Can I have dedicated solar/battery circuits in a house connected to the grid?

[TGJR]

My house has 320a service coming into a meter base with two disconnects feeding two panels inside the garage with all of the house circuits. It is overkill but when I built the house a few years ago, I wanted plenty of expansion room. Right now I have one panel that has all of the important backup circuits (refrigerator, freezer, well pump, some lights, etc.) and it has a generator inlet for when the power goes out. I'm in the country so when it goes out, we are usually the last to come back on.

Eventually I would to take the whole house off grid but it is just not in the budget right now. So my idea was to disconnect one of the inside panels from the grid and powering those circuits via solar and battery backup. Effectively having the important circuits on the solar/battery system and the other less important and load-heavy circuits like the HVAC, oven, dryer, etc. still stay on the grid for now until I can expand the solar and battery backup system.

My biggest concern is grounding. Right now the inside panels are "subpanels" because the outside meter base is the first means of disconnect. So that is where the neutral and ground is bonded. If I split the house into two systems, am I creating a big grounding no-no situation?

 

[Bobert]

My house has 320a service coming into a meter base with two disconnects feeding two panels inside the garage with all of the house circuits. It is overkill but when I built the house a few years ago, I wanted plenty of expansion room. Right now I have one panel that has all of the important backup circuits (refrigerator, freezer, well pump, some lights, etc.) and it has a generator inlet for when the power goes out. I'm in the country so when it goes out, we are usually the last to come back on.

Eventually I would to take the whole house off grid but it is just not in the budget right now. So my idea was to disconnect one of the inside panels from the grid and powering those circuits via solar and battery backup. Effectively having the important circuits on the solar/battery system and the other less important and load-heavy circuits like the HVAC, oven, dryer, etc. still stay on the grid for now until I can expand the solar and battery backup system.

My biggest concern is grounding. Right now the inside panels are "subpanels" because the outside meter base is the first means of disconnect. So that is where the neutral and ground is bonded. If I split the house into two systems, am I creating a big grounding no-no situation?

If you wire your essential sub panel to an appropriate sized all in one unit that is not internally bonded to ground the grounding of your service panel would not be affected by the solar system the grounding would simply pass through Similar to how many generators work. You would need to do an accurate energy audit to size the AIO properly but once setup all of your essential equipment could operate from the grid and switch automatically over to grid without interruption in the event of a power outage or noteworthy brownout.

 

[TGJR]

Thanks Bobert.

If my ultimate goal is to be completely independent of the grid, would going the all-in-one route to begin with be the right first step?

 

[Ampster]

Yes, start with a hybrid based on the likelihood of outages. Later you can add GT solar less expensively and AC couple it to your All in One hybrid. Make sure you get a good hybrid that can do that. Outback, Schneider and SolArk are good quality. SMA also has a great reputation but I don't know it's capabilities as well.

 

[TGJR]

Thanks Ampster.

I wasn't considering an all-in-one since my ultimate goal is to be off the grid for good. So I figured taking one whole panel off the grid to start would be sort of dipping my toes into the water before I cut the cord for good.

Is there anything wrong with that approach other than losing out on redundancy?

 

[OffGridInTheCity]

Thanks Ampster.

I wasn't considering an all-in-one since my ultimate goal is to be off the grid for good. So I figured taking one whole panel off the grid to start would be sort of dipping my toes into the water before I cut the cord for good.

Is there anything wrong with that approach other than losing out on redundancy?

My goal was to have my 'whole house' off-grid as well. And to a large extent I've succeeded 8-9 months of the year - can run everything (heat/cool, hot-water, cooktop/kitchen, dryer, etc) except the hot-tub. Will to let the hot-tub go in an emergency

However - the winter 3-4 months of solar are just not doable and live fully. For example, last December I only got 250kwh for the whole month on 13kw PV array. The lowest before that was 500kwh and I need at least 1000kwh. I'd need a 60kw PV array!! So I finally relented and did some propane/generator backup for this contingency.

Bottom line - grid-assist is common sense for me. If the grid dies, I can live OK but no reason to avoid the grid. Thus, my off-grid system is built to use the grid via ATSs. It's simple really - if solar+battery is adequate it's solar 24/7 but in winter or prolonged cloudy days when solar+battery declines and I need grid for 4hrs/day or 8hrs/day then ATS automatically takes care of it. As I expand my system - I use grid less and less, but still the ATS auto switches to grid when I need it - which is particularly useful when I want to shut off the solar generator to work on it.

