Small Solar Energy Systems
I read a posting describing some possible small solar energy systems and how it would do us all well to begin to familiarize ourselves with such small systems. Small solar powered lighting systems, completely self-contained and DC powered. Lets look at some other small DC systems already in use on a daily basis, and you don’t even think about them.
If you have an RV or a Boat, you have seen self-contained DC systems in use; if you drive a car or truck, you have seen small DC energy systems in use. The major difference between an RV, Boat or Automobile vs. a home is the source of the electrical generation to start with: the internal combustion engine. Batteries are still part of the small-scale energy system, but solar does not play a part, instead the vehicle engine runs an alternator that creates a charging current for the vehicle battery. For the most part, this is the norm, but I am familiar with a small solar energy system being used on Tern Island by scientists studying wildlife behavior and habitats, as well as some boats can now be retrofitted to accommodate a fairly robust solar energy system.
Let’s look at the safety aspect of DC voltage vs. AC voltage. Have you ever licked the end of a 9volt battery? Sure you have, admit it. That is about the same amount of voltage that is required to power most DC motors. 12volts to be precise, but remember, “it’s the amps that kill you not the volts”. The current involved is somewhere in the neighborhood of milli-amps, that’s a thousanth of an amp, everything is measured in DC voltage which is much safer and easier to store than AC.; compare that to 15-40amps in most household AC systems, especially if 220v is involved.
My brother has a degree from the University of Washington in History and is also a Reforestation expert in Washington State and uses photovoltaic cells to power small appliances in his Condo in Seattle. (I have posted an image here of my brothers’ simple circuit…..simple, yes, but effective). Sure, it’s not an entire-home solar energy system, but it demonstrates principles and possibly dispels two myths with small solar energy systems that are missing in the equations about the cost-effectiveness of these solar energy systems.
One is that there needs to be sun all year round and all day round. I’ll give you that, I live in the desert Southwest and we have plenty of sunshine, but the Pacific Northwest could never use it, right? Maybe not as an exclusive source of energy, but it could be supplemented by wind power and other renewable resources.
Two is that there is not enough current generated to power an entire home. That is if the user is still utilizing AC-powered appliances, yes, the energy loss in the conversion process is ridiculous. But what if all those same appliances were DC powered? A little different equation now isn’t it? Hang out at your local Snowbird convention in your nearby WalMart parking lot when they are flocking through your area and see what DC power can do for the retiree….complete with satellite TV. No kidding. The reason AC power became popular in the first place was because of it’s ability to lose very little voltage over long distances. What if you only have to transmit the power from fuel cells on your back porch to the front yard landscape lighting.
My friends, what this comes down to is a change in mind-set, a paradigm shift if you will. First of all, we have to stop finding all the reasons why solar energy WILL NOT work, and find ways that it WILL work. (Please, at this point the cost is not the issue. This blog is all about thinking about it first).
Cost has indeed been a legitimate roadblock to the small solar energy system being put into viability anywhere in this country. I would welcome, however, for any of you budding electrical engineers, (or even seasoned veterans) to give us a break-down of how many DC volts would be necessary to power an entire household with TV’s, computers, a/c units, heat pumps and other appliances. Reaching into the future, let’s plan on charging a fully electric vehicle also. I live in the desert so the a/c will have to run all night long also, so battery backup/storage will be a must.
