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Old 04-11-2020, 01:01 PM   #15
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Quote:
Originally Posted by Brianna View Post
I think I will go with (5) 100 watt panels in series which will be about 100VDC and only 500 watts on that equator day I have planned for June 20th.
I suggest more study.

Yes, you could wire all 5 panels in series to get about 100vdc. BUT, the combined panel array will be seen as ONE large panel. Any shading of any part of any one panel will cut off power totally from all the panels.

Besides, 100vdc is a lot more dangerous to deal with. Most folks feel that 48v is about the highest voltage they feel safe dealing with from their solar array.

Since you have a 40-amp MPPT controller you'll have zero problem with 5-100w 12v panels. If your controller was a 30-amp model you'd be near the permissible limit with 500w.

To answer your initial question - a 40-amp controller can handle 40-amps of current coming in from the panels connected to it. As to output, I don't know but I assume it's the same.

NOTE: You will rarely, if ever see 40-amp of output coming in from 500w or panels. You might for a few seconds on a perfect day at the the perfect time of year. But it's the MAXIMUM and not the actual amount you'll see.
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Old 04-11-2020, 01:21 PM   #16
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Quote:
Originally Posted by Brianna View Post
Thanks everyone.

This is where i'm at right now:

My existing EPEver 40Amp MPPT controller can take in up to 150V and a maximum of 530 watts from the PV array.

Soooooo.....
I think I will go with (5) 100 watt panels in series which will be about 100VDC and only 500 watts on that equator day I have planned for June 20th.

Since I only have about 500 usable Ah of storage in the batteries (for now) this should be a good step 1.
Should work fine. I started with one string at 120 volts, then added another string at 60 volts through another solar controller when I added more panels.
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Old 04-11-2020, 01:28 PM   #17
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Should work fine. I started with one string at 120 volts, then added another string at 60 volts through another solar controller when I added more panels.
Out of curiosity, why would you want to run your PV at such high voltage? I understand line loss, but wouldn't it be easier and safer to run at a lower voltage with larger wire?
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Old 04-11-2020, 02:13 PM   #18
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Out of curiosity, why would you want to run your PV at such high voltage? I understand line loss, but wouldn't it be easier and safer to run at a lower voltage with larger wire?
More efficient, less voltage drop, smaller wires. I have worked with electricity all my life, so am not worried by higher voltages.
Most single inverter professionally installed home solar systems run at up to 600 volts from series panels.
Tesla powerwall and most EV's are 400 volts.
My home system which I installed myself, runs 240 volts through 250 volt solar controllers to a 48 volt battery bank.
On my coach, I am running two sets of 10 gauge wires which leaves plenty of room for expansion.
But everyone should only do what they are comfortable with.
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Old 04-11-2020, 02:14 PM   #19
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After trying to read all this it's just as Clear as the Mub in the bottom of the Chesapeake Bay!

Trust me you can't see a thing down there. -
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Old 04-11-2020, 02:29 PM   #20
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If you are going to work with electrical system need to fully understand Ohms Law. Watts = Volt x Amperage (w=v x a). In simple terms watts is a measure of work.

Pay attention to what Twinboat and others have said a controller does not generate (create) power. What goes in = what comes out - internal controller losses. Those losses are usually very small. A good MPPT controller will only accept the amps from the panels that it can use. I have 1050 watts feeding a 80 amp controller. Anything coming in over 80 amps is just dumped by the controller. The controller will only produce the amount of power needed by the batteries based on the charging program being used. Controller output voltage and amps will vary as to what stage of recharge the battery is at.

A 100 watt panel can only produce that under idea labs conditions, standard test conditions all solar panel manufactures use. In real life you very rarely ever see that number. If a few cases you may get more than the faceplate rating. This can happen because of the way panels are made and rated in the factory. For an example a manufacture may sell say a 330, 350 and 380 watt panel. They may all come off the same assembly line and tested for one by one for real output. A panel will only be sorted to the 380 watt stack if it produces 180 or more watts. Thus a 350 watt rated panel may have produced 375 watts, thus it get sorted as a 350 panel. Thus may see greater than nameplate ratings.

The real out put from a panel depends on the sun angle, cloud cover and possible shading. Better moncrystalline panels will still work even with considerable shading. Mine produce useable but reduced power even parked under trees. Another point for the naysayers about solar and shading. Multiple panel manufactures are producing bifacial (double sided) panels. Yes top and bottom are active surfaces. The bottom side is in the shade!

As pointed out above the power to the controller depends on the electrical specs of the panels, wire size of the down haul wires and quality of the various connections.

I use three 350 watt panels all wired in parallel, each panel produces about 44.4 volts on a typical day. I have a Morningstar MPPT controller that accepts 80 amps from the panel. This feeds a 460 AHr battery bank.

I recommend that anyone planning a solar install first does a power budget study to determine how much power you really use in a typical day and design a system from there. Start with a good battery monitor. Many stories of people unhappy with their first or even second solar installs because of lack of planning and design on the front end.

Just saying....
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Old 04-11-2020, 03:16 PM   #21
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...So, in other words, can a 60A controller slam more amps into the batteries, or at a faster rate, than a 40A controller using the same battery bank and the ***same solar panels***?...

Answer = NO.

The 60a controller can handle a larger PV array than the 40a controller, so if a larger PV array then can charge at a faster rate.
No is an incorrect answer, as is Yes. It is a bit of a trick question, in that “same solar panels” has no value.

A coach equipped with 1400W of panels, would, under the same circumstances, charge batteries faster with a 60A controller than a 40A controller. “Same panels” different controllers, different charging rates. Correct answer: Yes.

Likewise, a coach with 400W of panels, same circumstances, would not charge faster with a 60A controller than a 40A controller. “Same panels” different controllers, same charging rates. Correct answer: No.

