More Solar On Our 5.0

[Perry Butler]

We purchased our 5.0 in October 2018 with the ETI supplied GoPower 170 watt panel on the rear and a GoPower controller supplying our Crown 220 ah AGM batteries. We also have a Victron BMV-712 Smart Battery Monitor.

The roof of the 5.0 is not flat. It angles up 7-10 degrees.

When we have adequate sun the 170 watt panel on the rear of the 5.0 will charge our AGM’s to 100% with ease, even in the winter. We’re not heavy users, no inverter, but when the furnace is running our daily use is around 20 ah’s.

For shade, we have a Renogy 100 watt portable panel with 45’ of cable, hooked separately to a Victron 100/20 smart controller. When needed, it works great, but is a PITA to deploy and store. When we were in Death Valley NP someone had their portable stolen. I’d like to only use the portable when all other choices aren’t working.

The biggest problem is in January/February, with the low sun. The AC unit can shade the panel if the camper is parked with the rear toward the north. Last winter we were at Death Valley in late January/early February, with the 5.0 nearly perfectly north/south and got virtually zero watts out of the panel because of the AC shade (and then purchased our Renogy/Victron setup). Later in March (or September) if we have a site where the 170 watt roof panel is on the direct north we have problems with inadequate solar. Again, I want to rarely use the portable. If we can just angle 20 to 30 degrees from due north our 170 watt panel works fine.

Looking at Jim Bennett’s Solar Installation thread he has two 60 watt flexibles mounted between the powered vent and the bed’s escape hatch. There is room for two Lensun 80 watt flexibles, but want to start out with only one Lensun 80 watt panel. I can also install a Lensun 100 watt flexible, but only one.

Specs for the GoPower 170 watt panel

Rated Current - 8.79 A
Rated DC Voltage - 19.3
Open Circuit Voltage - 22.8

Specs for the Lensun 80 watt flexible

Maximum power voltage: 18V
Maximum power current: 4.45A
Open circuit voltage: 21.24V
Short circuit current: 4.89A
Dimensions: 940 x 535 x 2.5mm/37 X 21 X 0.1 inches

Specs for the Lensun 100 watt flexible

Maximum power voltage: 18V
Maximum power current: 5.56A
Open circuit voltage: 21.24V
Short circuit current: 6.11A
Dimensions: 960 x 670 x 2.5mm/38.6 X 26.4 X 0.1 inches

The above specs are what each company has on their websites. Each company’s specs are dissimilar.

I have a spare set of MC4 connectors that I had ETI install for adding a second 170 watt panel. I don’t want a rigid panel in front, so I would like to hook one or two 80 watt Lensuns into those MC4 connectors.

Questions:

Can I keep my GoPower controller if I use two different spec panels?

Considering the spec’s for each panel (170 watt GoPower and an 80 watt Lensun) are different, can I just hook the Lensun into the ETI supplied MC4’s?

How much realistic loss will I see by having the GoPower and Lensun(s) panels use the same cables, or is it so minor not to worry about the slight loss?

Thanks,

Perry

[Centex]

Sounds like an interesting project.

Perry, what's the model number of your GoPower Controller, please?

[Perry Butler]

Originally Posted by Centex

Sounds like an interesting project.

Perry, what's the model number of your GoPower Controller, please?

It's a 2018 GoPower PMW-30. It does not have bluetooth. Considering this same controller was used with two GoPower 170 watt panels it should be fine for my one GP 170 watt panel and 80, 100, or two 80 watt Lensun panels.

Do I NEED to change the controller is the question. I've never had a problem milking the last watt out of the panel, once I realized you need to get up top and keep your panels clean. Numerous times I got up top and saw filthy panels that were washed a week or two earlier. Our problem is the north/south AC issue from October to March where the AC shades the panel.

I might consider switching the Victron 100/20 from the portable panel to the roof panels, if needed.

Right now Lensun has really great pricing on these panels.

Thanks,

Perry

[Centex]

Originally Posted by Perryb67

It's a 2018 GoPower PMW-30. It does not have bluetooth. Considering this same controller was used with two GoPower 170 watt panels it should be fine for my one GP 170 watt panel and 80, 100, or two 80 watt Lensun panels.

