Enphase M250 Specs for off-grid, tips and tricks and results

[SunEagle]

Perhaps I am lost in this discussion, but I don't think so. This is what I understand, so please correct me if I am wrong.

The OP was proposing that grid-tie solar is fed into a battery system that mimics the grid exactly. Naptown asked what happens if the loads cause the pseudo-grid (battery system) to be depleted. That is a valid concern that I have not seen addressed by the proponents of this proposal.

I suggested that using a generator for the case where something happens to the battery bank makes a lot of sense. Others including the OP seem to have great objections to using a generator and made the comment that one could run out of gas and then what? My response is that the generator is a way to save the system as a last resort, because the battery backup is a single point of failure.

And when I one can get in the car to buy gas if it suns out then they say they can get more batteries! So I ask if they are going to buy more batteries every day if they get two weeks of cloudy weather. Of course that is ridiculous, and I said it to make a point, that they have no way to fix this situation if it happens.


So, am I not understanding what they are proposing? But now the OP says no batteries are involved. I don't understand that at all. So then what does the grid-tie inverter feed when the actual grid goes down?

No you are correct. The OP started out suggesting a minimum of 300-350Ah battery system and then stated (at least how I read the post) that batteries (or generator) were not really needed. That was confusing.

What I stated was that I agreed with solarddy when he stated a micro inverter mini grid would be a better choice to generate power for a home, with the condition that as long as you had a way to get power at night or when the sun didn't shine. How that power is generated is a choice. Or don't generate and you can read by candlelight and cook food over a wood fire. The choice is open.

[lkruper]

No you are correct. The OP started out suggesting a minimum of 300-350Ah battery system and then stated (at least how I read the post) that batteries (or generator) were not really needed. That was confusing.

What I stated was that I agreed with solarddy when he stated a micro inverter mini grid would be a better choice to generate power for a home, with the condition that as long as you had a way to get power at night or when the sun didn't shine. How that power is generated is a choice. Or don't generate and you can read by candlelight and cook food over a wood fire. The choice is open.

I have a fireplace for heat and cooking, plenty of batteries, candles, food stores, etc. But if I had expensive batteries I still would not want to let them sit in a discharged state for a few weeks because they would sulphate.

[SunEagle]

I have a fireplace for heat and cooking, plenty of batteries, candles, food stores, etc. But if I had expensive batteries I still would not want to let them sit in a discharged state for a few weeks because they would sulphate.

I agree. I have a situation where my battery system is not being used and is just sitting there waiting on the need to be used as a quiet emergency power source. But it takes work to keep them happy even though I know they are slowly losing life.

[Mike90250]

BTW- this is "solar panel talk", not bash solar threads with gas generator comparisons, so let's do one.
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As we go into the winter months, having extra solar power production is key when considering cloud coverage, and shorter days, but solar power works every day all day without having to fill up a gas tank.

Not sure what sort of gas you are sniffing, but last year, I had to run my generator quite a lot in winter, because we had many contiguous weeks of cloudy/rainy weather. If I did not run it, thousands of dollars of batteries would have been destroyed, and power would shut off.

[lkruper]

Not sure what sort of gas you are sniffing, but last year, I had to run my generator quite a lot in winter, because we had many contiguous weeks of cloudy/rainy weather. If I did not run it, thousands of dollars of batteries would have been destroyed, and power would shut off.

I am going to keep on pressing them till I see an answer

I had said:
"I think you are missing the point. Yes, a generator could run out of fuel, however if that happened your underlying infrastructure was poorly designed. I can easily see a number of likely scenarios how a set of backup batteries which are intended to mimic a grid could be depleted by a single accident and then you will need another outside source of power to "reboot" the service. That is because the batteries are a single point of failure. But for a generator to run out of gas, it would take a series of failures AND the inability to get more gas, such as driving to the gas station or siphoning it from a vehicle gas tank."

And then Solardreamer said:
"Not really. You seem to be implying that you can go get gas for the generator but you can't go get batteries? If you can get gas for a car then you have a backup charger for batteries. (e.a.)

I fully understand the need to design safe and reliable battery based backup for solar systems but I don't see how generator is the really the answer. "

After that the other member of the tag team Solarddy came to Solardreamer's defense. So it looks like it to me that the both of them would rather you replace your batteries than buy gas to run your generator. But if they have a different explanation, I would really like to hear it.

