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paulz
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# Posted: 22 Nov 2020 09:26am
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Thanks raz. The battery I used for the test holds a full charge if not connected. I don't know how old this panel is, came off a friends shipping container when he moved. Easy enough to test by unplugging it at night and seeing what happens. I'll do that. I was hoping to leave it hooked up to my tractor battery while I'm gone for a few days.
A quick web search shows others having this situation but haven't come across an explanation. I'll report back after more testing.
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FishHog
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# Posted: 22 Nov 2020 09:43am
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your charge controller should not be allowing back flow, so in my mind it is faulty. I can't believe the CC alone would drain that much power overnight.
If the solar panel is providing a charge, its doing its job, it has to be the CC that is faulty.
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paulz
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# Posted: 22 Nov 2020 11:50am
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Thanks Fish. I'm at the grid house for a couple days so more testing next week.
Meanwhile, the Epever CC and 16 panels in the shade seem to be doing the job on my shop roof keeping the 4 lead marine batteries charged. I need to set the Amp/Hr setting on the MT50 meter, it's at the default of 200 and I'm somewhere near 500 (assuming the batteries were new, they are not). But I think I have to wait until the green battery light is slow blinking, indicating fully charged, then set it, right? If I understand correctly this really has no function on the charging rate, just a way of knowing how much battery life is left?
Up at the cabin, I have installed 3 more panels hanging off the deck. 3 facing east, 3 south and 3 west (that's the one tractor battery panel in the foreground). Pretty ugly, looks like a tanning salon. But it's the only spot with any sun at all. I have one old lead car battery hooked to the Renogy controller with no load at the moment, need to do some wiring next week to try powering the cabin with lithium again.
Spending a lot of time with electrical stuff lately but it seems to be paying off, and will be much more come spring.
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FishHog
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# Posted: 22 Nov 2020 11:55am
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well that is the one downside of solar panels, they just aren't that attractive. The peace and quiet they offer over a generator makes up for that in my mind.
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paulz
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# Posted: 22 Nov 2020 02:01pm
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You're right about that. Hmm, business opportunity: Decorative solar panel bordering..
Yeah, even though I have 15 generators I'm not big on charging batteries with them. Never figured out how to charge a days worth of battery use back in an hour or two and not going to listen to them longer than that.
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razmichael
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# Posted: 22 Nov 2020 04:24pm
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Quoting: paulz If I understand correctly this really has no function on the charging rate, just a way of knowing how much battery life is left?
Be really careful with this - it really has little value as the CC does not know how many amps are being used by the rest of the system, only the load circuit off the unit itself. When i did some checking on what the setting was for the response was mostly "nothing useful". If you find otherwise let me know.
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paulz
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# Posted: 23 Nov 2020 08:23am
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Raz, the bar graph on my MT50 will show 100% when I get to the shop. As I use lights and tools it drops, as does the voltage reading. Is the bar graph and percentage used just based on the voltage then, not any current measurement?
I have nothing hooked to the load terminals yet.
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razmichael
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# Posted: 23 Nov 2020 09:56am
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It can't measure the current as the current being used is not going through the CC. From what I could determine is it is only an estimate based on the voltage as you suggest (so from a % point of view it doesn't really matter what it thinks the total aHr is). As things are drawing power the voltage will drop then bounce back when turned off. Best to play with it and see if it really is useful or not.
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paulz
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# Posted: 23 Nov 2020 11:12am
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Quoting: razmichael It can't measure the current as the current being used is not going through the CC.
Oh yeah. Doh! So even if you set the AHs and use the load terminals, if anything is hooked up battery direct it's not going to be accurate. Don't think I'll bother with it.
Thanks again.
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paulz
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# Posted: 30 Nov 2020 11:07am
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A bit more on that one panel and small SCC that I thought was draining my battery at night. I tried it again with a different battery and put an ammeter in line. Noticed at night the battery draw was only .01 amp, and the next morning the battery hadn't lost any voltage. Curiously though I charged the first battery on the grid and it too is doing fine stand alone. Not sure what happened there but I'm going to keep a battery on it long term and see what happens.
