03-26-2014, 04:27 AM
The inverter makes the electrons go back and forth (alternating current, AC) instead of just from negative to positive (direct current, DC). On an off-grid installation the output of the panels would go to a charge controller. The output of the charge controller would go to the batteries. The charge controller babysits the batteries, feeding them just the right amount of DC electricity from the panels so they charge right and don't overcharge. You could in theory hook the panels directly up to the batteries but there are many problems with that and no one with a clue does so.
The inverter takes DC power (usually 12, 24, or 48 volts, although 36 volts is not unheard of) from the batteries and converts it to 120 volts AC. Because both the inverter and the charge controller are hooked up to the same points on the battery bank, depending on battery charge and sunlight, sometimes the power is just flowing straight from the charge controller into the inverter without going into and out of the batteries. This is often a good thing because the batteries are not 100% efficient. You shove the electrons in at 14.5 volts and take the same electrons out at 12.5 volts, close to a 20% loss right there. I run the washing machine in the morning when the sun is on the panels and there is plenty of time left in the day to top the batteries off after having been drawn down. Most charge controllers have lights that show the state of charge ob the batteries and what charge mode the controller is in. When flashing that means that the batteries are topped off and the controller is feeding them only a part of the power that is available from the panels. Save up your laundry and run the washer then to use the PV power that would otherwise be wasted.
The inverter takes DC power (usually 12, 24, or 48 volts, although 36 volts is not unheard of) from the batteries and converts it to 120 volts AC. Because both the inverter and the charge controller are hooked up to the same points on the battery bank, depending on battery charge and sunlight, sometimes the power is just flowing straight from the charge controller into the inverter without going into and out of the batteries. This is often a good thing because the batteries are not 100% efficient. You shove the electrons in at 14.5 volts and take the same electrons out at 12.5 volts, close to a 20% loss right there. I run the washing machine in the morning when the sun is on the panels and there is plenty of time left in the day to top the batteries off after having been drawn down. Most charge controllers have lights that show the state of charge ob the batteries and what charge mode the controller is in. When flashing that means that the batteries are topped off and the controller is feeding them only a part of the power that is available from the panels. Save up your laundry and run the washer then to use the PV power that would otherwise be wasted.