Sol-Ark 15K with 44x440W panels, Tigo Optimizers and Homegrid Stack'd 38.4kWh battery pack AMA

GregTR · Dec 11, 2022

My install is finally complete. This is a grid-tie system in DFW, Texas within the Oncor delivery area with no net metering available with a possible self consumption rate of 94% and estimated annual production of 24,000 kWh.

The full setup includes:
-Sol-Ark 15K
-44x440W Aptos 144 DNA panels
-Tigo 44xTS4-O optimizers and 3xTAP and CCA for panel level monitoring and rapid shutdown
-Homegrid Stack'd 38.4kWh battery
-2x Easy Start units for the A/C units

Total Cost:
- $2.55/W for PV
- $575/kWh of storage
- Total cost $71,500 before tax rebate, $50,050 after tax incentive.

This was an extremely competitive price, other quotes I have received were $3.30-$3.40/W for PV and $700-$800/kWh for storage.

Timeline:
- Started getting quotes mid-June, picked installer by end of June
- Paid 50% deposit mid-July
- Plans were ordered 7/21
- Tigo Optimizers were added to the quote on 7/29
- Got first draft of plans 8/3
- Final plans accepted 8/22
- Got city permit on 9/8
- Panels and inverter were installed 9/13-15
- Battery was installed 9/28 and I also got PTO the same day for export
- Tigo Optimizers were turned on 11/24 as I had to wait for the CCA that was backordered

Issues so far:
- One Tigo Optimizer was faulty and shut down the panel for overvoltage as soon as it was producing over 150W or so. The optimizer was replaced and the new one is working fine
- Originally my setup only had two TAP installed which caused flakiness with the communication on the east side panels. A third TAP was installed on December 8th and everything is happy now.
- The Sol-Ark 15K needed a new main board module, the one I had was not working properly with the rapid shutdown, ie. it did not shut down the system when the button was pushed. Sol-Ark sent a replacement board and I swapped it out and sent the faulty one back.

Peak generation was on 10/1 with 89 kWh. Lowest generation day was 2.7 kWh on 11/24.
Tigo is providing about 6% improvement which is well worth the 1.5% I paid for them.

I'm on a free nights plan where I pay nothing between 9PM and 7AM. I also get $0.03/kWh for solar export. So far for the last two months I had negative bills with this setup and I'm using electric heating at night to save money on natural gas even. I'm locked in for 2 years on this utility plan, if I can extend it my ROI will be 7.5 years for the entire system.

GregTR · Dec 11, 2022

Panel stringing is:
East: 8s2p on 48 degree incline
South: 8s2p on 30 degree incline
West: 6s2p on 48 degree incline, except two panels are on 45 degree incline

Shading issues:
East side: some panels get shade from neighbor house in the early morning and there are some drain vent pipes that do some partial shading in the early morning. (A6,7,8_
South side: I have a chimney surrounded by panels that causes some shading (D8,C8)
East Side: Dormer causes several panels to be in the shade for good amount of times during the day (E5,6, F5,6)

GregTR · Dec 11, 2022

Overall impressions:
The Sol-Ark 15K is truly incredible and I'm so glad I got to get one for my install. It made the setup a truly whole house backup system where I don't have to worry about critical loads or what I'm using and when.

The Homegrid battery is very nice, it has a base consumption that is a bit too high for my liking, it is around 100W but I think the latest firmware dropped it to about 56W which is much more manageable. Overall it's a beast of a battery that pairs really well with the Sol-Ark 15K.

The Aptos Panels are nice, aesthetically pleasing and produce solid power. I did get over 440W from them on an overcast day where clouds acted like reflectors and I got a TON of light on them. Time will tell how they will produce 20 years down the line but their day 1 performance is impressive.

NEpowerandlight · Dec 11, 2022

Am I reading your power bill correctly, 29 cents a Kwh?

GregTR · Dec 11, 2022

Additional Equipment:

I bought a Solar-Assistant setup for monitoring that I mounted on the DIN rail next to the Tigo CCA. It works really well, I modified it a bit so it does hourly backups onto a USB stick in case the SD card decides to die. The author had to add the 3rd MPPT as most other inverters only have 2. I created some custom graphs, such as the east/west/south production overlays I showed above.