In other Paul's Solar Saga news, I still have that original 900w array on wheels that started this whole adventure. So I'm going to put it out by my front fence, by the road, where my property gets the most sun. And if I understand correctly, if I put a SCC, battery bank and inverter there too, I can run 110AC for 100 or even 200 ft., right? Not for anything major, maybe some yard lights.
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razmichael
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# Posted: 30 Nov 2020 12:22pm
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I would play with one of the many online voltage drop calculators. 200 ft is a long way (either 120 or 12V) especially depending on how many amps you expect. Wire can get fairly costly as you try to keep drop to a reasonable amount. This way you can determine options for what it will cost and what you can actually run reasonably.
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paulz
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# Posted: 30 Nov 2020 03:43pm
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Will do, thanks raz. I have run a 100ft extension cord off the inverter in the shop and run a saw, seemed OK.
Some good news this morning. Got to the cabin after being gone since last Thursday. I had left the Li battery hooked to the CC, no load, showing 12.9 volts. Today it showed 13.29 before switching on the cabin. So there is solar hope going on around here. 3 weeks to the solstice..
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gcrank1
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# Posted: 30 Nov 2020 09:17pm
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Fwiw, Im running some 75' of 2 outdoor 16ga. extension cords from my little 300w psw or 400w msw inverter at the bat-bank on my ice shanty/power house/tool shed.
The dig-voltmeter reads 116vac on the 300w psw at the outlet , the msw doesnt read right, 98-99vac on my non-rms cheap meter (common for these) but works fine. I get the same voltage read at the end of each of the 2 extension cords and all 4 of the 120v led Edison base bulbs in the cabin are nice and bright. The 120vac cheap ceiling fan runs fine also with no bulbs dimming.
I have bigger gauge rv grade cords to use, this was my quick&dirty hook up and trial the other day. If my loads were bigger and I had more batteries I could run my 750w msw or 1Kw psw inverters but the overhead is probably too much with my poor solar exposure. Ive been using inverters sized closer to my loads with success this year.
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Brettny
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# Posted: 1 Dec 2020 07:08am
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The MT50 really shows little useable data becids the current voltage and amps in. For how much power is left in a bank you need something more like a shunt meter. There about $50 on amazon.
Paulz for your 100-200ft run of 120v yard lights that would be perfectly fine. I believe a 100ft 12g cord is good for 15a at 120v. To get the same 15a at 12v you would need huge wires for a 100ft run.
For long wite runs always use the highest voltage you can. This goes for the wireing from your pannels to the CC too.
Since your in such a shaded area have you messed with series or parallel wireing of your pannels?
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Steve_S
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# Posted: 1 Dec 2020 07:25am
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I'll offer a small point of ponderance. Ever wire a house ? Most of us have, so we know the answer already. What is the longest run from main AC Panel to the end plug in your circuits ?
In a fairly typical home, 100' run is not that unusual. Think about it, even if you have a straight line of 40', by the time the wire is routed through the walls, up & down and around, it's much longer than the straight line.
Running stranded copper wire (extension cords) derate faster over distance than solid core copper... With extension cords you have to counter the deration by increasing conductor size to carry the juice. In a home you'd run 14/2 100' no problem but with an extension cord to run 100', you'd be looking at 10 gauge wire.
You could run Solid Core NMWU (non metalic, wet unground) wire from your inverter to a "Power Bollard" and from there take extension cords for use or run to your yard lights from that point. Now if you used low watt LED lights they are really tolerant of voltages because of the stepdown transformer being able to take 80V to 130V (pending on brands).
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paulz
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# Posted: 1 Dec 2020 08:30am
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Quoting: Brettny Since your in such a shaded area have you messed with series or parallel wireing of your pannels?
Yes. I got so many panels (30) off the roof of that grid house that I was able to put 16 panels in a 4x4 array on the shop roof. That SCC has a 150v PV max, I'm getting about 130 out of each 4 panels in series.
The cabin SCC has a 100v limit, I have a 3x3 setup there, getting about 90v out of each.
And I still have a half dozen panels I can add in parallel.
