Differences Between Power Back-up, Off-grid And Grid-Tie Solar Solutions


The concept of a (1) normal power back-up system differs somewhat from a (2) grid interfacing power back-up and we refer to the latter as an off-grid system.

Furthermore, there is a third option for Photovoltaic solar solutions, referred to as a (3) Grid-Tie system, in which there is NO Backup power available. It is purely a system which generates and supplies power when the Sun is up and photovoltaic energy harvesting is possible, only really suited for reducing electricity bills.

Very briefly, the differences are as follows:

Hybrid power backup system – these systems are more intelligent. Here a more expensive type power inverter system is generally used - such as those supplied by Victron or Outback, etc. The concept is as follows:

These systems are the most common and practical systems for a household or office who want to convert to alternative energy and have the option of using their photovoltaic solar panel (PV) system as an energy source, which can be expanded with time, but will also have Eskom as a convenient backup. However, a well-designed system allows you a backup when it’s cloudy and ESKOM has failed.

Grid Tie system – these systems are very intelligent, usually bigger systems, and a Battery power backup does not form part of the greater system.

NB: The prices displayed here are merely ballpark indications and are subject to change. Prices are influenced by the R/$ and R/€ fluctuations as well as product availability. These are also basic system prices and exclude Energy Monitor and remote measurement system. Plan My Power retains the right to modify or change prices at any time.

Suggested KITS and Budget Prices

Stand Alone Photovoltaic solar systems (No Grid Power Available)

These systems kits are for dwellings from small Rural to Urban homes, depends on system requirements – 40 Square Meter to 600 Square meter houses with no Grid supply, purely photovoltaic Solar Panels.


Power Backup (With Grid Power. No Solar Included)

These systems, are for dwellings and offices in which the main purpose is power backup power, Alternative energy is an optional input. Eskom grid is available and power backup is given to critical components or all

solar-system-kits-and-budgets-hybryd-off-gridOff-grid Hybrid power backup system

These are the first of the so-called off-Grid solar power systems, but with a backup power component present. It is not necessary to use all the alternative energy that might be available, as the energy gets stored and usually a level of autonomy is already built into these systems. Such a system could supply back up from 3 hours, to 72 Hours. Such options are for small rural dwelling of 40 M^2, up to 1000M^2 such as for use in Rural houses, Urban houses, Offices etc. The purpose here is to allow for expansion at a later stage and even to a full hybrid power operation (when possible).

These prices include 8 hour power backup autonomy


Grid-Tie solar system

These KITS do not offer backup power options. The concept here is to install a certain rated Grid-Tie inverter, with matching rated Photovoltaic energy; i.e. 3KW inverter and 3KV Panel array's. The load should typically be greater than the photovoltaic solar solution , so that whatever is supplied by the Photovoltaic solar panel array is directly consumed into the load (any excess could be sold back to the Grid) . Systems such as these are ideal for Office complexes or dwellings, Mines, Hospitals, or wherever occupancy only occurs during the day. The savings represented below are directly calculated on a Municipality rate of 75c - R1.30 per kW.h and exclude any other rebates and Carbon Credits which can help to amortize the cost of such systems.


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