I have several Emporia Vue meters in my house to monitor every breaker in all panels and to track solar production outside of the Sol-Ark. I had to build a custom CT coupler to be able to measure solar production with the Sol-Ark and it works really well. I also have 8 smart switches to control some oil heaters to offset some of the gas heating with free electricity. I also use a Vue EV charger which works well to load excess solar into the EV or to do timed charging at night with adjustable current flow.

I added a rapid shutdown button connected to the Sol-Ark and driving the Tigo CCA via a DIN rail mounted relay. Also mounted the Solar-Assistant on the same DIN rail.

Nobodybusiness · Dec 11, 2022

GregTR said:
My install is finally complete.

The full setup includes:
-Sol-Ark 15K
-44x440W Aptos 144 DNA panels
-Tigo 44xTS4-O optimizers and 3xTAP and CCA for panel level monitoring and rapid shutdown
-Homegrid Stack'd 38.4kWh battery
-2x Easy Start units for the A/C units

Timeline:
- Started getting quotes mid-June, picked installer by end of June
- Paid 50% deposit mid-July
- Plans were ordered 7/21
- Tigo Optimizers were added to the quote on 7/29
- Got first draft of plans 8/3
- Final plans accepted 8/22
- Got city permit on 9/8
- Panels and inverter were installed 9/13-15
- Battery was installed 9/28 and I also got PTO the same day for export
- Tigo Optimizers were turned on 11/24 as I had to wait for the CCA that was backordered

Issues so far:
- One Tigo Optimizer was faulty and shut down the panel for overvoltage as soon as it was producing over 150W or so. The optimizer was replaced and the new one is working fine
- Originally my setup only had two TAP installed which caused flakiness with the communication on the east side panels. A third TAP was installed on December 8th and everything is happy now.
- The Sol-Ark 15K needed a new main board module, the one I had was not working properly with the rapid shutdown, ie. it did not shut down the system when the button was pushed. Sol-Ark sent a replacement board and I swapped it out and sent the faulty one back.

Peak generation was on 10/1 with 89 kWh. Lowest generation day was 2.7 kWh on 11/24.
Tigo is providing about 6% improvement which is well worth the 1.5% I paid for them.

I'm on a free nights plan where I pay nothing between 9PM and 7AM. I also get $0.03/kWh for solar export. So far for the last two months I had negative bills with this setup and I'm using electric heating at night to save money on natural gas even. I'm locked in for 2 years on this utility plan, if I can extend it my ROI will be 7.5 years for the entire system.

Very nice system…
I think you will be very happy with that..

GregTR · Dec 11, 2022

NEpowerandlight said:
Am I reading your power bill correctly, 29 cents a Kwh?

Yes, but don't be alarmed, this is to offset the fact that 9PM to 7AM is free. Since I use NOTHING between 7AM and 9PM, it could be $10/kWh for all I care...

The plan is called "free nights plan", one which they give you free electricity at night and charge you a lot during the day. For most people it comes out to about 16 cents/kWh on average but for me it comes out to ZERO.

zephyranthes · Dec 11, 2022

Im in the DFW area and are glad to hear about the 15k. PTO was back in September and it’s just panels and microinverters now.

I’ve been looking at adding the 15k and building my own LFP batteries.

System looks great!

JB solar · Jan 20, 2023

Awesome system, since power is free at night, I guess you could charge a few delta pro's during the night. I would be curious to know how many Ecoflow Delta Pro's you will need to be off grid and if you would need few solar panels and what the cost would be.

Great job!

Danke · Jan 23, 2023

GregTR said:
Yes, but don't be alarmed, this is to offset the fact that 9PM to 7AM is free. Since I use NOTHING between 7AM and 9PM, it could be $10/kWh for all I care...

The plan is called "free nights plan", one which they give you free electricity at night and charge you a lot during the day. For most people it comes out to about 16 cents/kWh on average but for me it comes out to ZERO.

Do you have an EV or two? Sounds like free “gas” for two years at least.

GregTR · Jan 23, 2023

Danke said:
Do you have an EV or two? Sounds like free “gas” for two years at least.

