FlexBoss21 / GridBoss Issue List

[42OhmsPA]

I wired one of my south facing panels into the 4 panel array in a way my AHJ may not approve awaiting resolution of this. 5 panels works fine.

So they are on different planes/ facing different directions? 1 one way 4 the other?

 

[mciholas]

I think if the working voltage range is higher than the minimum voltage rating of the MPPT, It should be able to produce good power.

MPPTs are only boost circuits in most inverters as they are trying to boost the string voltage to the AC generator input rail. Boost circuits are limited by a maximum input current, thus MPPTs publish a maximum current. The lower the input voltage, the less efficient they are due to higher out to in ratio. That's the nature of DC boost circuits.

The AC generator section converts the high rail voltage to a variable sine wave output. It needs a minimum voltage, usually around 360 volts, to operate. The MPPT boost assures this regardless of string input voltage. But it can operate with higher voltages up to the max input, like 500 volts or so. The problem is that having more voltage than you need increase the in to out voltage ratio and reduces the efficiency. This is the nature of AC generation.

The video above doesn't address these optimizing considerations. Your ideal setup is a string that runs about 360 volts under Vmp conditions at your normal temperature. At this setting, the MPPT has little to no boost requirements and so operates very efficiently (99.9% is sometimes quoted). The AC generator has the minimum voltage it requires and thus operates as efficiently as possible, too. Further, power flowing in or out of the battery is working to/from the 360 volt rail and higher makes that less efficient, too.

No inverter maker I've seen publishes efficiency curves that show the effect of variable MPPT input voltages so these effects are not widely known. A set of charts with the X axis being MPPT input voltage and showing PV to AC, PV to battery, and battery to AC efficiency would be interesting and enlightening.

While it seems many MPPTs have a wide voltage range, it really isn't as wide as it appears once you consider the Vmp versus Voc numbers, and the temperature effects.

The video suggests you can ignore temperature unless you live in a "cold" area, but that's not really true, you should always check temperature to be sure.

There really are three operating points that need to be evaluated for string voltage: maximum, minimum, and ideal.

For maximum, you take the panel Voc and adjust by the coldest temperature you will ever see. Then divide inverter maximum MPPT operational voltage (as opposed to the survival voltage) by the value you computed, round down, that is maximum panels.

For minimum, you take the panel Vmp and adjust by the hottest temperature you will ever see *plus* what you expect the panel temperature rise to be (25 C is a reasonable number, say). Then divide the minimum *full power* MPPT voltage by that number and round up to get the minimum number of panels to produce full power.

For ideal, you take Vmp and adjust by your "typical" temperature. Then divide the MPPT ideal input voltage, usually around 360 volts, by that number. Round to the nearest integer and this is your ideal panel string size. It is usually better to round down more than up which helps with PV to battery and battery to AC efficiency.

You will find string length tolerance is relatively low when you consider all the factors.

An example:

EG4 FlexBOSS21
MPPT max operating: 440 VDC
MPPT min full power: 250 VDC
MPPT ideal: 360 VDC

Aptos DNA-120-BF26-370W
Voc (25 C): 41.4 VDC
Vmp (25 C): 34.5 VDC
Temp co: -0.28%/C

Las Vegas
Min temp: -15 C
Max temp: 50 C

Max voltage is Voc at 25 C (41.4 volts), then adjusted for temperature of -15 C which is 40 C below Voc measurement point. 40 C * 0.28%/C is 11.2% higher. This makes the panel voltage 46.04 volts. Max MPPT operating is 440 volts, so a maximum of 9 panels.

Min voltage to achieve full power is Vmp at 25 C (34.5 volts), then adjusted for temperature of 50 C ambient plus 25 C panel temp rise in sunlight minus 25 C Vmp measurement point. Thus voltage will be 50 * 0.28%/C lower, or 14% lower, yielding a panel voltage of 29.67 volts. To reach the MPPT minimum full power voltage of 250 volts, that takes 8.4 panels, so 9 panels.

Neither computation above is a hard limit as the MPPT survival voltage goes to 600 volts, and being under max power doesn't break anything, but if you want your array to generate full power under all conditions you would see, you need 9 panels.

The ideal MPPT voltage is 360 volts. If we assume 25 C ambient typical conditions and 25 C rise, we will get a panel voltage of 32.1 volts, which works out to 11 panels. If you go with 11 panels, the FB21 will survive that (600 volt MPPT survival rating), but it may stop producing power if the string goes over 440 volts.

