Adding a portable panel to roof mounted panel

BFL13 wrote:

Then all the panels are in the shade

My bad. I missed that they wanted to camp under the trees. Would still add a panel onto the roof though. For when they are not under the trees. And a portable for when they are under the trees. Portable is a pain if you leave the camp for a day, or if storage space is limited, or if it's windy, or if you move often.

hammick wrote:
I called Renology about their 100w briefcase system and they told me that if I put a 100w panel in parallel with my 160w panel my 160w panel will attempt to match the power of the 100w panel effectively giving me 200 watts. Does this sound right?

I just did some quick research and it sound like the Renology tech doesn't understand parallel connections. He would be correct if I was going to connect a 160w panel and a 100w panel in series. Is my logic correct?

IIRC you are using a PWM controller if this is the case you will get 260 watts but...if you are using a MPPT controller he would be correct.

grizzzman wrote:

hammick wrote:
I called Renology about their 100w briefcase system and they told me that if I put a 100w panel in parallel with my 160w panel my 160w panel will attempt to match the power of the 100w panel effectively giving me 200 watts. Does this sound right?

I just did some quick research and it sound like the Renology tech doesn't understand parallel connections. He would be correct if I was going to connect a 160w panel and a 100w panel in series. Is my logic correct?

IIRC you are using a PWM controller if this is the case you will get 260 watts but...if you are using a MPPT controller he would be correct.

Can you explain that please? I can't figure out what difference the MPPT makes. There could be a difference between series and parallel connecting the panels of course, where PWM would not work in series except with a 24v battery bank.

BFL13 wrote:

grizzzman wrote:

hammick wrote:
I called Renology about their 100w briefcase system and they told me that if I put a 100w panel in parallel with my 160w panel my 160w panel will attempt to match the power of the 100w panel effectively giving me 200 watts. Does this sound right?

I just did some quick research and it sound like the Renology tech doesn't understand parallel connections. He would be correct if I was going to connect a 160w panel and a 100w panel in series. Is my logic correct?

IIRC you are using a PWM controller if this is the case you will get 260 watts but...if you are using a MPPT controller he would be correct.

Can you explain that please? I can't figure out what difference the MPPT makes. There could be a difference between series and parallel connecting the panels of course, where PWM would not work in series except with a 24v battery bank.

If you are using an MPPT charge controller, mixing panels of different voltages and/or currents within an array will have an adverse effect on the entire system. Different module outputs make it impossible for the controller to determine the optimal operating voltage and current because they will be different between the different types of panels.

In fact this is one of several reasons i chose PWM over MPPT. My system will grow over time and i don't need to be concerned about if panels match.

grizzzman wrote:

BFL13 wrote:

grizzzman wrote:

hammick wrote:
I called Renology about their 100w briefcase system and they told me that if I put a 100w panel in parallel with my 160w panel my 160w panel will attempt to match the power of the 100w panel effectively giving me 200 watts. Does this sound right?

I just did some quick research and it sound like the Renology tech doesn't understand parallel connections. He would be correct if I was going to connect a 160w panel and a 100w panel in series. Is my logic correct?

IIRC you are using a PWM controller if this is the case you will get 260 watts but...if you are using a MPPT controller he would be correct.

Can you explain that please? I can't figure out what difference the MPPT makes. There could be a difference between series and parallel connecting the panels of course, where PWM would not work in series except with a 24v battery bank.

If you are using an MPPT charge controller, mixing panels of different voltages and/or currents within an array will have an adverse effect on the entire system. Different module outputs make it impossible for the controller to determine the optimal operating voltage and current because they will be different between the different types of panels.

In fact this is one of several reasons i chose PWM over MPPT. My system will grow over time and i don't need to be concerned about if panels match.

Got it now, thanks. Yes their Vmps must be similar or the MPPT will go crazy. I didn't check to see how close the OP's Vmps were. Also I don't know how close they have to be so the MPPT does not go crazy.