I do! And I do get to charge it every night for free past 9PM

cm119 · Jan 23, 2023

GregTR said:
I bought a Solar-Assistant setup for monitoring that I mounted on the DIN rail next to the Tigo CCA. It works really well, I modified it a bit so it does hourly backups onto a USB stick in case the SD card decides to die. The author had to add the 3rd MPPT as most other inverters only have 2. I created some custom graphs, such as the east/west/south production overlays I showed above.

@GregTR I'd like more details on these parts. Hopefully starting my install soon, and I've already loaded SA onto a Pi with a M.2 SATA disk as I was afraid of SD card failures. I'd still like to configure backup though, wondering how you accomplished this.

Nobodybusiness · Jan 23, 2023

GregTR said:
I do! And I do get to charge it every night for free past 9PM

Wow what a deal. That would be great..
You really don’t even need the panels just recharge from the grid.

Quattrohead · Jan 24, 2023

Very nice system and realistic cost breakdown.

FunnyLogic · Jan 27, 2023

Awesome setup. I'm looking at a very similar setup, but debating between the HomeGrid and a EG4 LLv2. Also debating between Aptos and Qcell. Did your installer use a gutter for the inverter install? What about an isolation switch (double throw) if you have any problems with the 15k? I'm surprised your REP allows solar buyback and free nights. That's a huge gift with that setup.

GregTR · Jan 27, 2023

FunnyLogic said:
Awesome setup. I'm looking at a very similar setup, but debating between the HomeGrid and a EG4 LLv2. Also debating between Aptos and Qcell. Did your installer use a gutter for the inverter install? What about an isolation switch (double throw) if you have any problems with the 15k? I'm surprised your REP allows solar buyback and free nights. That's a huge gift with that setup.

EG4 LLv2 wasn't UL listed nor had closed loop control with Sol-Ark when I got my system but the price is very lucrative and they also solved the closed loop monitoring problem making it a very viable option today. I like the form factor and the look of the HomeGrid but overall I don't think it really matters all that much.

My installer told me that HomeGrid pricing has changed significantly for the worse just recently and the targets they need to hit to get the rebates/discounts are unattainable so they're looking at alternative options going forward, including the EG4 rack.

As for Aptos vs. Qcell, I really don't think there is a lot to consider with panels, they are all pretty much the same, I'd go with the one that you can source cheaper. The efficiency differences are marginal and usually not worth the cost, you'd be better off just buying a few extra panels of the cheaper ones to make up the difference if your system allows.

I do not have an isolation switch, I kind of wish I did but I bought three 2/0 connectors instead that I keep in the gutter (they put in a 4ft section under the sol-ark) in case I need to cut out the Sol-Ark. https://www.amazon.com/gp/product/B00CBK66Q4/ The odds of needing to isolate the inverter from the system is pretty low and when it happens it is for a reason where the solution/replacement will be measured in days so spending 10 minutes on bolting on three connectors is a non-issue for me.

I'm going to milk the free nights and solar buyback for as long as I can, after that I should have enough data and modeling to see whether a system upgrade (AC coupled PV, extra batteries) would make financial sense.

FunnyLogic · Jan 27, 2023

GregTR said:
EG4 LLv2 wasn't UL listed nor had closed loop control with Sol-Ark when I got my system but the price is very lucrative and they also solved the closed loop monitoring problem making it a very viable option today. I like the form factor and the look of the HomeGrid but overall I don't think it really matters all that much.

My installer told me that HomeGrid pricing has changed significantly for the worse just recently and the targets they need to hit to get the rebates/discounts are unattainable so they're looking at alternative options going forward, including the EG4 rack.

As for Aptos vs. Qcell, I really don't think there is a lot to consider with panels, they are all pretty much the same, I'd go with the one that you can source cheaper. The efficiency differences are marginal and usually not worth the cost, you'd be better off just buying a few extra panels of the cheaper ones to make up the difference if your system allows.

I do not have an isolation switch, I kind of wish I did but I bought three 2/0 connectors instead that I keep in the gutter (they put in a 4ft section under the sol-ark) in case I need to cut out the Sol-Ark. https://www.amazon.com/gp/product/B00CBK66Q4/ The odds of needing to isolate the inverter from the system is pretty low and when it happens it is for a reason where the solution/replacement will be measured in days so spending 10 minutes on bolting on three connectors is a non-issue for me.

