solar panel positioning control

[David Nelson 3]

Hello fellow guru's. some of you may know that i have a home automation project going. Now i would like to try to put a small 12 volt solar panel on my house to charge a battery bank.what i would like to do is track the sun basically. a few things that i had in mind is - update position every 15 minutes or so -if voltage is lower than last reading search for higher voltage. -if higher voltage cannot be obtained from last reading search for 1 complete cycle and go to highest voltage not sure if i can do this but i would like to try. have SLC 5/04 and 7 slot rack a few analog i/o cards to play with. any suggestions or logic ideas? thanks guys, David

[BobLfoot 301]

Sounds Like a great application for a couple of sequencers. One Master Sequencer to control position stepping. A slave Sequencer to control the search routine. You'll probably need a stepper motor, or servo encoder or vfd encoder arrangement. Would help if you knew the resolution of rotation change needed.

[David Nelson 3]

well what i have is a 24vdc gear motor that turns like 8 rpm. so it doesnt turn so fast that real time adjustments couldnt be made. i think i could use this and just start stop as needed. not sure if i can afford to go with an encoder or not ( will have to see what i can get one for on ebay)may just set it up to run for 1 second intervals to act as a stepper and put micro switches every so far to give a rough position. i like the thought of maybe going with a sequencer if i can figure out how to do it

[BobLfoot 301]

Some random Thoughts. 1. Unless you are using slip rings you'll need to have forward and reverse control of your gear motor. 2. More than Likely you'll only need 180 degrees of rotation in your panel. The sun usually moves from east to west thru south. 3. I like the microswitch idea. Try placing five switches at E, SE, S, SW & W or if East = 0 switches are at 0, 45, 90, 135 & 180. 4. Since you gear motor is 8 rpm I'd suggest a 16:1 reduction ration between motor and panel. This means that you'll cover the 180 degrees in one minute or three segrees per second. Switches would be located at 0, 15, 30, 45 and 60 seconds. If that makes sense I can send you some kernel code for the sequencers.

[Snerkel 0]

If you can get say 5 LDR (Light Dependant Resistors) and position these at suitable locations along your arc along with microswitches. Monitor the resistance using your analogue inputs. Move the solar panel to the location of the lowest resistance LDR. You may need to place the LDR in short tubes to make sure the best one is chosen according to the suns angle. ps Like the idea but won't the PLC use more energy than your solar panel creates if it is only a small one. The LDR version could be built using a PIC microchip and a small amount of electronics.. it would be much more efficent (but not as much fun) Edited 6 May 2006 by Snerkel

[Chavak 2]

Check this old thread from plc.net, some info maybe helpful http://www.plctalk.net/qanda/showthread.ph...ht=tracking+sun Good Luck

[TimWilborne 108]

Don't know the size and weigh of your solar panel but you may want to do some calculation and determine if the additional KWHs from optimum position is greater than the energy the motor will use to keep it in optimum position. From what I have read larger panels gain from adjusting for the sun but smaller panels can be too wasteful for the adjustment

[David Nelson 3]

sure boblfoot send code and i will see what ican make of it. i am doing reasearch and playing with what i have now to see if what TWCONTROLS is saying is an issue. before i buy a panel first i want to see if i can control a panel. if i can then i will see how big of a panel i can control and how much energy per day it will take to run versus output powerof panel versus no control at all TW and SNERKEL what you guys are telling me is on my front burner as of now. at the same time i am getting all these wonderful ideas from all of you to throw in a bag shake it up and see what we all can come up with....hopefully the most efficent and advanced solar panel control ever

[BobLfoot 301]

Here's the kernel - Placeholders for Data File Addresses are in Bold itialic It also assumes a Pushbutton to step thru - this can be changed to sensros, timers or etc. Rung 1 - Sequencer Initialize and Reset SOR BST XIC First_Scan NXB XIC End_Sequence_Bit NXB XIC Sequencer_Reset_Pushbutton BND MOV 1 Sequence_Integer EOR Rung 2 - Pushbutton Deboune Rung using One Shot SOR XIC Pushbutton_Input ONS One_Shot_Bit OTE PushButton_One_Shot EOR Rung 3 - Sequencer Advancement Control Rung SOR BST XIC Sequence_Integer.Bit_0 XIC PushButton_One_Shot NXB XIC Sequence_Integer.Bit_1 XIC PushButton_One_Shot NXB XIC Sequence_Integer.Bit_2 XIC PushButton_One_Shot NXB XIC Sequence_Integer.Bit_3 XIC PushButton_One_Shot BND MUL Sequence_Integer 2 Sequence_Integer EOR Rung 4 - Step 1 Execution Logic SOR XIC Sequence_Integer.Bit_1 Your Logic is written here EOR Rung 5 - Step 2 Execution Logic SOR XIC Sequence_Integer.Bit_2 Your Logic is written here EOR Rung 6 - Step 3 Execution Logic SOR XIC Sequence_Integer.Bit_3 Your Logic is written here EOR End of program.

[TimWilborne 108]

Just as an alternative, why not set the panel at it's optimum position and use reflectors to route additional sunlight to the panel during the non optimum times. Also look at the specs on the solar panels, how direct does the sunlight have to be to get the maximum output out of the solar panel? Also as far as the 180 degrees, don't forget about the winter and summer.