My ATSs + UPS (for sensitive circuits) are separate components but these days - as suggested above - the off-grid all-in-one MPP Solar and GroWatts are COOL! You feed grid + solar + battery into it and it sends power out. If solar + battery become depleted, it auto-uses the grid to keep things going on the output - e.g. it has ATS/UPS built in.

Plus you can parallel these all-in-ones (e.g. grow things out over time). MPP Solar let's you do up to 9 (I think) which can be 9 * 6000w = 54,000w (225a@240v). I have 24,000w (100a@240v) and I can run the whole 2600sq ft house.

 

[Ampster]

Is there anything wrong with that approach other than losing out on redundancy?

No I think All in One versus components is a personal choice. To be clear hybrids come in different flavors or are you talking about an Off Grid inverter from the get go? I like the flexibility of a grid interactive hybrid although I run it in self consumption mode and it never draws much from the grid but I use the pass through part to sell my GT production for a little credit in the summer because my winter production does not meet my needs and I could not afford a battery big enough to store one month of summer to use it during the 3 months of the winter that I am at a daily deficit. @OffGridInTheCity is in the same situation as me. We both need the grid as backup in the winter.
I do not know the price difference between a grid interactive inverter and a true Off Grid inverter. You can always use the hybrid while Off Grid but you can't use the grid as backup with an Off Grid inverter NOTE: As explained below by @GLC below you can use a transfer switch .

Additionally some building codes including mine say that if grid services are available you have to be connected. They don't required usage but they do required a connection to a meter. That does not mean you would be required to have a hybrid but if you were required to have a grid connection I would prefer an inverter that can help me manage my usage to keep my consumption and costs the lowest. Your mileage may vary.

 

[GLC]

My house has 320a service coming into a meter base with two disconnects feeding two panels inside the garage with all of the house circuits. It is overkill but when I built the house a few years ago, I wanted plenty of expansion room. Right now I have one panel that has all of the important backup circuits (refrigerator, freezer, well pump, some lights, etc.) and it has a generator inlet for when the power goes out. I'm in the country so when it goes out, we are usually the last to come back on.

Eventually I would to take the whole house off grid but it is just not in the budget right now. So my idea was to disconnect one of the inside panels from the grid and powering those circuits via solar and battery backup. Effectively having the important circuits on the solar/battery system and the other less important and load-heavy circuits like the HVAC, oven, dryer, etc. still stay on the grid for now until I can expand the solar and battery backup system.

My biggest concern is grounding. Right now the inside panels are "subpanels" because the outside meter base is the first means of disconnect. So that is where the neutral and ground is bonded. If I split the house into two systems, am I creating a big grounding no-no situation?

I did the very thing you are speaking of. I installed 2 manual transfer boxes , 10 circuits each, to be able to switch from inverter solar to grid as needed. I am running pretty well all my 110 circuits off of solar. I have two inverters, a 110 and a 110/220. 220 is for my well pump if i need to. I can switch from solar to grid with the flip of a rocker switch. Transfer boxes are made for generators but work great with solar.

Connecticut Electric... https://www.amazon.com/dp/B005FQJD7K?ref=ppx_pop_mob_ap_share

 

[TGJR]

No I think All in One versus components is a personal choice. To be clear hybrids come in different flavors or are you talking about an Off Grid inverter from the get go? I like the flexibility of a grid interactive hybrid although I run it in self consumption mode and it never draws much from the grid but I use the pass through part to sell my GT production for a little credit in the summer because my winter production does not meet my needs and I could not afford a battery big enough to store one month of summer to use it during the 3 months of the winter that I am at a daily deficit. @OffGridInTheCity is in the same situation as me. We both need the grid as backup in the winter.
I do not know the price difference between a grid interactive inverter and a true Off Grid inverter. You can always use the hybrid while Off Grid but you can't use the grid as backup with an Off Grid inverter NOTE: As explained below by @GLC below you can use a transfer switch .

Additionally some building codes including mine say that if grid services are available you have to be connected. They don't required usage but they do required a connection to a meter. That does not mean you would be required to have a hybrid but if you were required to have a grid connection I would prefer an inverter that can help me manage my usage to keep my consumption and costs the lowest. Your mileage may vary.

I was originally talking about an off grid inverter from the get go for that panel (half of the house) but now you have me reconsidering. I was wanting to eventually have enough PV and battery backup to not even miss the grid at all. My local provider does not buy back power. So at best I would be connected to the grid and paying the monthly meter charge without using any of their power.

