HeLp! New to solar and can't figure out what wrong.

bluewave

Hello!

We recently set up a solar system in our yurt (parts acquired from Renogy). The components consist of :

two 100W solar panels joined together in series.
Rover 20Amp Charge Controller
1000w inverter
and two Gel Seal-Lead Acid Batteries join together in parallel
And battery is grounded to our metal yurt cable....not sure about this really but was the most obvious solution. 

Everything seems to be hooked up correctly. The system turns on normally and we are able to power lights and charge our devices. BUT there is something wrong. The panels as of right now get dappled light so we have the charge controller on the MPPT setting to grab the available light more effectively, however there are parts of the day where they do receive direct sunlight. When we first set everything up the system seemed to work quite well. We were getting 14+ Volts coming through on the main display of the charge controller. The last few weeks even when it is sunny all day we wont get more than 12.8 volts. Then right when it gets dark it will drop to 12.4 and we will only be able to power 2 lights and a computer for 1-3 hours. We barley use the system during the day.

Troubleshooting---
I unhooked the solar panels the other day for the whole day. The batteries were at 50 %, when I re connected the panels the batteries were still at 50%, so I guess that means the batteries are not just draining themselves.

I had another inverter, so I replaced the 1000w inverter with the other exact same one and it is working the same. So I guess that means the inverter is ok.

I really don't think the charge controller is broken (its brand new) but have another and could replace it to see?

Today, with everything re-hooked up I took note of the reading on the charge controller. (Note: the inverter was off all day, no power was being used). It was a cloudy/rainy day so the reading were extra low...but I don't know what normal.

the panels had been receiving light (cloudy )for 5-6 hours and the charge controller read 12.4. The panels read ( screen with panel symbol?) 35.4 v. Panel to battery screen read 1.13 A, battery was at 64%, 0 output to lights.

Do those kind of reading seem normal?

It seems like the whole system charges very slowly and drains very quickly. A friend in the area has the same set and gets lot more hours of use from his system. 

Also, does using extension cords drain the batteries quicker?

Any advice would be helpful or trouble shooting ideas. Thank you!!!!!

mike95490

Welcome.
  Sadly, you bought solar panels. Dappled shade and cloudy weather will reduce their output effectively to zero.  The panels must be in bright sunlight.  even the shade from a leaf laying on the panel will greatly reduce it's output.  Shadows from tree branches, even without leaves on the tree, will reduce the output.
  The power drain caused by a large 1,000 w inverter idling along, is likely close to 1/3 of your daily harvest, try leaving the inverter off, unless you are using it. 
  Batteries slitting low for  couple days can quickly degrade the batteries, use your generator to get them charged back up before they are toast.

BB.

As Mike says... It sounds like a combination of shade, really too small solar array, too large of AC inverter, and expectations of power generation that this unit cannot meet as is. More than likely, everything is working as best it can.

Lets look at the battery first... Guessing 2x 12 volt @ 100 AH Gel batteries? If so, the size of solar array would be something like--Assuming 5% rate of charge (summer/sunny weather usage) to 10-13% rate of charge (full time off grid):

• 200 AH * 14.2 volts charging * 1/0.77 panel and controller deratings * 0.05 rate of charge = 184 Watt array minimum
• 200 AH * 14.2 volts charging * 1/0.77 panel and controller deratings * 0.10 rate of charge = 369 Watt array nominal
• 200 AH * 14.2 volts charging * 1/0.77 panel and controller deratings * 0.13 rate of charge = 184 [fixed. -BB.] Watt array "typical" cost effective maximum
  

And the maximum cost effective array on a 20 amp MPPT charge controller:

• 20 amps * 14.2 volts charging * 1/0.77 panel+controller deratings = 369 Watt array cost effective maximum

And for an off grid home/cabin, suggest that the battery bank supply 2 days of "no sun" and 50% maximum discharge (for longer battery life):

