More solar questions....

[dhays]

The sensor is designed to be in close proximity to the controller & the controller close to the bank. If you can't make this happen you will be best to turn off temp compensation and accepth the volt drop, or beef up the wire gauge. Another option, if voltage getting to the battery terminals is lower than ideal, is to simply extend the absorption duration.

Thanks. As long as we have enough sun, the absorb duration is long enough that it normally changes to float due to the tail off amperage before the time runs out. If we don’t have enough sun, then it just has to wait until the next day.

Dave: what are the loads under these tests? Is/are your fridge and/or freezer on? Are you on shore power? Your panels should be switched to off if you are on shore power. What happens while you are on shore power will be very different when you are away from the dock.

I have the shore power plugged in to run the AC loads, but have the charger turned off. I also have the AC/DC fridge’s AC turned off so it is running only on 12v. In addition I have another 12v freezer that is running. All in all, not that much of a load.

 

[CMS]

Thanks. As long as we have enough sun, the absorb duration is long enough that it normally changes to float due to the tail off amperage before the time runs out. If we don’t have enough sun, then it just has to wait until the next day.

My point is that the higher the absorption voltage, at the battery terminals, the shorter the charge time will be. Dropping to float before the batteries are actually at 99-100% SOC eventually leads to PSOC damage and shorter cycle life. This can be somewhat mitigated by extending the absorption time to compensate for the lower absorption voltage.. In other words the lower the absorption voltage the longer the absorption duration needs to be.

 

[FF]

"In other words the lower the absorption voltage the longer the absorption duration needs to be."


And the less often water will need to be added to the batt set.

 

[IntoTheBlue]

I noted @maerins comment that he sees a max of 365 W out of 480 W panels in the Bahamas. I just increased my battery bank and added another panel to 4 x 100 W, total 400 W. Using the VE Direct App from my Vernitron MPPT controller I am getting readings around the upper 200’s at midday, while traveling up in Quebec. Is this OK? Or can I improve (is it worth improving) this by replacing the wire from the panels to the controller to a 6 gauge. (Wire runs about 25 feet, panels in series). It seems to keep the batteries charged with normal usage. Or should I consider the system adequate?

 

[foggysail]

I noted @maerins comment that he sees a max of 365 W out of 480 W panels in the Bahamas. I just increased my battery bank and added another panel to 4 x 100 W, total 400 W. Using the VE Direct App from my Vernitron MPPT controller I am getting readings around the upper 200’s at midday, while traveling up in Quebec. Is this OK? Or can I improve (is it worth improving) this by replacing the wire from the panels to the controller to a 6 gauge. (Wire runs about 25 feet, panels in series). It seems to keep the batteries charged with normal usage. Or should I consider the system adequate?

The wires from your panels to the controller are oversized now so I do not recommend larger wire. For example, I assumed two things, first is that you have restricted your series panels to two in series with the series paralleled. Further I assumed that your panels have a Vmp of 18V. So for 400 watts the expected current is 400W/36V or only 11 amperes.

Things get far better if your panels are all connected in series (<6 amperes) and if your panels have a higher Vmp than 18V it further reduces the panel to controller current. I did not take the effort of calculating the actual voltage drop for your wire run, you can do that. Just remember that if your panels are 25 feet from the controller, your wire length is actually 50 feet when calculating the drop

 

[IntoTheBlue]

Checking today at St. Catherine’s Lock in Montreal, at noon, I was getting a reading of 367 watts from my Vernitron app. So during midday, 367 out of 400 is satisfactory. My only confusion now is that my day history stat’s indicate 97 % Bulk Absorption, with the batteries never going below 12.7 volts. Does that mean that during the day with solar active, the demand for power is about or less than the amount being provided by the panels?

 

[janice142]

Don't forget to check the diameter wire your controller will accept. When the upgraded to 6-gauge I also had to change controllers. The new one required this cool toy aka tool. I had to get a square ferrule to fit the wire into my controller.

Ferrule crimper:

To make this end:

(During the project)

I labeled the heat shrink too

 

[dhays]

Checking today at St. Catherine’s Lock in Montreal, at noon, I was getting a reading of 367 watts from my Vernitron app. So during midday, 367 out of 400 is satisfactory. My only confusion now is that my day history stat’s indicate 97 % Bulk Absorption, with the batteries never going below 12.7 volts. Does that mean that during the day with solar active, the demand for power is about or less than the amount being provided by the panels?

My ignorant understanding is that during the day, the solar was never able to get the voltage of the batteries to the absorb voltage (maybe 13.4v depending on the battery type). So either the bank was drawn down enough over night, or there was a load during the day that kept the bank from achieving the absorb voltage. I have seen that on my own bank when I have had a few days of cloudy weather. The bank is low enough at the beginning of the day that the solar charger stays in bulk all day. After a couple days of normal sun, then it gets to absorb and then to float.

Keep in mind that I only have a single panel rated at 365W and it gets shaded in my slip by the arch in the afternoon. During the day I had a freezer and refrigerator running.