I'm going to milk the free nights and solar buyback for as long as I can, after that I should have enough data and modeling to see whether a system upgrade (AC coupled PV, extra batteries) would make financial sense.

Thanks for the detailed reply. I see your points.

The LLv2 batteries went up a little, but are still the best per kWh with closed loop and UL. Too bad it's not 9540 UL certified, but the current UL listing should work for my jurisdiction since we are still on NEC 2020 and 9540 isn't necessary, just UL listing.

Because of my limited roof space, I can only fit so many panels. I have an all electric house, so that's why I look at efficiency and such. I was looking at REC, but the premium isn't worth it for me.

The double throw 200A bypass switch is expensive, but I need a simple solution for the other members of my family.

What made you choose your installer over others? I have gotten a bunch of quotes, but none as low as that and those that were close to that were new to the area/solar or just didn't know much about or didn't sell the Sol-Ark.

2TrevorJ · Jan 27, 2023

GregTR said:
My install is finally complete. This is a grid-tie system in DFW, Texas ...

Hey Greg! I'm on the North side of Fort Worth with a really similar system in a 4100 sq ft house. I had been planning it for like a year, got quotes over last summer, and we finished the install Wednesday. Although the installer I selected was on Sol-Ark's website back then I had to hand-hold quite a bit for both parts and configuration/schematics. I was out there working with them for the whole install. Good people with sound fundamentals...just not as familiar as I hoped with Sol-Arks or batteries.

51 x 400W REC Alpha Pures (Tigo TS4-A-O's, 3 TAPs, and a CCA)
2 x Sol-Ark 15K's
2 x 28.8 kWh Homegrid Stack'd Batteries
Micro-Air Easy Starts on the two AC units (3 & 4 Ton)

I swear I didn't copy your homework.

Should be (barely) enough production and storage to not need the grid in my worst month (July); even with my daughters Nissan Leaf pulling 300-500 kWh month. That said...I'm not going to go shutting off my service quite yet. ? Winter is not a problem as I'm on gas heat (dryer, cooktop, and water heater are also gas so that eases the electrical burden). I've been nerding out on heat pump modeling and what I might be able to do with my excess winter power. So far I'm thinking I might be able to heat the house down to 37F ambient then gas would have to take over but that's a whole other topic.

I got my PTO from the electric coop today but after initially charging the batteries from the grid I've been running completely off-grid/islanding (limited to load) since Wednesday night. After the city inspection tomorrow I'll throw the breaker to use grid as backup. ? In the meantime, after the initial firmware update on the 15K's the setup is behaving exactly as I thought it would. Runs both A/C units no problem, charges the car (6.6 kW)...the whole nine. When the sun went down yesterday I was at 100% SOC, bottomed out at 66% this morning when the sun came out, and was back to 99% by 11:28 AM.

Unfortunately that means that I didn't get to see the full PV curve as it was still climbing when the batteries called knock it off and there was nowhere left to put the power.

By the way, what are you seeing for charge limit from the Stack'd setup? My master 15K displays 240A charge limit from the BMS between 66-99% SOC which the 15Ks adhere to (IE I only saw sustained ~6200-6300w (120A) from each inverter simultaneously while charging from grid). Not what I expected when the Homegrid spec sheet says 300A for a single stack (and the 15K's can do 275A each). Of note, discharge limit reflects 600A which I assume means the BMS properly recognizes the config is 2 stacks. I'm probably going to call Homegrid support next week and poke them in the eye. I'm on the latest firmware for both BMS and the individual slabs so maybe this will require some work on their part. I have a feeling I'm going to need more charging amps to capture solar noon power in realtime...especially during the summer.

I integrated the Tigo CCA's rapid shutdown the same exact way with a relay driven off master 15K's 12V output. Works like a champ.

Also, once I found out from Sol-Ark that there are some rare failure modes where you may not have pass-through power we added a GE bypass switch to the mix. You may have to drop by sometime and check out the install.

FunnyLogic · Jan 27, 2023

2TrevorJ said:
Hey Greg! I'm on the North side of Fort Worth with a really similar system in a 4100 sq ft house. I had been planning it for like a year, got quotes over last summer, and we finished the install Wednesday. Although the installer I selected was on Sol-Ark's website back then I had to hand-hold quite a bit for both parts and configuration/schematics. I was out there working with them for the whole install. Good people with sound fundamentals...just not as familiar as I hoped with Sol-Arks or batteries.