• 200 AH * 1/2 days of storage * 0.50 max discharge = 50 AH @ 12 volts per day
• 200 AH * 12 volts * 0.85 AC inverter eff * 1/2 days * 0.50 max discharge = 510 WH of 120 VAC power per "no sun" day (or over night)

Your 1,000 Watt inverter--If you ran it at 100% rated power, would support ~30 minutes per day usage, for 2 days (4 days if you take batteries "dead"). The typical load for this size battery bank would be in the 100 Watt range

• 5 hours per night * 100 Watts = 500 WH per night

From your 2x 100 Watt solar panels--If they  are tilted towards south, near Duluth Min:

http://www.solarelectricityhandbook.com/solar-irradiance.html

Duluth
Average Solar Insolation figures

Measured in kWh/m2/day onto a solar panel set at a 43° angle from vertical:
(For best year-round performance)

Jan	Feb	Mar	Apr	May	Jun
2.54	3.79	4.46	4.85	5.03	5.03
Jul	Aug	Sep	Oct	Nov	Dec
5.29	4.99	4.20	3.38	2.59	2.18

For example... 200 Watts of solar In October running an AC inverter (efficiently sized, DC turned off when AC power is not needed):

• 200 Watts * 0.52 off grid AC system eff * 3.38 hours of October sun (long term average) = 352 WH per day average (some days more, some days less)

It sounds like you are using "a lot" of power (for battery bank size, size of solar array, hours of "no shade" sun per day) and the battery bank is just going to take a number of days to recharge (by solar):

• 200 Watts * 0.77 panel+controller eff * 1/14.2 volts charging * 3.38 hours (October) sun = 36.7 AH per day October AH charging
• 200 AH * 0.50 state of charge = 100 AH to charge
• 100 AH / 36.7 AH = 2.7 days of "full" October sun to recharge your bank (based on 50% SoC estimate)

Anyway--Lots of guesses about your location (really Ashland Wi--Duluth Min looked close/similar to Ashland).

Your thoughts and power needs?

-Bill

Photowhit

Always preferable to be hard wired. That said for a small system, it's not a huge deal.

Might say what inverter you have so we can give some feedback on that, you should learn the 'idle' energy use, I like that you went and turned it off. Generally we would encourage using a true sine inverter. Modified sine wave inverters can be hard of some delicate equipment and motor. Shortening their life and using more energy to do it!

Using an MPPT type charge controller gives you some flexibility. You might buy some 10 gauge wire and move your 200 watt array in to the sun/a sunnier area. The charge controller should stay near the battery bank. Solar panels are pretty cheap, if your 20 amp chagre controller can be 'over paneled' I'd go ahead and use 4-500 watts of array. If not you might squeeze what you can on it. Solar panels typically only produce about 75% of their panels rating.

bluewave

Thanks for all of the help. Here are all the links to the exact set up. Maybe helpful.

Batteries: https://www.renogy.com/deep-cycle-hybrid-gel-battery-12-volt-100ah/

Panels:  https://www.renogy.com/100-watt-12-volt-monocrystalline-solar-panel-compact-design/

Inverter:https://www.renogy.com/1000w-12v-pure-sine-wave-inverter/

Charge Controller:https://www.renogy.com/rover-li-20-amp-mppt-solar-charge-controller/

**all wires, excluding the one that are connecting the batteries, came with the products. So I am assuming they are sufficient. 

The reason I think something is wrong,  beyond just not having a deal location for long term direct sunlight, is because yesterday when I left the batteries were 64 percent charged and charging,12.4 v. The inverter was off completely. We always turn it off when we are not using lights or charging. When I got home the battery was 54 percent charged and 12.2v. The only thing receiving power while I was gone was the charge controller, which I am assuming is designed to use minimal power for display. Why in this case does the battery discharge when the panels are no longer charging the system? how can the batteries be at 64 when I leave and 54 when I come home? 

Also reminder we have been having this problem for several weeks, not just on cloudy days. On a sunny day the panels get direct sun light for 5-6 hours. Still on these days, getting barely any juice from the batteries in the evening.


