Are micro invertors the future of residential installations?

Should I ignore invertors and go for micro? It appears micro is more expensive. I'm looking for a So Cal 5kW grid system with no battery, but battery added later. I read that micro have less failures.

A single inverter can fail and you won't know which one it is unless you have wifi monitoring software. They are more costly to install but great if you have partial shading throughout the day or multiple roof angles. Otherwise strings are great for large roof areas with lots of sun.

Too expensive
Not worth it.
unless you are going grid tied.
Which in my opinion, isn't worth it either.

Microinverters make for a cleaner installation as they are under the panels, no bulky inverter on the side of the building. If one fails the system still works. One of the big advantages of microinverters is the ability to place the solar panels in different orientations on the roof. Personally I prefer the idea that the whole system is 120/240V AC no HV DC or rapid shutdown modules. The flip side is having to potentially go up on the roof to change a microinverter and yes overall the cost of purchasing individual microinverters may be slightly higher. I believe the biggest disadvantage to Enphase microinverters is the rather anemic battery systems they offer but there are other microinverter companies rolling out new products all the time. Many of which can support 2 panels so you only purchase half as many.

Noho said:

Should I ignore invertors and go for micro? It appears micro is more expensive. I'm looking for a So Cal 5kW grid system with no battery, but battery added later. I read that micro have less failures.

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Enphase has a few new things coming out this year including (cheaper?) 5kWh batteries instead of their 3.3kWh based units atm.
I like the idea of having a lot of helpful microinverters to get the job done, including each 3.3kWh battery that has 4 microinverters.
There is one thing though Enphase doesn't mention: There is a component with a single point of failure: the brains of the whole setup.
The IQ Gateway (formerly known as the Envoy) has both PLC (powerline communications) with the microinverters under the panels *AND* wireless communication (zigbee) with the battery units and the IQ system controller. That is the box that seperates he house from the grid and has the autotransformer to generate 120 volt from the 240 volt from the micro inverters . It has both a wifi connection (grid tied only) or in case of batteries a 4G unit installed (because of outage of power your wifi probably no longer works).
Afaik in a grid tied situation and the IQ gateway fails the IQ8 microinverters will act standalone and will continue sending power to the grid.
But in case of a power outage & the IQ gateway going down (for whatever reason) there is no disconnect from the grid, no buildup of the micro grid from either the batteries or the IQ8 under the panels (which are capable of generating micro grid without batteries).
And afaik there is no way to double up the IQ gateway at the moment.

I am in the process connecting up the megarevo hybrid inverter. The good news is that with new software I should be able to connect up to 4 of those 8kW units in parralel. Those units can either share a large battery or each have their battery storage.
If one of those units fails I will lose inverter power, PV power and battery power but I should have at least one or more units running in parallel.

Given the $/kWh for the enphase batteries, I think my current solution is cheaper per kWh in the long run.

Source: I did the hands on training course for Enphase last week

My goal is to get away from the grid. Not to continue relying on it.

timselectric said:

My goal is to get away from the grid. Not to continue relying on it.

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Ditto. One of the incentives of going with AC Micro inverters is it negates need (and code compliance headaches) for DC Arc fault prevention.
I took another approach for my off-grid design: Keep panel string VOC DC voltages below 80V, and use several small stand-alone charge controllers.

Noho said:

Should I ignore invertors and go for micro? It appears micro is more expensive. I'm looking for a So Cal 5kW grid system with no battery, but battery added later. I read that micro have less failures.

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Hoymiles Quad HM-1500NT is less than half the price of an Enphase, per panel, has a 25y warranty and the cable is plug-n-play all the way to the main switch and service panel. It's cUS Listed and I can get them for anyone here at near wholesale prices. I'm hooked up with them now. I have 6.48kW residential kits for $1.14/Watt. Definitely not too expensive now! And easy to install. Feel free to msg me. I can do a savings simulation for you given your address and utility. The ROI is typically over 300% for many rate schedules.
Best,
Todd

pullin_gs said:

Ditto. One of the incentives of going with AC Micro inverters is it negates need (and code compliance headaches) for DC Arc fault prevention.
I took another approach for my off-grid design: Keep panel string VOC DC voltages below 80V, and use several small stand-alone charge controllers.