[Naptown]

IIRC they are both talking about AC coupled systems
Very bad idea and would require a generator and charger if the batteries ran too low. or lights out till the grid came back up

[solarddy]

No you are correct. The OP started out suggesting a minimum of 300-350Ah battery system and then stated (at least how I read the post) that batteries (or generator) were not really needed. That was confusing.

What I stated was that I agreed with solarddy when he stated a micro inverter mini grid would be a better choice to generate power for a home, with the condition that as long as you had a way to get power at night or when the sun didn't shine. How that power is generated is a choice. Or don't generate and you can read by candlelight and cook food over a wood fire. The choice is open.

No battery Enphase System Diagram M190.jpg

No batteries M190 diagram, sleep at night, use less batteries, for the "connected" internet family 300-350Ah battery bank is required for nighttime power needs, I call that phase 4 of a deployment of residential micro-inverters. After the system produces enough peak power as measured to allow for battery storage. Most people with grid power do not need to go Off-grid capable immediately, it's better to get your feet wet and pay off phases 1-3.

[solarddy]

The sun'll come out tomorrow.

IIRC they are both talking about AC coupled systems
Very bad idea and would require a generator and charger if the batteries ran too low. or lights out till the grid came back up

Too many posts about the sun not coming out again like it has for billions of years. Ok in a northern climate you may have to double or even triple your solar array estimate, unless you live in the waaaaay north where darkness lasts for longer... I would say that geothermal or wind would be the best bet in those places for renewable energy sources. Gas is a short term not all year long option that is "easy" compared to solar, now as for the single inverter approach, I can see lots of issues with that, mainly a single point of failure that turns the lights out even if the sun does comes out tomorrow.

Either way the sun'll come out tomorrow, I'd bet my bottom dollar on that.

So that when it does my batteries would charge like they always seem to when the sunlight hits my solar panels.

[ButchDeal]

Too many posts about the sun not coming out again like it has for billions of years. Ok in a northern climate you may have to double or even triple your solar array estimate, unless you live in the waaaaay north where darkness lasts for longer... I would say that geothermal or wind would be the best bet in those places for renewable energy sources. Gas is a short term not all year long option that is "easy" compared to solar, now as for the single inverter approach, I can see lots of issues with that, mainly a single point of failure that turns the lights out even if the sun does comes out tomorrow.

Either way the sun'll come out tomorrow, I'd bet my bottom dollar on that.

So that when it does my batteries would charge like they always seem to when the sunlight hits my solar panels.

ok this is getting silly. you are arguing with people who ACTUALLY live off grid and currently have solar systems. You can check their locations and they do not live north of the arctic circle. I live near DC and there are many weeks with no sun. That doesn't mean that the earth hasn't turned such that the sun is facing my little home but rather that the sun is behinds clouds all day. Thus not nearly enough power to run a home much less recharge batteries. Just take a little glance around PVOutput and you can see many homes with long stretches of not enough sunlight to do anything.

[ButchDeal]

[ATTACH]7989[/ATTACH]

No batteries M190 diagram, sleep at night, use less batteries, for the "connected" internet family 300-350Ah battery bank is required for nighttime power needs, I call that phase 4 of a deployment of residential micro-inverters. After the system produces enough peak power as measured to allow for battery storage. Most people with grid power do not need to go Off-grid capable immediately, it's better to get your feet wet and pay off phases 1-3.

The claim was made that micros some how work OFF GRID without batteries. Further that they would be MORE reliable in such a situation even though that situation would require an AC coupled design making MORE points of failure with an over stressed and complicated design. If the hybrid inverter fails everything is down. Get a nice DC coupled system like say an outback Flexpower 2 and you have redundancy in inverter and CC.

[lkruper]

Too many posts about the sun not coming out again like it has for billions of years. Ok in a northern climate you may have to double or even triple your solar array estimate, unless you live in the waaaaay north where darkness lasts for longer... I would say that geothermal or wind would be the best bet in those places for renewable energy sources. Gas is a short term not all year long option that is "easy" compared to solar, now as for the single inverter approach, I can see lots of issues with that, mainly a single point of failure that turns the lights out even if the sun does comes out tomorrow.

Either way the sun'll come out tomorrow, I'd bet my bottom dollar on that.

So that when it does my batteries would charge like they always seem to when the sunlight hits my solar panels.

I have highlighted the part of your comment above which shows you don't understand the problem of lack of sun during long periods of bad weather.

The only way to overcome a lack of solar energy over a few weeks is to store it. Every heard the saying of storing up something for a "rainy day"? Extra panels don't help when the sun don't shine unless you have stored it. So to get past a long bout of clouds, without the stored sun in the form of gasoline **, one would need a larger battery bank. The concept is called "autonomy." ## Have you heard that term before in the context of solar?