The ideal for this setup is probably 10 panels. The chance you go over 440 volts is rather slim (you might not get power in those rare times), and that gets you closer to the 360 volt ideal point n most operating conditions. 11 panels will work too, more optimal in the heat, but you will spend more time above 440 volts and without power.

The basic take away is that string lengths are not as flexible as they appear once you take into consideration all the factors and try to optimize your system performance.

Mike C.

 

[Will Prowse]

MPPTs are only boost circuits in most inverters as they are trying to boost the string voltage to the AC generator input rail. Boost circuits are limited by a maximum input current, thus MPPTs publish a maximum current. The lower the input voltage, the less efficient they are due to higher out to in ratio. That's the nature of DC boost circuits.

The AC generator section converts the high rail voltage to a variable sine wave output. It needs a minimum voltage, usually around 360 volts, to operate. The MPPT boost assures this regardless of string input voltage. But it can operate with higher voltages up to the max input, like 500 volts or so. The problem is that having more voltage than you need increase the in to out voltage ratio and reduces the efficiency. This is the nature of AC generation.

The video above doesn't address these optimizing considerations. Your ideal setup is a string that runs about 360 volts under Vmp conditions at your normal temperature. At this setting, the MPPT has little to no boost requirements and so operates very efficiently (99.9% is sometimes quoted). The AC generator has the minimum voltage it requires and thus operates as efficiently as possible, too. Further, power flowing in or out of the battery is working to/from the 360 volt rail and higher makes that less efficient, too.

No inverter maker I've seen publishes efficiency curves that show the effect of variable MPPT input voltages so these effects are not widely known. A set of charts with the X axis being MPPT input voltage and showing PV to AC, PV to battery, and battery to AC efficiency would be interesting and enlightening.

While it seems many MPPTs have a wide voltage range, it really isn't as wide as it appears once you consider the Vmp versus Voc numbers, and the temperature effects.

The video suggests you can ignore temperature unless you live in a "cold" area, but that's not really true, you should always check temperature to be sure.

There really are three operating points that need to be evaluated for string voltage: maximum, minimum, and ideal.

For maximum, you take the panel Voc and adjust by the coldest temperature you will ever see. Then divide inverter maximum MPPT operational voltage (as opposed to the survival voltage) by the value you computed, round down, that is maximum panels.

For minimum, you take the panel Vmp and adjust by the hottest temperature you will ever see *plus* what you expect the panel temperature rise to be (25 C is a reasonable number, say). Then divide the minimum *full power* MPPT voltage by that number and round up to get the minimum number of panels to produce full power.

For ideal, you take Vmp and adjust by your "typical" temperature. Then divide the MPPT ideal input voltage, usually around 360 volts, by that number. Round to the nearest integer and this is your ideal panel string size. It is usually better to round down more than up which helps with PV to battery and battery to AC efficiency.

You will find string length tolerance is relatively low when you consider all the factors.

An example:

EG4 FlexBOSS21
MPPT max operating: 440 VDC
MPPT min full power: 250 VDC
MPPT ideal: 360 VDC

Aptos DNA-120-BF26-370W
Voc (25 C): 41.4 VDC
Vmp (25 C): 34.5 VDC
Temp co: -0.28%/C

Las Vegas
Min temp: -15 C
Max temp: 50 C

Max voltage is Voc at 25 C (41.4 volts), then adjusted for temperature of -15 C which is 40 C below Voc measurement point. 40 C * 0.28%/C is 11.2% higher. This makes the panel voltage 46.04 volts. Max MPPT operating is 440 volts, so a maximum of 9 panels.

Min voltage to achieve full power is Vmp at 25 C (34.5 volts), then adjusted for temperature of 50 C ambient plus 25 C panel temp rise in sunlight minus 25 C Vmp measurement point. Thus voltage will be 50 * 0.28%/C lower, or 14% lower, yielding a panel voltage of 29.67 volts. To reach the MPPT minimum full power voltage of 250 volts, that takes 8.4 panels, so 9 panels.

Neither computation above is a hard limit as the MPPT survival voltage goes to 600 volts, and being under max power doesn't break anything, but if you want your array to generate full power under all conditions you would see, you need 9 panels.

