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Re: question

The best bang for you buck to reduce costs... 1. Conservation, 2. Conservation, 3. Probably Solar Hot Water (especially if electric heat now), 4. Solar Grid Tied electric power.

The nice thing about solar hot water--it is relatively inexpensive to install and the panels are relatively small (because of their high efficiency at gathering heat). Bad thing (from my point of view), need hot water tanks for storage (rough rule of thumb is 20 gallons per person per day), plumbing, and maintenance issues (freezes, air locks, pump failures, corrosion).

The nice thing about Grid Tied solar--virtually zero maintenance (you can clean your panels for a 5-10% increase in power--I have pretty much given up on regular cleanings at they are on a second story roof and it is a pain to get a ladder up for cleaning--plus as I get older, I found I have a new fear of heights). Bad thing--costly installation, pain with utility and PUC rules. Panels are large because they are only 12% efficient or so.

The 80 Watt panel is fun to experiment with and learn about solar, charge controllers, and batteries... But in real life, it is probably going to cost you more in money than it can ever save (batteries are large and expensive, should be recycled and changed every 3-10 years).

Start with your largest consumer of power... Electric Hot Water Heater, heating and A/C, electric oven, lighting, "standby loads" (computers, printers, TVs, etc.), down to unplugging cell phone chargers when not needed...

The above is in rough order of importance. I.e., don't drive your wife nuts by bugging her about forgetting to unplug the cell phone charger when you have an electric hot water heater and a full flow shower head in the home.

For the smaller appliances, a kill-a-watt meter is a great tool (120 VAC, 15 amps). For larger appliances, you can do estimates (water heater costs), or what I have done before is get an old utility meter and wire that into the heavy loads and let it run for a week or a month to see how much power is used.

The electric hot water heaters are already pretty energy efficient--and a new one will just have a little bit more insulation and shave another couple percentage points off the energy bill.

Converting to natural gas or propane would be a stop gap change to reduce costs... Or, get a good electric hot water heater either with an internal heat exchanger or a open loop type (if you are in an area that does not get freezing temperatures) and add solar.

Configure it so that you can turn off the lower element in the summer and the solar panels will provide the heat. The upper element is still there to give you hot water even when it has been cloudy or all of the day's solar hot water has been used up.

Solar Guppy recommended SolarRoofs.com as they have well thought out kits for home installation.

Since you have electric hot water--your conversion to solar hot water should be a natural. (for those of us with gas, the issues are a bit more complex to add a second demand heater or something else).

There have been a couple threads in the last few days asking about solar thermal hot water--and we have posted links to a few threads and products to read through... A good place to start.

I think you will be best served by looking at your home as a "system" and address the major issues in a well thought out way... Everyone is different and lives in different locations. If you have A/C, a geothermal heat pump with attached water heating system would be a great way to go--but if you don't have A/C, maybe not. etc...

-Bill

Re: question

Many folks use 120/240 VAC twist lock type connectors from the local hardware store... More reliable than Cig. plugs, and safer too (if you have kids, they can get fingers and metal objects into the Cig. outlet).

Regarding surge protection--actually, you still need fuses, and while it would be nice to have surge protection, on low voltage DC, it is pretty difficult to achieve.

If you live in a lightning prone area, following grounding recommendation for DC solar systems is imperative. Your DC system is just as likely to have surges as your AC system.

For your home theater setup--I would suggest using a smaller pure sine wave inverter to power them. It is easy to isolate AC with a transformer (and a surge protected power strip). Plus, AC appliances are generally protected (and factory tested) for better than 2,000 volts against common mode surge voltages. DC systems just can't do that.

Lastly, DC distribution of power is a pain...

You need relatively large ware gauges because of the high voltage drops at 10x current levels (120 vs 12 volts) and the low voltage range (12 volt circuit drops 2 volts, 10 volts left, most devices won't work--vs 120 volts -2, left with 118 volts--works fine).

And, your Battery Bus voltage has a very large range--it is not 12.0 volts, but in a properly operating system will be between 10.5 volts and 15.5+ volts... Most DC appliances (many intended to plug into a car's cigarette lighter) will either die below much 12 volts or get killed above 15 volts.

The last major pain in 12 vdc is the grounding and ground loop issues. A typical 12 volt appliance ties 12 volt ground to the chassis and audio ground for external cables (as an example). You connect all of these together, and you can have DC power currents flowing through your audio and chassis grounds--In worst case / high power situations, this can fry cables and cause sparks as chassis are moved around.

-Bill