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That seems like a lot of work and expense.
But, it's one way to go.

timselectric said:

That seems like a lot of work and expense.
But, it's one way to go.

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Not at all.
For 3KW system, I spent $250 each on a pair of 60A charge controllers. Wire costs more than doubled. But level of effort actually much less.
Or I could spend $3000 for 10 micro-inverters, and another $500 for arc-fault mitigation.
3KW wall-mounted (currently only have 1KW up)
16 KWH solar generator (self-contained wheeled unit including 440AH 36V Ford Mach-e modules, charge-controllers, 3500W 120VAC inverter).

I can reach the inverter on the wall, anything with the solar panels need a contractor/scaffolding and someone willing to scramble about on the roof.

Even now I'm looking at the 2x5 panel array - they have connectors underneath many of which are inaccessible without removing panels.
I don't want 'clever' 'expensive' boxes up there too.

Less complexity on the roof/out of reach/cost $ to fix/maintain the better for this particular customer.

pullin_gs said:

Not at all.
For 3KW system, I spent $250 each on a pair of 60A charge controllers. Wire costs more than doubled. But level of effort actually much less.
Or I could spend $3000 for 10 micro-inverters, and another $500 for arc-fault mitigation.
3KW wall-mounted (currently only have 1KW up)
16 KWH solar generator (self-contained wheeled unit including 440AH 36V Ford Mach-e modules, charge-controllers, 3500W 120VAC inverter).

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Way too expensive for me. When I'm finished, I will have 110 roof mounted panels. That would be 55 SCC's. lol

Micro-inverters build a system which is incredibly fault-tolerant, but, unless your panels and inverters are easily accessible, those faults can be difficult and expensive to fix.

I know this system isn't micro based but ...

timselectric said:

My goal is to get away from the grid. Not to continue relying on it.

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I think that's a smart move considering what's going on in the world these days

Micros seem elegant and safe(r). On a pitched roof, I’d be hesitant. But on a roof where you have access, they make sense. The old guys (no offense) seem to have some bias against them. I think that will change over time. AC is simply safer.

I’ve been thinking about this microinverter topic for a new install also. It seems easier and more redundant to 1) use micro inverter solution, specifically with output going to critical loads panel and 2) have an inverter that can frequency shift sit between critical loads and main grid panel. This same inverter could be used specifically for energy storage and doesn’t need its own DC PV but can keep power on if grid down, charge batteries from microinverter power and/or even put energy back to main panel.

Micros can be one approach to the future of residential installations. Every place in the Country is going to be different because there are 50 States and each state has its own unique policies.
I am in California and NEM benefits have been and continue to be eroded. My approach is to have a reasonable GT system and then behind the meter, have a hybrid system with batteries that can allow me enough capacity to be self sufficient from the grid. Because of seasonal differences in production and consumption I have to save up credits in the summer to use in winter. My GT system was self installed and I chose micros because of their compliance with rapid shutdown requirements. I have had both string and micro system and the optimal system depends on where you are standing.

Ampster said:

Micros can be one approach to the future of residential installations. Every place in the Country is going to be different because there are 50 States and each state has its own unique policies.
I am in California and NEM benefits have been and continue to be eroded. My approach is to have a reasonable GT system and then behind the meter, have a hybrid system with batteries that can allow me enough capacity to be self sufficient from the grid. Because of seasonal differences in production and consumption I have to save up credits in the summer to use in winter. My GT system was self installed and I chose micros because of their compliance with rapid shutdown requirements. I have had both string and micro system and the optimal system depends on where you are standing.

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@Ampster I believe you have a skybox which is what I want to have at my main home, still trying to get past in my mind the 200w draw of it. Anyway do you have your skybox AC coupled or just just feeding a load panel and charging batteries from Grid/Microinverter?

