Micro Inverters vs String for off-grid home

[S610]

In a nutshell planning a new 5kw system with battery backup. No grid tie. This will be professionally installed on a new home build in the Ozarks where summer temps reach 100 degrees on warm days.

Have gotten a quote for a system with an 8kW Sol-Ark inverter with EMP protection (5 year warranty) but am now wondering if Enphase micro-inverters would be a better way to go especially with the 25 year warranties. Have to admit the warranty difference seems huge especially considering the price! Plus this is a passive cooled home so the string inverter won't be kept at a comfy 70 degrees all summer.

Thoughts? I want a resilient long lasting system.

 

[Rednecktek]

Both string and micro inverters require grid power to operate, so you'll have to figure out how to get AC power to the units for them to synchronize with the provided AC and start generating.

 

[DIYrich]

Thread 'Micro Inverters or EG4-18k' https://diysolarforum.com/threads/micro-inverters-or-eg4-18k.68320/

I'd still go with something like Growatt off-grid (or sol-ark 8k in your case). You will need more equipment to go off-grid with enphase, expensive, and you are stuck with their equipment.

 

[S610]

Both string and micro inverters require grid power to operate, so you'll have to figure out how to get AC power to the units for them to synchronize with the provided AC and start generating.

A generator would work.

 

[S610]

Thread 'Micro Inverters or EG4-18k' https://diysolarforum.com/threads/micro-inverters-or-eg4-18k.68320/

I'd still go with something like Growatt off-grid (or sol-ark 8k in your case). You will need more equipment to go off-grid with enphase, expensive, and you are stuck with their equipment.

I could buy 5 growatt inverters for the price of one Sol-Ark. Might make more sense to go that route and have a spare.

Some questions about the warranty though, Signature Solar says 2 year warranty whereas Growatt claims their standard warranty is 5 years. Often resellers sell an 'extended warranty" to match the manufacturers warranty so that would be one thing to clarify.

 

[DIYrich]

A generator would work.

Unless you plan running it 24/7, what will you do when the generator is off?

 

[S610]

Unless you plan running it 24/7, what will you do when the generator is off?

Ummmm...pretty sure people use off-grid solar systems all the time. I am not understanding your point.

 

[SilverbackMP]

I would look at Schneider or Victron. Schneider can AC couple if you ever want to go that way (and up until about an hour ago, I would say do this with SMA Sunny Boys and would have recommended SMA Sunny Island rather than Scheider). From what I've read, Enphase (at lease some models) has issues AC coupling with Schneider. Maybe Schneider makes their own AC coupled line inverter? IDK. But I wouldn't want cheap azzed micro inverters installed under panels and baking in the sun for resiliency. Especially offgrid. Nor would I want cheap Chinesium offgrid.

I would want at least 10,000 watts with 240v available unless one wants to live like a pauper. And preferably with a low frequency inverters that will last 15-20 years at a minimum.

 

[S610]

I would look at Schneider or Victron. Schneider can AC couple if you ever want to go that way (and up until about an hour ago, I would say do this with SMA Sunny Boys and would have recommended SMA Sunny Island rather than Scheider). From what I've read, Enphase (at lease some models) has issues AC coupling with Schneider. Maybe Schneider makes their own AC coupled line inverter? IDK. But I wouldn't want cheap azzed micro inverters installed under panels and baking in the sun for resiliency. Especially offgrid. Nor would I want cheap Chinesium offgrid.

I would want at least 10,000 watts with 240v available unless one wants to live like a pauper. And preferably with a low frequency inverters that will last 15-20 years at a minimum.

Haha...guess I already live like a pauper. Use about 5kW a day now so there should be plenty of power to spare. And you are right, I want something that will last!

I just assumed 240v was standard with these systems. Isn't that required for well pumps and some other appliances? I am aware of Grundfos well pumps but still...seems 240v would be necessary for some things.

 

[SilverbackMP]

Haha...guess I already live like a pauper. Use about 5kW a day now so there should be plenty of power to spare. And you are right, I want something that will last!

You mean you use just 5KWHs? If so, then you don’t need all that much. No large power tools? No big pumps? Tiny house? One or two mini splits?

