarise any system.

Is it best to go completely Off-Grid

This depends upon your circumstances. It can be very expensive, due to the large battery bank that is required. Most people already connected to Mains usually stay connected and the solar system usually covers between 20-80% of their total consumption. If you are already Off-Grid and employing a Genset, then obviously it is better to get all your power from the PV array and only employ the Genset in case of inclement weather and emergencies.

Can I build up my solar system in phases

Modern solar systems are designed to be scalable so you can start small and expand without making any major component redundant. One could start off with just the backup part of the system. Then later on and more and more solar panels as required.

How does a solar system pay for itself

There are many different models for justifying solar systems. One needs to take into account that the rewards of Solar are not measured over a few weeks or months, but rather a period spanning a few years. Battery based systems will always take a few years more than Grid-tied systems for the ROI to pay off. The most important factor is that it has a definite value, which is added to the value of the house. We recommend taking 75% of the pre VAT price of any system, and ‘capitalising’ that onto the value of your home or building. You can depreciate this ‘investment’ over say 25 years and work back your ROI. Most serious investors acknowledge that solar gives a better return than the Stock and Bond markets.  Of course, as Eskom prices climb (and they will, increasingly, after they privatise!) so the value increases.

What are the risks to PV with regards to storms (hail, lightning)

With regards to hail. All solar panels are tested to withstand hail up to 25 mm diameter in size. It is very rare that one gets hail storms with hail larger than that.

With regards to lighting. On all our systems we insist to install lighting protection on both the AC and DC sides of the installation. Additionally one can also install lightning protection on the roof. Solar systems can also be included with your building insurance but must be specified.

 

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