Asked and answered

Based on that I can't see a need to change, IMO it'd be worth giving it a run with the additional panels, conducting your usual tests / experiments and see what you get before taking that step, if at all.

And, if I understand correctly that you've already got the MC4 parallel connectors that were installed in anticipation of a second 170W panel on that cable .... sure, I'd use those too. If that's a 10AWG cable as I suspect, the loss attributable to the additional current will very small, most likely insignificant unless the run from that connector to the controller is surprisingly long.

EDIT, just FYI - using one online 'rough quickie calculator' assuming 20VDC, 10AWG and 15ft run ....
0.26V drop @ 8.79A
0.53V drop @ 17.69A (8.79+4.5+4.5)

For a 10ft run ..... 0.18V and 0.35V respectively

Obviously you can plug in your actual runs for each leg of the system and compare the alternatives .....

[Brian B-P]

Originally Posted by Perryb67

Can I keep my GoPower controller if I use two different spec panels?

Considering the spec’s for each panel (170 watt GoPower and an 80 watt Lensun) are different, can I just hook the Lensun into the ETI supplied MC4’s?

Yes, because the operating voltages of the panels are not substantially different - they can just be connected in parallel, using the provided connections.

[Centex]

All of the above notwithstanding (all panels will 'work' on the one GoPower PWM controller), one might wonder if there'd be benefit in being able to switch-off (disconnect) the shaded panel in Perry's worst-case scenario (all panels in parallel, one shaded by the AC, all to a PWM controller) to yield best net output to the battery?

Perhaps that's when having the added (unshaded) Lensun panels on a separate controller as he does with his Renology portable would be beneficial, albeit with more / separate wiring required

[Brian B-P]

Originally Posted by Centex

All of the above notwithstanding (all panels will 'work' on the one GoPower PWM controller), one might wonder if there'd be benefit in being able to switch-off (disconnect) the shaded panel in Perry's worst-case scenario (all panels in parallel, one shaded by the AC, all to a PWM controller) to yield best net output to the battery?

No, disconnecting a shaded parallel-connected panel won't increase the output of the remaining panels in this scenario. The shaded panel may not contribute anything, but it won't hurt (as long as it has a blocking diode, in the most extreme case).

In another scenario, if the controller is of the maximum power point tracking (MPPT) type then disconnecting the shaded panel would allow the controller to track to a higher voltage point; this may produce more net power, only if the output of the shaded panel shifts the panel voltage very far off of the ideal voltage for the panel in full sun.

[alanmalk]

Originally Posted by Brian B-P

No, disconnecting a shaded parallel-connected panel won't increase the output of the remaining panels in this scenario. The shaded panel may not contribute anything, but it won't hurt (as long as it has a blocking diode, in the most extreme case).

In another scenario, if the controller is of the maximum power point tracking (MPPT) type then disconnecting the shaded panel would allow the controller to track to a higher voltage point; this may produce more net power, only if the output of the shaded panel shifts the panel voltage very far off of the ideal voltage for the panel in full sun.

Given that the shaded panel has a blocking diode, it doesn't exist if the panel's voltage is less than the voltage on the controller side of the diode. That's the whole point behind a blocking diode. The panel just isn't there - it is disconnected for all practical purposes - until the sun hits it and the voltage rises to equal the other panels, plus the diode drop (about .3V).
--
Alan

[Brian B-P]

Originally Posted by alanmalk

Given that the shaded panel has a blocking diode, it doesn't exist if the panel's voltage is less than the voltage on the controller side of the diode. That's the whole point behind a blocking diode. The panel just isn't there - it is disconnected for all practical purposes - until the sun hits it and the voltage rises to equal the other panels, plus the diode drop (about .3V).

I agree, but if both panels are delivering any current at all (the shaded panel produces any more than the controller input voltage plus the diode drop), the blocking diode becomes irrelevant. An MPPT controller will adjust the apparent load to maximize the net output of all connected panels - it doesn't "know" or care what the combination is, it just hunts up and down in voltage (that's the tracking" to find the maximum power. That voltage will be different with two panels of similar operating voltage but different exposure than with just one panel.