The ideal MPPT voltage is 360 volts. If we assume 25 C ambient typical conditions and 25 C rise, we will get a panel voltage of 32.1 volts, which works out to 11 panels. If you go with 11 panels, the FB21 will survive that (600 volt MPPT survival rating), but it may stop producing power if the string goes over 440 volts.

The ideal for this setup is probably 10 panels. The chance you go over 440 volts is rather slim (you might not get power in those rare times), and that gets you closer to the 360 volt ideal point n most operating conditions. 11 panels will work too, more optimal in the heat, but you will spend more time above 440 volts and without power.

The basic take away is that string lengths are not as flexible as they appear once you take into consideration all the factors and try to optimize your system performance.

Mike C.

I actually used to mention those points about MPPT and boost/buck circuits in my older videos. This video is for beginners, so I did not dive into those graphs. The efficiency difference is not that big, but yes you need a high enough voltage for good performance. That is why I tell people to ignore the low minimum voltage requirement, and push it up to 220V minimum. It is true that it is better for it to be higher, but people have smaller array constraints, like mobile systems. So they need to have a lower voltage in some instances. You are actually agreeing with the video. I still recommend the lower voltage to be higher than recommended.

Yes, I had those efficiency curves in past videos and covered them a lot, but it's only a few percent less in most instances. Boost performance is compromised significatively though. And again, I mentioned that in the video. It is not disagreeing with any of your points.

Actually, a lot of manufacturers have the efficiency curves, but you need to request them, or they are difficult to find. Seems harder to find for hybrid inverters for some reason. Standalone SCC's often publish them publicly. Like EP ever or victron.

Yes, total efficiency between various parts of the system would be fantastic. That would be incredible.

Ignore the temperature?? Most of my video is about the temperature. What are you talking about? And then for low voltage input, I saw you need to get it as high as you can and tell people to flat out ignore the recommendation by the manufacturer. How are we not saying the same exact thing here? You are not disagreeing with me at all.

Yes, mentioned the rounding down in the video, to avoid issues in cold weather.

Yes, agreed about string voltages not being that flexible at all. And that was the conclusion of my video as well.

Did you even watch the video or think about why I made those recommendations? I showed my logic in the video, and we have arrived to the same conclusion, so I think you did not watch it at all.

 

[Will Prowse]

MPPTs are only boost circuits in most inverters as they are trying to boost the string voltage to the AC generator input rail. Boost circuits are limited by a maximum input current, thus MPPTs publish a maximum current. The lower the input voltage, the less efficient they are due to higher out to in ratio. That's the nature of DC boost circuits.

The AC generator section converts the high rail voltage to a variable sine wave output. It needs a minimum voltage, usually around 360 volts, to operate. The MPPT boost assures this regardless of string input voltage. But it can operate with higher voltages up to the max input, like 500 volts or so. The problem is that having more voltage than you need increase the in to out voltage ratio and reduces the efficiency. This is the nature of AC generation.

The video above doesn't address these optimizing considerations. Your ideal setup is a string that runs about 360 volts under Vmp conditions at your normal temperature. At this setting, the MPPT has little to no boost requirements and so operates very efficiently (99.9% is sometimes quoted). The AC generator has the minimum voltage it requires and thus operates as efficiently as possible, too. Further, power flowing in or out of the battery is working to/from the 360 volt rail and higher makes that less efficient, too.

No inverter maker I've seen publishes efficiency curves that show the effect of variable MPPT input voltages so these effects are not widely known. A set of charts with the X axis being MPPT input voltage and showing PV to AC, PV to battery, and battery to AC efficiency would be interesting and enlightening.

While it seems many MPPTs have a wide voltage range, it really isn't as wide as it appears once you consider the Vmp versus Voc numbers, and the temperature effects.

The video suggests you can ignore temperature unless you live in a "cold" area, but that's not really true, you should always check temperature to be sure.

There really are three operating points that need to be evaluated for string voltage: maximum, minimum, and ideal.

For maximum, you take the panel Voc and adjust by the coldest temperature you will ever see. Then divide inverter maximum MPPT operational voltage (as opposed to the survival voltage) by the value you computed, round down, that is maximum panels.

For minimum, you take the panel Vmp and adjust by the hottest temperature you will ever see *plus* what you expect the panel temperature rise to be (25 C is a reasonable number, say). Then divide the minimum *full power* MPPT voltage by that number and round up to get the minimum number of panels to produce full power.