Quoting: Steve_S You could run Solid Core NMWU (non metalic, wet unground) wire from your inverter to a "Power Bollard" and from there take extension cords for use or run to your yard lights from that point.
Sounds like a plan.
Thanks gjys.
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paulz
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# Posted: 18 Dec 2020 04:40pm
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I guess I should install the battery temp sensor that came with my SCC, on the lead acid battery. Do you just tape on the top of the battery? Doesn't say. Looks like this.
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Nobadays
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# Posted: 18 Dec 2020 06:55pm
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Preferably taped to the side and wedged between 2 batteries, or taped to the side of a single battery with some foam insulation over it.
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paulz
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# Posted: 19 Dec 2020 12:59pm - Edited by: paulz
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Thanks Nobs. I went through both my manuals (Epever and Renogy), both just say 'attach to battery', like there is a bracket or something. Also both say 'for temperature compensation'. I don't imagine I have much need for it now with all my panels in shade but maybe in the spring. I did see the Epever kick out 6amps charge the other day for some reason, almost peed my pants.
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Nobadays
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# Posted: 19 Dec 2020 02:56pm - Edited by: Nobadays
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The temperature compensation is related to battery temp... charging profile changes some depending upon how cold or hot they are. Some sensors come with a lug at the end which looks like you should attach it to the battery terminal but.... this is not near as accurate as getting 8t down on the side between two batteries.
Yeah winter can be tough on solar charging... just looked, our 2250w of PV were putting out a measly 1800w with ~38amps to the battery bank...
Wife will be watching Hallmark movies today!
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paulz
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# Posted: 28 Dec 2020 10:15am
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Got to the cabin yesterday to find the solar gods had smiled on me over Christmas. We left the cabin on Christmas eve, and there has been no sun (not that any would hit my panels anyway), even rained.
Despite it, the SCC at my shop showed a whopping 14.6v (FLAs), and the cabin SCC at 13.4 (Valence LFP). No load on either while I'm not here. Encouraging, looks like my grossly over paneled setup is working. Going to have to cut back when the sun starts to rise higher, or at least get some fusing in place.
I'm wondering about all those MC4 connectors sitting out in the rain. They look water tight..
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gcrank1
Member
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# Posted: 28 Dec 2020 10:42am
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I use dielectric grease on my connections and on the MC3's I have, both inside and outside the connector.
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paulz
Member
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# Posted: 29 Dec 2020 09:33am - Edited by: paulz
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Good idea. I did some panel isolation testing yesterday and all connections were dry inside, so far..
Been trying to figure out why my shop solar is performing much better than the cabin solar. Got up to 7 amps yesterday, while the cabin was only getting 1. The shop does have 16 panels while the cabin has only 9, but the cabin actually gets a touch of sun, the shop zero.
I have tried tilting the shop panels, and I think they may actually perform better flat (shop roof is flat), maybe they actually get more light that way in the shade? Can't easily tilt the cabin panels flat as they are cantilevered out or I would try it.
The shop panels are 4 panels in series x 4. So it has about 135 open voltage. The cabin has 3x3, so about 90 volts. Maybe the higher voltage helps with the MPPT? Both are 12v output.
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gcrank1
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# Posted: 29 Dec 2020 10:58am - Edited by: gcrank1
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If I understand it correctly the bat-bank can only take what it can take, if my bank is low from use my mppt cc shows a higher amps output (2s/2p for 24v to cc, 12v to bank). Once the bank is 'up' the indicated amps drops off. This means the amps I see on the cc dont mean much and wont be much if that bank is charged up.
If I want to see what my array and cc are actually doing I have to have a bat-bank at a certain level of discharge, and have that repeatable if I want to do comparisons. That can be difficult in your case with varying light/cloud cover and two different bat-banks?
To my thinking, to test/compare your two arrays you need a battery discharged to 'x level' to jumper into the cc output/bat input cable, disconnect the reg bat-bank and watch what the cc reading goes to.
Hook the bat-bank back up and note the reading.
Then go to your other array and do likewise; ie, the test battery being the constant.
