Residential Systems

FT - Residential Solar Power Systems

Grid Tie Systems

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On Grid Systems usually require:

• Solar panels and an appropriate mounting system,
• Grid tied solar inverter(s) and monitor(s),
• Solar cables and MC4 connectors,
• AC and DC safety isolator switches, and
• Grounding earth cables and clamps.

On Grid Solar Power Systems (also known as ‘grid tie systems’ or ‘integrated systems’) are connected to the main power supply just like a regular home. This means that main power can still be used any time your solar panels generate less electricity than is needed, e.g. at night.

Home appliances will always use PV energy first before using electricity from the grid.  Excess energy that is not used will flow into the grid and supply other loads on the municipal grid. When excess energy flows back onto the grid credits are built up to be used at a later stage when there is no solar PV available. Please note that “grid-sell” functionality is only available in certain parts of South Africa where the utility permits it.

The benefits of Grid tied systems are that they are fairly inexpensive and offer a high return on investment especially The benefits of Grid tied systems are that they are fairly inexpensive and offer a high return on investment especially where “grid-sell” functionality is available. Another benefit is that the size of the Inverter does not limit the Load capacity because whatever the Inverter cannot supply just gets imported from the Utility.

On the negative side, when there is no Utility power available there will be no PV power as well. Grid tied systems use the utility frequency to sync and when there is no frequency it cannot produce PV energy.

Links: Conext RL

Grid Tie Systems with Backup

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Grid Tie Systems with Backup usually require:

•  Solar panels and an appropriate mounting system,
•  Grid tied solar inverter(s) and monitor(s),
•  Solar cables and MC4 connectors,
•  AC and DC safety isolator switches, and
•  Grounding earth cables and clamps.
•  Backup Ready Grid Tie InverterBackup Ready Grid Tie Inverter
•  Tesla Powerwall

Unlike regular Grid tie systems, SolarEdge has developed a StorEdge system that integrates with TESLA’s Powerwall. The SolarEdge’s StorEdge DC coupled storage solution automatically provides homeowners with backup power in case of grid interruption, and allows home owners to maximize self-consumption for maximum energy independence.

Unused PV power is stored in a battery and used during a power outage or when PV production is insufficient. When there is a power outage, a combination of PV and battery is used to power important loads such as the refrigerator, TV, lights and AC outlets, day or night.

The solution is based on a single inverter for PV, storage and backup power.

Links: Solaredge, Tesla

Off Grid Systems

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Off Grid Systems usually require:

• Solar panels and a suitable solar mounting system,
• Off grid solar inverter(s),
• Solar power controller and batteries,
• Solar cables and MC4 connectors,
• AC and DC safety isolator switches, and
• Grounding earth cables and clamps.

The problem is that in many countries it is either not permitted or not practical to connect on grid solar power systems to the mains utility grid.

Off Grid Solar Systems do not need to be connected to mains power. As there is no ready source of reserve power, they rely on generators or storage batteries to provide electricity on days when the solar panels generate less electricity than is required, e.g. on cloudy days or at night time. The idea is that at times when the system provides more electricity than required the surplus can be used to recharge the batteries.

Our solutions provide inputs for Genset connections when long periods of low light conditions are present.

If you have a Utility connection, you can also use the utility as a backup instead of a Genset so that you only use grid power when there is no Solar available and the batteries have been depleted.

Benefits of Off grid systems are Independence from the Utility. You are in charge of your power needs.

The drawback of Off Grid systems are the huge capital expenses because of expensive batteries that need to be purchased and maintained. Batteries with long life cycles are usually very expensive and make return on investment period very long.

Links: Microcare, Conext SW, MPPT, Powesafe Bateries

Hybrid Solar Systems

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Equipment for Hybrid Solar Systems
Typical hybrid solar systems are based on the following additional components:

•  Charge Controller
•  Battery Bank
•  DC Disconnect (additional)
•  Battery-Based Grid-Tie Inverter
•  Power Meter

Hybrid solar systems combines the best from grid-tied and off-grid solar systems. These systems can either be described as off-grid solar with utility backup power, or grid-tied solar with extra battery storage.

Advantages of Hybrid Solar Systems

Less expensive than off-gird solar systems

Hybrid solar systems are less expensive than off-grid solar systems. You don`t really need a backup generator, and the capacity of your battery bank can be downsized. Off-peak electricity from the utility company is cheaper than diesel.

Smart solar holds a lot of promise

The introduction of hybrid solar systems has opened up for many interesting innovations. New inverters let homeowners take advantage of changes in the utility electricity rates throughout the day.

These type of systems are the best of both worlds. Self-consumption of PV power is first priority, then excess PV These type of systems are the best of both worlds. Self-consumption of PV power is first priority, then excess PV power gets stored in batteries for later use. Whatever cannot be stored gets exported to the grid for credit. When power outages occur, PV generation can still continue. Batteries are then used to power the loads. When there is excess battery power, that can also be exported onto the grid during peak times to support the grid and maximise return from peak Utility charges.

Benefits are that power is always available and where “grid-sell” is permitted high ROI can be expected.

Battery-Based Grid-Tie Inverter

Hybrid solar systems utilize battery-based grid-tie inverters. These devices combine can draw electrical power to and from battery banks, as well as synchronize with the utility grid.

The bottom line is this: Right now, for the vast majority of homeowners, tapping the utility grid for electricity and energy storage is significantly cheaper and more practical than using battery banks and/or backup generators.

Links: Imeon, Conext XW+

Which do I need?

In many cases this decision will be made for you. If you are unable or not permitted to connect to your local mains electricity supply, you only choice is an off grid system.

If you are in the lucky position of choosing, we would advise that, in most cases, an on grid solar power system will be the most reliable and cost effective choice.

On grid systems do not require batteries, which can be expensive and require frequent replacement, and require fewer panels, as you don’t need to generate extra power for cloudy days. This cuts down the initial cost and reduces the payback time considerably. When coupled with payments from the utility company for surplus generation, these systems can often pay for themselves in seven years or less.

If you have the opportunity to install an on-grid system, you owe it to yourself to research your options. Get in touch with your local grid operator or your current electricity provider to find out if you could be saving money with solar.

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