My Tesla Solar Roof is underperforming by at least 20%

[MorrisonHiker]

And if he's in Denver or Boulder, then the solar radiation is a bit more through a mile less atmosphere ....which is the densest mile.
On cooler days in the Central Valley, my 8.16kw system is peaking at 7.5 kw.

We're in Morrison, just west of Denver, at 5900 feet elevation. We're in a valley so we miss out on a little sun in the mornings and evenings but that helps us stay a few degrees cooler than neighborhoods just east of us. Our original system in 2018 was 16.5 kW with three Delta Solivia inverters: 7.6, 5.2 & 5.2. When we expanded our system in 2019 to 20.5 kW, Tesla added a SolarEdge HD Wave 3.8 inverter with optimizers, so our inverters are oversized at 21.8 kW. On cloudless days, we are currently seeing a little over 18 kW maximum. On days with high, intermittent clouds, we've seen it spike as high as 22.3 kW for 15 minutes or more. Yesterday's production of 142 kWh was within 1 kWh of tying our production record.

 

[h2ofun]

I remember reading somewhere that clipping at the peak is less important than the total output for the day. Oversizing inverters to collect every bit of the peak output results in less efficiency during the rest of the day which actually results in lower daily output. If I'm correct could that apply here?

I have heard the same thing. But I still think for most folks, it is they want the cheapest price so they can say how much better the price was than a 3rd party

 

[h2ofun]

We're in Morrison, just west of Denver, at 5900 feet elevation. We're in a valley so we miss out on a little sun in the mornings and evenings but that helps us stay a few degrees cooler than neighborhoods just east of us. Our original system in 2018 was 16.5 kW with three Delta Solivia inverters: 7.6, 5.2 & 5.2. When we expanded our system in 2019 to 20.5 kW, Tesla added a SolarEdge HD Wave 3.8 inverter with optimizers, so our inverters are oversized at 21.8 kW. On cloudless days, we are currently seeing a little over 18 kW maximum. On days with high, intermittent clouds, we've seen it spike as high as 22.3 kW for 15 minutes or more. Yesterday's production of 142 kWh was within 1 kWh of tying our production record.

Those are a lot of panels, and inverters. Did they make you put a disconnect per inverter?

I forget, you must be charging lots of stuff I have that many panels? Electric heat? How many batteries? (you should consider adding this info to your tag line)

 

[jimm01]

And there is the main rub. And I have seen this with the 4 years of remodeling I have done on my home. Everyone wants the cheapest price. But everyone then wants to be hand held with phone calls, visits, etc!!! Cannot have it both ways. I know talking to my battery/solar installer, the amount of time they have spent with me on the phone is WAY more than the average person gets, let alone from most companies. So is this therefore costing me more working with them, you bet. Is it worth it to me to make sure they have considered all the things I have thought about, YOU BET. At the end it has been a win win for both of us, since things get down the first time, correctly, for what I wanted to pay for.

While I agree and have experience what you describe ( try selling sheds). But in My experience in selling building materials it’s not a majority. However, most want the same price discounts, which is not viable. I worked at least 60 hours a week, tried not to take calls after 10 pm, and was on the street before 7 am. I’ll admit many homeowners are misinformed, but most of that misinformation came from sales people and contractors. Holeydonut alluded to it here:

My Tesla Solar Roof is underperforming by at least 20%

Can you post some screen shots? Sure seems from what he has posted, he is doing all the system he purchased is designed to do. Cannot get over 8 with the inverters he purchased.

teslamotorsclub.com

In someway we are our own worse enemy not wanting to upset the equilibrium.

 

[MorrisonHiker]

Those are a lot of panels, and inverters. Did they make you put a disconnect per inverter?

I forget, you must be charging lots of stuff I have that many panels? Electric heat? How many batteries? (you should consider adding this info to your tag line)

No separate disconnects...just breakers for each inverter and then the one disconnect. In the first picture below, you can see wiring from the four inverters goes into the wire gutter below. From there, it is connected to a subpanel with breakers for each inverter. That connects into the disconnect switch which then leads to the production meter. That then connects into the generation panel, gateway, whole house electrical panel and then the utility meter box. The Powerwalls are in the garage, about 90 feet away. Since our systems were installed before Gateway 2 and Tesla inverters came out, it's not the prettiest setup but it works!