For ideal, you take Vmp and adjust by your "typical" temperature. Then divide the MPPT ideal input voltage, usually around 360 volts, by that number. Round to the nearest integer and this is your ideal panel string size. It is usually better to round down more than up which helps with PV to battery and battery to AC efficiency.

You will find string length tolerance is relatively low when you consider all the factors.

An example:

EG4 FlexBOSS21
MPPT max operating: 440 VDC
MPPT min full power: 250 VDC
MPPT ideal: 360 VDC

Aptos DNA-120-BF26-370W
Voc (25 C): 41.4 VDC
Vmp (25 C): 34.5 VDC
Temp co: -0.28%/C

Las Vegas
Min temp: -15 C
Max temp: 50 C

Max voltage is Voc at 25 C (41.4 volts), then adjusted for temperature of -15 C which is 40 C below Voc measurement point. 40 C * 0.28%/C is 11.2% higher. This makes the panel voltage 46.04 volts. Max MPPT operating is 440 volts, so a maximum of 9 panels.

Min voltage to achieve full power is Vmp at 25 C (34.5 volts), then adjusted for temperature of 50 C ambient plus 25 C panel temp rise in sunlight minus 25 C Vmp measurement point. Thus voltage will be 50 * 0.28%/C lower, or 14% lower, yielding a panel voltage of 29.67 volts. To reach the MPPT minimum full power voltage of 250 volts, that takes 8.4 panels, so 9 panels.

Neither computation above is a hard limit as the MPPT survival voltage goes to 600 volts, and being under max power doesn't break anything, but if you want your array to generate full power under all conditions you would see, you need 9 panels.

The ideal MPPT voltage is 360 volts. If we assume 25 C ambient typical conditions and 25 C rise, we will get a panel voltage of 32.1 volts, which works out to 11 panels. If you go with 11 panels, the FB21 will survive that (600 volt MPPT survival rating), but it may stop producing power if the string goes over 440 volts.

The ideal for this setup is probably 10 panels. The chance you go over 440 volts is rather slim (you might not get power in those rare times), and that gets you closer to the 360 volt ideal point n most operating conditions. 11 panels will work too, more optimal in the heat, but you will spend more time above 440 volts and without power.

The basic take away is that string lengths are not as flexible as they appear once you take into consideration all the factors and try to optimize your system performance.

Mike C.

For example, the SmartSolar MPPT RS can "turn on" at 65-80V, and I am telling everyone to flat out ignore that and have a minimum of 220. This is considering max temp that people will see, especially here in las vegas. I feel like James, and now you are not looking at my actual content and what I am saying and why I am saying it. I have mentioned these points over and over again and now youre saying that I am disagreeing or not mentioning it? Why do you think I recommend boosting the voltage so high and ignore the recommendation? I live in Vegas, and I am well aware of the effects of temperature on these panels. I have multiple videos covering that as well.

When you say my video does not mention it, and my entire video and my recommendations revolve quite literally around what claim for it to be missing, it is very frustrating.

My point about the minimum voltage on the Flexboss was also correct, and now they are changing the spec sheet and how these units are programmed from the factory. And what occurs when the battery is not connected. I am also mentioning these points in my next video about the unit. Why not mention what occurs for batteryless mode, and the default setting that comes on these units? @mciholas

 

[NC_hydro]

For reference this mciholas guy is a known troll so I wouldn't worry too much about what he/she says or thinks about anything anyone says. I do wish the forum had the ability to not only ignore someone but make it so if you have ignored said person not only can you not see their posts but they aren't able to see your posts.

 

[Brucey]

For example, the SmartSolar MPPT RS can "turn on" at 65-80V, and I am telling everyone to flat out ignore that and have a minimum of 220. This is considering max temp that people will see, especially here in las vegas

Rs450 startup voltage is 120V minimum then can run as low as 65V.

 

[Tommytwotone]

For example, the SmartSolar MPPT RS can "turn on" at 65-80V, and I am telling everyone to flat out ignore that and have a minimum of 220. This is considering max temp that people will see, especially here in las vegas. I feel like James, and now you are not looking at my actual content and what I am saying and why I am saying it. I have mentioned these points over and over again and now youre saying that I am disagreeing or not mentioning it? Why do you think I recommend boosting the voltage so high and ignore the recommendation? I live in Vegas, and I am well aware of the effects of temperature on these panels. I have multiple videos covering that as well.