I’d still consider something that you could expand if you want and low frequency. Others will say differently.

 

[Rednecktek]

AirCon's over 12k BTU, electric stoves, deep well pumps, electric water heaters, electric dryers, electric furnaces, welders, etc.

 

[S610]

You mean you use just 5KWHs? If so, then you don’t need all that much. No large power tools? No big pumps? Tiny house? One or two mini splits?

I’d still consider something that you could expand if you want and low frequency. Others will say differently.

Small house, one person, there is a shallow well pump and an electric stove now. The off-grid house will use propane for heating, cooking, and hot water. I am planning for redundancy in case the solar power goes out. The stove and heater won't require any electricity to operate with a backup wood stove. Hoping for a hand well pump too but not sure on the logistics yet.

 

[S610]

AirCon's over 12k BTU, electric stoves, deep well pumps, electric water heaters, electric dryers, electric furnaces, welders, etc.

Yeah 240v would be required for the deep well pump if nothing else. I just assumed all the complete systems came with 240v! God solar is complicated.

 

[DIYrich]

Ummmm...pretty sure people use off-grid solar systems all the time. I am not understanding your point.

Enphase microinverters require additional enphase equipment to work off grid. That additional equipment is expensive. Off grid inverters can work off grid as is. Enphase were designed primarily to work on grid, and backed into working off grid.

 

[S610]

Enphase microinverters require additional enphase equipment to work off grid. That additional equipment is expensive. Off grid inverters can work off grid as is. Enphase were designed primarily to work on grid, and backed into working off grid.

Yeah I ditched the enphase idea. Back to looking at Sol-Ark, Victron and Schneider.

 

[S610]

I would look at Schneider or Victron. Schneider can AC couple if you ever want to go that way (and up until about an hour ago, I would say do this with SMA Sunny Boys and would have recommended SMA Sunny Island rather than Scheider). From what I've read, Enphase (at lease some models) has issues AC coupling with Schneider. Maybe Schneider makes their own AC coupled line inverter? IDK. But I wouldn't want cheap azzed micro inverters installed under panels and baking in the sun for resiliency. Especially offgrid. Nor would I want cheap Chinesium offgrid.

I would want at least 10,000 watts with 240v available unless one wants to live like a pauper. And preferably with a low frequency inverters that will last 15-20 years at a minimum.

FYI I called a Victron distributor (he mostly does RVs but will quote the equipment for a residence). He said I need two inverters to get 240V so we are going with that. Another distributor is also going to quote SMA though I haven't looked into them at all.

Still working on finding a Schneider distributor. They appear on google but when contacted they don't offer Schneider solar.

 

[SilverbackMP]

FYI I called a Victron distributor (he mostly does RVs but will quote the equipment for a residence). He said I need two inverters to get 240V so we are going with that. Another distributor is also going to quote SMA though I haven't looked into them at all.

Still working on finding a Schneider distributor. They appear on google but when contacted they don't offer Schneider solar.

I don’t know if I would go SMA at this point. They really shit the bed IMHO by discontinuing Sunny Boys. The value proposition is no longer there for new off grid systems.

I’d probably lean to Schneider which can also AC couple as well as natively use DC coupling.

I don’t know about Victron. AC coupling isn’t necessary but it’s nice to have.

 

[DIYrich]

FYI I called a Victron distributor (he mostly does RVs but will quote the equipment for a residence). He said I need two inverters to get 240V so we are going with that. Another distributor is also going to quote SMA though I haven't looked into them at all.

Still working on finding a Schneider distributor. They appear on google but when contacted they don't offer Schneider solar.

Might as well consider outback too.

 

[SenileOldGit]

Both string and micro inverters require grid power to operate, so you'll have to figure out how to get AC power to the units for them to synchronize with the provided AC and start generating.

So a string inverter requires grid power to operate, even if it's an off grid inverter that doesn't actually require AC input?

 

[SenileOldGit]

Plus this is a passive cooled home so the string inverter won't be kept at a comfy 70 degrees all summer.

Voltronic inverters will have two built in fans that run nice and fast and keep the temperature within the right parameters. Plenty of other inverters have fans too.