However, he could still do MPPT with the panels in parallel as a 12 I think.

PWM does give you some wiggle room for panel Vocs (Vmps don't mean anything with PWM) in parallel to work together.

My CC is the Blue Sky Sun Charger 30 PWM. Should have it Monday.

I went to the trailer today to measure my wiring length from the panels to CC and CC to battery. I don't think I'm comfortable adding more panels given my stock wiring and the extremely difficult if not impossible job to add bigger wire.

I have four or five feet of 10ga wire from the panel to the CC. I have about 19 feet of 10ga from the CC to the batteries. I can probably trim 6" off the panel slack and about a foot of the battery slack. If I had built the trailer I would have used 6ga.

Go Power does say that your can go up to 25' from panels to battery with 10ga wire up to 240 watts of panels.

If I get a portable panel I will go directly to the batteries with a separate CC.

An alternative plan I had was to splice the panel wires to the battery wires and then install the Bogart PMW controller underneath the trailer in a waterproof gang box by the batteries. I would then install the Trimec monitor and connect it to the Bogart CC with telephone cable (the Bogart CC sounds like the cat's ass being able to regulate charging based on amps out). This way the run from the CC to the batteries would be about 2' and I could easily use bigger wire. My factory CC would then be in the wall as an ornament.

Yank your solar controller from where it is, and splice the array and battery wires together there. Now go to the battery bank and find the solar wires that go onto the battery bank.

Now insert your original controller by using the previous battery wires as the array side new wires to the controller and by adding new wires to be the controller -to- battery wires. Ta Da !

You can still add your portable panel- to -controller wires to the array side of the controller in its new position as previously discussed.

You don't need a second controller unless your new total array Isc exceeds about 16a Isc for the original 20a controller.

I had a picture somewhere of this whole deal from 2013:

The controller for the 130w on the roof is up front by the batteries using the "pre-wired for solar wires". The controller for the other set of panels (two 100s in a twirler) on the ground is behind the fridge side vent where you can see the array wires going in the slots above the RVQ. It all worked properly as 330w on the battery bank, adding their amps.

BFL13 wrote:
Yank your solar controller from where it is, and splice the array and battery wires together there. Now go to the battery bank and find the solar wires that go onto the battery bank.

Now insert your original controller by using the previous battery wires as the array side new wires to the controller and by adding new wires to be the controller -to- battery wires. Ta Da !

You can still add your portable panel- to -controller wires to the array side of the controller in its new position as previously discussed.

You don't need a second controller unless your new total array Isc exceeds about 16a Isc for the original 20a controller.

Exactly the plan but I scrapped it. Didn't want to mess with finding a waterproof box to mount under trailer. Now if you can point me in the direction of such a waterproof gang box at a reasonable price I might send the Blue Sky back and buy the Bogart and then connect it to the Trimetric.

A chance I could also do this and drill a hole from below to storage compartment and then put the CC in there.

Anybody using the Bogart tied to the Trimetric? Is it the holy grail or too good to be true?

I did a voltage drop test today on the 10ga wires from CC to battery. Disconnected them from the CC and they read the exact same voltage as the battery. Now I suspect this might not mean much since there were no amps being pushed through the wires.

hammick wrote:
I did a voltage drop test today on the 10ga wires from CC to battery. Disconnected them from the CC and they read the exact same voltage as the battery. Now I suspect this might not mean much since there were no amps being pushed through the wires.

Yes, as long as the amps get through you are ok, except! The controller having been set at 14.8v high set point for Vabs will think the battery is at 14.8, when in fact the batteries are only at less than that if there is voltage drop.

So how much less than 14.8 can you stand for? Or, if you only want 14.6 set it at 14.8? Except now when in late Absorption Stage and amps have tapered down low, there is not much voltage drop so you hit 14.8 instead of the desired 14.6. How much does that matter? Up to you. :)