Updating a 2010 2.4kw system with minimum of changes/replacement/ destruction.

[pretzelboy]

Hello all,

I have a roof mounted 2.4 kw system that was installed professionally on my house roof in 2010.
The system has functioned well but is not keeping up with increased house usage and car charging needs.

the current set up is all (20) 125 watt Sunpower panels, 2 strings going to a Sunpower SPR 4000 inverter.

All grid tied with appropriate cutoffs and system meter in basement. Everything is functioning well, if inadequate.

My question is:

In the interest of economics is it possible to remove and replace the array with a set of panels yielding closer to 5kw, using the existing wiring that currently is in weatherproof conduit and feeds from roof to basement. There I would like to remove the SPR 4000 and replace with a new appropriately sized string inverter.

Would this be possible? Or do you think I need to do larger scale parts replacement that would necessitate using a solar contractor?
I ask bc the retail solar contractors all want to start completely from scratch to make more money.


Thx Greg

 

[OffGridForGood]

Interesting problem, lets see if we can put some useful comments:
Panels:
20 x 125W panels, 14 years old. First thing that comes to mind, what are these producing? I would expect when new they would give you 2kW per hour in normal sunny day. Do you know what these produced when new? What do they produce now that they have aged? If they still produce 1.6-1.8kW per hour in normal sun, maybe you should keep them, and just add new array. If you have space. (Do you have space?)
PV Cables:
The cables would have been sized for the 2.5kW array voltage and amperage. What are the VOC and IMP of the panels, and how are they arranged (series and parallel) - can you determine the PV cable sizes - either directly from the cables or from a diagram?
If a new PV set up used higher voltage and lower amperage string, you may be able to reuse the cables, but it depends how it was run. New PV panels are likely far larger than those 125W panels, how will the new layout affect racking, and cable locations?

I ask bc the retail solar contractors all want to start completely from scratch to make more money.

They may, or they might be more concerned with wasting time/relying on work of others. If they start from scratch, then they are responsible for it all.
They may also be concerned with changes in code requirements since 2010, like rapid shut down, and arcfault detection.

 

[pretzelboy]

Here' an update. Did some sleuthing (measure voltage at inverter, junction box and then "roof work") and found that one of my panels had shorted at the junction box, including s bit of melting at the plastic fitting inside right before the diode. The screw on cover/fitting for the wire was loose to the point of not being screwed on at all - I think it may have been that way for 13 years (!) Anyhow the panel is out of commission, and i was operating on one string with significant enough shading that it may have not met the inverter minimum. For now, we disconnected one more panel and re-adjusted the array to balance at 2 strings of 9 panels. That has me operating again and I will monitor output over the next few days.

BTW I had a brain fart in describing my system, which accurately is 20 Sunpower spr-210-blk-u panels (210 watts) and the spr-4000 inverter

Wondering how hard it might be to find at least one, maybe an extra for backup Sunpower 210 watt panels from 2010?

Greg