51 x 400W REC Alpha Pures (Tigo TS4-A-O's, 3 TAPs, and a CCA)
2 x Sol-Ark 15K's
2 x 28.8 kWh Homegrid Stack'd Batteries
Micro-Air Easy Starts on the two AC units (3 & 4 Ton)

I swear I didn't copy your homework. Should be (barely) enough production and storage to not need the grid in my worst month (July); even with my daughters Nissan Leaf pulling 300-500 kWh month. That said...I'm not going to go shutting off my service quite yet. ? Winter is not a problem as I'm on gas heat (dryer, cooktop, and water heater are also gas so that eases the electrical burden). I've been nerding out on heat pump modeling and what I might be able to do with my excess winter power. So far I'm thinking I might be able to heat the house down to 37F ambient then gas would have to take over but that's a whole other topic.

I got my PTO from the electric coop today but after initially charging the batteries from the grid I've been running completely off-grid/islanding (limited to load) since Wednesday night. After the city inspection tomorrow I'll throw the breaker to use grid as backup. ? In the meantime, after the initial firmware update on the 15K's the setup is behaving exactly as I thought it would. Runs both A/C units no problem, charges the car (6.6 kW)...the whole nine. When the sun went down yesterday I was at 100% SOC, bottomed out at 66% this morning when the sun came out, and was back to 99% by 11:28 AM. Unfortunately that means that I didn't get to see the full PV curve as it was still climbing when the batteries called knock it off and there was nowhere left to put the power.

By the way, what are you seeing for charge limit from the Stack'd setup? My master 15K displays 240A charge limit from the BMS between 66-99% SOC which the 15Ks adhere to (IE I only saw sustained ~6200-6300w (120A) from each inverter simultaneously while charging from grid). Not what I expected when the Homegrid spec sheet says 300A for a single stack (and the 15K's can do 275A each). Of note, discharge limit reflects 600A which I assume means the BMS properly recognizes the config is 2 stacks. I'm probably going to call Homegrid support next week and poke them in the eye. I'm on the latest firmware for both BMS and the individual slabs so maybe this will require some work on their part. I have a feeling I'm going to need more charging amps to capture solar noon power in realtime...especially during the summer.

I integrated the Tigo CCA's rapid shutdown the same exact way with a relay driven off master 15K's 12V output. Works like a champ.

Also, once I found out from Sol-Ark that there are some rare failure modes where you may not have pass-through power we added a GE bypass switch to the mix. You may have to drop by sometime and check out the install.

Double 15k. Nice. What model number is the GE bypass switch you used? I also think it's a good idea to be able to isolate the inverters.

2TrevorJ · Jan 27, 2023

We used a GE TC10324R.

GregTR · Jan 27, 2023

FunnyLogic said:
Because of my limited roof space, I can only fit so many panels. I have an all electric house, so that's why I look at efficiency and such. I was looking at REC, but the premium isn't worth it for me.

The double throw 200A bypass switch is expensive, but I need a simple solution for the other members of my family.

What made you choose your installer over others? I have gotten a bunch of quotes, but none as low as that and those that were close to that were new to the area/solar or just didn't know much about or didn't sell the Sol-Ark.

That's fair about roof space, most people are limited by budget not roof area. If your limiting factor is indeed the roof then higher efficiency might make sense, but if all you're doing is trying to offset the majority of your grid use not entirely eliminate it then the cost might not worth it, as you pointed out.

I work from home and I'd say the chances of something breaking while I'm not at the house to rectify the situation is pretty slim so I feel pretty confident with the poor man's setup but we all have different use cases and wife acceptance factors

.

So the installer I picked, I got through EnergySage. I don't want to say I went with the cheapest one but I actually did. They were the only ones on Energy Sage that offered a real battery back-up hybrid system with a Sol-Ark 15K at the heart of the setup straight from the start. Every other installer was pushing Enphase micros and their IQ battery system that was just not price competitive or they didn't even read the original request and quoted a bare system with no battery, not even after follow ups. There are a lot of questionable companies out there so it takes caution and time to separate the good ones from the bad ones.

