Outback Radian questions and suggestions for new grid tie hybrid system.

[df0rster]

(moved from equipment forum, made more sense to put it here)

I'm planning to install a small PV system around 4kw to our newer home, we use about 600 kwh/month winter and more in summer so will still pull some from the grid for AC in the summer. I talked to a solar sales company and he recommended a hybrid inverter with a small battery bank for backup. as we do have frequent shorter outages.

Anyway, the sales guy seemed knowledgeable but didn't give me a lot of details yet so I had some questions to fill in some of the blanks.

I don't want to do any exporting to the grid right now (our net metering options suck and are a pain to setup up through our coop), but want to remain on the grid with the small battery backup and be able to quickly switch to battery/solar power only during outages.

He said the Outback radian 4kw was the best choice. He said it would automatically draw power from the batteries or from the grid at night or when solar wasn't keeping up. He says there is a lot of control options to have it draw from the grid or batteries to save money, etc. I didn't ask too many questions regarding that. I'm more concerned with physical setup.

One concern is setting up my main panel safely to work with the Radian. What I gathered from him, I think I may have to add a subpanel that would be fed during outages from a separate AC out on the inverter and breaker it with a lock out to the main manel. And of course switch off my main panel breaker to the grid. Can that subpanel just be a single disconnect that feeds 220v into my pain panel breaker that is locked out during grid connection? This is how I have seen generator setups done by some folks. Does the radian supply 100% of its output during outages, either via battery or PV?

other less important concerns are does it have the ability to export power for net metering if that becomes an option later on?

He said it will but didn't sound too sure. He also says I do not need their load center, but would need their Mate controller..

I'm sure I'll have other questions as I go. The sales guy is very helpful and says they'll provide tech support as I go also. I do have quite a bit of electrical experience and an electrician to help me do everything safely. and have had a small PV battery system up and running my shop for a few years just for playing with so I've done some of this already, although much simpler than the hybrid system.

Thanks!

[Ampster]

You most likely should consider a subpanel anyway for any hybrid inverter.. I had a Radian for several years. It is a good inverter and service from Outback is excellent. There are a number of additional components needed to make the Radian a truly grid interactive hybrid inverter.
I sold the Radian when I moved and installed an Outback Skybox which was designed from the ground up to be a grid interactive hybrid inverter. It is All In One and includes charge controller, display, web interface and Load center with transfer switch. It does not have the surge capacity which the Radian does and is limited to 5000 Watts. Another All In One is the Sol Ark, and there are others. I would focus on capacity and define the features you want. The Skybox and others offer a variety of implementation scenerios. AC coupling, Grid Zero and/or parameter driven export to name a few.

[df0rster]

You most likely should consider a subpanel anyway for any hybrid inverter.. I had a Radian for several years. It is a good inverter and service from Outback is excellent. There are a number of additional components needed to make the Radian a truly grid interactive hybrid inverter.
I sold the Radian when I moved and installed an Outback Skybox which was designed from the ground up to be a grid interactive hybrid inverter. It is All In One and includes charge controller, display, web interface and Load center with transfer switch. It does not have the surge capacity which the Radian does and is limited to 5000 Watts. Another All In One is the Sol Ark, and there are others. I would focus on capacity and define the features you want. The Skybox and others offer a variety of implementation scenerios. AC coupling, Grid Zero and/or parameter driven export to name a few.

Very good to know. I saw the Skybox on another site and it looked interesting, I don't know why they recommended the radian instead. By the time you put the add ons to the Radian its as much or more than the skybox. I think my quote for the radian with the mate+ comm manager and 100 amp charge controller was around $4k and the skybox looks like $3400.


I'm not very familiar with all the terms for what I want to do, but I think the three you mention look like what I probably am thinking about (ac coupling, grid zero and parameter driven export).

I don't think the extra surge would be an issue for me. I"ll look at the others as well but for the money the Skybox is looking very attractive. Unless I'm missing something.

[df0rster]

You most likely should consider a subpanel anyway for any hybrid inverter.. .

specific question on the subpanel. Should I set it up like a critical load subpanel with all the circuits I want to run in an outage. Or could I just run a single double pole breaker that I would turn on in the main panel, it could be installed with an interlock that would force turning off the main 200 amp grid breaker before it was activated. This way all my circuits would be active during an outage. This is how I have seen backup generators setup.

[Ampster]

specific question on the subpanel. Should I set it up like a critical load subpanel with all the circuits I want to run in an outage. Or could I just run a single double pole breaker that I would turn on in the main panel, it could be installed with an interlock that would force turning off the main 200 amp grid breaker before it was activated. This way all my circuits would be active during an outage. This is how I have seen backup generators setup.

Yes, i would set it up like a critical loads panel. On my next project, I am going to do that with wiring gutters top and bottom, so I can move circuits later. Initially you would feed the sub panel with a breaker from the main. Later that Main breaker would feed the Grid In breaker on the hybrid inverter and AC Out on the hybrid would feed the sub panel.

I also put in an interlock in on my sub panel in case i ever needed to take the hybrid off line for maintenance. That way I could bypass the hybrid inverter altogether. It has been convenient when I have had to do firmware upgrades. Many All in One hybrids also have a Generator In breaker.
Speaking of firmware upgrades, to me that is another "feature" that was important to me because of the evolving nature of the standards surrounding interaction with the grid. For example UL1741 has evolved into UL1741SA and California and Hawaii have their own Rules.

[Ampster]

I made a detailed response but it was flagged. Stay tuned until it clears moderation.

