Designing Off-Grid System With Possible Solar Later- Need Design Advice

Scargod

Re: Designing Off-Grid System With Possible Solar Later- Need Design Advice

Was hoping I could get some help with this.
I'm out here in the middle of nowhere with nobody to come and fix this or teach me how to set it up.
The system is stable and works fine now but what about in January when there is very little sun? I don't want to run the generator unnecessarily because of similar reasons as above. Getting competent help to come here and change out propane and check that the system is all functioning properly is very difficult. I don't want a third year of flat batteries. It was a lot of charging to get them back. My investment in the batteries is significant but just as important is the difficulty of hauling eight 140 pound batteries in and out of my location.
Among my other questions, is the generator exercise program going to charge the batteries if they need it?

Alaska Man

Re: Designing Off-Grid System With Possible Solar Later- Need Design Advice

If there is no load on your batteries (I.E. Inverter is off, no DC loads) then the array should keep them up. Depending on what you have, many inverters come with a control panel and an AGS (Automatic Generator Start) should be part of that equipment. Generators use fuel, so it still requires some attention.

Walking away from a battery Bank for months is not something I would do. You may be better off hauling them home with you and putting them on a trickle charge for the winter. We have over $7,500 in our battery bank. For that kind of scratch, one or two days of huffing and puffing a year is easily justified. In My Humble Opinion, anyway.

You should also have a LVC (Low Voltage Cut-Off) as part of the system.

Scargod

Re: Designing Off-Grid System With Possible Solar Later- Need Design Advice

Alaska Man wrote: »

If there is no load on your batteries (I.E. Inverter is off, no DC loads) then the array should keep them up. Depending on what you have, many inverters come with a control panel and an AGS (Automatic Generator Start) should be part of that equipment. Generators use fuel, so it still requires some attention.
I do have all that stuff if you look at post 20, third line. I have five 40# tanks to last the generator for the six to eight, dormant winter and spring months. I may come up after 5-6 months and check on it.

Walking away from a battery Bank for months is not something I would do. You may be better off hauling them home with you and putting them on a trickle charge for the winter. We have over $7,500 in our battery bank. For that kind of scratch, one or two days of huffing and puffing a year is easily justified. In My Humble Opinion, anyway.
That just isn't an option. We are remote and have two boat trips and one portage before we can put them in a car and haul them somewhere, where we could get someone to store and keep them up.
You should also have a LVC (Low Voltage Cut-Off) as part of the system.
I do have a low battery cut-out (LBCO) setting, but how will this help me if the inverter is going to be turned off anyway?

Right now, when I limit the generator to running for an hour (it can do bulk at 80 amps in that hour) it shuts off and turns off the inverter and gives me a blinking fault light. I don't understand that. It's also kind of hard to experiment with the system while we're here. Like trying an exercise routine every third day for one hour...with the inverter off.
I am also interested in finding a way to trickle-charge my four deep cycle 12V. batteries that I use for trolling, during the winter. I don't know what's the best way of doing this. Do I want to tie them in with the power system batteries? Use a DC to DC charger?

Alaska Man

Re: Designing Off-Grid System With Possible Solar Later- Need Design Advice

I would think with 5 PV panels and no loads on your battery you would be fine for the winter. Unless your solar array gets burried under the snow or something.

Scargod

Re: Designing Off-Grid System With Possible Solar Later- Need Design Advice

Given what I have, with three panels 235 watt panels in series and two 240 watt panels in series and then them hooked in parallel, I am seeing high 60's for voltage and almost 13 amps. Is this what they should be putting out? I was told to hook them up this way, seeing as how I have a Flexmax 60 charge controller. I think that is why.
Back to my main issue: I tried to setup the AGS to shut off the generator when it reached 90% SOC. It did not do that. The generator will shut off based on a run-time setting of a half-hour but I end up with a blinking red fault light. I tried the "test button" on the AGS and that worked fine. I dn't know if I have conflicting settings or not.

