RV solar noob here

[Chasleyko]

Thanks chrisski. My son are an EE, and he said google it. Ha

[Chasleyko]

Thanks for your patience Mike. I’m just using the panel portable in front of my trailer. I’ve noted that the single panel will top up my batteries from 50-60% in 2-3 hrs with full sun. As I said before, the controller doesn’t seem to be reading battery levels accurately tho. So do I need a better PWM controller?

[chrisski]

T Would it matter if nothing is connected to the load side of the controller?

As far as needing a load, I don't know if there's a good way to answer that when the instruction manual says hook a load, and the only direction it gives is a "cutoff value like at 10.6 Volts," power is no longer supplied and perhaps a mention of "don't hook the battery to be charged to the load."

I don't know how the circuitry inside is designed.

What I did with my extremely cheap PWM controller is not hook the load to it, despite no direction from the manufacturer. I hooked it to a 100 watt solar panel anda 96 ah 12V battery and a 400 watt inverter to a battery that powered a 19 watt light, and left that on for only a few minutes. That is what I consider my emergency household generator, Which I would only use to charge 4 to 8 USB charging devices.

That's only a limited experience I have with a single cheap PWM charger,

Years ago I looked at cheap homemade wind power generating devices, and these needed a load to dump any power in should the windmill get hit with a sustained burst of wind creating too much power. In this case the guy used a space heater above the fireplace to bleed off the extra energy.

From my limited understanding, the load outputs on the PWM chargers are not intended to "Bleed off" the extra energy produced, but will power a DC device that does not draw a lot of power and dies not need to be left on when panel voltage and battery voltage drop below that 10.6 VDC or whatever you set threshold.

I think the only way to know for sure is to be an electrical engineer, and I was only an electronics technician for a few years three decades ago, so my understanding only scratches at the surface and sometimes dangerously.

[Mike90250]

slow down. A MPPT controller is wasted on a single100w panel. There is nothing for it to do except run in PWM mode. MPPT controllers take moderate DC voltage (20-90V) from several panels in series, or a 50V 300w grid-tie panel. The MPPT tracks the array to its most efficient voltage and downconverts that to your battery charge, transforming volts for more amps.

PWM controller : amps in = amps out 18V 3Ain = 14V 3A output (54w in , 42w out )
MPPT controller : watts in = watts out 87V 3A in = 14V 18A output ( 260W in = 260W out)

But that power gain comes at the cost of a much more expensive controller. Also, wires to carry 3A from the panels on the roof, or far away, are much less expensive than wire rated for 18A

[Chasleyko]

Thanks for your response guys I don't have an inverter, so I never run anything that uses 120v unless I'm plugged in at a campground. I use only the 12v side of the system when dry camping, and generally can run for three days off my 2-12v batteries. I got a single 100w panel solely to be able to stretch that 3 days if I want to. Asterix my controller shows the load in manual setting, but havent gone into the menu to see if it's on or off. Would it matter if nothing is connected to the load side of the controller? I will follow your suggestion and find a MPPT controller to see if it will show current values accurately.

[Asterix]

I recently acquired a Wiese 100w solar panel with an HP 2410 controller. I dry camp with my trailer frequently and am looking to just keep my 2-12v batteries topped up. We don’t use a ton of power, nothing 110 off an inverter. I have two questions: When I hooked the system up, the connections for the batteries and the panel were obvious, but it also instructed me to hook up the load. Since the load (trailer) is already connected to the batteries I assumed this was unnecessary. Secondly, the controller shows proper output voltage and existing levels in the battery (consistent with the trailer readings). However, after a couple cycles the controller shows a greatly reduced battery level, ie from 75% to 15-20%. This does increase with charging, but when I unhook the panel it always goes to 100% battery level even if it showed 45% hooked up. Any thoughts out there?

Well here is a quick run down of the setup.
Solar panel to charge controller, the battery to the charge controller and as far as the load is concerned, you don't need to connect anything. If you look at your handbook for the controller you can turn the load on and off at will. I am presuming you are connecting the inverter directly across the 12V batteries and not trying to use the load out.
I would suggest buying an MPPT controller, given it is more efficient than the PWM controller you have. You can pick up a 20A MPPT controller for around the same price as the HP 2410

If you take into account what Mike has said above, then you need to be looking at what is draining power. The only thing you have on is the inverter and I know from personal experience that these are just power hogs.

An inverter will draw power constantly, no matter if you are using the 110V or not, disconnecting the inverter via a switch and turning it on, only when you use it is the obvious way to save power.
Just to pre-empt the question about the inverter being turned off at the switch, that just turns the inverter output off, leaving the inverter itself, on and drawing power.

Just remember that whatever you connect to the batteries will drain power, if it is turned on.

[Mike90250]

There are so many low grade solar controllers out there, it's impossible to figure out what is wrong.
You can do it right, or you can do it cheap. You now see the results of cheap.

Now a 100w panel is not going to do much for you, figure an average of 4 usable solar hours a day, and a poorly aimed panel, in full sun, you can expect to harvest about 300 watt hours daily.

That would recharge usage of 240 watt hours. You can allocate that usage anyway you want
50w fan for 4.8 hours
20 watts of lighting for 12 hours
Charging a cell phone for 6 hours

Figure the wattage of the load, x hours and you get watt hours Don't mess with amps & volts

[Chasleyko]

I recently acquired a Wiese 100w solar panel with an HP 2410 controller. I dry camp with my trailer frequently and am looking to just keep my 2-12v batteries topped up. We don’t use a ton of power, nothing 110 off an inverter. I have two questions: When I hooked the system up, the connections for the batteries and the panel were obvious, but it also instructed me to hook up the load. Since the load (trailer) is already connected to the batteries I assumed this was unnecessary. Secondly, the controller shows proper output voltage and existing levels in the battery (consistent with the trailer readings). However, after a couple cycles the controller shows a greatly reduced battery level, ie from 75% to 15-20%. This does increase with charging, but when I unhook the panel it always goes to 100% battery level even if it showed 45% hooked up. Any thoughts out there?