Grid Connected Systems
Grid connect (sometimes called grid tie) systems are implemented to provide energy independence - to reduce and say good bye to high power bills, to save money, to watch an investment grow by limiting purchase of power off a retailer, for environmental reasons or simply to choose a better lifestyle!. The power generated is used within the property (commercial or domestic) with excess generated power fed back into the grid.
- In a residential property, this typically happens during the day when power usage is at its lowest and generation is at its optimum or highest. As the peak power demand times are in the morning and early evening, some market offerings now include battery storage where power generated can be stored and used at peak demand times, with excess generation still fed back to the grid
- For a commercial property, the generation outputs are typically a closer match to the usage profile, as office, warehouse, factory and associated commecial activities require constant power supply. Unlke the residential space, the peak demand times in the morning and evening dont exist, so any excess is directed back to the grid.
An agreement is negotiated with a power retailer who will pay you an amount per kWh for the power you feed back or "export" to the grid. Conversely when additional power is required, beyond the generation capacity of the system, it is drawn from the grid. Net metering is the preferred mechanism to manage this process.
The result is reduced power bills. Retailers leading the way with higher pay rates are Contact Energy and Meridian. SEANZ recommends consumers talk with a SEANZ installer/system integrator member as they are versed in negotiating arrangements as part of a solar, wind or hydro implementation.
Current government policy and legislation does not mandate compulsory setting of tariff rates, a set formula or a defined contract period by retailers to pay you as a micro-generator. However they cannot impose erroneous admin or connection costs as defined under the "Distributer Generation (DG) Rules and Regulations" (Available in the SEANZ Members Section)
Current rules dictate that it is up to each individual consumer/micro-generator to negotiate an agreement on a commercial basis at this time. The issue here is a major generator/retailer or gentailer, who is effectively in competition to all micro-generators, sets the tariff rate and agreement terms, as legislated by governement.
This is a market failure, being addressed by SEANZ and other partners.
SEANZ has expertise to provide assistance for its individual consumer members in this space.
An important consideration is to use what you generate. The greater the number of consumers that become grid connected, the greater the reduction in loading at peak usage times when other consumers demand for power from the grid is highest. Critical mass hightens this position as attested in other countries like Germany.
With market offerings that now include battery storage, this position assists the consumer at peak demand times and helps the lines company/distributor as storage allows them to re-distribute power locally and it assists with delayed infrastructure investment and costs.
A typical grid connected solar system utilises solar modules/array, mounting frame (roof or ground), inverter, cabling, connection to the main board, an export or net meter and a qualified SEANZ designer/installer/system integrator.
Grid Connected Systems with Storage/Batteries
An addition to grid connected systems is batteries to capture excess generation from solar PV and store it for use at other times during the day and night. Other storage systems can also be used to capture and use the excess generation from solar PV systems like power diverters that send power to a hot water cylinder.
A range of battery technology exists from Lithium iron to Saltwater based tech. Battery prices are reducing at a similar rate as occurred with solar PV systems several years ago. A significant reduction in prices will contribute significantly to Electricity Version 2.0 as prosumers can generate, store excess power and use the power on demand, significantly reducing the need to buy power off the grid.
The grid will become insignificant and provide a backup support service for electrcity delivery. In New Zealand the trend started and grid connected solar PV systems with storage/batteries are already being installed - a trend which commenced in 2013 with the early adopters. By 2020 it is forecast that this trend will become mainstream.
For more info visit our sister organisation Stored Energy New Zealand Inc
SPS Systems/Off-grid Systems
These are common in remote locations and at end of lines companies, distributor’s networks where it is difficult to access grid supplied power.
It may make economic sense to implement an SPS system where the cost of sourcing grid connected power is prohibitive (requires additional infrastructure and power lines) or if there is no access to any power.
A typical off-grid SPS solar system requires - solar modules/array, mounting frame (roof or ground) inverter, battery bank for storage, cabling and connection to the main board and a qualified SEANZ designer/installer/system integrator.