This is how my system is setup:
Under CTRL button/category I have the AC in Control set to VDC connect.
AGS:
AGS is set to be controlled by DC volts.
AC input amps set to 30.
Battery type is "custom": I plugged in 420AH wet batteries to the equation. I set SOC to run from 20 to 90%.
Run amps: start=30/stop=20
Run time: 7AM to 7PM
Max run time: 30 minutes (generator at 70% charge rate can normally do bulk charge in under 30 minutes)
Quiet time: 7PM to 7AM Redundant?
Exercise: off

BMK: Charge efficiency=auto, Battery size=420 AH

Inverter setup:
02B LBCO=23
02C AC in time=7AM to 7PM
02D AC In-VDC connect=24.4 / disconnect=28.8

Charger:
30 amp AC input
Custom battery:
Absorb voltage=30.8
Float=26.8
Equalization=31.0
Max charge rate=70% (80 amps) (FYI, Generator at 100%=112 amps)
VAC dropout=80 VAC
Absorb Time is set to SOC=85% Should be higher, like 90%?
Max charge time=30 minutes
Final charge state=Silent
DC Volts to rebulk=24.4

westbranch

Re: Designing Off-Grid System With Possible Solar Later- Need Design Advice

Here is my take on your problem, maybe it will help.

Site is too isolated to remove batteries for winter.
You have suffered a 'damaging incident' to your batteries due to poor care by the caretaker. Light/inverter left on or ?...

Solution: wire in a separate circuit to power that needed lite, powered by a lone 12 v battery that is charged from the main bank after Float reached, by a Small CC to the 12V battery... (don't know the CC make so don't know it it has Aux functionality ie Classic?) If the battery goes dead then that is all...

If you leave the battery bank fully charged just leave the CC hooked up and disconnect all else , Inverter lights etc. If it is getting a maintenance charge all winter it will be fine in the spring...

hth

Alaska Man

Re: Designing Off-Grid System With Possible Solar Later- Need Design Advice

I'm not sure how to help with all your settings. I don't know your equipment so I would have to read through your manuals and I'm new to all this stuff myself.

I do know with my system a 30 minute generator run time wold not be near enough to charge by bank. If I have to charge using my genny it's more 4-5 hours before I float. And that's using a 150Amp charger connected to a 12Volt system.

I will say that from what I know with no loads and your bank connected to the array they should stay charged up enough for the winter.

You may want to get in touch with tech support to figure out what's going on with your AGS.

inetdog

Re: Designing Off-Grid System With Possible Solar Later- Need Design Advice

Alaska Man wrote: »

I'm not sure how to help with all your settings. I don't know your equipment so I would have to read through your manuals and I'm new to all this stuff myself.

I do know with my system a 30 minute generator run time wold not be near enough to charge by bank. If I have to charge using my genny it's more 4-5 hours before I float. And that's using a 150Amp charger connected to a 12Volt system.

And I am willing to bet that much if not most of that time is spent in absorb.
Have you noted how long it takes to finish just the Bulk stage?
So, weather permitting, and if you are using the generator primarily to catch up on a series of poor sun days or heavy loads, running the generator in the morning to take care of the Bulk stage and leaving the rest to the PV system makes a lot of sense.

Alaska Man

Re: Designing Off-Grid System With Possible Solar Later- Need Design Advice

inetdog wrote: »

And I am willing to bet that much if not most of that time is spent in absorb.
Have you noted how long it takes to finish just the Bulk stage?
So, weather permitting, and if you are using the generator primarily to catch up on a series of poor sun days or heavy loads, running the generator in the morning to take care of the Bulk stage and leaving the rest to the PV system makes a lot of sense.

Yup, that's what I have decided to do. At least until I get panels on the east and west side the place. It makes much more sense to let the array top of the bank after the genny bulks it up.

Scargod

Please comment on my update! I overwintered the battery banks with no issues. Nobody touched the system for nine months... I stopped the tracker in a low position, where it gets the most sun in the early part of the day. After a few hours it goes behind the mountain in the winter and then it's just ambient light. I then turned off the inverter and disabled the auto generator start. After being back here for two months the batteries are better than ever.
When I left last fall I tied six, 12V automotive style batteries in parallel and trickle charged them off a fixed position, small solar panel. They were just out in the weather, under plastic.
One battery is for starting the generator. Others are mainly for backup, fishing electronics, etc. Mostly, they are 750-850 CA/70-180AH batteries. When I returned I found that they were all 11.9 volts.
I am hoping to do something better this winter so they are kept in better shape without another solar panel or a big investment. I'm wondering if there is something commercially available to DC to DC trickle charge them separately, but as a group, where they will not pull down the larger 24V banks I run the cabin off of. Or, should I just tie them in? I do have a 50A fuse I can use in the wiring. Are they dissimilar enough from the 450AH batteries that it would be detrimental to one or the other if they were all connected together?