However, NOONE has a month's worth of autonomy. Maybe if your only load was charging your iPhone, but for a household with people who need lights, heat, refrigeration, entertainment, hot water and so on, that size of a battery bank will break the bank.

If you don't believe me, then put some meat !! on the bone ### you tossed out when you said all it would take would be to increase solar panels by 2X or 3X.

1) What are the daily *** loads for this scenario?
2) What are the size of your panels?
3) How much battery capacity do you have so that you can last for three weeks of cloudy weather.


Footnotes
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** Gasoline could refer to anything that can fuel a generator such as natural gas or propane.
*** A literal 24 hour day, not general like in "my grandfather's day"
## Energy stored in a battery for a rainy day
### Bald assertion with no proof
!! Evidence to back up a claim.

[SunEagle]

[ATTACH]7989[/ATTACH]

No batteries M190 diagram, sleep at night, use less batteries, for the "connected" internet family 300-350Ah battery bank is required for nighttime power needs, I call that phase 4 of a deployment of residential micro-inverters. After the system produces enough peak power as measured to allow for battery storage. Most people with grid power do not need to go Off-grid capable immediately, it's better to get your feet wet and pay off phases 1-3.

I agree with you and understand what you are refering to. There was some confussion concerning your original post but I feel you have cleared it up.

Start with a grid tie system and use the POCO as your "battery". If and when you expand the system to a point that now makes sense to capture the excess energy in a storage system instead of selling back (if that is even allowed) to the POCO. That is a true hybrid system.

It is a plan that can work and is easier to do using micro inverters then if you started out with a string inverter that is not hybrid capable.

[nomadh]

My understanding was the batteries were there to feed the "fake" grid signal to the micro inverters not to use for the household. Just enough power to run the sine wave generator to kick on the panels that would then recharge that feeder system plus the household. If it was at night or a cloudy day then you would have no power , just like any other grid tie system. Only diff is this one could run during sunny days. So many people seem to think if you cant make it work all the time every time 24/7 for years on end then they don't want it at all. Well on cloudy days I need less refrigeration and no AC. In the winter I'm more likely to worry about firewood that electricity. I am currently scrapping all my micro inverter and power optimizer plans just because of the silly little Sunnyboy offline power feature. Its only 1500 watts and only during sunny days but at least I have some power and get some use of my very expensive solar investment without doubling the cost and giving me tons of maintenance work and costs. If microinverters would do what the op suggests in a low price easy maintenance way I'd love it.

[sensij]

It is a plan that can work and is easier to do using micro inverters then if you started out with a string inverter that is not hybrid capable.

No, using microinverters makes the system more complicated, and more prone to failure. The grid can be faked for any grid-tie inverter equally well, and the rest of the islanded system will look the same. It is much easier to balance the generation with the demand when it is managed through a single point (MPPT controller) than when it is distributed and communication with each device needs to occur. Please see ButchDeal's comments in this thread. With some re-programming it might be possible to make microinverters support islanding at least as well as SolarEdge does, but as they exist right now, they are probably the worst choice for building a hybrid system.

[ButchDeal]

No, using microinverters makes the system more complicated, and more prone to failure. The grid can be faked for any grid-tie inverter equally well, and the rest of the islanded system will look the same. It is much easier to balance the generation with the demand when it is managed through a single point (MPPT controller) than when it is distributed and communication with each device needs to occur. Please see ButchDeal's comments in this thread. With some re-programming it might be possible to make microinverters support islanding at least as well as SolarEdge does, but as they exist right now, they are probably the worst choice for building a hybrid system.

Right now the best choice for starting on grid and going to off grid in the future is SolarEdge and specifically the SE7600 inverter which can be upgraded latter to support StorEdge. The second best choice would be a traditional Hybrid system like (mine) the Flexpower1 which can be expanded by adding more CC and more inverters as you grow and be programmed for on or off grid.

Going with a micro system and then adding a hybrid system latter like the Flexpower in order to make the micros work off grid will cost more, and the only control over the micros is on or off. The OutBack inverter will handle this on off but is obviously more stressful on it and the batteries as well as clearly more costly and with the more failure points as the flexpower with CC system.
As for using the micros with a SMALL battery and SMALL inverter, until there is a LOT more control capabilities of the micros than is currently possible that will not work. You will need a hybrid system with batteries sufficient to handle the charging of micro inverter array.