I had requested quotes from three other Sol-Ark installers off the Sol-Ark website, two of them did site surveys and quoted systems in the $3.30-$3.40/W range with a much smaller Homegrid (24kWh) for about $700/kWh. Both companies were very professional in their consultation, their offer, and their email exchanges, their pricing reflected their size and overhead. I think they were the two largest Sol-Ark installers in the area but they also installed Enphase and Tesla power walls if that is what the customer wanted. The $3.40/W quote was for a 17kW system using 440 W panels while the $3.30/W system was for a 13.5 kW system using 370 W panes from Mission Solar (that company was very proud of selling American veteran made inverter and panels).

The third one was a smaller mom and pop operation who were struggling with illness in the family at the time and never got me a proper quote but they were the only ones who asked for my smart meter data access to pull energy usage info in 15 minute intervals from last year for data modeling. I think their price would have been probably in the $3.00/W range if I got a quote.

The installer I chose were fairly new to the area with few but 5 star reviews and I checked out the owner on LinkedIn and they owned a solar install company for many years in another state where they sold the business to their employees before making the move here. So you can say I took a calculated risk and it paid off. They were really good folks, I treated the crews right when they were on-site (bought them nice lunches, provided Gatorade/water etc.) and overall we had a really good experience.

GregTR · Jan 27, 2023

2TrevorJ said:
Hey Greg! I'm on the North side of Fort Worth with a really similar system in a 4100 sq ft house. I had been planning it for like a year, got quotes over last summer, and we finished the install Wednesday. Although the installer I selected was on Sol-Ark's website back then I had to hand-hold quite a bit for both parts and configuration/schematics. I was out there working with them for the whole install. Good people with sound fundamentals...just not as familiar as I hoped with Sol-Arks or batteries.

51 x 400W REC Alpha Pures (Tigo TS4-A-O's, 3 TAPs, and a CCA)
2 x Sol-Ark 15K's
2 x 28.8 kWh Homegrid Stack'd Batteries
Micro-Air Easy Starts on the two AC units (3 & 4 Ton)

I swear I didn't copy your homework. Should be (barely) enough production and storage to not need the grid in my worst month (July); even with my daughters Nissan Leaf pulling 300-500 kWh month. That said...I'm not going to go shutting off my service quite yet. ? Winter is not a problem as I'm on gas heat (dryer, cooktop, and water heater are also gas so that eases the electrical burden). I've been nerding out on heat pump modeling and what I might be able to do with my excess winter power. So far I'm thinking I might be able to heat the house down to 37F ambient then gas would have to take over but that's a whole other topic.

I got my PTO from the electric coop today but after initially charging the batteries from the grid I've been running completely off-grid/islanding (limited to load) since Wednesday night. After the city inspection tomorrow I'll throw the breaker to use grid as backup. ? In the meantime, after the initial firmware update on the 15K's the setup is behaving exactly as I thought it would. Runs both A/C units no problem, charges the car (6.6 kW)...the whole nine. When the sun went down yesterday I was at 100% SOC, bottomed out at 66% this morning when the sun came out, and was back to 99% by 11:28 AM. Unfortunately that means that I didn't get to see the full PV curve as it was still climbing when the batteries called knock it off and there was nowhere left to put the power.

By the way, what are you seeing for charge limit from the Stack'd setup? My master 15K displays 240A charge limit from the BMS between 66-99% SOC which the 15Ks adhere to (IE I only saw sustained ~6200-6300w (120A) from each inverter simultaneously while charging from grid). Not what I expected when the Homegrid spec sheet says 300A for a single stack (and the 15K's can do 275A each). Of note, discharge limit reflects 600A which I assume means the BMS properly recognizes the config is 2 stacks. I'm probably going to call Homegrid support next week and poke them in the eye. I'm on the latest firmware for both BMS and the individual slabs so maybe this will require some work on their part. I have a feeling I'm going to need more charging amps to capture solar noon power in realtime...especially during the summer.

I integrated the Tigo CCA's rapid shutdown the same exact way with a relay driven off master 15K's 12V output. Works like a champ.

Also, once I found out from Sol-Ark that there are some rare failure modes where you may not have pass-through power we added a GE bypass switch to the mix. You may have to drop by sometime and check out the install.

