I'm hoping some the folks here can weigh in on whether they think Tesla's recent suggestion to swap my Delta inverter to improve my solar roof's production makes sense.
Apologies for the long-winded description ...
I have a 9.94 kW Tesla solar roof with a Delta M8-TL-US 8kW inverter that was installed in December 2020.
The roof's 170 PV tiles are connected in 6 strings that are joined into 3 parallel string pairs.
More specifically, the strings are organized as follows:
The PV1 parallel string pair has:
- 36 tile string with tiles on south facing (azimuth 167, pitch 40) roof
- 36 tile string with tiles on south facing (azimuth 167, pitch 40) roof
The PV2 parallel string pair has:
- 28 tile string with tiles on south facing (azimuth 167, pitch 40) roof
- 28 tile string with tiles on east facing (azimuth 78, pitch 45) roof
The PV3 parallel string pair has:
- 21 tile string with tiles on west facing (azimuth 258, pitch 45) roof
- 21 tile string with tiles on west facing (azimuth 258, pitch 45) roof
My roof's production has been lower than expected since install. I was originally concerned that misplaced PV tiles might be contributing to the poor production (see Incorrectly Placed Solar Roof Tiles) and then later was concerned about the PV2 parallel string pair which combines tiles from different facing roof planes. In August 2021, Tesla sent a crew out to debug/resolve the production issues and they discovered that my PV1 and PV2 strings had been crossed. So the PV1 pair had a 36 tile string paired with a 28 tile string and the PV2 pair also had a 36 tile string paired with a 28 tile string. The crew fixed the pairing and it now matches the original design listed above.
My roof's production improved, but one year later production was still only 74% of Tesla's original estimate of 11,112 kWh per year. In late July 2022, I asked Tesla to investigate why production remains low. A week or so ago, I learned that they plan to swap my Delta inverter. I don't know whether the inverter is to be replaced with a similar model, a different size Delta, or a different brand (e.g. Tesla), but after looking at
data from my current inverter, I don't see how swapping it out will help since there is no clipping.
Here is an aggregated screen shot of my inverter's data from one of my better (recent) production days:
Does anyone see anything in this data that indicates the inverter has a problem that would limit production?
I'm thinking that the PV2 pair with different oriented strings is a more likely culprit, but am not sure.
Maybe Tesla just made a poor initial estimate.
Any ideas or thoughts are welcome - thanks!
Apologies for the long-winded description ...
I have a 9.94 kW Tesla solar roof with a Delta M8-TL-US 8kW inverter that was installed in December 2020.
The roof's 170 PV tiles are connected in 6 strings that are joined into 3 parallel string pairs.
More specifically, the strings are organized as follows:
The PV1 parallel string pair has:
- 36 tile string with tiles on south facing (azimuth 167, pitch 40) roof
- 36 tile string with tiles on south facing (azimuth 167, pitch 40) roof
The PV2 parallel string pair has:
- 28 tile string with tiles on south facing (azimuth 167, pitch 40) roof
- 28 tile string with tiles on east facing (azimuth 78, pitch 45) roof
The PV3 parallel string pair has:
- 21 tile string with tiles on west facing (azimuth 258, pitch 45) roof
- 21 tile string with tiles on west facing (azimuth 258, pitch 45) roof
My roof's production has been lower than expected since install. I was originally concerned that misplaced PV tiles might be contributing to the poor production (see Incorrectly Placed Solar Roof Tiles) and then later was concerned about the PV2 parallel string pair which combines tiles from different facing roof planes. In August 2021, Tesla sent a crew out to debug/resolve the production issues and they discovered that my PV1 and PV2 strings had been crossed. So the PV1 pair had a 36 tile string paired with a 28 tile string and the PV2 pair also had a 36 tile string paired with a 28 tile string. The crew fixed the pairing and it now matches the original design listed above.
My roof's production improved, but one year later production was still only 74% of Tesla's original estimate of 11,112 kWh per year. In late July 2022, I asked Tesla to investigate why production remains low. A week or so ago, I learned that they plan to swap my Delta inverter. I don't know whether the inverter is to be replaced with a similar model, a different size Delta, or a different brand (e.g. Tesla), but after looking at
data from my current inverter, I don't see how swapping it out will help since there is no clipping.
Here is an aggregated screen shot of my inverter's data from one of my better (recent) production days:
Does anyone see anything in this data that indicates the inverter has a problem that would limit production?
I'm thinking that the PV2 pair with different oriented strings is a more likely culprit, but am not sure.
Maybe Tesla just made a poor initial estimate.
Any ideas or thoughts are welcome - thanks!