Over panel question

[Clowy699]

I recently ordered a Pecron e1500LFP. I would like to maximize the solar input as close as possible, but not be dangerous.

Solar CC is rated at 32-95v 700w 15a

I found some REALLY cheap 250w panels on marketplace. They are 10yrs old but still working. 37.6VOC 30.3v@pmax 8.85a short circuit current. 8.27a at pmax.

I have to run 2 in series to meet the minimum volts. But I recently learned about over paneling, and believe I could run 2s 2p. This would give just under 80v (well within the specs) just over on amps at 16-17 but what seems like a lot over on watts. I expect shading so the parallel would help. I’ve done a lot of research on this forum and other places lately, and my understanding is this should be fine. But I am a beginner at solar and would appreciate any input from more experienced members before I try this. It just feels weird putting 1000w on 700w cc.

 

[Andrewr05]

It should only ever take in what it calls for, a max of the 15A.

So you should be fine to pile in as much amperage as you want, that way you're guaranteed that you should always be getting your full 700W input.

But you still may want to directly ask the folks at Pecron to see what their thoughts are.

Some people have pointed out that certain companies specify that their amperage limit is not to be exceeded, but most only state warning about exceeding voltage.

 

[hwy17]

Should be fine I think, but different judgement should be used based on how bad it would be to have a fire where it is when it's charging.

I.e. If it's in the house, be more cautious.

 

[MisterSandals]

Solar CC is rated at 32-95v 700w 15a

Assuming this is a 48V battery?

Is that 15A charging?

 

[chrisski]

Although it’d probably be OK, I recommend looking at the specs in the manual for overpaneling.

My Victron SCC is very clear that what you’re suggesting would work.

My much cheaper generic SCC is not very clear and makes no mention of overpaneling.

Lack of documentation Part of this comes to how you feel about the SCC running at 100% for hours on end, day after day. IMO, daily usage over the years probably does not improve lifespan. IMO 70% max ratings for equipment extends life compared to all out.

If this is something to max out once a week for a few hours, I’d feel good at 10@%

 

[Clowy699]

Assuming this is a 48V battery?

Is that 15A charging?

Yes, the power station has 48v battery. The solar charge controller is rated at 15amp

 

[Clowy699]

Although it’d probably be OK, I recommend looking at the specs in the manual for overpaneling.

My Victron SCC is very clear that what you’re suggesting would work.

My much cheaper generic SCC is not very clear and makes no mention of overpaneling.

Lack of documentation Part of this comes to how you feel about the SCC running at 100% for hours on end, day after day. IMO, daily usage over the years probably does not improve lifespan. IMO 70% max ratings for equipment extends life compared to all out.

If this is something to max out once a week for a few hours, I’d feel good at 10@%

This is exactly why I asked. If I had a known charge controller like Victron I would know it’s perfectly fine. Everything I read seems to say ‘newer mppt should be fine to over panel.” But that’s dedicated units. If I were trying to double or triple the amps, I would play it safe with unknown controller and not do it.
But, going over by only 1-2 amps…?what I’m also accounting for, is that it’s a very bad panel placement, only a small window per day with direct sunlight on all panels. Small yard, tilted, south facing at ground level(only option since I can’t put on roof). with old panels that will likely rarely if ever reach vmax. I bought the Pecron for emergency backup, but figured why not save some money and run my garage refrigerator off of it.

 

[MisterSandals]

Yes, the power station has 48v battery. The solar charge controller is rated at 15amp

So it will charge at 15A max.

15A x 56V charging = 840W
This is the maximum that the SCC can process.
If you have ~32Vmp (?) panels, 2 in series, thats 64Vmp

840W / 64V = 13A would be the max that SCC will pull from the array (but MPPTs do vary this to find the max power point obviously).

Even if you run 2S2P, the SCC pulls the current.

 

[Clowy699]

So it will charge at 15A max.

15A x 56V charging = 840W
This is the maximum that the SCC can process.
If you have ~32Vmp (?) panels, 2 in series, thats 64Vmp

840W / 64V = 13A would be the max that SCC will pull from the array (but MPPTs do vary this to find the max power point obviously).

Even if you run 2S2P, the SCC pulls the current.

Thank you for this. I now know how to math it up. My vmp is ~30…so it is 840/60= 14amps. Still under. Thank you all for helping. I feel way more confident with this set up now.

 

[Clowy699]

So it will charge at 15A max.

15A x 56V charging = 840W
This is the maximum that the SCC can process.
If you have ~32Vmp (?) panels, 2 in series, thats 64Vmp

840W / 64V = 13A would be the max that SCC will pull from the array (but MPPTs do vary this to find the max power point obviously).

Even if you run 2S2P, the SCC pulls the current.

Just out of curiosity, how did you get 56v charging?

 

[MisterSandals]

Just out of curiosity, how did you get 56v charging?

Thats just a rough max charge voltage.

16 x 3.65V = 58.4V theoretical limit.
56V / 16 = 3.5V ... a bit higher than i charge but right in line with what more aggressive chargers use.