Saturday, May 31, 2008
In addition to individual efforts, it’s good to see corporate projects. We’re closer to having practical electric vehicles than we were on this date last year. The GM Volt seems to be progressing on schedule, and the Norwegian Th!nk City car should arrive in the United States sometime next year. Both will have Lithium Ion batteries, and that technology seems to be progressing nicely. Because of the rapid progress, I’m no longer sure if my first electric car will be a plug-in-hybrid-electric, or an electric-only vehicle. As long as I have enough range to meet my daily driving requirements, an electric-only car will meet my needs. I’ll continue to enlarge my PV system so that at least a portion of my driving will be via free energy from the sun.
Another winter has passed, and my corn-burning stove once again supplemented my home heating system. I’m happy to have replaced fossil-fuel heating with corn, but I didn’t really save money this year due to the high cost of corn. I hope someday to own enough land to not only grow my own food, but also to grow corn to be used for home heating. I’ve been told that I can meet all of my home heating needs with just one acre of corn. I know that this will be an ambitious project, so I may hold off until I’m ready to retire from my day job.
In addition to my solar electric and bio-fuel projects, I’m now experimenting with solar water heating. Besides cutting my use of fossil fuels, this project has the potential for cutting my natural gas bill. Check back later for a progress report.
As we go forward we follow different paths, but diverse strategies are good. There will be no single solution to the problems we’ll face as oil declines. Short-term solutions, like hoarding gasoline, will be of little value. Let’s continue to share information as we face the challenges of the future, including our successes and failures, for the benefit of all. As we make the transition to alternative sources of energy, let's enjoy the journey. I appreciate blog comments, and hope to see more of them as I enter the third year of this blog.
Friday, May 16, 2008
I started with a plan to pump water from the pool, circulate it through tubing where it would be heated by the sun, and return the heated water back into the pool. I planned to mount PVC tubing to the side of a storage shed, and to paint the tubing black to increase its ability to absorb the sun’s heat. As the experiment progressed, family members hinted that the backyard was beginning to look like a wastewater treatment plant. I had to admit that they were right, and I decided to change my approach. Since the storage shed has an insulated ceiling, I decided to take advantage of the heat that builds up in the attic. Instead of mounting the tubing on the side of the shed, I’ve mounted it to the inside of the roof. I currently have 120 feet of 1” PVC pipe installed, and I’ll add as much as 200 feet more if necessary. The cost for the tubing is $2.42 per 10 foot section. I’ve purchased a small pump, and it seems to be able to circulate the water. I won’t know how well the system works until I can test it on a hot day. I’m currently using a 55 gallon plastic drum as a substitute for the pool.
Mounting the tubing in the attic means that it will be out of sight and out of mind during the winter. I won’t have to clean around and under the pipe array. I’ll just have to make sure that the pipes are drained, and gravity will help with that. In addition to its use as a pool water heater, I also have the option of using it as a solar-heated shower. I can make that conversion by connecting a garden hose to the pipe array, instead of pumping water from the pool. Regulating the amount of flow should also regulate the water temperature. The entire project will cost less than $300.00, and it should last for years. I’ll post additional details later, but here are some pictures of the project as it stands today.
Many thanks to Solar Gary for ideas and advice on solar water heating strategies. Anyone considering a related project should check out his website for ideas: http://www.builditsolar.com/
Thursday, May 08, 2008
With each grid power failure I learn new things, and Wednesday’s power failure was no exception. This power failure occurred early in the afternoon while I was at work. It was a gloomy day, and batteries were not fully charged at the time of the failure, making it necessary to switch the system on manually. This would have been easy for me to do, had I been home at the time, but not so easy for a family member. The simple system I once had is now an automated system with several components and switches. Explaining over the phone how to switch the system on is not as simple as it was in the past. It went something like this:
Me: Flip the Inverter toggle switch on.
Family Member: Which one is the inverter?
Me: The black box that says Exeltech on it.
Family Member: Where is the on/off switch?
Me: It is under the Kill-A-Watt meter.
Family Member: Which one is the Kill-A-Watt meter?
Me: It’s the grey thing that’s plugged in to the inverter.
Family Member: I don’t see a switch under the Kill-A-Watt meter.
Me: The switch isn’t on the Kill-A-Watt meter, it’s on the front of the Inverter.
