Real world results for flat solar

[steveluannj]

I just upgraded my solar setup, and was wondering what I should see from it. I have the factory Furrion 175W panel, and added 2 more 165W Renology panels, connected in series. I checked the open circuit voltage, and got the expected 16V (sorry- 61V), and as the sun came up today I started charging, currently getting about 12A at about charging current at 11AM in Boise, clear day. I realize that I can not expect to get 500W, but I was thinking more than 150. What do people see in real world charging of flat to the roof panels as a fraction of the panel rating? I am trying to find any major issues before I seal the mounting brackets with Dicor.

[TucsonJim]

Remember that your controller will limit your current flow based upon the charge status of your batteries. You will only get maximum solar charging when the batteries need a substantial charge.

For example. I have 2000 watts of solar. When I checked a little while ago, my charging was way below that because my batteries were at 98%.

Jim

[steveluannj]

Remember that your controller will limit your current flow based upon the charge status of your batteries. You will only get maximum solar charging when the batteries need a substantial charge.

For example. I have 2000 watts of solar. When I checked a little while ago, my charging was way below that because my batteries were at 98%.

Jim

Agreed- I emptied out my batteries, since I am not sure where I was due to my shunt meter being way out of calibration.

What is the most you have ever seen with 2KW of panels?

[TucsonJim]

What is the most you have ever seen with 2KW of panels?

I hit 1,600 today while running one AC. I'll be boondocking tomorrow and I'm at about 60% SOC. So I might even hit higher.

Jim

[acoleman43]

I just upgraded my solar setup, and was wondering what I should see from it. I have the factory Furrion 175W panel, and added 2 more 165W Renology panels, connected in series. I checked the open circuit voltage, and got the expected 16V, and as the sun came up today I started charging, currently getting about 12A at about charging current at 11AM in Boise, clear day. I realize that I can not expect to get 500W, but I was thinking more than 150. What do people see in real world charging of flat to the roof panels as a fraction of the panel rating? I am trying to find any major issues before I seal the mounting brackets with Dicor.

16V with 3 panels in series??? Seems super low to me. Was the sun almost perpendicular to panels at that point? What solar charge controller do you have?

With 3 panels (going off the Furrion 165W panel OC voltage of 2.12v...x3 is over 60V) in series at around 11:00 you should be seeing about more than 3X that much voltage.

[howson]

steveluannj -- I agree with acoleman43. According to the specs, the Furrion's operating voltage is 18.7. The Renogy's is 18.1. Since these are in series, the voltage will add but operate at the lowest of the rated specs with the mix of panels. So 18v x 3 (panels) = 54V.

If we're using the Open Circuit Voltage (as stated in the OP) these values will be even higher.

If the 16V was measured at the input to the MPPT then could the panels be wired in parallel instead of series? Even 16V seems low for the Open Circuit Voltage of panels in parallel.

Remember that the amperage is modulated in an MPPT-controller array (thus power changes based on available sunlight, or total generated PV). Below is an example from my Victron setup -- note how voltage is relatively constant (after stabilizing) but amperage changes based on demand and PV. (Power = Voltage x Amperage)


Howard

[steveluannj]

16V with 3 panels in series??? Seems super low to me. Was the sun almost perpendicular to panels at that point? What solar charge controller do you have?

With 3 panels (going off the Furrion 165W panel OC voltage of 2.12v...x3 is over 60V) in series at around 11:00 you should be seeing about more than 3X that much voltage.

Sorry- I should have been more careful. I have over 60V open circuit. I am at 43 degrees north, so the sun does not get that high- 56 degrees at solar noon. I have the Renology Rover 40A charge controller. There is some shading of the panels in the afternoon, so I will move it into the open this afternoon to see if I can get more.

[steveluannj]

I moved the camper into a place where the sun will be unobstructed at solar noon, and the most I was able to record was 25 amps charging at 13.82 volts to the battery. This is 345W output from the charge controller. If I read the specs correctly, the most I should ever get with the Furrion in series is 8.82A at about 55V, so I am looking at a best case 484W from the panels. Since it is hazy today, and we are barely past the spring equinox, I expect to see proper numbers on a sunny day in summer. I also heard back from the suppliers of my shunt meter, and they are sending me a new unit, so once I eliminate that source of confusion I can better measure what I am getting and using, to work out the performance of this system for boondocking. I am jealous of the data Howson gets though. I hope the engineer in me has retired long enough that I can just let it go and enjoy camping before I need to upgrade to keep up. ;-)

[acoleman43]

I moved the camper into a place where the sun will be unobstructed at solar noon, and the most I was able to record was 25 amps charging at 13.82 volts to the battery. This is 345W output from the charge controller. If I read the specs correctly, the most I should ever get with the Furrion in series is 8.82A at about 55V, so I am looking at a best case 484W from the panels. Since it is hazy today, and we are barely past the spring equinox, I expect to see proper numbers on a sunny day in summer. I also heard back from the suppliers of my shunt meter, and they are sending me a new unit, so once I eliminate that source of confusion I can better measure what I am getting and using, to work out the performance of this system for boondocking. I am jealous of the data Howson gets though. I hope the engineer in me has retired long enough that I can just let it go and enjoy camping before I need to upgrade to keep up. ;-)

That's not bad. I have 1260W solar array and will typically get 800W-1000W at peak hours. I have gotten up to 1200W, but that is super rare. Expect about 80-85%% production during peak solar hours

The voltage to the batteries looks right. The solar charge controller will convert the voltage form your solar array to the voltage needed to charge the battery.

[bilco82]

Sorry for the dumb question, but how do I check the charge level from solar controller. Do I have to disconnect it form the batteries?

[StephenO]

Sorry for the dumb question, but how do I check the charge level from solar controller. Do I have to disconnect it form the batteries?

Assuming a lithium battery system, it would be rather difficult to tell the state of charge (SOC) with just the charge controller. I guess if you are in direct sun, and the current out of the charge controller is zero, then you could assume that the SOC is 100%. However, determining a SOC somewhere between 0 and 100 would be rather difficult, since lithium has a fairly flat voltage to SOC relationship, unlike lead acid. You're better off to get a battery shunt monitor, that can measure current in and out of the batteries, and give you an accurate SOC reading.

[acoleman43]

Sorry for the dumb question, but how do I check the charge level from solar controller. Do I have to disconnect it form the batteries?

If you have a multimeter, use it to determine voltage from lithium battery (without charger connected). Use this chart below for reference.