Off-grid power systems supply electricity to properties that are not connected to the public electricity network. These systems are often referred to as “stand-alone power systems” (SAPS), or “remote area power systems” (RAPS).
These systems are independent power stations capable of powering a wide range of applications with reliable electricity. Whether it be for a small or large new or existing home, a station, business or an entire community that depends on large diesel generators, off-grid stand alone power systems are commonly the clean and cost-competitive answer!
How do Off Grid Systems Work ?
Off grid systems supply electricity to properties that are not connected to, or have chosen to disconnect from, the public electricity network.
Photovoltaic (PV) solar panels convert sunlight to direct current (DC) electricity, which is then fed through the solar inverter to create usable alternating current (AC) electricity. AC electricity is then sent to the switchboard, where it is sent to the household appliances that are using electricity at the time, and any surplus electricity is sent to the battery bank to recharge it.
The inverter/charger will stop the solar system from recharging the batteries once they are full. When your solar system is not producing electricity, your battery bank will send power to your household appliances.
If the battery bank state-of-charge level gets too low, the inverter/charger will turn on the fuel generator automatically to power the house electrical appliances and recharge the battery bank.
There are two different ways of configuring an off grid system – AC-Coupling and DC-Coupling – and each have unique advantages. The configuration type will have an impact on the life expectancy, efficiency and flexibility of your system.
Off-Grid System Design
During your system consultation and design with Off-Grid Energy Australia we provide you with recommendations and information about where the system equipment is to be installed.
Following contract acceptance we provide you with detailed infrastructure guides and plans to clearly communicate where equipment is to be installed, requirements before installation and what Off-Grid Energy and the customer is responsible for.
All system components and sizes are chosen for many factors. Including capacity, performance and cost. Your Load Profile information, or specific energy demand, forms the basis of all our equipment and system design recommendations.
Your equipment location is also very important when designing an appropriate system for your property.
Solar arrays should be located as close as practical to the standalone equipment enclosure. It must be capable of producing enough electricity (kWh) to replace what is used by your property on any given day – including days of poor weather.
Below are some guides to where a solar array should be installed:
- Orientated to true North if practical (slightly different to Magnetic North)
- Inclined to a high pitch – The steeper the solar array pitch the better Winter performance you will receive. This reduces fuel consumption from a backup generator, while still retaining adequate power production in summer
- Avoid shading at all times of the year, this is especially critical in Winter when shadows are the longest
- When solar panels are mounted on a suitable existing roof structure the need for a separate ground mounted system; additional cable; conduit and trenching costs are removed.
- Solar panels sited on the roof of an equipment enclosure (Shed) can also assist in lowering internal operating temperatures; this helps to prolong the battery bank and equipment life.
- In some cases it may be more economical to install more solar panels at a lower tilt angle to acheive a similar Winter performance to higher tilt angles.
Sizing your battery bank is incredibly important when designing your system. Understanding when and how much electricity (kWh) is used will determine the battery capacity required.
The inverter/charger needs to be sized to the peak power (kW) requirements of your property. If you boil the kettle, run the air conditioner, and do a load of washing simultaneously, the inverter/charger needs to be capable of delivering this power all at once.
Generator sets require much careful thought and planning when it comes to their installation and operation. The generator should be installed as close as is reasonably practical and convenient to the main residence and other stand alone equipment while giving careful consideration to the possible noise level when in use. Please note different safety regulations are applicable to permanently installed generators and portable directly supervised use generators.
Below are some prompters as to where and how a generator is to be installed:
- Permanent or portable generator set
- Auto-starting or manual start
- Exhaust gas ducting/extraction
- Air intake, ventilation and heat dissipation
- Noise – Many people under estimate how much nuisance the noise can be
- Storing fuel and oils safely
- Maintenance – Easy access to parts of the generator for maintenance
Safety – Insulating hot exhaust pipes, protection of moving parts within the generator, electrical safety
- Security – Theft of generators has been known to happen
- Access – Excluding unauthorised personnel; pets and various wildlife
Off-Grid Energy Australia’s standalone power systems are built using leading technology, and designed to last and outperform competitors’ products. Our knowledgeable consultants will help guide you through the off-grid power process. You can confidently rest assured that a correctly sized and professionally installed Off-Grid Energy Australia system will help you attain a comfortable lifestyle on your property, with no need for large changes to your lifestyle. Once installed, you can rest easy in the knowledge that you own your own ‘power station’ and are immune from the ever increasing quarterly grid supply charges and electricity prices.
Living ‘off-grid’ can mean many things. From simply not having a grid electricity connection – through to being completely self-sufficient in energy, food, water, etc. Whatever your off grid lifestyle choice, we can power your needs.
An Off-Grid Energy Australia standalone power system has the following ‘green’ benefits:
- Power is generated and consumed locally, greatly reducing losses in power transmission.
- Power is generated – mostly – from a renewable source. (Note: Our GenFree system does not include a fuel generator and uses 100% renewable energy)
- The carbon created during your system installation is calculated by us and completely offset through tree plantings.