We have four Teslas and four Powerwalls. Before getting solar, are electric bills were $200 to $300 a month and now we really don't have one since our system covers our needs from March through October or so. Our overproduction can be rolled over to cover winter months. Later today, we'll hit 100% solar offset for the year so far. Lifetime solar offset is currently at 95% but if we have a good summer, we should be able to pass 100%.

Good idea. I will add some details to my signature.

 

[h2ofun]

No separate disconnects...just breakers for each inverter and then the one disconnect. In the first picture below, you can see wiring from the four inverters goes into the wire gutter below. From there, it is connected to a subpanel with breakers for each inverter. That connects into the disconnect switch which then leads to the production meter. That then connects into the generation panel, gateway, whole house electrical panel and then the utility meter box. The Powerwalls are in the garage, about 90 feet away. Since our systems were installed before Gateway 2 and Tesla inverters came out, it's not the prettiest setup but it works!

We have four Teslas and four Powerwalls. Before getting solar, are electric bills were $200 to $300 a month and now we really don't have one since our system covers our needs from March through October or so. Our overproduction can be rolled over to cover winter months. Later today, we'll hit 100% solar offset for the year so far. Lifetime solar offset is currently at 95% but if we have a good summer, we should be able to pass 100%.

Good idea. I will add some details to my signature.

Very impressive. One with the most boxes wins.

4 Tesla's? You must own stock. Are you going to get the truck?

So your utility does not limit how much solar you can have? I am trying for more panels, but shall see. I have 14K now, trying to go to like 28K. But, many would be shaded and facing north

I think by overproduction, with NEM2, has gotten me so my total ENERGY bill will be negative. House is 99% electric now.

Batteries are sure fun! I love being off the grid, in summer, 99% of the time. With the generator, I could be 100, but got to take a little from PGE.

In 2 weeks I hope to be like -300 against electricty cost. My true up now if mid july, so it would be larger. But, they may changed stuff since my batteries
just got PTOed and will shall see what the system does to my rate plan.

 

[MorrisonHiker]

Very impressive. One with the most boxes wins.

4 Tesla's? You must own stock. Are you going to get the truck?

So your utility does not limit how much solar you can have? I am trying for more panels, but shall see. I have 14K now, trying to go to like 28K. But, many would be shaded and facing north

I think by overproduction, with NEM2, has gotten me so my total ENERGY bill will be negative. House is 99% electric now.

Batteries are sure fun! I love being off the grid, in summer, 99% of the time. With the generator, I could be 100, but got to take a little from PGE.

In 2 weeks I hope to be like -300 against electricty cost. My true up now if mid july, so it would be larger. But, they may changed stuff since my batteries
just got PTOed and will shall see what the system does to my rate plan.

We do have orders in for the cybertruck, S and X and are preparing to sell the 3 and one S to make room in the garage.

Our utility does limit a solar install to 120% of previous year's electrical usage. They will also allow something like 3000 kWh for each newly purchased EV whose charging hasn't been recorded for the previous 4 months. Based on our 2017 usage, we were only able to install 16.5 kW in 2018. After a year, we proved that solar system wasn't enough and we were able to add an additional 4 kW at then end of 2019. Early in 2020, I started working from home and that probably reduced our usage by 25% or more. We actually had a 124% solar offset in 2020 and had a surplus of 4176 kWh (11009 kWh from the grid vs. 15185 kWh back to the grid). That was with 27054 kWh solar produced and 21703 kWh used. Our utility lets us get paid for surplus kWh at ToU rates or roll the credits over. We chose to just rollover the credits so that our production from March - October will help offset our usage from November - February.

 

[h2ofun]

We do have orders in for the cybertruck, S and X and are preparing to sell the 3 and one S to make room in the garage.

