PIP mpp 812LV-MS

[NoSmokeYet]

Has anyone hooked up more than four 100w panels to this controller ? I have four installed 2S2P just wonder if I'm not reading the data/spec sheet correctly on the pip.

 

[JoseAgustinV]

If you buy another solar panel and get 3 in Series, 2 Series the connect those 2 in parallel you will have a voltage loss and you will end up with the same 400W, and you cannot connect two 3 series arrays since you will get 600W and that will exceed the PV array voltage that is only 500W.

I think the best way to get more watts is to buy 3 150-160w panels in series to get 450-480W. Anyone correct me if I'm wrong pls since I am just an apprentice.

I have the same system but with 2 100w solar panels in series, and I have a doubt. It's safe to connect 4 100w solar panels in series? that will have around 88-90Voc I think, this is near the 102Voc max voltage of this unit.

 

[NoSmokeYet]

I have sensed installed four golf cart batteries and didn't think my 400 watts in panels would charge them in one day. Well it turns out they do and while powering my desktop computer. By 1:00pm they're at 100%. Today I was charging at 338w/21amps. This system is now very usable.?
Looks like four panels in series would be pushing it a little. I really don't know that's why I posted here. I was worried about the "MPPT Voltage Range" of 80 Vdc. You should do what I did...2S2P and four 6 volt batteries.
Thanks for the reply, Jose

 

[JoseAgustinV]

I'm not sure, but I think the Vdc is the voltage of the solar panels array, 4 solar panels in series will be like 48Vdc or I'm wrong?

 

[NoSmokeYet]

I was thinking 22Voc x 4= 88 volts.

 

[JoseAgustinV]

VOC is open circuit voltage, the unit has a 102V max, I don't know if it's safe to get 88V, that is near the max 102V, but I see that other users in this forum are using 4 100w panels in series for this unit with no problem.

 

[Hedges]

You may be able to connect 6, 100W (STC) panels as 3s2p. That's 600W STC but probably only 500W PTC, and well centered in the voltage range. This is assuming the inverter will avoid burning itself up if presented with slightly over 500W.

https://www.mppsolar.com/v3/catalogs/PIP-LV.pdf

You can also orient the strings differently to get morning and afternoon sun.
Assuming the inverter does protect itself you might even get away with connecting panels having STC ratings totalling 1.5x the inverter's spec, but not all getting full sun at the same time.
A day has sunlight 8 or 12 hours, but we figure 5.5 effective hours for fixed orientation mounts.
If you had 3 strings, each 300W, oriented toward winter morning, winter afternoon, and summer noon, it could have a peak of about 500W but deliver around 4 kWh per day. Do use a fuse per string if you have more than 2 strings in parallel.

 

[JoseAgustinV]

You may be able to connect 6, 100W (STC) panels as 3s2p. That's 600W STC but probably only 500W PTC, and well centered in the voltage range. This is assuming the inverter will avoid burning itself up if presented with slightly over 500W.

Max pv array is 500w for the charge controller, im planning to get two more 100w solar panels to get 4S for 400w, but im not sure if is safe, these are the limits on voltages for this unit:

 

[NoSmokeYet]

Hi Hedges
Right now my system is working perfect in the summer sun. Maybe this winter I'll add a couple more panels and face them west into the setting sun. There is a lot of direct sun light I'm missing out on because I'm not willing to turn my panels. If I do burn my PIP up it will be a good excuse to get the 24 volt PIP? Thank you for your reply.

 

[Hedges]

Hi Hedges
Right now my system is working perfect in the summer sun. Maybe this winter I'll add a couple more panels and face them west into the setting sun. There is a lot of direct sun light I'm missing out on because I'm not willing to turn my panels. If I do burn my PIP up it will be a good excuse to get the 24 volt PIP? Thank you for your reply.

Ask the manufacturer if it is OK to connect well over 500W of panels, if the inverter will limit itself or not. Could be it can only handle delivering 40A max to the battery but will put out more if available, burning something up. Also, it may or may not reduce its output when it gets too hot. Some brands have that protection built in. Life of electronics tends to be shortened by heat (and water.) I found some fans that operate directly off PV as the sun comes up and use them to cool an inverter.

 

[NoSmokeYet]

The highest incoming watts from my solar panels has been 314w that I have seen. Tomorrow I keep an eye on it and see if it goes much higher. So it looks like there is plenty of room for another two panels. I do have the 5-way MC4 connectors to hook up five 100w panels in parallel just don't have 5 panels yet. I'm using #6 wires from the panels to the house already(25ft).

 

[Hedges]

Max pv array is 500w for the charge controller, im planning to get two more 100w solar panels to get 4S for 400w, but im not sure if is safe, these are the limits on voltages for this unit:

View attachment 13167

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Check the spec for your PV panels. There should be one of approximately 0.5%/degree C or some volts/degree C. You have to consider coldest winter day and calculate maximum Voc. May be too close to the limit and you risk killing the inverter. I have grid-tie string inverters with 600V absolute max input. After checking the math I use 24, 12V panels, 12, 24V panels, 8, 36V panels.

