It seems to have all started with the inverter. The last piece of the puzzle I needed to get my system up and running. Finding a reasonably priced 24VDC inverter that could at least stand up to the demand I am going to put it through was difficult. Then factor in $$$ is an issue. Yeah, when isn't it? Anyhow I finally get an inverter as noted in an earlier post, but it's pretty much DOA. Anyhow I finally get that resolved and now have a Tripp-Lite 2400W 24VDC inverter online and operational.
So I get the batteries online and I have the generator running to top the batteries off and to run my fridge so I can get the temp down and reduce the load on my batteries during the start up of my off-grid array. Makes sense since I have a lot of heat to remove (the refrigerator has been off line for almost a year) from the fridge and that was going to take a lot of power and time.
In total it took 8 hours on the generator to get the fridge temps stable for the most part. But the compressor was still cycling a lot and as noted in the owners manual that was normal for the first 24 hours after start up and or a major change in temperature control. Now here is where things get cool... no pun intended... or maybe there is? I knew from my research that running a fridge off-grid was going to require extra insulation in order to reduce energy demands once the temperature was stable. So part of my off-grid design and plan was to wrap both my refrigerator and deep freeze with an extra layer of insulation. By doing this I could slow the transfer of heat and thereby increase the efficiency of both components.
I calculated about a 35-40% increase in efficiency. I need to go back to school as my math SUCKS! I am getting about a 70% increase. Okay let's quantify this. So under normal operations without the extra insulation my refrigerator consumes about 1.2 to 1.4kWh of power a day. This is verified through a Kill-A-Watt over a 2 week period (back when I was designing the system and learning the power demands of my existing devices). Using the same Kill-A-Watt after the fridge had reached thermal stability total power use over a 24 hour period for the last 5 days has been 360Wh. Yes you read that correctly By adding a double radiant barrier 2in thick insulation to the outside of my fridge I have seen a reduction of 840Wh of power consumption. Good thing too... if you keep reading you will understand why.
Okay, now let us get back to the rest of the system. SO we ran the fridge on batteries for 5 days before the inverter shut off on a low voltage alarm. Yeah, we ran the batteries down to 10%!!! WHAT THE $^&#!!!! How the hell?!?!?!? Oh, it gets real good from here. So let's go to the charge controller I got from Missouri Wind and Sun. It came with two sets of instructions that conflicted with each other and that had not only myself confused, but an electrical engineer (friend I had checking my system out and answering questions) but another fellow that is far more intelligent than I am. After 2 days we finally agreed on a method to connect the charge controller to the panels. So we did it and... nothing was working?
Well no worries, we are charging the batteries off the generator. See we sell water from our property to a fella that trucks it to people in the area that need water but are not connected to the city and or whose wells dried up back during the Loma Prieta earthquake in 1989. So when we pump right now we run a generator to do this, so we will charge batteries and do laundry and so forth. Well this is where I got hammered, the battery charger I bought said it was designed for 12 and 24V systems. So I wired it to charge my 24V battery array. And I didn't bother to verify by taking voltage readings and just assumed because the lights were on that the charger was doing it's job. Well when the batteries died, that's when I started to investigate and found that NO the charger WAS NOT DESIGNED for a 24V system... even though it says so on the box! So while I thought it was charging... it wasn't.
Well the day before everything came crashing down I called Missouri Wind and Sun and explained my dilemma (the panels were still not charging) and they told me how to wire the panels to the charge controller (so word of advise... stick with Trace Xantrex, Outback and Blue Mountain... more on that later.) So after getting off the phone I realize that I have my panels wired to the wrong side of the solenoid on their charge controller. So essentially I had dead headed my panels. Okay no worries I can fix this when I get home. Yeah... I fixed it alright!
Now a little lesson and you better pay real close attention here... it's so important that I will now increase the font size AND put the text in bold red.
Pay close attention here, on MC4 connectors there is a + and a - side. The positive side is the male side and the negative side is the female side. This is true even on the panels themselves!! DO NOT CONNECT YOUR MC4 CABLES TO YOUR COMBINER BOX UNTIL YOU HAVE VERIFIED POLARITY!!! When you connect the MC4 cable positive leg to your panels MC4 negative leg that MC4 cable is now negative!! And the same is true of the MC4 cable negative leg that is connected to your panels positive MC4 leg that negative cable becomes positive.
I made the mistake of connecting my MC4 cables to the combiner box using the polarity markings on the cables as my guide. This basically set me up for failure. What pushed this failure into motion was the fact the Helios panel MC4 cables were NOT marked. Here is where a polarity test should have been done, but I made an assumption and was wrong. So basically I wired my panels in reverse and didn't realize it. Now when I got home to wire the combiner box out put cables to the charge controller I isolated the panels with the switch I put in place for things like this. Keep in mind each panel is circuit protected with a 15A breaker (now that is changing as I will double protect with both a fuse and breaker)
So I made the connection corrections then placed the panels online... the time it took my to flip the switch and walk out to where my panels are mounted was about 3 seconds. In that time I burned my panels. See the images of shame below.