Our utility does limit a solar install to 120% of previous year's electrical usage. They will also allow something like 3000 kWh for each newly purchased EV whose charging hasn't been recorded for the previous 4 months. Based on our 2017 usage, we were only able to install 16.5 kW in 2018. After a year, we proved that solar system wasn't enough and we were able to add an additional 4 kW at then end of 2019. Early in 2020, I started working from home and that probably reduced our usage by 25% or more. We actually had a 124% solar offset in 2020 and had a surplus of 4176 kWh (11009 kWh from the grid vs. 15185 kWh back to the grid). That was with 27054 kWh solar produced and 21703 kWh used. Our utility lets us get paid for surplus kWh at ToU rates or roll the credits over. We chose to just rollover the credits so that our production from March - October will help offset our usage from November - February.

That seems fair.. A little over a year ago, I use 40000 kwh in 12 months. No EV's. Just running 10 space heaters in winter. Was using 240kwh a day!
So when I applied for what cals said was 20K, made it easy since my net was a - 20Kwh. Since the PTO has been less than a year, I am hoping they can still use that, or see I now have 5 batteries, and give me another 15K. Would be total over kill, but if I ever got an EV(s) in the future, this is as many panels I have roof area to put them on. And, boy would I keep my house warm next winter

Wow, you are a telsa person! Love all the cars, and truck. We are just a mini van family. And since my car only drives like 1K a year, hard to sell a 1990 with 120K miles, for something a lot more money that would not be driven. Would rather spend the money trying to get more panels. I will have to get a drone picture above my house if this works.

That is a lot of solar production!! I just have neighbor shading, and house so I do not get close to spec. I did like 18360kwh last year,

 

[jboy210]

That seems fair.. A little over a year ago, I use 40000 kwh in 12 months. No EV's. Just running 10 space heaters in winter. Was using 240kwh a day!
So when I applied for what cals said was 20K, made it easy since my net was a - 20Kwh. Since the PTO has been less than a year, I am hoping they can still use that, or see I now have 5 batteries, and give me another 15K. Would be total over kill, but if I ever got an EV(s) in the future, this is as many panels I have roof area to put them on. And, boy would I keep my house warm next winter

Wow, you are a telsa person! Love all the cars, and truck. We are just a mini van family. And since my car only drives like 1K a year, hard to sell a 1990 with 120K miles, for something a lot more money that would not be driven. Would rather spend the money trying to get more panels. I will have to get a drone picture above my house if this works.

That is a lot of solar production!! I just have neighbor shading, and house so I do not get close to spec. I did like 18360kwh last year,

40000 kwh in 12 months! That is a lot of juice. We consume around 10000 kWh/year on a 3,100 sq foot house with central air. Gas for heating, tankless water, and cooking. I can sure see why you went for the extra solar and 5 Powerwalls.

 

[h2ofun]

40000 kwh in 12 months! That is a lot of juice. We consume around 10000 kWh/year on a 3,100 sq foot house with central air. Gas for heating, tankless water, and cooking. I can sure see why you went for the extra solar and 5 Powerwalls.

Since I was running 10 space heaters for 2 winters, yep, it was NUTS.

 

[holeydonut]

Since I was running 10 space heaters for 2 winters, yep, it was NUTS.

Can you put all your space heaters in a pile and then we beat on them with some blade disconnects?

 

[MorrisonHiker]

We do have orders in for the cybertruck, S and X and are preparing to sell the 3 and one S to make room in the garage.

Our utility does limit a solar install to 120% of previous year's electrical usage. They will also allow something like 3000 kWh for each newly purchased EV whose charging hasn't been recorded for the previous 4 months. Based on our 2017 usage, we were only able to install 16.5 kW in 2018. After a year, we proved that solar system wasn't enough and we were able to add an additional 4 kW at then end of 2019. Early in 2020, I started working from home and that probably reduced our usage by 25% or more. We actually had a 124% solar offset in 2020 and had a surplus of 4176 kWh (11009 kWh from the grid vs. 15185 kWh back to the grid). That was with 27054 kWh solar produced and 21703 kWh used. Our utility lets us get paid for surplus kWh at ToU rates or roll the credits over. We chose to just rollover the credits so that our production from March - October will help offset our usage from November - February.

We've had a few clouds this morning so it hasn't been a perfect solar day like yesterday. With that said, at 70F, our 20.5 kW system is currently producing at 20.9 kW.