BB.

More or less, you should look at 1% to 2% rate of charge to float already fully charged batteries. So, if you have 6x 100 AH batteries:

• 6 * 100 AH * 1% = 6 amps charging
• 6 amps * 17.5 volt Vmp typical "12 volt panel" = 105 Watt minimum panel.

Put all 6 batteries in parallel verify that they are around >12.5 volts each--Then connect with a simple solar battery charger to your >105 Watt of solar array.

A simple PWM controller will prevent over charging/gassing the batteries and boiling them dry. For pure storage--You want a controller that can be set to float the batteries (around 13.5 volts) or get a PWM controller with AGM/GEL/Sealed battery charge setting--This will help keep the battery voltage lower and lessen gassing.

I would suggest that you check the batteries every 1 month, or at least every 2-3 months to make sure that they do not "boil dry" (expose the lead plates to air, the battery is pretty much trashed).

http://www.solar-electric.com/inverters-controllers-accessories/chco/mochco/stpwmchco.html

You can parallel batteries to float them... The down side is that if one gets a shorted cell--It can take down the rest of the batteries and ruin all of them (especially if you are not there to check them every so often).

There are other options--But one relatively small solar panel + single controller + a few batteries is probably the least risky (limit a single failure from taking down a large number of batteries/your expensive off grid battery bank).

-Bill

Scargod

Thanks, Bill for that info. I like the Morningstar Duo 25 amp/12 volt charge controller... and was thinking I'd get a 140 watt panel. Wouldn't the "Duo" help mitigate the chance that a single, bad battery would take down all the batteries if I had them in two separate banks that are in parallel?

BB.

It depends on your luck. More interconnected devices, the higher chance a single failure will take out other equipment.

If you have other events (such as lighting), you may need to design for those factors too.

-Bill

Scargod

OK. I hear what you're saying but that introduces another factor and level of complexity. I did not know that this basic battery charging/maintaining system would need to be grounded. Yesterday I found an electrical contractor, who does solar, and they are willing to come to my remote location and go over what I have and troubleshoot the anomalies I am seeing with my AGS and make any recommendations on system upgrades.
I purchased a 150 watt "kit" that has a panel, wiring and a basic controller and ordered the Morningstar Duo 25. Thanks

BB.

Scargod wrote: »

OK. I hear what you're saying but that introduces another factor and level of complexity. I did not know that this basic battery charging/maintaining system would need to be grounded.
...
I purchased a 150 watt "kit" that has a panel, wiring and a basic controller and ordered the Morningstar Duo 25. Thanks

They do not need to be grounded... And for most small systems/portable battery/solar, nobody does "ground them".

But for larger systems (RV, cabins, homes), you have several types of grounding...

1. Grounding to vehicle chassis--Most cars use the chassis as the negative/return conductor.
2. RV grounding--The chassis may be used for grounding vehicle components... But for Fans/lighting/AC inverters, they typically have two (hot and return) power leads, and usually a "chassis" green wire lead that is tied (somehow) to chassis ground. (green wire grounding is to "pop" a fuse/breaker in the case of a hot to metal case, metal sink, etc. short.
3. Vehicle static grounding--Hang a conductive rubber string to drag on the ground--Reduce the chance of static buildup and getting a shock when you put the key in the lock.
4. Earth Grounding. Driving a 10' rod into the ground... This is for lightning (direct strike energy to earth vs inside the home) and protection against high voltage crossover shorts (the 12kVolt utility line falls on your 120/240 VAC home drop).

There are very few instances where green wire to earth bonding is needed functionally. Mostly some tube type florescent fixtures (helps them start), and some automatic spark ignition systems for stoves/water heaters (uses the ground lead to detect if flame is present or not).

We can talk about the "safety" of floating power systems (ungrounded) vs ground referenced power systems. Each has its reasons to be used... Floating systems can help reduce the chance of shock (hot to earth shock). Grounded systems are cheaper to build (only need breaker on "hot circuit") and help prevent secondary fire/hazard issues (multiple hot/return to earth faults with single breaker/fuses can cause wiring to overheat and start fires).

-Bill