Adding Solar panels to a Trolley setup

Greglsh

Greglsh

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Hi,
I have an RCT 1000w inverter with 2 x 12v 100ah AGM batteries, just to keep my small office running, load is +_ 200w to 350w at maximum. I want to add a solar panel or 2 to this setup. The Label on the side says:
Solar Charger Mode:
Rated Power: 500w
System Voltage: 12vDC
Max Solar Voltage (VOC): 102VDC

Was thinking of adding 1x 330w panel (could I get away with maybe 2 x 330w panels as I have these), what else do I need to put between the panel and the inverter? Would I need a fuse on both the negative and positive or a DC circuit breaker on the positive only?
 
Greglsh said:
Hi,
I have an RCT 1000w inverter with 2 x 12v 100ah AGM batteries, just to keep my small office running, load is +_ 200w to 350w at maximum. I want to add a solar panel or 2 to this setup. The Label on the side says:
Solar Charger Mode:
Rated Power: 500w
System Voltage: 12vDC
Max Solar Voltage (VOC): 102VDC

Was thinking of adding 1x 330w panel (could I get away with maybe 2 x 330w panels as I have these), what else do I need to put between the panel and the inverter? Would I need a fuse on both the negative and positive or a DC circuit breaker on the positive only?
Click to expand...
Hi!
I assume the solar charger on the inverter is a MPPT, solely from the VoC rating.

I have 3x trolley units setup with Longi 550W panels -> panels are overkill for the solar chargers but they work extremely well for winter as they are overspecced - the solar charger will only 'use' what it needs to charge the batteries or power the loads.

Basically:
Panel + and - -> DC fuses in fuse holder (330w/12V = +-28amp so opt for a 30amp fuse) close to the inverter -> solar charger input. Make sure your panels are earthed with a copper spike/rod as close as possible to the panels and that the installer uses the correct trunking for the cables.
 
Greglsh said:
The mounting system for 1 panel costs almost as much as the solar panel itself?
Click to expand...
If you can, rather go for 2 panels in parallel -> double the amps charging and keep the VoC more or less in the mid of the range of the MPPT. Cost of mounting 1 v 2 panels is negligible and you are sorted for some cloudy days or when the LS hits the pesky lvl 6 onwards again.

@TheChamp @LandyMan @RonSwanson
Any extra advice?
 
Mista_Mobsta said:
If you can, rather go for 2 panels in parallel -> double the amps charging and keep the VoC more or less in the mid of the range of the MPPT. Cost of mounting 1 v 2 panels is negligible and you are sorted for some cloudy days or when the LS hits the pesky lvl 6 onwards again.

@TheChamp @LandyMan @RonSwanson
Any extra advice?
Click to expand...
I was going to suggest what you did. :thumbsup:
 
Greglsh said:
The mounting system for 1 panel costs almost as much as the solar panel itself?
Click to expand...
You are shopping at a wrong place, don't by those kits, get separate components.

Tip, for small systems you can cut the rail into smaller pieces that goes at each corner of the panel instead of using the whole rail that runs the entire end of the panel.

Of course make sure that the pieces are properly secured to the roof.
 
wingnut771 said:
Why not series, then you don't need thick cable?
Click to expand...
Not sure about the VoC of the panels as some 330W+ panels are >45VoC
Better to push higher amperage into the controller at the midrange of the MPPT than maxing V and getting losses due to potential shadow on parts of the panel?

Not to get into the real nitty gritty of it and don't want to derail the thread unnecessarily so happy to carry on the above chat on another thread if needs be and not confuse the OP
 
Greglsh said:
Hi,
I have an RCT 1000w inverter with 2 x 12v 100ah AGM batteries, just to keep my small office running, load is +_ 200w to 350w at maximum. I want to add a solar panel or 2 to this setup. The Label on the side says:
Solar Charger Mode:
Rated Power: 500w
System Voltage: 12vDC
Max Solar Voltage (VOC): 102VDC

Was thinking of adding 1x 330w panel (could I get away with maybe 2 x 330w panels as I have these), what else do I need to put between the panel and the inverter? Would I need a fuse on both the negative and positive or a DC circuit breaker on the positive only?
Click to expand...
Don't run those 330w panels in series, just in case. The Voc of the panels x 2 is likely going to be a little too close to the Max Solar Voltage on the inverter in winter, and release the magic smoke.