- Prior to designing your system our consultants will give you advice on reducing your energy usage, using clever house design and appliance choice.
Energy Load Profile
Completing an accurate load profile is an essential part of correctly designing an off grid solar system. The load profile is a list of all your appliances and utilities that require electricity, with an estimate of their usage frequency (e.g. how many days per week, and hours per day). Once we have this information, our system design team can accurately recommend appropriate system design and size for your needs.
Efficient appliance choice and efficient home design are by far the best way of minimising your electricity requirements, system size, and cost – meaning you don’t have to change your lifestyle to live comfortably off grid.
For a printable copy of our Load Profile Form CLICK HERE. Or for a Microsoft Excel version please contact us.
AC Coupled configuration
The most recent innovation in stand alone power is the AC (Alternating Current) coupled system. Energy generators (E.g. Solar array) are coupled into the system via regular 230V AC wiring.
- Solar array can directly power household loads during daylight hours resulting in higher efficiency. Directly powering appliances during the daytime can bypass batteries which reduces battery cycling; the solar inverter and other AC inputs are added/layered onto the capacity of the main battery inverter/charger. Excess solar power during daylight hours is then used to charge the batteries via the inverter/charger.
- AC coupled systems work at higher DC solar voltages which typically results in lower solar array wiring efficiency losses and increased system performance.
- In AC coupled systems greater flexibily is available about the placement of solar arrays or other electrical equipment.
Battery bank life expectancy is enhanced; all energy inputs are controlled via the one central control system (Inverter/Charger).
- The fuel powered generator is also fully AC coupled; its generation capacity can also be ‘layered’ to the battery inverter/charger capacity providing a significant system advantage at times of high system demand or low renewable energy input.
- The equipment cost is typically a little higher; in the case of small systems the additional cost may not be justified however for most customers the costs are quickly recovered in lower cable and installation cost and enhanced system performance.
- Additional safety measures are required for AC coupled systems and the DC solar array component; these requirements add some additional cost but this is not excessive.
- Inverter manufacturers that use the AC coupled configuration (Eg. SMA, Victron Energy) use the frequency shift method of solar output control. In some cases sensitive devices such as some inverter type air conditioners, low quality lights may not operate at certain times of the day. Digital clocks (Eg. oven and microwave clocks) also won’t keep accurate time due to the power frequency variation.
DC coupled configuration
Until recently the traditional method has been to use a DC (Direct Current) connection method in which energy generators are directly coupled into the system battery bank via a regulator or charge controller.
- DC coupling of system inputs for small systems may have an advantage in simplicity and lower component cost were the power transmission distance is short and the system power is fairly low.
- The solar array and associated wiring operates in the extra low voltage class mode therefore it could be considered by some to have some safety advantages.
- Working with the DC extra low voltage class typically means high electric currents need to flow in the solar array and sub array cables to obtain the same power as systems working at higher voltages. High currents often need to be carried by very heavy costly copper cables which can also be difficult to manage and very costly to install.
- Where the solar array is located well away from the other standalone equipment problems of prohibitive cable cost or voltage loss can be very problematic; often undersized cables may be installed to cut the installation cost; this often results in inferior system performance.
- In the DC coupled system all power must be delivered to the home via the main battery inverter; the solar generating capacity can’t add onto the capacity of the main battery inverter/charger therefore the inverter/charger having limited capacity may at times limit the system performance because it can’t transfer all available solar array power when it is available in the daytime.
Connecting Electricity To Your Home
Determining the cost to connect your house or property to the electricity grid is an important first step when deciding whether to live on or off-grid.
Often the power lines will appear quite close to your dream block of land but when you begin to chat with your electricity utility about the cost of connecting up to mains power, you get a nasty shock!
What is the National Electricity Grid ?
‘The Grid’ refers to the normal mains electricity network that supplies the vast majority of Australia with electricity. The electricity distributors are companies that own sections of the national grid and are responsible for grid maintenance and purchasing the electricity from power plants . Electricity retailers are companies that purchase electricity from the electricity distributors and on-sell it to the end user or customers, i.e. anyone living on-grid.
Determining Grid Connection Cost
There can be large variations in the cost of bringing mains power to your property, and in some cases it may not even be possible. The cost to connect to the electricity network depends on a range of factors, including distance from the grid, underground or over ground cabling, crossing neighboring properties, easements, SWER line capacity, transformer requirements, and many more things. It’s not uncommon for electricity distributors’ quotes to be tens or hundreds of thousands of dollars when all charges are factored in.
Off-Grid Energy Australia can assist you in obtaining an accurate cost of connection with the electricity distributor for your area. Contact us to get our handy ‘Cost of Connection – How to Guide”, and chat to our consultants about the process.
Off-Grid System Range
The Complete System is the most versatile of our off grid product range, capable of powering a broad range of medium to large properties.
Ideal for low-consumption users, the Essential System offers a perfect green solution for your holiday retreat without the ongoing commitment and cost of grid connection.
The Shed Power systems are our smallest hardwired standalone power options. Designed for very small loads – such as a fridge, a TV, and a few lights – these systems are ideal for the back shed.