Question about Renogy solar panel system

[flee27]

IMO there is some correct and some incorrect info in the thread regarding you solar install. Watch these two video and learn some more.

Part 1

https://www.youtube.com/watch?v=odyacv-sS-o

Part 2

https://www.youtube.com/watch?v=5521Zaz92N8

Good Luck sorting out your solar. Happy sailing.

Foster

[mvweebles]

Originally Posted by Rohan

Question for the forum about Renogy solar panel system. I'm just not getting the results I need, not even close.

(BTW, I tried to post this to the Renogy support group - but it says my account has been suspended, which is funny because I have never posted there!!)

Recently I bought 2x 100w flexible panels and installed them on the bimini. This was my first time installing solar. I hooked them in series for now instead of parallel. Per the instructions, the wires go from the panels, to the charge controller, to a fuse, to the battery. My boat has 4x very large AGM batteries, all connected together. I attached the wires to one of the batteries.

To experiment, I turned off shore power to see how well the panels would keep my batteries up with my small refrigerator running (which only draws 2.2 amps!). I turned the fridge on the lowest setting and left it that way for a couple days. Returned to the boat, and my battery voltage was 12.9, which is excellent. I was very happy. So I carried the experiment further and set my fridge at halfway setting, came back a few days later. Batteries were drained down to 12.2 which is unacceptable, and those days were pretty sunny too. I couldn't really believe that just changing the fridge setting a couple notches would make that much of a difference! But to make sure, I tried again. I plugged batteries into shore power until they were fully charged, then turned off shore power, turned the fridge back down to the lowest setting, and left for three days (two of which were very sunny).

When I returned the batteries were at 11.9 volts!! Nearly a drained battery. I can't tell you how bad that is. Seriously, by my experience, that's even WORSE than I would normally expect if I had left for three days with no solar power at all. So what the heck is happening?? How did I go from 12.9v to 11.9v?

By comparison, I have two buddies in the same marina with similar sized boats and refrigerators. One has 2x 40w panels, and the other has 1x 50w. Yet both of them brag that they never need to plug into shore power because the panels keep their fridge running and batteries topped off. Yet I have four times that amount of solar and my battery is dying??


I have read the manual many times, and I don't see anything I did wrong. The charge controller indicates that everything is charging normally. It should give an error message if I hooked things the wrong way. It displays that I am pulling in up to 6 amps in the middle of the day when it's sunny, to about .1 amp in the evening or very cloudy day.

Here's one anomaly I can't figure out and this might be related to the problem. The display shows my battery voltage, which always agrees with my voltmeter. But it also shows something else called "photovoltaic array voltage". What does that mean? The manual doesn't explain. The crazy thing is, sometimes that voltage will read 12.6v or so, about the same as my battery voltage, and sometimes it reads 39 to 40 volts!! Where does come from? Even if it's adding all four of my batteries together, that should be like 48 - 50 volts or so.

Anyone have an idea why this isn't working for me?

OP dodged a bullet by not being able to access Renogy Tech Support forum. Their support is riddled with mistakes and stupidity ("12.8v is a dead battery bank." And I've seen them state 12v batteries should be cabled in series to maintain 12v system voltage. Or Their 50a DC-DC charger requires 75a input to output 50a but is totally stumped when asked how they dissipate that much heat if their statement is true). They apparently contract-build their stuff and dump it. Their success is due to an integrated app that's pretty cruse compared to Victron, but neophytes like it. Their BBB rating is just awful due to refusal to accept returns (hint: buy via Amazon vs direct on Renogy.com)

To the OP, I know you believe you've given full info, but there are a lot of variables you apparently don't know. Even a crude system diagram showing battery configuration and where the wires are connected along with wire size would help a lot.

Or you could call Renogy Tech Support. You'll likely be 45th in queue and get some sort of moronic assistance .

[Spot]

Originally Posted by mvweebles

To the OP, I know you believe you've given full info, but there are a lot of variables you apparently don't know. Even a crude system diagram showing battery configuration and where the wires are connected along with wire size would help a lot.

Rohan, feel free to take the one I did, save it as a file, and erase/redraw the wiring to match your system as-is (with a program like Paint) and re-post with the 'paperclip' icon in the advanced option window.

[pcmm]

Originally Posted by Rohan

By comparison, I have two buddies in the same marina with similar sized boats and refrigerators. One has 2x 40w panels, and the other has 1x 50w. Yet both of them brag that they never need to plug into shore power because the panels keep their fridge running and batteries topped off. Yet I have four times that amount of solar and my battery is dying??

Your "buddies" are lying through there teeth! Unless they both have super insulated fridges that rarely cycle. 1 50watt panel (at best in perfect conditions) will put out roughly 18ah worth of power in a day. The math just doesn't work or them. 200watts (at best in perfect conditions) will put out roughly 80ah per day

[Rohan]

Originally Posted by Grattaway

But it was a bit unclear as to what you are doing at the battery end as you said you had 4 batteries connected together but in a later post you said you had two banks

So is it 4 12 volt batteries all in one bank giving 12 volts out or is it 2 batteries together giving 12 volts out and then another 2 batteries together giving 12 volts out such that you could switch from one to the other.

