Adding to "Go Power" solar system

[johnwuch]

I have a Go Power solar system with (3)160watt panels and a 30 amp charge controller. I would like to add another 160watt panel to my system but I don't think my controller will handle it. Are there any reasonable solutions that don't require rewiring the whole system?

[vsheetz]

You likely never get full rated output from your panels so some oversubscribtion can be ok. Flat mounted panels will lose about 15-50% depending on latitude and time of year.

Also depends on what your controller does if presented with excess power at their input - some gracefully dump excess, others do not.

[garbonz]

You could always unplug one if you get close to the edge in mid summer with the sun high and benefit from the power other times. If you have a monitor, which you should, then you would know when to limit power. Or toss a cardboard over one.

[ByeTheWay]

Originally Posted by johnwuch

I have a Go Power solar system with (3)160watt panels and a 30 amp charge controller. I would like to add another 160watt panel to my system but I don't think my controller will handle it. Are there any reasonable solutions that don't require rewiring the whole system?

Your thought is probably accurate. I'd be safe rather than sorry. I'm on my third controller. That's the problem with not planning in advance. Same w/ wiring.

[johnwuch]

Originally Posted by ByeTheWay

Your thought is probably accurate. I'd be safe rather than sorry. I'm on my third controller. That's the problem with not planning in advance. Same w/ wiring.

Are there any larger controllers that would mount in the closet? The only ones I could find are larger units. This might be more work and cost than its worth for minimal gains. Thanks to all for the advice.

[twinboat]

My math says you already are exceeding the controller input with 3, 160 watt panels. ( 480 watts÷12volts=40 amps ). Adding another will probable burn it out.

From GoPower
" The GP-PWM-30 will limit PV current above 30 Amps.

Although the GP-PWM-30 will accept PV current greater

than 30 Amps for a short duration, damage may occur if the GP-PWM-30 operates continuously with greater than 30 Amps of PV input. "

Best suggestion I have is to get a MPPT controller and run 2 series sets of panels. That way the wire gauge from the roof can remain the same and you will only need to upgrade the controller to battery wiring and fuse.

[DaveG39]

I would suggest calling Go Power tech support. When I installed my solar system some time back they were very helpful.

[garbonz]

Originally Posted by twinboat

My math says you already are exceeding the controller input with 3, 160 watt panels. ( 480 watts÷12volts=40 amps ). Adding another will probable burn it out.

From GoPower
" The GP-PWM-30 will limit PV current above 30 Amps.

Although the GP-PWM-30 will accept PV current greater

than 30 Amps for a short duration, damage may occur if the GP-PWM-30 operates continuously with greater than 30 Amps of PV input. "

Best suggestion I have is to get a MPPT controller and run 2 series sets of panels. That way the wire gauge from the roof can remain the same and you will only need to upgrade the controller to battery wiring and fuse.

While the math says that, the spec for maximum wattage is at at the perfect temperature, with the panel perpendicular to the sun and the panels putting out rated power, no shading at all, etc.. I have never seen that come even close, more like half to 75 % maybe.

I wouldn't be to concerned until I actually observed the amperage getting close.

[twinboat]

So, your suggesting that the OP add the 4th panel and watch for controller overload ?

Sorry but I don't agree.

[garbonz]

Gosh I am so sorry you don't agree I guess I should change my totally logical post. Evidently you don't have much experience with the true output of solar panels.

Anyone can buy new equipment, wiring etc. but a good engineer knows when to evaluate a situation and work with what they have and change when necessary after analysis, not rote specifications. Anyone can count, but few can actually analyze which takes an engineering mind and willingness to look at the whole picture.

Last post, thank you

[OLYLEN]

Gosh I'm sorry, I agree with Twinboat. While you experimental engineering might be OK and I do say might, your advising over the top of being conservative with possible fire consequences. YUP the engineers said the Titanic was unsinkable, tell that to the swimmers.

LEN

[Searching_Ut]

Originally Posted by twinboat

My math says you already are exceeding the controller input with 3, 160 watt panels. ( 480 watts÷12volts=40 amps ). Adding another will probable burn it out.

From GoPower
" The GP-PWM-30 will limit PV current above 30 Amps.

Although the GP-PWM-30 will accept PV current greater

than 30 Amps for a short duration, damage may occur if the GP-PWM-30 operates continuously with greater than 30 Amps of PV input. "

Best suggestion I have is to get a MPPT controller and run 2 series sets of panels. That way the wire gauge from the roof can remain the same and you will only need to upgrade the controller to battery wiring and fuse.

Since he's currently using a PWM controller, your math doesn't apply since the PWM controller doesn't do anything but pass the panel current through. In use his current will be something less than ISC. According to the data sheet I looked at ISC for a GoPower 160w panel is 9.29 amps, so the current controller is a good match to his panels.

As for trying stepping up to 640 watts of panels with the OP's current controller, I wouldn't recommend it unless you're willing and able to make seasonal modifications to your system. I know first hand that if I put 6 100 watt panels to my SC-2030 30 amp controllers they will overload to the point of not just limiting current but cycling through a full shutdown in most of the summer months during part of the day. How long it could do that without damage is something I didn't choose to find out. If you're camping through the late fall and winter months with the extra panel however it shouldn't ever hit a full 30 amps.

What size/length is the existing wiring? Considering wire size as well as controller capability should also be part of the equation.

[johnwuch]

Thank you all for your valuable input. I don't think it is worth installing a new controller and wiring at this point. I dry camp in death valley / panamint valley quite a bit and see about 20 amps this time of year. I do not want to worry about remembering to unplug panels. As of now I am getting by with running the gen an hour in the morning and an hour before bed depending on heater usage, so I really cant complain.

[MisterT]

whats to keep you from adding another panel and it's own controller?