Grid tied with battery backup

Grid tied with battery backupHaving a grid tie system with battery backup offers you the best of both worlds.

When the grid is up you have access to electricity from your power company and you can also sell back any excess electricity you produce for a credit with your utility.  This allows you to lock in the energy rate you pay for the portion of your bill which can be produced by your renewable energy source, protecting  you from future price increases.

When the grid fails you will be able to ride out the power outage by relying on the stored energy in a battery bank and the energy coming in from your renewable resource.  These types of systems offer the security that comes from producing your own power, they level out your energy costs, and they give you power during grid outages – which can be extensive in our bioregion.

These systems are much more complicated than a grid tie system without battery backup and should be designed and installed by seasoned industry professionals.  The system consists of several components:

  • A PV array, or array of solar panels, which can be roof, ground or pole mounted in the sunniest area possible.
  • A charge controller works in tandem with the inverter (see below) to charge your battery bank from the solar panels or from the power supplied by your utility company.
  • An inverter changes the direct current from the solar panels into alternating current, the kind of electricity used in your home. The inverter will also send excess energy – not needed to keep your battery full – from your solar panels into your home’s service panel for your own use. What you don’t need will be sent back out onto the grid for a credit on your electricity bill.  If the grid goes down this same inverter will seamlessly switch to the energy stored in your battery bank and the energy power from your solar panels.
  • An energy storage battery bank.  This battery – either a flooded lead acid or sealed AGM type – will deliver backup power to the inverter for your use.  Its size will determine how much electricity will be available to you while the gird is down. Rocky Grove Sun Company will determine the size of battery bank you need based on a detailed inventory of your energy needs while the grid is absent.
  • A backup generator – gas, diesel, propane or natural gas fired  – lets you save money on the storage battery.  This type of generator is used as a last resort when the battery is nearing depletion and the renewable resource is not producing enough power to satisfy the loads.  This type of generation source can be started manually or automatically by the systems electronics.

This type of system is slightly less efficient than a simple grid tie system, usually delivering 5 – 7% less electricity to your loads or the gird on average.  But when the grid goes down and you still have power these efficiency losses will be a price well worth paying.