Also @BB. I might need some help decoding that info, more explanation or simpler terms would be helpful We are located near Bayfield WI

Thanks for all your replies!

Photowhit

bluewave said:

... when I left the batteries were 64 percent charged and charging,12.4 v. The inverter was off completely. We always turn it off when we are not using lights or charging. When I got home the battery was 54 percent charged and 12.2v. ....

Yes, this is something that is likely more of a perspective thing...

Unless you have a shunt based battery monitor, the percent of charge is based on voltage. So in an active system, charging and discharging, like a broken clock it'll only be correct twice a day.  

I suspect it was an over cast day with minimal charging if any?

The system voltage based State of Charge (SOC) said it was 64% but while charging the batteries with current moving toward the batteries the voltage is the artificially high. When discharging the system voltage will be artificially low. Consider that when a battery is around 80% full more like 90% for a SLA (sealed lead acid battery) the voltage would run away without the charge controller connected. Even limited by the charge controller the voltage is around 14.5 volts, at rest (disconnected from the system) a SLA battery would be around 13 volts.

I really don't care for voltage based SOC readings. There are shunt based SOC monitors, that measure the current going into and outf the battery, but even they can create confusion when not setup properly. Better to stick with what you have and understand what is going on!

I suspect when you came home it was at duck or later with no actual charging going on...

Here are the basic cycles of charging, I left in the first paragraph from a reply I saved, since it's a common misunderstanding, this relates to flooded lead acid batteries, but SLA will be similar;

To run through your original post, The voltage you are seeing is the system voltage and not the battery voltage. If you are connected to charging or a load it will effect the system voltage.

During charging, there are basically 3 stages of charging, Bulk, Absorb, and Float.

BULK;

First thing when charging starts you will be in bulk, the voltage rises from what ever the system voltage was to a set point, around 14.5 volts. At that point the Charge controller stops the voltage from rising. Higher voltage can damage sealed batteries.

ABSORB;

Once the battery hits the preset point the charge controller keeps it at that point. Your batteries are roughly 80% full. Flooded batteries will start accepting less current at 80-85% full AGM/Sealed may go a little longer before accepting less current.

On many controllers you can set this point, Some will have different presets for Flooded, and sealed batteries, or flooded, AGM, and sealed batteries. 

The charge controller has a couple ways to know when to switch to float, Most inexpensive Charge controller are just timed for 1.5-2 hours. Some will also see less current flowing through the charge controller and shut it down when minimal current is flowing through the controller. On more expensive charge controller. You can set battery capacity to give the Controller a better idea of when to stop. you can also set a longer Absorb time. Or set 'end amps' a amount of amps flowing through the charge controller to stop Absorb and switch to the final stage.

FLOAT;

Once the Controller has determined the battery is fully charged it reduces the voltage to a point where very little current is flowing to the battery. This will prevent the battery from over charging and heating up.

While in 'Float' the charge controller watch for voltage drop, which would indicate a load. If the voltage begins to drop the charge controller will allow as much current to flow from the panels/array to compensate and maintain the voltage. If the voltage can be maintained, the load will in essence be running directly off the array/solar. If the voltage drops below the preset float voltage, the controller may start a whole new cycle if it stays there for a period of time.

The system voltage drop you see at night when the sun goes down is the charge controller moving into a resting mode with no energy to contribute to the system.

The morning voltage may reflect a load present that is effecting the voltage level. With sealed batteries, you would want to disconnect the battery from the system and allow it to 'rest' for a while to get an accurate idea of it's SOC (State Of Charge) from the voltage

Photowhit

bluewave said:

Also reminder we have been having this problem for several weeks, not just on cloudy days. On a sunny day the panels get direct sun light for 5-6 hours. Still on these days, getting barely any juice from the batteries in the evening.

As Bill has pointed out, your array is very minimal for your battery bank in a daily system.

I don't know what you have running on those sunny days, but you should do an analysis of you energy usage, what you use, how much it uses and how many hours you are using it.

