Renewable Energy Systems for Your Home
Electrical renewable energy systems for your home generally fall into one of two categories:
- Off-grid
- On-grid (also known as Grid-tied)
Off-Grid Homes
Homes which operate in isolation from the local electric utility are referred to as being “off-grid”.
Off-grid homes produce their own electricity using the sun (photovoltaic PV modules), wind generation, running water (micro-hydro), or combinations of these. Electricity sources charge a battery system which stores energy for later use. When more than one electricity source is used, the home is said to use an “off-grid hybrid” electrical system. A backup AC generator is used to ensure batteries remain properly charged during periods of low sunshine and/or wind.
An “off-grid” inverter converts the DC (direct current) electrical energy from the batteries to 120/240V AC (alternating current) required to operate lighting, appliances, and other household loads.
Riverside Energy Systems has extensive experience with off-grid home electrical systems. We have designed and installed systems employing fixed mounted solar electric (PV) modules, tracker mounted PV modules, wind generation, and micro-hydro generation for many off-grid clients. (See our off-grid home gallery for more details)
Fixed Ground Mounted Solar Electric Array
Careful consideration must be given to loads and energy usage when designing an off-grid system. Battery sizing, PV array capacity, inverter ratings, and other factors should be assessed in detail to ensure satisfactory performance of the system.
Backup Diesel Generator
1 kW Wind Machine
1.6 kW Tracker Mounted Solar Electric Array
Please contact us for full service and support with any of your off-grid renewable energy needs.
On-Grid (“Grid Tied”) Homes
Homes which are connected to local electric utility are referred to as being “on-grid”.
On-grid homes which produce renewable electricity using the sun, wind, running water (micro-hydro), or combinations of these are said to be “grid tied”. The electric utility makes up the home’s electrical energy needs if load exceeds what the renewable systems can meet. When the home is producing more electricity than required, the surplus energy flows into the utility grid for use by other customers.
Grid-tied homes require that the utility provide a “net-metering” system which is able to measure and bill (or credit) the customer on the difference between energy drawn from the grid and energy returned to the grid.
Two approaches can be used to grid-tie renewable energy systems in a home:
- Grid Dependant
- Grid Interactive
Grid Dependant Grid-Tie
Grid dependant renewable energy systems operate without battery storage and only produce energy when the grid is powered up. In effect, the grid behaves like a battery, “absorbing” any excess electricity the home produces.
The grid dependant inverter connects the renewable energy system to the grid only when it is safe to do so. If a grid power outage occurs, the inverter disconnects to avoid a dangerous “islanding” condition where the home could energize the grid posing a safety risk for utility personnel.
Because no battery system is required, grid dependant systems are less costly to implement. However, the renewable energy system produces no electricity during grid outages.
Grid Interactive Grid-Tie
Grid interactive renewable energy systems use battery storage to provide the home with electricity during grid power outages. When the battery system is fully charged, the inverter directs any surplus electricity to the grid for use by other customers.
The grid interactive inverter provides the same operational and safety functionality as the grid dependant inverter. However a grid interactive inverter is additionally able to
- Power the home from the battery during grid outages as in an off grid system.
- Charge the battery from the grid if the renewable energy sources are unable keep up.
At the expense of a battery system and renewable source charge controller, a grid interactive system is able to provide electricity during power outages.
Riverside Energy Systems has designed and installed solar electric (PV) systems for grid-tied buildings of both the grid dependant and grid interactive varieties. (See our grid-tie gallery for more details)
Grid-Tie Example: The 2010 Kamloops Green Dream Home
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The roof-top PV system has a capacity of 6.8 kw. Bi-facial PV modules have been integrated into the south balcony railing panels for an additional 1.5 kw of capacity. Both systems are grid-tied using grid interactive inverters. |
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Inverters and switchgear for grid connection of the roof-top PV system. |
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Balcony bifacial modules are translucent, allowing some light to pass through while providing privacy. These modules can harvest energy from sunlight striking either the front or rear surfaces. |
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Inverters and switchgear for grid connection of the of the balcony railing PV system. |