My New Solar Electric System

[Tom in NH]

I had 12 homemade panels get damaged beyond repair after a horrific wind storm about a month ago. I used the ebay cells that were selling awhile back. These were super thin "Evergreen" type cells, and they couldn't withstand the shaking they got with gusts of up to 80mph all day.

I had a sick feeling all that day as I watched my panels die a horrible death. Then I thought about all the poor people in Hurricane Katrina and how their insurance companies refused to pay because their damage was not wind damage. That planted a seed in my mind to try and submit a claim on my homeowner's insurance for my wind damage. I didn't think I would get anything, but I was wrong. My insurance company was extremely helpful, and they paid the complete replacement costs minus my deductible. Thank goodness for homeowner's insurance.

Today my new system generated its first significant power, and I had to take a couple of pictures to show off my new babies. The first shot shows the 6 new Matrix Photowatt 165 watt panels mounted on the frame. In the foreground are the old panels, or what's left of them, showing how the cells shattered.

 

Here is a closer image of the Photowatts. They are configured as 24v panels. They are paired together in series and two separate lines of about 80v open circuit carry the electricity of four panels and of the remaining two panels into my cellar where

all of the control circuitry and the battery bank are located.

Items in the picture above are 1. Iota Charger, controlled by my Grid Charger Voltage Switch with an analog ammeter; 2. BZ MPPT500 Controller (the sustem will ultimately utilize two of these controllers);3. Solar panel fuses and disconnect; 4. Controller output fuse; 5. Battery output fuse; 6. Battery array (eight Walmart special 125 amp-hour deep cycle batteries; 7. Battery DC output disconnect switch; 8. Xantrex 3500 watt modified sine inverter; 9. 120vac out (goes to a distribution panel located elsewhere)

I have been running a separate string of outlets in my house so in places I have two outlets side by side. One is grid power; the other is solar power. At present this system powers the electronic ignition and blowers on my two propane heaters, the propane tankless water heater, the ignition and oven glow tube on my propane range, the refrigerator, a couple lights in my living room, and an outlet on my porch.

This is a very hefty load for the panels. They are able to keep up when the sun is shining, but need help when we get extended periods of cloudy weather (which we do for weeks on end in spring and fall). That's where the Iota charger comes in handy. My grid power voltage switch turns the Iota charger on when battery voltage falls to 12.1 volts, and it runs for 1, 2, or 3 hours depending on a jumper setting on the board. The Iota is capable of delivering the current necessary for powering all of my load so I don't have to worry about under charged batteries or disconnecting loads when the sun doesn't shine. The upshot is, when the sun shines I run my load for free. When it doesn't I pay the utility company for the power. It's a little like a grid tie system in reverse. One benefit over a true grid-tie system is when the grid goes down, I still have power for as long as the batteries hold out. So if I should lose my power, I will have heat and hot water, kitchen facilities, and a light in my livingroom to read by. What more could I want?

[mitcamp]

Thats a great set of panels you have up now. Sorry to hear of the damage you got from that storm. I got a burned stator in my 18 footer from the same storm, I am rebuilding at this time and my machine will be a clone of Dan B,s 17 footer with the big magnets.

Looks like you are planning to add some more panels in the near future, from the look at your panel stand. I have to tell you, you have a great set-up in the basement. You should get a few comments on it for sure. Looks great,keep up the good work. Mitcamp

[DanG]

Thanks for the control panel picture!! If'n I were you me thinks I'd modify the panel rack for more protection & stability, just a once-burned twice-shy reaction - and I am curious what exactly elapsed with the insurance claim; were they documented beforehand, etc. I will soon be fabricating the first module of what will be a 200-plus square foot array of the eBay cells & need to know the paces to go through to have some coverage.

Thanks again...

[richhagen]

Wow, I missed the story on your panels destruction.  You had the strings loose, with a plexiglass front.  I guess the wind just buffeted them to bits.  My much small experiment with home made panels didn't last long due to moisture, but I had sealed mine with silicone where as you did not.  Since then I have only added commercially made panels.  I am glad to hear that you were able to get and install replacements.  You have an MPPT charge controller and a 130 foot run.  I don't know what the maximum voltage of your MPPT controller is, but I am guessing it is less than the open circuit voltage of three of the 24 volt panels in series, or otherwise you would have run them two strings that way.  I have plans for a similar but different system.  I am planning an 'or' setup, where the AC can be supplied by either the grid, or the RE system depending on battery voltage or other conditions using heavy duty DPDT relays.  I may make the circuit the computer is on all grid, or all RE, to avoid the switchover problems there.  I am still in the planning stages at this point, all I have is a basic 48V system installed and normal grid wiring for the AC.  Anyway, nothing is set in stone yet other than that it is a 48V system here.  Rich  

[Volvo farmer]

Wow, Those are nice panels. I've been running my whole household with less solar than you have. I suppose that wooden rack has held up well so far but it still scares me to see $5000 worth of panels on a wooden rack.

