Residential Grid Connect Solar
Residential grid connect solar systems are power systems energised by photovoltaic panels which are connected to the utility grid. Grid-connected photovoltaic power systems consist of Photovoltaic panels, grid connect solar inverters and grid connection equipment. Unlike Stand-alone photovoltaic power systems these systems seldom have batteries. When conditions are right, the grid-connected PV system supplies the excess power, beyond consumption by the connected load, to the utility grid.
The feedback is done through a meter to monitor power transferred. This is called Net metering. Photovoltaic wattage may be less than average consumption, in which case the consumer will continue to purchase grid energy, but a lesser amount than previously. If photovoltaic wattage substantially exceeds average consumption, the energy produced by the panels will be much in excess of the demand. In this case, the excess power can yield revenue by selling it to the grid. Depending on their agreement with their local grid energy company, the consumer only needs to pay the cost of electricity consumed less the value of electricity generated. This could be a negative number if more electricity is generated than consumed. Additionally, in some cases, cash incentives are paid from the grid operator to the consumer.
A grid connect system supplies instantaneous electricity in most cases from solar PV generation which can be used immediately by the systems owner(s) from appliances in the house and the reminder be fed to the public grid in order to be used by other consumers. As the QLD Government has not committed any longer than 30th of June 2014 to the 8 cents feed in tariff it is more vital to attempt fitting as much of your normal amount of energy consumption within daylight hours in order to maximise your savings in electricity cost.
To give you an example we have documented the usage of a customer before a solar installation and after.
The graph below is showing combined usage tariff 11 and tariff 33 before residential grid connect solar power installation. The high squarisch peaks are the time the electric hot water system is energized, induced by the control device from Energex in the meter box at times with low energy demand on the public grid (tariff 33).
The result from switching the electric hot water system to tariff 11 (you could also time a pool pump or other high consuming device) and connecting it to a dedicated timer had following result for the customer:
- T 33 5.4kWh per day before changes
- T 11 2.4kWh per day before changes
After installing the solar system and connecting the electric hot water system to tariff 11 the daily usage:
- T11 1.5-2 kWh per day after changes
The reminder of usage is covered instantaneously in peak sunshine hours. These graphs should be seen as an example only. Each customer’s usage habits are different. However if a customer can change usage patterns to fit into the peak sunshine hours of the solar system without sacrifices on their personal life style then this will result in the best financial savings of electricity cost and the quickest way to make an investment in a solar pv system pay for itself.