To Grid-Tie or Not

[Ampster]

Someone mentioned there is no ATS in the Radian, but I thought it could consume grid power when PV/Battery is not enough. Anyone know that answer?

I don't have a definitive answer. The Radian does have relays but since it's heritage is Off Grid I don't think the Radian has the functionality that a true grid interactive inverter like the Skybox has. Clearly it can island to protect Linemen.

My first Inverter was a Radian seven years ago before it had AC coupling and I just used it as a crude load shifting device using some batteries from an EV conversion project. I sold it when bought another home and bought a Skybox when it first came out. By then (2018) I was more informed about where NEM policies, rates and TOU periods were heading and knew I wanted a true grid interactive inverter.
My only caution about the Skybox is that with the new Mohawk, I don't know what it's future is? Certainly Outback will support it and continue firmware updates. It continues to work for me with my DIY battery pack. The Mohawk offers a NEC 2020 compliant battery system that is integrated with communication between the two. The cost is significantly higher than a Skybox with DIY batteries.

 

[onokai]

I am using the Tigo optomizers for 4 months of winter tree shadows from neighbors trees which they will not let me trim. That shadow crossing my 24 panel array for about 1-2 hours-Nov-Feb.
I have not turned on the fire protection feature and may never do that.

 

[ChrisG]

I don't have a definitive answer. The Radian does have relays but since it's heritage is Off Grid I don't think the Raxian has the functionality that a true grid interactive inverter like the Skybox has. Clearly it can island to protect Linemen.

My first Inverter was a Radian seven years ago before it had AC coupling and I just used it as a crude load shifting device using some batteries from an EV conversion project. I sold it when bought another home and bought a Skybox when it first came out. By then (2018) I was more informed about where NEM policies, rates and TOU periods were heading and knew I wanted a true grid interactive inverter.
My only caution about the Skybox is that with the new Mohawk, I don't know what it's future is? Certainly Outback will support it and continue firmware updates. It continues to work for me with my DIY battery pack. The Mohawk offers a NEC 2020 compliant battery system that is integrated with communication between the two. The cost is significantly higher than a Skybox with DIY batteries.

@Ampster what BMS are you using if using DIY LifePo4 and does it integrate with Skybox? If it doesn’t integrate how is Skybox assessing SOC. I’m currently using JBD 100amp 16s BMS for some testing.

 

[Ampster]

what BMS are you using if using DIY LifePo4 and does it integrate with Skybox? If it doesn’t integrate how is Skybox assessing SOC. I’m currently using JBD 100amp 16s BMS for some testing.

I had an Orion BMS from an EV conversion which I am using. It has good CAN communications but Outback has not opened their CAN protocol so it is just a contactor based BMS with no communication to the Skybox. The Orion does have a fairly accurate Coulomb counter as does the Skybox so I use those to give me a sense of where my pack is in terms of SOC. They both get out of sync but if I get a full charge cycle they each reset to 100%. I use conservative charging parameters of 3.45 volts per cell so the 100% is really not 100 percent of actual capacity but good enough for my purposes. The important numbers for me are how many kWhs of my batteries I used the previous day and based on the weather I can usually be fully charged by Noon on sunny days.
I built a 12 volt pack and used an Overkill BMS which has the same heritage as the JBD and it resets the same way my Skybox and Orion reset when charging is done.

 

[ChrisG]

@Ampster ,
Thanks for the info. I already have 2 48v packs of 280ah Eve cells with JBD 16s BMS built and have 2 more JBDs still in the box and need to order more cells. Goal is to have 4 13.4kw packs in parallel to an inverter (skybox or radian) which will give me a few days on critical loads of no PV and no Grid. Whichever inverter I choose, this should work. For non surge really leaning to Skybox for simplicity, no sell back and reliability.

 

[ChrisG]

After reading all the newer code requirements and info from @FilterGuy threads on impact of NEC2020 and other, I think the only way to go Solar is to get a grid tied system like enphase if it was a new install today. Get the enphase landing point in a subpanel with critical loads. Later place an Outback/Sol-Ark/Schneider in between main panel and sub panel and do AC coupled and call it done. Seems to be so many things blocking they way for DIY in the near future.

 

[Ampster]

After reading all the newer code requirements and info from @FilterGuy threads on impact of NEC2020 and other, I think the only way to go Solar is to get a grid tied system like enphase if it was a new install today.

Actiually any GT inverter would work. I have an Enphase GT system AC coupled to an Outback Skybox. I chose an Enphase system because I was doing it myself and it was easier for me to add capacity later with an AC micro systeem and I have some shade issues. On another home I had a Solaredge GT system AC coupled to the same Skybox.

 

[ChrisG]

Actiually any GT inverter would work. I have an Enphase GT system AC coupled to an Outback Skybox. I chose an Enphase system because I was doing it myself and it was easier for me to add capacity later with an AC micro systeem and I have some shade issues

Yes. You and I had a few threads on this topic. Anyway it seems to be the most ‘compliant’ way to have Solar with backup in the future. I have no interest in a full enphase IQ8 system with backup, want my own backup setup. I know I’ll add thousands to the full install with an additional inverter but may be the only way.