How long have you had that BZ controller? I had a BZ MPPT200 that recently died. It lasted a little more than a year. The thing is about the size of a roll of masking tape, less than a pound and they wanted me to include $10 return shipping to have it fixed under warranty. I told them what they could do with their controller and bought a Xantrex C35. It seems like you are building this thing on a budget but those panels would work very well with an Outback MX60.

[ghurd]

Looks great!

G-

[pepa]

hi tom, looks good. just wanted to say that the grid charger voltage switch that you built for me works great. at present i am using it to maintain a extra battery bank and i have not had to wory about these batteries sinse i hooked it up. thanks again, pepa.

[Tom in NH]

The frame is solid. It has about 800 pounds of cement in the foundation. The 2-bys are pressure treated and tied together with truss plates. The whole frame is tied down with steel cables and earth anchors. What hurt the old panels was they were hinged on the top side so I could adjust them to match the sun angle. I relied on gravity to hold the bottoms down. Big mistake. During the storm they were stretched out horizontal and then the gust would stop and CRASH. That kept up all day long.

I called the insurance company. They sent out an adjuster. She didn't know anything about solar panels which I kind of anticipated. I did some homework on the web and priced out a few setups. She chose the middle one and told me I forgot to add the shipping costs and if I would obtain a shipping estimate from the vendor she would mail me a check for the total minus the deductable. Ironically, the most expensive price I got was for building the panels myself. --tom

[Tom in NH]

Hi VF,

I've had my BZ 500 watt controller for just over a year now. I've pushed it hard. 600 watts input when its rated at 500 watts. It runs so nice I decided to buy a second one since the new panels put out more wattage than my old panels. I used to run a C40, but switched in order to be able to run a higher voltage across my 130 foot run. --tom

[Tom in NH]

Glad to hear that Pepa. After you got it, I never heard back and I was afraid you couldn't get it to work. I think it's a great little device and adds a lot of functionality to a solar electric system that is made to run in less than ideal situations. --tom

[Tom in NH]

You're right, Rich. The BZ can take 100 volts. I was getting 80 volts open circuit from two of the panels so I didn't figure I'd push it any more than that. Besides, I'm saving my pennies for two more of these panels and they will nicely fill out the second controller. Then I'll have four panels on each one.

If you need assistance with your relay circuits I could change the program in my PIC microcontroller on the grid charger voltage switch do do what you want. The logic outputs can control solid state relays. --tom

[Tom in NH]

Thanks for the kind words, mitcamp. That was one heck of a blow. I had my VAWT freewheeling in it. You should have seen it spin! But it is built like the proverbial sherman tank and it survived just fine. --tom

[richhagen]

Tom, I will keep that in mind with the Pic controller.  I am still in the planning stages.  I have the 48V in place, and have just picked up a used Xantrex sw4048 inverter.  It has 4 or 5 spdt relays that appear to be programmable, but I will have to read up on their parameters.  Initially I am thinking I can duplicate the function of the Pic controller with the trace to throw these relays.  I had orignally thought to use dpdt relays, but I might not want to disconnect the nuetral (which in the U.S. is ultimately tied to ground) even for the short switchover time.  I am sure there is a reason that this inverter has the single pull double throw relays.  I might think about setting it up like yours where everything is powered off of the batteries and inverter, but the battery bank would then be charged from the line with the grid charger if the batteries get too low.  This only makes sense if I can draw most of my power from the batteries with them being charged through my panels, and only need to use the grid power occasionally, and this is not nearly the case at this point.  Otherwise I think the inefficiencies of charging batteries and inverting that power would far exceed the value of not having the switching of the power in the circuits.  I need more power, and bigger batteries for that to be practical.  I will probably therefore stick to a scheme of having the system use RE power when it is available, and then switch relays back to grid power when it is not.  I still have a bunch of research to do.  Rich