When you say my video does not mention it, and my entire video and my recommendations revolve quite literally around what claim for it to be missing, it is very frustrating.

My point about the minimum voltage on the Flexboss was also correct, and now they are changing the spec sheet and how these units are programmed from the factory. And what occurs when the battery is not connected. I am also mentioning these points in my next video about the unit. Why not mention what occurs for batteryless mode, and the default setting that comes on these units? @mciholas

Has anyone tried the firmware update for the Flexboss/18Kpv/12Kpv that came out yesterday as I understand it? How many of you are waiting to see what it does and how it works before installing it?

 

[RARankin]

I just installed it; I'll let you know of any issues... I don't have solar hooked up yet so I won't be helpful there.

 

[Tommytwotone]

I just installed it; I'll let you know of any issues... I don't have solar hooked up yet so I won't be helpful there.

Fingers crossed

 

[RARankin]

<Edit> Apparently if you link the the link it doesn't work, but if you click it from within the monitoring site it works... anyways...

FlexBoss

EG4_FAAB-2021​

2025-03-11​

• Same as fAAB-2021, change based on FAAB-1E1E.
• 1. Add the new startup option "Soc/Volt + Time" for AC charge startup. （Compatible with LCD V20）.
• 2. Add two-time settings to the generator startup setting.
• 3. Add AC couple on EPS port function to Flex Boss that paralleled with Grid Boss.
• 4. Optimize when either ‘charge control’ or ‘discharge control’ setting changes, the settings for both will be updated synchronously.
• * synchronized Charge and Discharge. if a customer sets the charging control to SOC, the discharging control setting will automatically switch to SOC.
• 5. Changing the CT ratio on monitor site no longer requires a system restart.
• 6. Optimize the issues of flicker.
• 7. Optimize the standard voltage of BUS1 to 370V.
• 8. Optimize the communication fault logic when connecting to Grid Boss.
• *it has been modified to alert when disconnecting the communication line when on-grid or off-grid
• 9. Optimize the issue of switching and EPS output interruption when PV is weak
• 10. Optimize DCDC operation to make it more stable.
• 11. Fix the parallel phase error issue when connecting generator in split phase parallel system.
• LCD V20
• 1. Add the new startup option "Soc/Volt + Time" for AC charge startup.

GridBoss

EG4_IAAB-13​

2025-03-11​

• Based on IAAB-11.
• 1. Add Separate Panel Mode to make GridBoss work as the separate panel. 
• 2. Optimize the range of battery voltage setting, it is limited from 40V to 59V. 
• 3.Optimize overcurrent detection and short current detection.
• 4. Optimize the issue of the monitoring still reporting a notice of abnormal frequency or voltage of generator even when there is no generator connected.
• 5. Optimized the issue of update failure when there is no communication between GridBOSS and inverter .
• 6. Fix the issue of the GridBoss system time may be inconsistent with the inverter.
• 7. Fix the issue where the charge or discharge do not work in non-shared battery mode.
• 8. Fix the issue of the alarm not displaying on the monitoring when generator voltage is abnormal.
• 9. Fix the overcurrent issue of smart Load2 .

 

[Zapper77]

Has anyone tried the firmware update for the Flexboss/18Kpv/12Kpv that came out yesterday as I understand it? How many of you are waiting to see what it does and how it works before installing it?

I've been running 18Kpv 2021 and GB v13 for a few weeks, all good on my end. GB v12 was being a pain...just had to skip 12 and move on to 13.

Edit to add, My personal System.

 

[CaySol]

IAAB-13 fixed my pass through limitation. Passed through 43kw from grid without incident.

 

[Tommytwotone]

I've been running 18Kpv 2021 and GB v13 for a few weeks, all good on my end. GB v12 was being a pain...just had to skip 12 and move on to 13.

What was 12 doing to you?

 

[CaySol]

I’m interested in the ac coupling for the ac out ports on the Flexboss.

 

[jharrell]

IAAB-13 fixed my pass through limitation. Passed through 43kw from grid without incident.

Question is how far can it be pushed since normal 200 amp service and breakers can far exceed 48kw / 200a for short periods, still interested to know if they try and use the relays as circuit breakers at some limit power rather than letting the CB’s handle that.