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| This is the middle panel in the array of three. |
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| A close up of the middle panel. |
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| This is the left panel and the furthest from the charge controller |
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| Top view of the damage. |
But I am stubborn and refused to give up, even though I had burned my panels, purchased the wrong battery charger, purchased a non-standard charge controller and drained my batteries down to 10%... I couldn't just quit. So it's been over a week now and we have power somewhat. Even though the panels are seriously damaged (all three together produce maybe 300W of power) they are maintaining my batteries at 85%. Currently the only load I have is the fridge and the inverter. I have since taken half my batteries to my brother in-laws and put them on charge for the last 5 days. Today that bank comes home and the bank in service will be delivered for their 5 days on charge.
The panels replace all the power we consume with a slight increase over demand. But as we move into shorter days that will cease to be a truism. I have right now 2 - 250W Talesun 24V panels on order for pick-up in San Jose. I should be getting them Monday or Tuesday. I also got a good deal on a Blue Mountain MPPT charge controller AND I just found a place just outside of San Francisco where they have new solar panels for as low as $0.75/W and since I can DRIVE THERE, it's well worth it. The panels are brand new and basically are extras that are not needed. See, to get a decent price on panels you have to order them by the pallet. If you order individually you pay more per watt and even more for shipping (how the hell does that work?!?). So installers will order pallets of panels, install what they need for the job they are on then the left overs are either used in another project or this guy gets them and turns around and sells them
http://king-solarman.com/ This is the local place where I will be getting all my future panels. Another place you the reader can look is here: https://pvdepot.com/ this is who I ordered my two new Talesuns from.
So the two new panels will be coupled with the new Blue Mountain MPPT charge controller and the damaged Helios panels will be maintained on the Trace Xantrex PWM charge controller I got from a friend as a gift. Helios has agreed to work a deal with me so I can replace the panels at a special rate, what that rate is I won't find out until either Monday or Tuesday. I did open a dialog with Helios the day everything happened. In the beginning I thought it was the charge controller but as time passed and I continued my investigation I found where I had made my error. But I also noted that Helios had failed to mark their MC4 connections with polarity. Granted someone in the business would already know many of the things I now do... but I am an amateur that lives off grid trying to save some hard earned cash and get power up.
At the end of next month I will have my system up and all my appliances running on it. The 12V system I started with will be partially dismantled and used for lighting only in the cabin. The remainder will be used to generate power in another location for lights and laptop / printer operations for my wifes business. It's funny how easy life is in the United States and you don't realize it until you move away from it and live outside the box. It's hard and it's frustrating and it's initially expensive. But in the end it's worth the freedom. I will leave this with an image of the next step in my systems implementation, a step that I will start to put in place next weekend (I have the property all to myself for 4 days!!!). Oh and a side note, once I have the new panels working I will remove the 3 damaged panels (after the replacements arrive) and use the worst of the three panels as a source of cells and see if I can repair the other two panels. I have been reading up and watching YouTube videos on how to do this... I figure might as well since the warranty is void anyhow. What could I possibly do wrong?
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| Drawing 1 of my system reconfiguration |
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| Drawing 2 of my system reconfiguration |
Dear Mr. Brucker,
It is with extreme humility that I write to inform you that the damage to the panels is due to reverse wiring, which was done by myself. The only thing that would be "wrong" on the side of Helios, is that the MC4 connectors on the panels were not clearly marked positive / negative as the MC4 cables I used to connect the panels to the combiner box were. Essentially I used the markings on the MC4 cables that I bought separate from the panels as my guide to connecting the terminal leads to the combiner box, reversing the polarity in doing so. I also failed to take voltage readings prior to energizing the string to the charge controller, and had I done so I would have noted the reversed polarity and been able to correct it then, and only I can be held culpable for this.
I humbly apologize for any inconvenience I may have caused with this "issue". Essentially I made a rookie mistake one that I didn't make with my 12V system as the connectors on the panels were clearly marked and that let me know how to connect the wires to the combiner box. How this happened is that when I was connecting the 12V panel to my other system, I saw the + symbol on the solar panel connector and when I plugged it into the MC4 cable, it was the - cable that went into the + cable. Seeing this I realized then that what it marked - is actually + and + is actually -. I came to this realization this morning after sleeping on the issue at hand when I woke up, went out to the array and validated it with a multi-meter.
My wife has asked that I inquire about the possibility of replacing these panels at cost, and all I can do is ask. I realize and admit that I am the one that made the mistake (one I will never make again), and that the only culpability I can find on the part of Helios is the lack of polarity identification on the MC4 connectors / cables on the panels which influenced the error. In closing thank you for your time and effort on this matter.
Sincerely,
McDian
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