Family Member: OK. I’ve switched it on and I see a green light.
Me: That’s what you should see. The system is now on.
From this experience I’ve learned that I need to better educate family members so they’ll be prepared for the next grid power failure. To help with this, I’ve created a visual aid. The name of each device is listed next to its picture, along with a brief description. Basic operating instructions are also provided. The challenge is to provide enough information, but not too much. Too much information could be confusing.
First of all, family members need to understand the system configuration. There are two common system configurations:
Configuration #1: In the event of a grid-power failure, the inverter switches on, and the loads are automatically switched from grid power to battery power.
Configuration #2: Loads are powered by battery power until battery voltage drops to a preset level. Loads are then automatically switched to grid power.
My system is wired for Configuration #2. The system doesn’t automatically switch on when a power failure occurs; it switches on when batteries are fully charged. The refrigerator, freezer, and anything else plugged into the system’s AC outlet will automatically switch to grid power when the inverter switches off, but a grid power failure does not automatically switch the loads to battery power.
Because it is sometimes necessary to switch the system on manually, it must also be switched off manually, and users also need to know when to do that. Users need to monitor battery voltage, and must avoid letting battery voltage drop too far. This can be a little tricky too, since battery voltage is influenced by the size of the load. And so, without supplying too much information, I need to set a low-battery-voltage limit for them to follow.
To complicate things just a little, I’ve also provided information about the back-up battery bank, and how to switch it into the circuit. As with the main battery bank, battery voltage must be monitored and voltage must not be allowed to fall below a predetermined low-voltage limit.
Wednesday’s grid power failure was brief, about 2 hours, but it was a valuable learning experience. With the visual aid I’ve created, and a little instruction, we’re better prepared for the next power failure. We’ve been having a lot of storms lately, so we may not have to wait long to find out.
Saturday, May 03, 2008
Since my solar panels have the ability to fully charge the existing battery bank by noon on a sunny day, it’s obvious that I have the capacity to charge a larger battery bank. It seems that a battery bank upgrade will allow me to get more from the system on a daily basis while at the same time increasing the amount of stored energy. For that reason, I’ve just replaced my old battery bank, increasing the amp-hour capacity from 420 to 675.
I’ve known that I could greatly improve system performance with a bigger battery bank for some time, but I’ve been holding off because my old batteries are still in good shape. Since batteries of different sizes, types, and ages shouldn’t be included in the same battery bank, I was confronted with the problem of what to do with the old batteries. I decided to isolate the two battery banks from each other, and to use a switch to connect or disconnect the old battery bank as needed. The diagram below shows how I did that:
The new ones are 6-volt batteries, most commonly used in golf carts. I series wired three pairs of these to create the equivalent of three 12-volt batteries at 225ah each, and paralleled the three pairs for 675ah at 12-volts. I’ve installed a heavy-duty switch, allowing me to switch in bank 1, bank 2, or both banks at the same time. I’ll switch in the new battery bank for day-to-day operation, only switching to the old bank once in awhile to keep it fully charged. In the event of a power failure, when I’ll need the extra capacity, I’ll switch in both battery banks. With both battery banks connected, I’ll have one large battery bank with an awesome 1095 amp-hour capacity.
Understanding that batteries should not be allowed to fall to more than 50% of their capacity, I now have a useable capacity of 547 amp-hours, a significant upgrade from the previous 210 amp-hour useable capacity I previously had. After monitoring the new battery bank for a few days I observed that:
· It does indeed take more time to fully charge the bank.
· Loads are powered for a longer period of time each evening, after the sun goes down.
In the event of an extended power failure I’ll have light, refrigeration, communications, the ability to prepare food. I’ll be able to use my bio-fueled stove for heat, and fans to circulate fresh air. I’ll be able to watch TV or listen to the radio. I’ve had these capabilities previously, but not to the extent that I have them now. This will serve me well in the event of an extended power failure. I’ll need to continue upgrading the system if I expect to use it to charge the electric vehicle I hope to purchase within the next two years, but I’m getting there. I’ll be doing some capacity tests soon, and I’ll record the results on this blog. Check back later.
For information concerning my recent system automation upgrade, check my February 25th post: http://solarjohn.blogspot.com/2008/02/ive-automated-my-off-grid-pv-system.html