Our system has 63 panels in 5 different arrays on 4 different inverters. 36 panels face southeast, 6 panels face east, 9 panels face west and 12 panels face northwest.

 

[Allen Baylus]

We've had a few clouds this morning so it hasn't been a perfect solar day like yesterday. With that said, at 70F, our 20.5 kW system is currently producing at 20.9 kW.

Our system has 63 panels in 5 different arrays on 4 different inverters. 36 panels face southeast, 6 panels face east, 9 panels face west and 12 panels face northwest.

View attachment 660302

We were pulling a max around 10kW off our 14kw roof until the inspector came out 2 weeks ago (we have not completed the installation yet). He shut the roof down (bypass switch) and now we are limited - dont seem to be breaking the 5-7 range. We had no power from when the inspector was onsite fir a week. I didn’t want to mess with the system since it was still waiting to pass inspection. We were getting around 55-60 solar produced a day then. We are running around 35 -40 now.

 

[Allen Baylus]

We were pulling a max around 10kW off our 14kw roof until the inspector came out 2 weeks ago (we have not completed the installation yet). He shut the roof down (bypass switch) and now we are limited - dont seem to be breaking the 5-7 range. We had no power from when the inspector was onsite fir a week. I didn’t want to mess with the system since it was still waiting to pass inspection. We were getting around 55-60 solar produced a day then. We are running around 35 -40 now.

Is there any way to interrogate the panels to make sure that they are functional? We had rain this week so pollen buildup in the surface is not an issue.

 

[jboy210]

We were pulling a max around 10kW off our 14kw roof until the inspector came out 2 weeks ago (we have not completed the installation yet). He shut the roof down (bypass switch) and now we are limited - dont seem to be breaking the 5-7 range. We had no power from when the inspector was onsite fir a week. I didn’t want to mess with the system since it was still waiting to pass inspection. We were getting around 55-60 solar produced a day then. We are running around 35 -40 now.

I wonder if it is because you do not have PTO from the utility. The system looks like it is trying to limit production. The May 12 and 21 peaks with difference in home consumption. But in both cases, you sent almost nothing to the grid which is what you are supposed to do prior to PTO. But more importantly, it looks like once you get PTO your system will go back to the higher output (12kW peaks).

Our install was 2 years ago before they Gateways had this limit before PTO capability. Back then, before PTO, to avoid sending power out to the grid I artificially limited the systems output by turning off the inverters each afternoon. And then turned them back on right before sunset to top off the Powerwalls so they could power the home through the night.

 

[h2ofun]

I wonder if it is because you do not have PTO from the utility. The system looks like it is trying to limit production. The May 12 and 21 peaks with difference in home consumption. But in both cases, you sent almost nothing to the grid which is what you are supposed to do prior to PTO. But more importantly, it looks like once you get PTO your system will go back to the higher output (12kW peaks).

Our install was 2 years ago before they Gateways had this limit before PTO capability. Back then, before PTO, to avoid sending power out to the grid I artificially limited the systems output by turning off the inverters each afternoon. And then turned them back on right before sunset to top off the Powerwalls so they could power the home through the night.

Not sure why anyone is messing with their solar before PTO. Technically, it is not supposed to be on

 

[jboy210]

Not sure why anyone is messing with their solar before PTO. Technically, it is not supposed to be on

As far as I know, as long as you are not sending back to the grid and passed your various electrical inspections you are legal to use you Solar and Powerwalls. Tesla added the no sending to the grid feature to prevent people from accidentally sending back to the grid before PTO.

 

[h2ofun]

As far as I know, as long as you are not sending back to the grid and passed your various electrical inspections you are legal to use you Solar and Powerwalls. Tesla added the no sending to the grid feature to prevent people from accidentally sending back to the grid before PTO.

Playing with words. Just read what PGE states. I did it anyways, but sure never expected support from anyone

 

[CrazyRabbit]

have you posted pictures of your system? i want to draw my own conclusions. did you have the engineering design?

your utility provide WILL see that you are operating, not exporting, you might come home one night and not have electric service. they have to approve you first, and if they have then export...

MorrisonHiker, you probably produce more because of your altitude, as well as lower temperatures...