If its 4 batteries together then your wiring is such that you charge all 4 batteries as a bank - and not just one of them - from your one controller with panels in parallel

if you have 2 separate banks then in my ideal world you would charge one then the other rather than both at the same time - could be via a switch, controller or some such smarts which others will have more understanding than I

Wayne

4x AGM batteries total. 2 banks of 2 batteries each, and I can switch to one bank or the other, or both at the same time. While experimenting with solar charging I had them all active.



I'll also experiment with charging one bank at a time. One anomaly is that one bank is new from 2020, the other bank are date stamped 2007. And I know - people on this forum have told me batteries don't last that long. But my multimeter shows them still putting out a very healthy charge (I bought the boat in 2019, and it's my theory the previous owner never used those batteries).

[newhaul]

Originally Posted by Rohan

4x AGM batteries total. 2 banks of 2 batteries each, and I can switch to one bank or the other, or both at the same time. While experimenting with solar charging I had them all active.



I'll also experiment with charging one bank at a time. One anomaly is that one bank is new from 2020, the other bank are date stamped 2007. And I know - people on this forum have told me batteries don't last that long. But my multimeter shows them still putting out a very healthy charge (I bought the boat in 2019, and it's my theory the previous owner never used those batteries).

Let's get your solar straight on the new bank . After that we can look at your battery situation but for now just use the new bank .

[Kolchac]

The series connection is correct if you use 24 V batteries. If they are 12V - only one panel would work.
If your boat is located at equator and your panels are at 90 degree to the sun light, you can expect ~75% of max during ~3 hours around 1 pm in a sunny day.

To check your panels, buy voltmeter/amperemiter (10A) and measure voltage and amps from each panel to make sure.
BTW, because panels are a matrix of diodes, you can connect any panels in parallel without any additional circuit.

[flee27]

I think some are confusing batteries and solar panels. You can hook your solar panels in parallel or series without concern to your battery voltage. As long as you don't exceed the solar charge controllers parameters. The charge controller is what controls the charging voltage and current.

Foster

[geoffa]

When all else fails check the cables from the solar panels, they might not be tinned and they may have corroded all ready. Most solar panel connections have dubious quality glands and are rarely suitable for a marine, salt environment!

[Indefatiguable]

Renogy is cheap Chinese crap. They're panels (esp. Monocrystaline) are acceptable but their charge controllers are absolute garbage.

Whereas I agree 100% with all of the above advice, I would Very Very Very ... Very highly recommend investing in a better MPPT controller. I use victron, and it's a world of difference. On my cobbled-from-spare-parts 1.2kw array in northern wisconsin I went from 2 watts generated to 180 the afternoon i switched controllers. That's in (almost) full permanent shade.

The cheapy renogy pwm ones in the Kits fail all the time. That's what happens when you brainwash an ethnic minority into doing your soldering sans pay. Btw, Victron does not use slave labor either...

[Tonali99]

Originally Posted by Spot

Rohan, feel free to take the one I did, save it as a file, and erase/redraw the wiring to match your system as-is (with a program like Paint) and re-post with the 'paperclip' icon in the advanced option window.

Nice diagram, as I understood it, he only connected to one battery. The rest were being drained by the fridge.
I avoided the selector switch and went directly to batteries. Never had a power drop. The panels can be turned off [disconnected] if needed for any reason.

[Spot]

Thanks T. The software is KiCAD and some of the schematic symbols are custom.
https://www.kicad.org/
The upper left quarter (first solar cell through first battery) is the same as my boat so this one was an easy copy and paste revision.

[eriksp]

I see you are measuring voltage regularly and state that the batteries are healthy because they are showing a good voltage. A simple thing that I don't think anyone has addressed directly:



Voltage is like a fuel tank level gauge for your battery bank. A high resting voltage like 12.7 is like your fuel gauge reading "Full." A low resting voltage like 12.1 is like your fuel gauge reading "Half Full." *


None of these voltages tell you how much capacity the battery has, just like a fuel gauge does not tell you how many gallons of fuel the tank holds. Battery capacity shrinks over time and usage. Imagine if your 30 gallon fuel tank was like a balloon, and each year it shrunk a little. Ten years later and it only may hold 10 gallons, but the gauge would read "Full" with 10 gallons. Batteries behave like this, but their capacity when new is measured in Ampere-hours or "Ah."


Your 2007 batteries do not have their new capacity anymore. For testing purposes, you may want to only work with your new battery bank until you determine your solar setup is charging correctly.


An old battery at 12.7 volts may only last minutes, and a new battery at 12.7 volts may last hours at the same discharge rate because... their Ah capacity is significantly different. They are actually capable of holding vastly different amounts of electrical energy in storage.



* I know I said 12.1v is approx. "half full" or 50% charge, but it's a good idea to not discharge below this regularly until you know what your usage patterns are.

[surf_km55]

This thread is a fine example of "knowledge is power."

Sorry, couldn't help it.