There are some on line calculators to help with this, Here's one, you don't have to sign in for it to run the numbers for you;
Off Grid Solar Load Calculator | Northern Arizona Wind & Sun (solar-electric.com)


So you have a 200 ah battery bank, being fed by 200 watts of array. 200 watts of array in full direct (angles perpendicular to the sun) will generate about 150 watts or power. This is the difference in Standard Test Conditions and Normal Operating Cell temperature values. More on this is you want it.

So about 150 ÷ 14.6 (charging voltage for 12 volts) = about 10 amps, so the most it can put in in 5-6 hours is 60 amps. To understand how much less this is than is possible the batteries specs say they can take u to 30 amps EACH or 60 amps.
10 amps an hour is about 5% of your 200ah battery capacity.

So look at your property layout, and figure out how to get better exposure. Can you pole mount the array? perhaps north of the Yurt so the clearing for the yurt will allow for more regular sun exposure? Can you add to your array, 20 amp charge controller says max array is 260 watts, 


It also says;

Understanding these bits of info might take a bit of interpolation. Solar Input would be the power coming into the charge controller, not the panel rating, The second says it appears to have some clipping ability. You might read through than manual and see if it refers to this, I just did a quick look for specs;

RVR203040-Manual.pdf (renogy.com)

I understand that you are living there and need some creature comforts, but would recommend charging with a generator if you have one. I certainly understand not wanting to use one. I haven't in 20 years, but batteries held at a low SOC are what typically ruins them.

Without looking at your exact location and doing a site review, You will likely want to get your panels into a better location, or cut trees or other shade producing elements so your array has better exposure. 

Without seeing your usage, I  would personally suggest moving to a 24 volt system, exchanging the inverter for a 24 volt version (if they have one or if within 30 days do their no hassle return). At 24 volts you can use the same batteries in series, Your 20  amp charge controller can handle double the array. That gets you to near a 10% charge rate. 

bluewave

Ok thats helpful!

So you are saying that the SOC reading of the battery is effected by the voltage flowing in. So when it is no longer light out the voltage coming from the panels will drop and the SOC battery reading will also drop. Hmm. Interesting. I guess I wonder what is the point of having a battery reading at all on the charge controller if it is not really giving you a reading of whats IN the battery to stay?

Until we can get a better set up with more panels is there anything I can do to program the charge controller to receive energy more efficiently? or should I just assume it is always pretty much in bulk mode because we are not getting anywhere close to 14.5 v?

BB.

Bluewave,

Just cut and paste a section and ask about it (one at a time is probably better than 5x at a time).

-Bill

Photowhit

bluewave said:

Ok thats helpful!

So you are saying that the SOC reading of the battery is effected by the voltage flowing in. So when it is no longer light out the voltage coming from the panels will drop and the SOC battery reading will also drop. Hmm. Interesting. I guess I wonder what is the point of having a battery reading at all on the charge controller if it is not really giving you a reading of whats IN the battery to stay?

I guess it is helpful at times, particularly at night discharging, though heavy loads will effect this greater than small loads. Say you ran a microwave for a minute or 2 with the batteries at roughly 60% SOC, you might see .2-.5 volt drop and then they would recover over a mew minutes to an hour.

bluewave said:

Until we can get a better set up with more panels is there anything I can do to program the charge controller to receive energy more efficiently? or should I just assume it is always pretty much in bulk mode because we are not getting anywhere close to 14.5 v?

Little you can do with the charge controller. 
...but I would suggest trying to get some addition charge into the battery bank. If you watch it on a sunny day, you should see some improvement during the day, charging without a load. I think you charge controller has an output in amps and volts to see how much you are pushing into the battery bank.

kvarnanna63

Some of the reasons your 200 watt solar panel might not be in good condition are inverter problems, a malfunctioning solar meter, snail trails. Other reasons your solar system might malfunction are micro-cracks, seasonal changes, shoddy installation workmanship, broken panels, dirt and dust, and PID effects.