Ultimately, a controller should be able to handle the maximum power output from the panels, even if that maximum is only for a few minutes a day.
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Old 04-11-2020, 04:44 PM   #22
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New question -

Need to keep three 12 volt deep cycle batteries charged on small trailer for TV and Chargers for Computer and Phone. With possibility to add panels as needed up to 4?

Would this be acceptable - https://www.ebay.com/i/252616770371?...CABEgL7n_D_BwE

200 Watt with 30 amp controller

Item specifics
Condition:
New: A brand-new, unused, unopened, undamaged item in its original packaging (where packaging is ... Read more
Model:
LCS 100 watt solar panel kit
Features: All Daylight Conditions, Corrosion Resistant, Maintenance Free, Portable Custom Bundle: Yes
MPN:
LCS-K200PC
Wattage: 200 Watts Total
Pliability: Rigid System Configuration: Off-Grid
Brand:
LightCatcher Solar
Product Line: LightCatcher-Solar
Solar Technology: Polycrystalline Expandable: Yes, up to 800 Watts
Application: Boat/RV/Vehicle/Home/Garden/Battery, Agriculture/Farming, Aquaculture, Automotive, Camping/Hiking, Commercial, Electronics, Home/Garden Solar Panel Max Wattage: 200 Watts total, 100 Watts each panel
Bundle Description: 2x 100 Watt Poly Panels 1x 30 Amp PWM Charge Controller Model PULSE365 Charge Controller Max Wattage: 800 Watts
Voltage: 12 V/ 24 V Type: Solar System/Kit
UPC:
Does not apply

Have read the post through twice and still is Greek -

TIA,
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Old 04-11-2020, 04:56 PM   #23
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back to the 5 -panels --100 watt @ 22v.. if you series.. it is 100 watts and volts can be 100+... 5 panels in parallel id 500 watts at 22v....

or is my brain fading again...
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Old 04-11-2020, 05:17 PM   #24
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Originally Posted by Busskipper View Post
New question -

Need to keep three 12 volt deep cycle batteries charged on small trailer for TV and Chargers for Computer and Phone. With possibility to add panels as needed up to 4?

Would this be acceptable - https://www.ebay.com/i/252616770371?...CABEgL7n_D_BwE

200 Watt with 30 amp controller

Item specifics
Condition:
New: A brand-new, unused, unopened, undamaged item in its original packaging (where packaging is ... Read more
Model:
LCS 100 watt solar panel kit
Features: All Daylight Conditions, Corrosion Resistant, Maintenance Free, Portable Custom Bundle: Yes
MPN:
LCS-K200PC
Wattage: 200 Watts Total
Pliability: Rigid System Configuration: Off-Grid
Brand:
LightCatcher Solar
Product Line: LightCatcher-Solar
Solar Technology: Polycrystalline Expandable: Yes, up to 800 Watts
Application: Boat/RV/Vehicle/Home/Garden/Battery, Agriculture/Farming, Aquaculture, Automotive, Camping/Hiking, Commercial, Electronics, Home/Garden Solar Panel Max Wattage: 200 Watts total, 100 Watts each panel
Bundle Description: 2x 100 Watt Poly Panels 1x 30 Amp PWM Charge Controller Model PULSE365 Charge Controller Max Wattage: 800 Watts
Voltage: 12 V/ 24 V Type: Solar System/Kit
UPC:
Does not apply

Have read the post through twice and still is Greek -

TIA,
Without a power budget(amp hours used per day) it is pretty much a wild guess if 200 watts will work or not. Either get a $16 monitor from Amazon(easier) or do the math(much more complicated and not as accurate).

Weather where you camp, roof or portable, camping in sun or shade all comes into play.

Do consider mono crystaline panels instead of poly crystaline. More efficient but also better performance on cloudy days.
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Old 04-11-2020, 05:30 PM   #25
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Without a power budget(amp hours used per day) it is pretty much a wild guess if 200 watts will work or not. Either get a $16 monitor from Amazon(easier) or do the math(much more complicated and not as accurate).

Weather where you camp, roof or portable, camping in sun or shade all comes into play.

Do consider mono crystaline panels instead of poly crystaline. More efficient but also better performance on cloudy days.
Mono, would be better - thank you.

Yes, correct on the wild guess - if more are needed then add a few more panels - that works too correct?

Forgot to mention that if more power is needed then the Generator could also be fired up -


Thanks for the simple concise answer,
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Old 04-11-2020, 09:10 PM   #26
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A thread highjacking in progress. Better results may be had by starting a new thread, particularly in the Going Green Forum.
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Old 04-11-2020, 09:19 PM   #27
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back to the 5 -panels --100 watt @ 22v.. if you series.. it is 100 watts and volts can be 100+... 5 panels in parallel id 500 watts at 22v....

or is my brain fading again...
The current will be 5X higher with the 22V parallel configuration.

It is similar to connecting 6V batteries in series and parallel. More voltage or more current?
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Old 04-11-2020, 09:44 PM   #28
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….don't have all the facts to offer here tonight, but about 4 years ago, I experimented with solar on my DP...... went with one of the better known providers to design the system. Installed 400 watts of panels [4], wired in series so higher voltage allowed for smaller wiring to controller. Went with series as panels were "advertised" to have built-in processors for minimizing shading impact. Also used 30amp MPPT controller.

Don't dry camp much but do have residential fridge and 660amp/hr bat bank. System has worked well at Q-site the past few years. Basically cuts out 1 of 2 daily genset runs but to be safe, usually do shorter run to top-off bats in the evenings, before lights out.

Have roof room for 300-400 more watts of panels, so now am thinking of adding more but will need to add a second controller to the mix.

It was a fun DIY project, at modest cost--but not sure if was totally worth it????
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