Monday, October 20, 2008

An Overview of Solar Power

Solar Power
and why it's not the answer for everyone.

First, a word about solar panels:
Harnessing energy from the sun the way that plants do is great and there is definitely a lot of potential in the idea. However, photovoltaic "solar panels" aren't all they are cracked up to be. I don't believe that photovoltaics are the best answer for society's energy needs. I think that there are more useful and efficient ways to use the sun's power than PV but I won't go into that right now. Today I'm talking about PV. Today's photovoltaics are expensive and inefficient. Perhaps in the future the PV technology will be better, but available PV systems today have a few major downfalls that prevent them from being a commercial energy source. Those downfalls are efficiency and power storage. Photovoltaics can only create power when the sun shines and if that power isn't being used, its wasted. So that means batteries must be used to store the power until it is needed. But battery technology hasn't advanced much in the several hundred years since it has been in use in western society. Lead-acid batteries are still the norm and they are extremely temperamental and contain toxic materials. Grid-tie PV systems avoid batteries but at the expense of being attached to a pre-existing power "grid" or a utility which then must manage the power. So in short, the biggest problem is not about getting the power but managing it. Some form of storage has to be used in order for large-scale solar to be viable. The power has to get used, wasted, or stored in a battery.
How it works:
The Panels:
The sun emits light which is converted into electric current by the PV panels. There are several brands of solar panels and for the most part, all the big names put out the same kind of product with a few exceptions. Panel prices vary and fluctuate often, so be patient and wait for a good deal. I got two 120 watt panels for $475 each when they usually start at around $700. The current produced by PV's is not constant. PV's put out the most power during the peak hours of the day and less during the early and late hours. That power, before going into a battery, must be fed into a charge controller which regulates the current and the voltage in order to keep the battery at an optimum charge without over or under charging it. Without regulation, the battery will be undercharged and/or overcharged which will shorten its life and in some cases cause it to explode or emit large amounts of explosive hydrogen gas. So it MUST be regulated.
The charge controller:
There are a lot of very cheap "regulators" out there but they are all crap and some only regulate either voltage OR current, when you really need to regulate both. There are even some cheap "regulators" that don't regulate at all but instead only limit the power going in while wasting the rest! If you skimp on the regulator you are going to lose at least 20% of your solar capacity right there. That means if you have 100 watts going into a crappy regulator, you're going to see 80 watts output at best. So invest in either a PWM (pulse width modulated) or better yet, a MPPT (maximum power point tracker) charge controller and stick with the known brands (don't by junk from china). The good charge controllers start at $150 and go up from there.
Batteries:
From the charge controller the regulated power is fed into your deep-cycle batteries. Most batteries must also be maintained regularly. There are super expensive AGM batteries that don't require maintenance BUT they have less capacity and a shorter life span. So stick with the maintainable flooded cell lead-acid batteries unless you are such a slacker that you would rather pay three times as much for a battery that won't last as long. Rechargeable "deep-cycle" batteries can only be cycled a number of times before they can no longer hold a charge and they are very temperamental about the kind of charging they get. All the more reason to invest in a good charge controller! A well maintained and properly charged battery can last for more than 5 years but an abused or neglected battery can self destruct in a matter of minutes. Also, deep-cycle batteries are not meant to be discharged below 50% of their capacity. For instance, if you have a 100 amp-hour battery, think of it more like a 50 amp-hour battery in terms of use. So not only do you have to monitor the power going into the battery, you also have to keep track of the power you are taking out of the battery. A lot to keep up with huh?
The yield:
After all that planning, money, work, and math what do you get? Not a whole lot compared to being hooked up to the evil corporate "grid" unfortunately. For their size solar panels put out very little usable power. PV panels are rated at their maximum output, which means that they will only put out their rated number for a couple of hours while the sun is highest, then the power will taper off into oblivion as the sun sets. But wait there's more! PV systems produce direct current (DC) SO if you plan on using you 110 volt AC (alternating current) appliances, you're going to have to convert the power once again. If you know anything about real-world physics you know that in every conversion there is a loss of efficiency. That means that even more of our expensive power is going down the drain! Because there is not as much power and you can't completely drain your batteries- using solar requires you to scale back your energy consumption. The upside is that most panels have a warrantied output for at least 20 years. So you have a very high initial investment that pays off very slowly but really barely justifies all that trouble. Solar doesn't create any emissions, except for manufacturing and lets not forget about the toxic batteries. The one advantage that makes solar great is that it can be hooked up anywhere and it will provide silent power without needing to be plugged in to any grid and that is why I'm using solar panels on my van-house-mobile.
Conclusion:
Solar is not free or easy. Which is the real reason why it won't work in America. Let me be clear that I don't hate America, it is a beautiful country. It is such a shame that it belongs to so many lazy, over-entitled, complacent, and greedy Americans. Solar works for me though, it is perfect for being mobile. I'm sure photovoltaics will become more viable on a larger scale as the technology progresses but the technology just isn't there yet. If you don't need to be mobile and are looking for power alternatives, look at wind power. Wind turbines put out much more power than PV and cost less.
That's all for now, more pictures coming soon!

3 comments:

Saracasey said...

this should be your essay for asu.
good entry!



oohhhh how you woo me when you talk amp-hours.

The Traveler said...

I love the above shot of your new solar panels.. Very nice!!

diane said...

Thanks for the solar panel 101 lesson, you are very good at explaining what you do. Loved it.