[TimWilborne 108]

Also hot water heaters in the attic are another great energy savings. Just put catch pans under them and you won't have to worry about them leaking. I have heard of people even using uninsulated tanks and sunroofs in their attic to heat water. There is a good website about this I will try to find the link Depending on how cool you really need your house and if you have a well you can use it in place of an AC. I have an additional small pump in mine that circulates water through a heat exchange and dumps it back in the well that does pretty good. I have a very shallow well, 6' from the ground to the water during good times, so it doesn't take much to pump the water. I don't know how this would work with a deep well. It may require too much energy. Caves were apparently used to cool houses sometimes before AC. I have been trying to figure out how to cap one off that is underneath my house. I can find all types of neat things about caves but no one seem to be able to tell me how to cap the thing off. For those of you who are not familiar with caves everytime the barometric pressure changes about ground the cave will let air in or out to equalize the pressure (breath). This makes a howling noise very similar to a haunted house everytime the weather changes Two of my property lines are creeks, I've been trying to figure out to put some mini water wheels in them without an act of congress and see what they would do. Not trying to highjack the thread but it is along the same lines, anyone have any thoughts?

[BobLfoot 301]

If this a hijacking then I am a co-conspirator. I''ve always dabbled in reading and trying some of the ideas found in and on Mother Earth News. They had this one story on a cave house with a winter heating bill of $1.29 for the entire winter in 1978. Edited 7 May 2006 by BobLfoot

[David Nelson 3]

no one is hijacking anything!!!! this is all great info right down my alley. as for the air conditioning project you speak of TW one thing i did was put my a/c on my plc and put a small fan in the fresh air intake for the old gas furnace i have taken out. the plc compares the inside versus out side temperature. at night time when it cools off, the house may still be a little warm so instead of the compressor coming in the small fan blows cooler outside air straight into the air handler and saves a few dollars month on light bill. one other thing i am playing with was to put a thermocouple and a flow switch inline with my water heater to control when the hot water is heated and how hot it gets. but any how i think i am going to look futher into all the ideas i have seen here and see what i can do. i may just change the topic to "neat stuff to do around the house to chop the electric bill down" Edited 7 May 2006 by David Nelson

[BobLfoot 301]

If you water heater is in the basement or cellar of a multi story building the following idea will save a bundle on heating water. When the hot line extis the heater run it vertically up for 18 to 24 inches. Then put in a pair of 90 elbows for 180 turn and run then line down for 12 to 18 inches. Next put in another 180 turn and run the line up 12 to 18 inches before connecting it back into the house. As the "hot" lines of the house cool and the cooler water sinks it will enter the loop trap, but not the water Heater. You'll have a cool slug when you turn on your hot, but not have to keep reheating the water that cooled in your house.

[OkiePC 14]

Shouldn't it be possible to plot the ideal course of travel for the panel based on time of day? I would think that using light sensors to do it could only be less efficient. I always thought of a ratcheting mechanical device that you could pop a solenoid every five minutes to let it move to the next optimum angle, then at night, run a motor for a few seconds to reel it back in. Hot Water? I personally used a black garden hose (100') to preheat my water (connected between the supply and the inlet on the tank) to save money in the summer when I was in my early twenties. I looped it back and forth on the roof aver my garage and the sun did a pretty good job, saving at least 10 bucks a month I guessed. I got the idea from a magazine article where they built a wood, plexiglass, and tin can water preheater that was intended to be roof mounted year round. My gas tank water heater cracked last month so I put in a BOSCH Aquastar (chosen due to emergency availability) tankless gas heater. Now I can take an infinite hot shower and save fuel/money. I am very happy with it, but I had to spend almost $600 all together! It's pretty cool to hear the big burners light up the instant I open a hot water valve, and shut down as soon as I close it. I am not sure how the flow sensor works with no electricity involved. The electric versions are even more efficient and cost half as much, but my little house has it's electrical system maxed out now, and the upgrade to go that route would have left me even more broke and out of hot water for a few days.

[TimWilborne 108]

Yes I looked a one of those, but at 150 amps I would have had to turn the light off to take a shower. Don't forget about the basics either. Install fluorescent bulbs. Not only do they use a fraction of the electricity but they last much longer and they do not attract bugs like an incandescent light bulb. Dry clothes in the evening during the summer or hang them. Keep blinds closed in the summer and open in the winter. This does more for my house than anything since the sides of my house that face the sun the most are over 75% windows Don't run an empty frig. It is not as efficient as a full frig. And by full I don't mean so you have to use a pry bar to get something out. Put jars of water in it if you don't have enough to fill it up Hot water heater timers Just turn the lights off when you leave the room. You would be amazed what this will save you. I don't care if you are getting ready to go right back into that room. You aren't going to where the light switch out that much quicker and with the fluorescent bulbs of can turn them on and off much more without them burning out. If it is 78 degrees outside you don't need that AC. Many more, I need to find that website. It had some very good tips

[BobLfoot 301]

Also Don't forget that if you catch your electrical supplier during the right time of year you can get free energy audits and grants and incentives to insulate and make other energy saving improvements.

[TimWilborne 108]

What are the energy audits? I have never had them. Are the nationwide? Edited 8 May 2006 by TWControls

[BobLfoot 301]

I had one done by NYSEG when I lived in upstate Ny and then again by my electric coop when I moved to Southern Indiana. The DOE website lists ways to get a free energy audit. And in some states they subsidize and encourage such audits. Especially if you coop or electrical supplier is near the limit of their production capability.

[TimWilborne 108]

Thanks, I'll have to look into that

[David Nelson 3]

TW did you ever find this web site that you were speaking of?

[BobLfoot 301]

David - I know that you are looking for TW's Link but this Link for Home Energy Audits may be useful as well.

[TimWilborne 108]

I can't lie to you. It's only Tuesday and I'm having trouble keeping my head above water. Very busy week. I will try to look this weekend, sorry

[David Nelson 3]

[TimWilborne 108]

No coffee needed. Just need a replacement brain. Mines about fried. Too much going on