Grid-Tied versus Off-Grid

A renewable energy system that generates electricity (solar electric, wind power, and micro hydro systems) can either be tied into your utility company’s electrical grid, or it can be a standalone system. Each type has unique ways of dealing with one simple fact:

Renewable energy systems may not be producing energy when you need it, and may be producing energy when you don’t need it.

Without backup, if the grid suffers a power outage, so do you.

Grid-tied with Backup

In a grid-tied system with backup, a bank of batteries is maintained at a full level of charge. The energy your system produces is still allocated whether you have a net-metered or sell-all system as described above.

If the grid suffers a power outage, your backup system will provide power to you until the grid power is restored. The length of time the backup will cover your energy needs depends upon your consumption rate and the size of the backup. Sundance will help you determine the size of the battery bank needed during the Load Analysis phase of our 5-Step Design process.

Sell-All
In a Sell-All system, all of the energy your system produces goes into the grid and is sold to your utility at wholesale rates. All energy you consume comes from the grid for which you are billed at retail rates. For every kilowatt-hour of energy you sell to your utility, you may also sell a ‘Renewable Energy Credit’ (or REC) to a third-party, who may also be your utility.
Net-Metered
In a Net-Metered system, the energy your system produces is used directly by you. When you produce more than you consume, the surplus is sold to your local utility. When you consume more than you produce, you purchase the shortfall from your utility. The difference between the amount of energy you produce and the amount of energy you consume determines whether you are a net producer or a net consumer, and it may vary from month to month or year to year. Depending on which state you live in, you can either sell the RECs for every kilowatt-hour of energy you produce, or only for those kilowatt-hours of energy you sell to your utility. Contact Sundance or visit the Database of State Incentives for Renewable Energy (DSIRE) for more information.
Off-Grid
In an off-grid system, your energy production and consumption is handled independent of the grid. No connection exists between your renewable energy system and the utility company’s equipment.Your renewable energy system charges a bank of batteries, which in turn, meet your energy needs. When the source of renewable energy – sun, wind, or water – is not available to keep your batteries charged, an optional back-up generator kicks in to maintain the charge state of the batteries and to power the loads. Sundance will help you determine the size of the charging source – PV array, wind turbine, or microhydro turbine – and battery bank needed during the Load Analysis phase of our 5-Step Design process.
For more information about:

Renewable Energy visit our Frequently Asked Questions or Resources pages.

State and Federal Financial Incentives visit the Database of State Incentives for Renewable Energy(DSIRE).