Home solar companies often tout the dream of being energy independent, where you produce what you need and don't consume any energy from the grid. This sounds great in theory and is actually very easy to accomplish. The problem is that these companies are not really addressing it in the best way, merely the way that will make them the most money.
Solar companies will cover your huge roof with solar panels, creating massive systems that will measure in the kilowatts! These systems will hopefully be able to match a percentage of your energy consumption by feeding into the grid during the day when no one is home and then drawing back from the grid by night when the solar panels are not operable.
The dream is that this plus during the day and minus during the night will cancel out and make your draw from the grid 0. The problem is that these solar panes are massive and yet still struggle to meet your energy needs! They feed into the grid by day instead of into a battery bank because the power demands are far to great for any battery bank to contain. While these companies talk about being energy independent, there is still a power line from the grid to your house that you are depending on at night.
To be truly energy independent, you need to cut the cord and address the situation from a different vantage point. The solar companies are trying to sell you a ton of solar panels. These panels are expensive and they want to sell you as many as they can. Instead of telling you the truth about energy, they tell you to buy more because it will make you happy and that you are saving the environment.
The truth to energy independence is not more, but less. Think about it for a moment. If you need a 30 kW array to meet a percentage of your needs, you have a serious problem! This means that for every hour of peak sun, your array is producing 30kW. There are roughly 4 hours per day when your array will be at its peak, so your 30kW system will produce 120kW during that time alone. Somehow this is not enough power to meet all your needs because, just like with the solar panels, your house is filled with many more things that are supposed to make you happy as well.
Instead of having more, things that require more panels to maintain, the easier and cheaper option is to have less. If you have less appliances, then you will also need less power and less panels. If you get down far enough, you will even be able to run everything off of batteries and be actually energy independent.
On the boat, we have a 300W array, or 0.3kW when compared to house standards that feeds into a 6.3kW battery bank (525ah @ 12vDC). This array feeds the batteries which charge up during the day and run the entire boat by night. By 10am, which is when the peak power production begins, the batteries are full charge again. This means that the power consumed all night by the boat is completely replenished by 10am. In reality, we could get by with a smaller solar array that would then finish charging by around 3pm. On cloudy days, the extra solar space means that we are still able to charge up and keep on top of our consumption, even though the sun is not being captured as efficiently.
How do we live on such little power? Simple, we have few things that consume that much power. Our biggest power draw is the refrigerator. This beast draws between 2 to 4 amps per hour, or 24W to 48W per hour. During the day, the panels are able to supply it with all the power it needs, but at night, this power hog falls onto the batteries for fuel. Having a large battery bank will allow us to continue to power this creature on a series of cloudy days, when the solar array is not as capable of topping off the charge while the refrigerator continues to draw.
Aside from the fridge, our only other sources of power drain are the lights, water pumps, and navigational equipment. These can also consume their fair share of power, but they only do so for a short period of time. If they are not being used, they do not drain the batteries. The fridge on the other hand runs non stop, every day, and draws on the batteries for its entire life.
In the end, a simpler life means less associated costs as well. We only needed to purchase one refrigerator. We also only needed to purchase 300W of solar power. If we had a washing machine, dish washer, home theater system, and every other consumer of electricity imaginable, then we would also need to shell out all the added money for a huge solar array.
Energy independence isn't about buying more things, it is about needing less.