Your system is a good bit larger than mine both PV and storage wise and probably cost accordingly. I have a 4,000 sq ft home and an EV that I charge ~300 kWh/month.

I bought Emporia power meters last April so I had a pretty good estimate on power usage and I used https://www.opensolar.com/ to design, build, and model my system using my power usage and various energy models and cost estimates to see if ROI makes sense. The goal was maximizing self consumption as solar buyback has questionable future and net metering is practically non-existent in Texas. With regular usage strategy I'm estimating 94% self-consumption where surplus only occurs in the winter. This is ideal and will likely provide the quickest ROI.

I'm also on gas heat but with the free nights plan I've been using electric heaters during the night and I am contemplating two split unit heat pumps for the office and the main bedroom. Once the gas furnace/AC kicks it I'll be looking at heat pumps with gas emergency heating as a replacement for the whole house to give me the option to use electricity for heating in a more efficient way than space heaters.

I also considered a heat pump water heater to augment my tankless gas heater but the cost was stupid. $3k for the 80 gallon unit and the installers were asking $2-$4k to install it. I would never recover $5-7k in savings, I'll buy a pergola, put some bifacials on top and AC couple it to my Sol-Ark through some micro inverters for that kind of money for a much better ROI.

I see 255A charging my single stack of Homegrid from a single Sol-Ark up to 84% then the current drops to 150A until full from grid power. Homegrid support had been OK, they sent me a skybox for firmware upgrades and I did upgrade my firmware once. It added kWh count on the unit itself but that is all I've seen out of the firmware upgrade, the batteries have been working fine before, I never had a problem with them.

GregTR · Jan 27, 2023

Here is a link to my Tigo data if anyone is interested: https://ei.tigoenergy.com/p/TakOakValley

FunnyLogic · Jan 28, 2023

2TrevorJ said:
We used a GE TC10324R.

All of the ones I were looking at allowed me to put the neutral through the bypass switch (3-pole) and they are a bit more expensive than that one (2-pole). I thought putting the neutral on the bypass would be needed, but I'm no electrician. I just dabble in the space. I wonder if someone explain why you would only use the conductors in a bypass/safety switch and not neutral if you want to use the double throw to isolate the inverter from the grid if there are issues? Maybe @robby would know.

GregTR said:
I work from home and I'd say the chances of something breaking while I'm not at the house to rectify the situation is pretty slim so I feel pretty confident with the poor man's setup but we all have different use cases and wife acceptance factors .

Ha. Don't discount your setup. It works for you. That's all we're all trying to do here. Figure out what works for us and our individual needs.
@GregTR- It seems our thoughts on Solar are very similar. I planned on a DIY system, but I think I'm leaning towards your route these days. I like the 15k and am really looking for a solid installer since I know my limits. I appreciate the advice and you sharing your experience with all of us.

2TrevorJ · Jan 29, 2023

2TrevorJ said:
By the way, what are you seeing for charge limit from the Stack'd setup? My master 15K displays 240A charge limit from the BMS between 66-99% SOC which the 15Ks adhere to (IE I only saw sustained ~6200-6300w (120A) from each inverter simultaneously while charging from grid). Not what I expected when the Homegrid spec sheet says 300A for a single stack (and the 15K's can do 275A each). Of note, discharge limit reflects 600A which I assume means the BMS properly recognizes the config is 2 stacks. I'm probably going to call Homegrid support next week and poke them in the eye. I'm on the latest firmware for both BMS and the individual slabs so maybe this will require some work on their part. I have a feeling I'm going to need more charging amps to capture solar noon power in realtime...especially during the summer.

Answering my own question here. Just got down to 64% SOC and the two stacks are now calling for up to 600A charge from the 15K's. I'm up to 65% now and it's still calling for 600A. We'll see how long it holds it.

I noticed some of the Homegrid documentation shows "Max Charge Current - 300A" vs others that state "Charge Current - 300A". Looks like they're working as designed and what I'm seeing is just the charge curve for the pair.

<= 64% 600A
65% 240A-600A
66-67% 240A
68-71% 200-240A
72-96% 180-240A

Sol-Ark 15K with 44x440W panels, Tigo Optimizers and Homegrid Stack'd 38.4kWh battery pack AMA

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