 

[CaySol]

Question is how far can it be pushed since normal 200 amp service and breakers can far exceed 48kw / 200a for short periods, still interested to know if they try and use the relays as circuit breakers at some limit power rather than letting the CB’s handle that.

I’m curious but don’t really want to push it to the point of anything breaking.

 

[Zapper77]

What was 12 doing to you?

enabling the standalone panel setting took longer than expected.

 

[mciholas]

Ignore the temperature?? Most of my video is about the temperature. What are you talking about?

Temperature should be part of ANY Voc MPPT limit computation. You implied that temperature only had to be considered if you live in a "cold" place.

Temperature is also something to consider for Vmp in hot conditions so that MPPT voltage doesn't sag too much.

Mike C.

 

[Will Prowse]

Temperature should be part of ANY Voc MPPT limit computation. You implied that temperature only had to be considered if you live in a "cold" place.

Temperature is also something to consider for Vmp in hot conditions so that MPPT voltage doesn't sag too much.

Mike C.

That's why my recommendation was 220 volts. I am well aware and I live in Las Vegas where it's over 120° f during the summer. That's the entire point of my video.

I did not imply anything. I said exactly what I meant. I had a calculation for cold temperature. And for everything else I said keep it above 220 volts. If you're on planet Earth that will work. How do you not see the logic there?

 

[skimandan]

Has anyone tried the firmware update for the Flexboss/18Kpv/12Kpv that came out yesterday as I understand it? How many of you are waiting to see what it does and how it works before installing it?

I'll try it out this weekend if I have the time.
I assume updating firmware erases all existing settings and shuts down the Gridboss, so an outage is required to switch the breakers to A/C passthrough. Correct?

 

[CaySol]

enabling the standalone panel setting took longer than expected.

What does standalone panel enable?

 

[Tommytwotone]

I'll try it out this weekend if I have the time.
I assume updating firmware erases all existing settings and shuts down the Gridboss, so an outage is required to switch the breakers to A/C passthrough. Correct?

This is my first update after the update at install so take what I am saying for what it is worth. I updated the GB and FB and the settings stayed. It did cause a brief (like a second) outage a couple times but that is likely due to the fact that I am running in off grid mode for a bit longer.

So it was easy let's hope it does not have any bugs.

 

[mciholas]

I did not imply anything. I said exactly what I meant. I had a calculation for cold temperature.

"For most people, this will work really well unless you have cold temperatures."

"For most environments, if it doesn't get that cold, this is perfect"

You gave the impression only people in "cold" climates should make Voc tempco adjustments. Everybody should check that regardless of how cold they feel their climate is or isn't. Even in "hot" Las Vegas, you should check it to -15 C which is 40 C lower than STC. For a panels with -0.35% tempco, that's 14% Voc rise, quite a lot. Even a place that never gets to 0 C, which is a really warm place, that's 9% Voc rise.

Basically, you gave the impression only "cold" places need to check tempco but really everybody needs to.

Mike C.

 

[Will Prowse]

"For most people, this will work really well unless you have cold temperatures."

"For most environments, if it doesn't get that cold, this is perfect"

You gave the impression only people in "cold" climates should make Voc tempco adjustments. Everybody should check that regardless of how cold they feel their climate is or isn't. Even in "hot" Las Vegas, you should check it to -15 C which is 40 C lower than STC. For a panels with -0.35% tempco, that's 14% Voc rise, quite a lot. Even a place that never gets to 0 C, which is a really warm place, that's 9% Voc rise.

Basically, you gave the impression only "cold" places need to check tempco but really everybody needs to.

Mike C.

Agreed. I think you should make a video on this. Let me know when you post it. Looming forward to it

 

[mciholas]

Agreed. I think you should make a video on this. Let me know when you post it. Looming forward to it

My explanation is posted above with some analysis.

M

Post in thread 'FlexBoss21 / GridBoss Issue List'

Tuesday at 6:41 AM

I think if the working voltage range is higher than the minimum voltage rating of the MPPT, It should be able to produce good power.

MPPTs are only boost circuits in most inverters as they are trying to boost the string voltage to the AC generator input rail. Boost circuits are limited by a maximum input current, thus MPPTs publish a maximum current. The lower the input voltage, the less efficient they are due to higher out to in ratio. That's the nature of DC boost circuits.

The AC generator section converts the high rail voltage to a variable sine wave output. It needs a...

• mciholas

• 

Video is not the only way to make a contribution.

Mike C.