Btw, you dont want that test bat to get too much charge input during array 1 test, and/or discharge it again to 'x level' to do array 2.
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ICC
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# Posted: 29 Dec 2020 11:04am - Edited by: ICC
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MC4 connectors are rated IP67 for water and dust resistance. That means it is rated dust-proof and can be totally immersion in water to a depth of 1 meter for 30 minutes. No need to worry about rain, no need for grease or anything else. IP dust and water numbers explained here.
Yes, higher voltage helps deliver more power through an MPPT charge controller.
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gcrank1
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# Posted: 29 Dec 2020 12:22pm
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Imo, no matter what those connectors are rated at the dielectric greasing will only make 'em better. And it isnt just the sealing aspects, it is the potential oxidation (or whatever) that takes place on the actual metal to metal connections. We all know that the fewer con's the better and that every one is a potential resistance and/or failure point. Ie, be kind to them and they will be kind back 
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ICC
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# Posted: 29 Dec 2020 01:08pm - Edited by: ICC
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Yes. Dielectric grease can't hurt... just may be un-necessary to use on MC4 connectors. Dielectric grease is a wonderful aid on things like tail-light and headlight connecting plugs and sockets.
However, lots of thought and effort went into the design of the MC4 connector to make the end product water and dust-tight. They are built to a standard for dust and water resistance. The standard tells us what we can expect from the item be it a smartphone, flashlight, or cable connector. There must be millions of MC4's in use all over the world.
By far the majority of the problems experienced are due to improper installation of the connector on the cable end, followed by improper use. Improper installations such as poor crimping and too much solder if the joint is also soldered. (Note that codes require crimping; if soldered they must also be crimped). Improper use includes disconnecting or connecting with current flowing. The arc can internally damage the connector. That is one reason to use a disconnect/breaker where the cables enter the charge controller.
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paulz
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# Posted: 30 Dec 2020 08:41am - Edited by: paulz
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Quoting: gcrank1 If I understand it correctly the bat-bank can only take what it can take, if my bank is low from use my mppt cc shows a higher amps output (2s/2p for 24v to cc, 12v to bank). Once the bank is 'up' the indicated amps drops off. This means the amps I see on the cc dont mean much and wont be much if that bank is charged up.
Yes, been wondering about that, especially when the SCC shows battery at 100%. I believe, however, that it's just an estimation, it uses actual voltage readings to determine charge rate, or state (bulk, float, etc.).
Yesterday I brought two panels and an MPPT controller back to the city. Hooked it up to the 2 Valence batteries in my truck which were somewhere around 50% soc. In full afternoon sun it showed a 2 amp charge (12v). Should I expect more? They are 260w panels, 80+ volts open circuit in series.
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ICC
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# Posted: 30 Dec 2020 01:55pm
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Quoting: paulz In full afternoon sun it showed a 2 amp charge (12v). Should I expect more?
Depends on the actual battery state of charge. If everything is working as intended, and connected correctly, a partially charged lithium cell battery should be taking more than 2 amps with those 2 panels in direct sun.
What is the panel rated Imp? 6 to 7 amps? In series, under bright sun a depleted battery should be getting near to the full Imp rating, possibly over that, plus or minus a little.
In other words, two 260 watt panels equal 520 watts total. Divide that wattage number by the voltage going into the battery will give you the theoretical amps going in. There will be some power loss in the charge controller, but the MPPT magic can increase the amps going out when the incoming voltage is considerably higher than the battery (the output voltage of the charger).
A depleted lithium battery is not as limited to amps input by internal resistance as a lead-acid battery. So if it is not fully charged it should be taking a considerable current from panels in bright sun.
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paulz
Member
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# Posted: 30 Dec 2020 02:26pm
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Thanks ICC. I hooked it up again this morning, in the bright sun it went up to 4 amps. Panels are 8 amp each.
Right now the SCC says battery is at 13.7 but only showing 13.3 at the battery. 2 amp charge, panels in full sun. I have this jury rigged with an extension cord and some alligator clip wires. It's a funky attempt to get my batteries charged for the cabin tomorrow, and it's working, slowly. Probably not a good time for diagnosis..
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