 

[JoseAgustinV]

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Check the spec for your PV panels. There should be one of approximately 0.5%/degree C or some volts/degree C. You have to consider coldest winter day and calculate maximum Voc. May be too close to the limit and you risk killing the inverter. I have grid-tie string inverters with 600V absolute max input. After checking the math I use 24, 12V panels, 12, 24V panels, 8, 36V panels.

Updated the attachment

 

[NoSmokeYet]

"if the inverter will limit itself or not" That is the question.
Hedges, the software allows you to set the battery charging rate. So that shouldn't be a problem.

 

[Hedges]

The highest incoming watts from my solar panels has been 314w that I have seen. Tomorrow I keep an eye on it and see if it goes much higher. So it looks like there is plenty of room for another two panels. I do have the 5-way MC4 connectors to hook up five 100w panels in parallel just don't have 5 panels yet. I'm using #6 wires from the panels to the house already(25ft).

If you have just one 12V panel per "string", it's MPPT voltage on a hot day and low illumination may drop below the inverter's MPPT range so you lose production. Probably works better with multiple panels in series. Some vendors publish efficiency curves vs. voltage and watts.

If you parallel 3 or more strings they should have fuses. You can buy MC fuse holders.

#6 wire is good for about 70 amps, more or less depending on temperature and how many in a bundle. If you had 5, 100W 12V panels in parallel I think the peak current is low enough that the #6 wire doesn't require fusing. Only the panels need fusing because 4 panels dumping their current into one panel (or MC wire) with a short would be too much.

More panels in series is usually the best way to go. Reduces IR drop and the insulation is good to about 600V. Compare to cost of copper and IR losses.

 

[Hedges]

Updated the attachment

Must be me or my browser? I still can't open https://diysolarforum.com/attachments/13167/

It just says, "
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[JoseAgustinV]

Must be me or my browser? I still can't open https://diysolarforum.com/attachments/13167/

It just says, "
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Its the same controller that we are talking on this post, check the first image, 1kva 12v

 

[NoSmokeYet]

Hedges, I saw those MC fuse holders the other day online. That would be the way to go.
Yeah the 5-way connectors will probably never get used. Bought them some time ago.

 

[Hedges]

Hedges, I saw those MC fuse holders the other day online. That would be the way to go.
Yeah the 5-way connectors will probably never get used. Bought them some time ago.

You may not need the fuses either.
But considering that picture you identify yourself by, there are two situations where fusing the panels might be necessary:
1) Three or more PV strings, and one has a short so the other two dump current into it.
2) The inverter has a fault which dumps battery current into the PV array, and there is a short in the array. (Even the #6 wire could be at risk in this case, so an additional fuse at the inverter end as well would be best.)

Is your battery fused? Since the inverter is rated 1kW, nominal current from 12V battery is around 80A. The fuse would be a bit larger to handle surges. Even though #6 can't carry 100A or more for an extended time, it is enough to serve as ground wire for a 200A breaker, which it can trip in case of a fault.

I think my grid-tie inverters were designed to be safe from having grid current dumped into them due to a fault, but even if not, the AC breaker on my smaller inverters has a suitable rating. The breaker for my larger inverters is too large for that, but I have a combiner box with touch-safe fuse holders for those PV strings.

You could do a twice/year seasonal tilt adjustment of the panels to maximize winter & summer production. With only about 150 pounds total of panels, not very difficult. Mine is about 20x that, so on very substantial and completely fixed mounts.

 

[NoSmokeYet]

*Batteries are fused with 100 amp at the batteries.
*Solar panels have a 40 amp breaker at the controller.
*If and when I go will 3 strings of panels I will use 3 inline fuses.
*Yes I adjust the panels 4 or 5 times a year. They're mounted to a frame just haven't built the tilting part yet(have the material). Thinking about making it pivot. The panels are close enough to the house to have a small rod going to them and adjust their position from inside the house while watching the watt meter. Or use a spring and cable.
And there is no way I'm going to ask you how you have your mismatched panels wired up?

 

[Hedges]

Sounds like yours is safe, good to know.

I now have all three species of panels connected in parallel, and multiple orientations. Their Voc were all within a few percent of each other. Multiple MPPT input per inverter might have been more ideal but I selected a model compatible with my battery inverters. I think it only loses a couple percent of output.

One thing that gave me some trouble was paralleling battery inverters. Off grid, each would limit its output to avoid overload. But on-grid, the only thing to balance current passing through the relay and wiring of each is resistance. I expected 60' of #6 wire to do the trick, but had a 2:1 or 3:1 imbalance. Turned out to be different resistance between two identical 70A QO breakers. Elsewhere, two identical 63A Schneider supplemental breakers were well matched.

Another issue I ran into was a 100A QO breaker that tripped repeatedly with no more than 70A, then wouldn't reset (until days later.) Replaced it and OK so far. I think I had a wire which had missed the screw terminal and only made pressure contact; that may have cooked the breaker over time before it was as heavily loaded.

I ran rigid conduit long ago, and while I'm not approaching the published conduit fill figures, it is difficult for me to pull additional wires. I may use fuses and parallel some strings at the array rather than at the combiner box.