[SunEagle]

I made a detailed response but it was flagged. Stay tuned until it clears moderation.

It is clear now.

[df0rster]

Yes, i would set it up like a critical loads panel. ...

This might be a dumb question.

What if I want every circuit in my main panel to be a critical circuit/load, well except for the tankless electric water heater? Is there an easier way to just backup the entire main panel rather than moving all my circuits into a subpanel?

I think that is what I was trying to explain earlier by using a disconnect from the AC backup on the inverter that would feed into a breaker that could only be turned on via an interlock.

I'm just not sure if that is a safe and acceptable way to do it. I don't' have any inspections to pass but do want to follow codes.

Thanks!

[Ampster]

..........
What if I want every circuit in my main panel to be a critical circuit/load, well except for the tankless electric water heater? Is there an easier way to just backup the entire main panel rather than moving all my circuits into a subpanel?

I think that is what I was trying to explain earlier by using a disconnect from the AC backup on the inverter that would feed into a breaker that could only be turned on via an interlock.

Following the code you could do that. That is what a backup generator does. Then you would only be using a hybrid inverter as a manual back up and you would lose all the functionality of the hybrid inverter as a grid interactive inverter. To get those interactive functions the loads have to be fed from the AC out connection of the hybrid and it then arbitrates whether that load will be served by the grid, the inverted solar or the inverted battery energy. That was the way my old Radian was wired as well for some of the same functionality. You are paying a lot for that functionality but if you just want a manual back up there are a lot of less expensive solutions and you would not need a critical loads panel.You could put a interlocked disconnect and when you were on backup you would have to remember to turn off your tankless water heater or the inverter breaker will go into overcurrent protection.

If you do not need battery back up then a less expensive option would be a grid tie inverter with a zero export mode. No subpanel would be needed. If your back up needs were small you could wire a backup plug and use a small generator or a small inverter and portable battery pack.

My main panel was outside my garage and I put my critical loads panel just behind it on the inside of the garage so swinging the circuits was easy. I don't know enough about your layout or your rate structure to know which would be the best plan for you.

[Mike90250]

The difference being that a main panel is rated for 200A / 24kw (usually, or even more! )

Your inverter or generator is not likely going to be rated for nearly that much.
So you have the instant duty to switch a bunch of gear off when the power fails. You could count on being lucky - and hope not all is running at the same time, but at some point, someone is going to turn on the hair blower, trip the generators main breaker (40A maybe) and you are in the dark again.

A critical loads panel lets you forget about YOU being the load management, and focus on brushing snow off the panels or changing oil in the generator after 4 days.

[df0rster]

You most likely should consider a subpanel anyway for any hybrid inverter.. .

That makes sense. I am not yet too familiar with all the features of the hybrid inverters. I just wanted it for its battery backup capability and zero export and other features and options, and the salesman recommended it to me. I thought he also told me that it didn't have an automatic transfer capability for backup, but maybe I misunderstood..

A subpanel won't be a big deal for me. I could probably move everything except my water heater and AC unit to the subpanel for backup.

Does the skybox provide all of its 5000w in backup mode also?

The skybox seems very reasonable for all it does..

[df0rster]

The difference being that a main panel is rated for 200A / 24kw (usually, or even more! )

Your inverter or generator is not likely going to be rated for nearly that much.
So you have the instant duty to switch a bunch of gear off when the power fails. You could count on being lucky - and hope not all is running at the same time, but at some point, someone is going to turn on the hair blower, trip the generators main breaker (40A maybe) and you are in the dark again.

A critical loads panel lets you forget about YOU being the load management, and focus on brushing snow off the panels or changing oil in the generator after 4 days.

Understood. Actually my 200 amp panel is almost always running well below 20 amps. during the day with a fridge running plus a tv and plenty of LED lights and computer equipment I am pulling about 7 amps. at night during bed time we might be pulling 2 or 3 amps. but I understand the hair dryer, microwave and toaster can pull some amps. That's when the grid will come in handy! but I understand your point that with the subpanel I won't have to worry about overloading the inverter.

The darn tankless water heater is a huge load, it can pull up to 180 amps, but usually will only pull 120 amps for a shower. I bet that thing accounts for 1/3 of our total electric usage. I plan to replace it with a propane tankless one day.

[Mike90250]

............
The darn tankless water heater is a huge load, it can pull up to 180 amps, but usually will only pull 120 amps for a shower. I bet that thing accounts for 1/3 of our total electric usage. I plan to replace it with a propane tankless one day.

Even the propane tankless will still require a lot of energy. Most require a 1" or 3/4" line because of their fuel demand.
depending on your climate, a rooftop storage/collector may work for you. I have one with a 30 gal tank and even in winter, the sun gets it up to 70F, summer 140F easy. Sure takes the load off the propane demand

FlatPlateSolarWaterRooftop.jpg

[df0rster]

I’ve actually thought about solar collectors for my radiant floor heat. We partially heat the house floors with a small propane tankless just to have warm floors and it can get expensive. The rest of the heat is from wood stove. Another option is an outdoor wood boiler for the floor heat. But that’s a project for later on.

im not sure if the solar collectors would be enough in the winter if it only heats to 70F. I heat the water to 115 with the propane tankless.

where did you get the solar collector? The ones I’ve found online are pretty expensive.

[Mike90250]

Mine was made by Rheem ( big water heater & furnace company) in 2011 and uses a glycol loop in the flat plate, and the cylinder above it, holds the heated water. If I had use an adjustable mount, I could get more heat in the winter, but I kept it simple.