Where we are at, we are pretty self sufficient outside of our grid dependency. It is sort of the last, albeit large, piece of the puzzle.

 

[TGJR]

I did the very thing you are speaking of. I installed 2 manual transfer boxes , 10 circuits each, to be able to switch from inverter solar to grid as needed. I am running pretty well all my 110 circuits off of solar. I have two inverters, a 110 and a 110/220. 220 is for my well pump if i need to. I can switch from solar to grid with the flip of a rocker switch. Transfer boxes are made for generators but work great with solar.

Connecticut Electric... https://www.amazon.com/dp/B005FQJD7K?ref=ppx_pop_mob_ap_share

My original desire was to get away from the backup generator that requires fuel and go to some type of solar/battery backup. The more I looked around and read the more I realized it would be silly to purchase and set up solar and batteries and not use them as much as possible instead of just sitting and waiting for the grid power to go down.

So I figured let's just take one of the panels and every circuit in it off grid and onto solar and batteries and see how we like it. But there wasn't much on the internet that talked about only taking certain circuits off the grid permanently while leaving others on. It's sort of a strange situation but here we are. Ha.

 

[GLC]

My original desire was to get away from the backup generator that requires fuel and go to some type of solar/battery backup. The more I looked around and read the more I realized it would be silly to purchase and set up solar and batteries and not use them as much as possible instead of just sitting and waiting for the grid power to go down.

So I figured let's just take one of the panels and every circuit in it off grid and onto solar and batteries and see how we like it. But there wasn't much on the internet that talked about only taking certain circuits off the grid permanently while leaving others on. It's sort of a strange situation but here we are. Ha.

Maybe you misunderstood me. I am not running a generator. I am running 3 separate solar setups. I am using manual transfer boxes that were designed for a generator but i am using them on solar. I normally run solar but if need to i can switch circuits back to grid if need be.

 

[12VoltInstalls]

I figured taking one whole panel off the grid to start would be sort of dipping my toes into the water before I cut the cord for good.

An AIO no feedback but plugged in to the grid with a split-out subpanel and proper regrounding would be a great choice for you imho.
Basically it will deal with itself for your purposes and charge from grid if necessary if you wish, or pas-through grid if you choose.
Then when you officially cut the cord it will still be able to use generator input instead of grid. The MPPSolar units mentioned are great for scaling up.

 

[TGJR]

My goal was to have my 'whole house' off-grid as well. And to a large extent I've succeeded 8-9 months of the year - can run everything (heat/cool, hot-water, cooktop/kitchen, dryer, etc) except the hot-tub. Will to let the hot-tub go in an emergency

However - the winter 3-4 months of solar are just not doable and live fully. For example, last December I only got 250kwh for the whole month on 13kw PV array. The lowest before that was 500kwh and I need at least 1000kwh. I'd need a 60kw PV array!! So I finally relented and did some propane/generator backup for this contingency.

Bottom line - grid-assist is common sense for me. If the grid dies, I can live OK but no reason to avoid the grid. Thus, my off-grid system is built to use the grid via ATSs. It's simple really - if solar+battery is adequate it's solar 24/7 but in winter or prolonged cloudy days when solar+battery declines and I need grid for 4hrs/day or 8hrs/day then ATS automatically takes care of it. As I expand my system - I use grid less and less, but still the ATS auto switches to grid when I need it - which is particularly useful when I want to shut off the solar generator to work on it.

My ATSs + UPS (for sensitive circuits) are separate components but these days - as suggested above - the off-grid all-in-one MPP Solar and GroWatts are COOL! You feed grid + solar + battery into it and it sends power out. If solar + battery become depleted, it auto-uses the grid to keep things going on the output - e.g. it has ATS/UPS built in.

Plus you can parallel these all-in-ones (e.g. grow things out over time). MPP Solar let's you do up to 9 (I think) which can be 9 * 6000w = 54,000w (225a@240v). I have 24,000w (100a@240v) and I can run the whole 2600sq ft house.

Makes sense. At the end of the day, having the grid for backup power would probably alleviate some anxiety of keeping the lights on.

 

[TGJR]

Maybe you misunderstood me. I am not running a generator. I am running 3 separate solar setups. I am using manual transfer boxes that were designed for a generator but i am using them on solar. I normally run solar but if need to i can switch circuits back to grid if need be.View attachment 98217

Oh yeah, I didn't mean to insinuate you were using a generator. I was just speaking on my situation and wanting to get away from the backup generator we currently use during power outages and into something more sustainable that doesn't require fuel.

Thanks for the pics of your setup.