 

[IntoTheBlue]

My ignorant understanding is that during the day, the solar was never able to get the voltage of the batteries to the absorb voltage (maybe 13.4v depending on the battery type). So either the bank was drawn down enough over night, or there was a load during the day that kept the bank from achieving the absorb voltage. I have seen that on my own bank when I have had a few days of cloudy weather. The bank is low enough at the beginning of the day that the solar charger stays in bulk all day. After a couple days of normal sun, then it gets to absorb and then to float.

Keep in mind that I only have a single panel rated at 365W and it gets shaded in my slip by the arch in the afternoon. During the day I had a freezer and refrigerator running.

Thanks. I agree. At the end of the day, the system is doing what I wanted it to do, which is to maintain power requirements for the day while on anchor and to have enough reserve power in the banks to cover the night. Really no need to over think it any further. Since in Canada, I have not been to a facility that offers straight 50 amp service, so even when on the dock or lock wall, the solar panels have been helpful.

 

[cardude01]

I know this is an older thread, but is your new single 360 watt panel keeping up with your fridge and other DC draws like you hoped it would?

I found a 60 cell 300w panel on eBay that’s local, and wondering if one will be enough (all I have room for).



My fridge and freezer are my biggest draws. I have two danfoss Bd50 compressors and they use about 100 amp hours per day IIRC. Total boat maybe around 150 AH per day. My battery bank is AGM with 700 AH.

I’m looking for something that lets me stay at anchor for at least three days in the Bahamas.

I also have a 120w panel installed.

 

[IntoTheBlue]

On our trip to Canada via the "Triangle Loop", we had used 4 100 Watt panels, which provided more than enough power to maintain the battery bank (3 x 225 aH Gel Batteries) and fridge (Vitro 2 drawer), allowing us to use lights, etc at night. Our water heater was not hooked up to the inverter, so that required running the Genset in the morning for about 1/2 hour. I do think that this set-up would be able to maintain the freezer as well, but we never used it. We did use a mini ice maker via the inverter for drinks.

This summer we'll be traveling to Maine, with the idea of staying on the hook or a mooring in one place for 2-3 weeks at a time (therefore not charging from the engines) Based on the experience we've had so far, I think the same 4 100 watt panels should suffice.

Hope this helps!

 

[hobbystuff]

A question. I want to be able to turn my solar system on/off and had planned to put a switch into the positive run to the battery. However, I also read some conflicting advice that says to put the switch into the solar panel positive feed. I'm guessing both would work, but which way is preferred?

 

[DavidM]

Not sure why you would want to turn off your solar system, but I believe the preferred place is to put the switch is near the panels. But realize that the connection from the controller to the battery will still be hot.



David

 

[cardude01]

Not sure why you would want to turn off your solar system, but I believe the preferred place is to put the switch is near the panels. But realize that the connection from the controller to the battery will still be hot.



David

I also wondered about how to turn off the power from the panels if I needed to rewire something. Someone here said just throw a towel over the panels. Would that work?

I looked at the connector plugs and they have a sticker that says to not disconnect or reconnect while the panel is active because they will arc and eventually damage the connector.

I wired my panels at night to get around this problem, but that may not always be convenient.

 

[fryedaze]

Put a two pole breaker in. One pole on the positive output of the solar panel to the controller. The other pole is on the positive output from the controller to the battery. One switch flip isolates everything.

 

[kchace]

A question. I want to be able to turn my solar system on/off and had planned to put a switch into the positive run to the battery. However, I also read some conflicting advice that says to put the switch into the solar panel positive feed. I'm guessing both would work, but which way is preferred?

The instructions on my solar controller specifically state to connect to the batteries BEFORE connecting the panel. I believe the reason is the controller's electronics are powered by the batteries. Connecting the panel first could damage unpowered electronics.


In my case, I have a small plug between the panels and the controller that I can pull, but for ease of use I have installed a small "battery switch" on the panel feed line right before the controller. Another possibility is if you have fuses between the panels and controller you could pull those.


Ken

 

[foggysail]

I installed battery switches between the battery and my solar controller and another between the solar panels and the controller. The cost for the switches is minuscule and allows me to have safe access to the controller.

Sure, panel isolation can be ignored most times but maybe not so with panels mounted in series. The open circuit panel voltage in my installation can easily be greater than 70V. For that reason, I prefer to have a safe installation

 

[hobbystuff]

Not sure why you would want to turn off your solar system, but I believe the preferred place is to put the switch is near the panels. But realize that the connection from the controller to the battery will still be hot.



David

Sometimes having another active charge source on my house bank causes my regulator to fiddle with the field current on the alternator, which makes my tachometer drop off or not register rpm. When the engine is running, I would like the option of being able to turn off the solar charger if it impacts my tach.

 

[JDCAVE]

Sometimes having another active charge source on my house bank causes my regulator to fiddle with the field current on the alternator, which makes my tachometer drop off or not register rpm. When the engine is running, I would like the option of being able to turn off the solar charger if it impacts my tach.

Yes, that happens with my system as well. I’ve also heard this has been a problem with other installs. Evidently there is a fix for it on with adjustment of alternator charge controller (Balmar 612). I believe this happens when the batteries approach near fully charged.

Jim