Run both in parallel.

Otherwise I think you'll be fine. Get PV cable rated for at least 20A.

Panels -> roof, cable -> **DC** breaker -> inverter.


Something along the lines of this is fine - https://e-glow.co.za/products/16a-dc-2p-circuit-breaker-600vdc?variant=42160019538096&currency=ZAR

Your local electrical supplier should have. You could add a fuse inline also after the breaker, but I don't think much point for a small install with 2 panels. Never hurts to add if you have space though.

More important is to have the fuses between the inverter and batteries. You have what I presume is a small inverter box with internal batteries, so that should have its own fuses inline already.
 
Last edited:
Mista_Mobsta said:
If you can, rather go for 2 panels in parallel -> double the amps charging and keep the VoC more or less in the mid of the range of the MPPT. Cost of mounting 1 v 2 panels is negligible and you are sorted for some cloudy days or when the LS hits the pesky lvl 6 onwards again.

@TheChamp @LandyMan @RonSwanson
Any extra advice?
Click to expand...
I haven't really looked at panelling for our trolleys. Will probably come in the next few months
 
itareanlnotani said:
Don't run those 330w panels in series, just in case. The Voc of the panels x 2 is likely going to be a little too close to the Max Solar Voltage on the inverter in winter, and release the magic smoke.

Run both in parallel.

Otherwise I think you'll be fine. Get PV cable rated for at least 20A.

Panels -> roof, cable -> **DC** breaker -> inverter.


Something along the lines of this is fine - https://e-glow.co.za/products/16a-dc-2p-circuit-breaker-600vdc?variant=42160019538096&currency=ZAR

Your local electrical supplier should have. You could add a fuse inline also after the breaker, but I don't think much point for a small install with 2 panels. Never hurts to add if you have space though.

More important is to have the fuses between the inverter and batteries. You have what I presume is a small inverter box with internal batteries, so that should have its own fuses inline already.
Click to expand...
It is a fine line if your panel voltage drops below mppt startup you get nothing

ie lets say your mppt is starts at 30v and the panel works 36v vmp

If shade takes out 1/3 you are dead in the water as the bypass kicks in you lose 12v per 1/3 section

Better off looking gor lower cell count panels that have lower voltage and can thus safely be in series

As long as you only use less than 80% of max voc you should be ok for cold voltage lift

If going parralel better to get a higher voltage panel imo
 
leon.davibe said:
It is a fine line if your panel voltage drops below mppt startup you get nothing

ie lets say your mppt is starts at 30v and the panel works 36v vmp

If shade takes out 1/3 you are dead in the water as the bypass kicks in you lose 12v per 1/3 section

Better off looking gor lower cell count panels that have lower voltage and can thus safely be in series

As long as you only use less than 80% of max voc you should be ok for cold voltage lift

If going parralel better to get a higher voltage panel imo
Click to expand...
Says 17v startup, so s/he'll be fine, even with one panel.

Max VoC on the other hand is a little too close for comfort to potential open circuit panel voltage as that can go higher in winter (cold, sunny days with a bit of cloud, can exceed panel specs), so parallel is the way to go.

S/he has the panels, why buy more, its more than sufficient for his/her needs.
 
itareanlnotani said:
Says 17v startup, so s/he'll be fine, even with one panel.

Max VoC on the other hand is a little too close for comfort to potential open circuit panel voltage as that can go higher in winter (cold, sunny days with a bit of cloud, can exceed panel specs), so parallel is the way to go.

S/he has the panels, why buy more, its more than sufficient for his/her needs.
Click to expand...
Yea 17v is nicer , you have to lose 2/3 before dead in the water
 
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