PV Gap

Isaac Said:

Can you help me with this solar application?

We Answered:

Your major power consumer will be the TV which may need anywhere from 200 to 500 watts depending on it's type. The clock might rely on the frequency of it's power source being exact if it is to maintain accurate time. While it requires only a few watts, it may need a much more expensive inveter. The TV Live only needs a few watts. You would probably want an inverter that is capable of delivering 1000 watts. It's entirely possible that it would be more efficient at converting 500 watts than one rated at 500 watts maximum would be.

A 500 watt TV running for 8 hours would consume 4 kWh. A typical car battery rated at 90 minutes reserve capacity will have about 0.4 kWh of energy stored in it. You would need a minimum of 10. Car batteries aren't intended to be run nearly flat on a daily basis and you may get only a few weeks of service life out of them. They will last far longer if you only use about 10% of their capacity. That would indicate 100 batteries.

How you wire them will depend on your inverter. If the input is 12 volts, all your batteries would be paralleled. 100 (or even 10) batteries in parallel can deliver dangerously high fault currents if something goes wrong. One shorted cell within just one battery could create a major meltdown or fire. Fusing each battery separately may be necessary.

Each of your solar panels will produce a little less than 2 watts under peak conditions and probably average about half of that during an average summer day for 10 hours. That means that each panel will contribute about 0.01 kWh towards your daily requirement. Assuming that your charging and inverting systems are 100% efficient (they won't be), you would need about 400 panels.

With 6 kids you might want look into a solar hot water system instead. Such a system would be far more likely to save you some money.

The link below will let you download a free sample issue of Homepower Magazine. You'll find the lead story in that issue to be well worth reading.

Don