My Skybox feeds the critical loads panel and my micros also feed that panel. When the grid is down the Skybox AC couples to the micros.
The Skybox is in Self Consumption Mode so the charging of batteries comes from a small solar panel system DC coupled to the Skybox and supplemented by the micros. The rest of the micro production exports to the grid after supporting other house loads.

I don't worry about the Skybox overhead which could be more than 200 Watts. I would rather send it to the Skybox so it can manage and reduce my need to use grid energy..

Ampster said:

My Skybox feeds the critical loads panel and my micros also feed that panel. When the grid is down the Skybox AC couples to the micros.
The Skybox is in Self Consumption Mode so the charging of batteries comes from a small solar panel system DC coupled to the Skybox and supplemented by the micros. The rest of the micro production exports to the grid after supporting other house loads.

I don't worry about the Skybox overhead which could be more than 200 Watts. I would rather send it to the Skybox so it can manage and reduce my need to use grid energy..

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@Ampster your seem to be doing exactly what I typed above. Awesome!! Do you need to have DC coupled to charge the batteries on Skybox? Or can you charge via AC coupled? See you said ‘supplement’.

ChrisG said:

Do you need to have DC coupled to charge the batteries on Skybox? Or can you charge via AC coupled? See you said ‘supplement’.

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I don't know. I decided to add them because I needed the capacity and it was less expensive than adding micros to those panels. Also I heard the Skybox performed better if it had some DC coupled solar. They are on a patio cover so I don't need RSD.
I used the term "supplement" because I see that my batteries charge at a higher kW rate than the DC coupled batteries produce so I assume the Skybox converts some of the AC from the micros to charging. I don't know if the other loads on the Skybox are served by the Skybox inverter or the AC from the micros.

For PV only today, batteries in the future, a "batteries optional" hybrid might be the way to go. They can even power loads during the day with grid down, given enough PV. Don't know about quality & reliability, however. You can also buy grid tie inverters (no option for DC coupled battery) and have PV direct operation for loads while sun is up. (e.g. 7kW 240V Sunny Boy "secure power" feature delivers 2kW 120V off-grid.)

I have high voltage string grid-tied inverters (older model Sunny Boy). Mine were installed before Rapid Shutdown, which would require a box per PV panel if on the roof. If you do ground mount, that isn't necessary. A single inverter is a point of failure, but my experience with 5 inverters was at 35 years MTBF when I took them down after 17 years (for different model and features.) When and if they do fail, you can buy new or old models, new or used, and swap a box cheaper than repairs.

My battery inverters are separate, AC coupled. This modular approach is more expensive than a hybrid. It is stackable for almost any wattage needed. What works for you depends on your needs. If possible, I recommend keeping the utility grid connection and having bypass switches so power can be restored without rearranging wires, no matter whether grid or inverter fails.

timselectric said:

My goal is to get away from the grid. Not to continue relying on it.

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My goal is similar in that I do not not want to rely on the grid or pay expensive prices to use it. I am using micros and a hybrid with batteries to give me energy independence. I can't totally get away from the grid because I need the grid for seasonal differences and to charge my EVs when traveling. I agree, batteries are the future.

My biggest issue when I looked at the micros was nothing was available to support my higher VOC panels. I still don't think any of them will go above 80VOC max, but I could be mistaken. Panel/micro accessability also needs to be considered. Distance was also a factor when a larger system is built using them, you're still limited to only 240V so higher amperage setups require some pretty beefy ($) wiring to run longer distances. Most are basically only grid-tie and AC battery systems are limited and costly compared to 48VDC systems. If you add up all the required parts to make a larger system and plan on possibly using battery storage, micro based systems can get pretty costly.

But I do agree micros can make a lot of sense for some applications, mostly for GT, smaller supplementary systems, or those with shading issues.

Most 72 cell panels don't go over 50 volt.
Some enphase go up to 60 volt.
What panels do you have?

I was involved with a setup where the panels due to shading were on the other side on an orchard. We used to 10kva transformers to stepup the voltage to 480 and back down at the other end. That saved a lot of expensive wire. They installed a light operated relay to minimize the phantom loads during the night from the 2 transformers