Solar Grid-Tie System Application

A Grid-Tie system allows you to plug into the sun and the utility company. It is composed of solar panels and an inverter (converts the solar energy into usable home energy). Optional battery backup systems are also available if needed with most Grid-Tie systems should utility service become unavailable.

Energy produced and not used by your home is transfered (saved) into the utility grid as a credit and can be used later when needed. So, when everyone is at work and/or school the Grid-Tie system is banking your energy.

Grid-Tie System
Monthly Average kWh (get this from your monthly utility bill).
Daily Sun Hours (Click this link to get the information: NREL Sun Hours ). On the International PVWATTS Viewer:
 1. Enter your Zip Code or drill-down on the map.
 2. In the results scroll down to 40km Monthly Grid Cell
 3  Enter the value to the right of ANNUAL (kWhs / m2 /yr):
Calculate Grid-Tie System
Daily Average kWh usage (Monthly / 30 Days)
Grid-Tie System needed in kWh (Daily Average kWh / Daily Sun Hours)
 1. Search the internet for available Grid-Tie, Grid-Interconnected, Grid-Connected Systems
 2. Visit the sites under Resource Links for more information
Battery Backup System (option)
Battery Backup Hours: Hours of backup needed during a utility outage. This varies from an hour or more to a day or two. Be careful, this can get expensive.
Battery Backup Watts: Total Watts of must-have energy during utility outage (the electrical loads you need to operate during the blackout). Be careful, this can get expensive as well.
Calculate Battery Backup System after performing Calculate Grid-Tie System
Maximum Solar Array Size (kWhs) needed (adjusted up for inverter loss (10%)(unadjusted for derate))
Battery Backup System (kWhs) needed (adjusted battery depth discharge (DOD) 20% limit)

NOTE: To convert kWhs to Watts, multiply kWhs times 1,000. Example: 2.5 kWhs = 2,500 Watts.

NOTE: The above are approximations. Contact a qualified representative for exact details.