Solar Primer continued...

Why do I need an inverter?

When you require AC power (either 120V or 220V), a power inverter is your solution. An inverter will convert your 12 or 24V DC system to AC so that you can run your AC appliances. Some sensitive AC appliances do not operate well, or at all, on standard modified sine-wave inverters, so Soltek provides sine wave inverters to solve this problem.

Two basic types of inverter output:

1. Modified Square/Modified Sine Wave: Creates alternating current (AC) in 4 steps per cycle. Will run 90% of appliances, exceptions include some laser printers and cordless battery chargers (which brands have problems is a matter of trial and error). Some equipment will hum or experience interference from this inverter power.
   
   
2. Sine Wave: Creates AC in upwards of 50 steps to closely approximate utility power. Will run any load with little or no hum or interference. Cost of these units is much greater.

Inverters are sized according to the loads that are likely to run at any given time +20%. An inverter's input voltage is matched to the battery bank used in the system. Inverters greater than approximately 800 watts in size do not have fusing on their DC input side and require an appropriate inline DC rated fuse.

The output of an inverter is connected to the AC breaker panel (main or sub panel) as if it were normal utility. All household wiring beyond the breaker panel can then be done according to standard building codes for AC, with some extensions.

The installation of an inverter should follow the manufacturer's recommendations in their installation guides.

Some special features offered by inverter manufacturers:

• Built-in battery chargers (stand-by models): Allows a generator or utility line (i.e. RV park service) to be connected directly to the inverter as back-up or intermittent system support. The inverter will provide AC from the batteries. When the generator or utility is present the inverter transfers this power to the household appliances (loads) and uses what excess there is to charge the battery bank with its built-in charger. When generator is shut-off or utility is disconnected, the inverter will switch back to inverting from the batteries without disrupting the power going to the appliances. This is usually very quick at approximately 30ms.
  
  
• Stacking interfaces: Allows two inverters to be connected together to provide 120/240 service. Remote/Automatic generator start: Trace Sine Wave series only, or via separate generator start relay.

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