Category
- Products
-
- Wiki
- Contact us
Inverter manufacturers
sales@inverters.cn
Tag:
Solar Inverters for grid connection and have been developed in order to minimize cost, better performance and extreme simplicity of construction, operation and maintenance. Applications: residential installations, industrial installations, big photovoltaic plants, isolated installations, etc. Multi-megawatt solutions customized to each project and string boxes to maximize the solar PV systems.
Gozuk photovoltaic inverters developed from its experienced designing and manufacturing industrial, robust, reliable, secure and high efficiency power electronics systems. The PV Inverter turns the DC mains coming from a solar PV field into a stabilized AC voltage power output. The central inverter works in grid connected mode, injecting the produced power.
Gozuk photovoltaic inverters developed from its experienced designing and manufacturing industrial, robust, reliable, secure and high efficiency power electronics systems. The PV Inverter turns the DC mains coming from a solar PV field into a stabilized AC voltage power output. The central inverter works in grid connected mode, injecting the produced power.
First of all, the test procedure DID imitate a "Global MPPT" algorithm. All data points where the Fronius inverter was off-MPPT (i.e. when it was causing the "Christmas light effect") were excluded from the results (even though it's arguable that these are valid data points). NREL noted this in "Inverter MPPT Error" section of the study, stating that there would be another 2% energy harvest gain for the microinverter system in the moderate shade scenario, if they had included these MPPT errors.
Regardless, that "Global MPPT" algorithms or dual-MPPT channels address shade mismatch are misleading for two reasons:
(1) The string-level MPPT will still "turn-off" any shaded sections of the array (using a bypass diode), even though there is a lot of diffuse light still reaching the shaded section. The result is that the string-level MPPT is ALWAYS exacerbating the impact of shade.
(2) The "Global MPPT" is still limited to the input voltage range of the inverter, so the term "Global" is really just marketing spin. And, this has a further consequence that the effectiveness of "Global MPPT" algorithms will be more limited in situations where the string is short or the weather is hot.
To summarize, if you rely on bypass diodes and "Global MPPT" algorithms to address mismatch effects, you will ALWAYS be at a disadvantage to micro inverters. It's only a question of how much.
Regardless, that "Global MPPT" algorithms or dual-MPPT channels address shade mismatch are misleading for two reasons:
(1) The string-level MPPT will still "turn-off" any shaded sections of the array (using a bypass diode), even though there is a lot of diffuse light still reaching the shaded section. The result is that the string-level MPPT is ALWAYS exacerbating the impact of shade.
(2) The "Global MPPT" is still limited to the input voltage range of the inverter, so the term "Global" is really just marketing spin. And, this has a further consequence that the effectiveness of "Global MPPT" algorithms will be more limited in situations where the string is short or the weather is hot.
To summarize, if you rely on bypass diodes and "Global MPPT" algorithms to address mismatch effects, you will ALWAYS be at a disadvantage to micro inverters. It's only a question of how much.
A failure of a roof-mounted micro inverter requires a much larger effort to replace, compared with a wall-mounted string inverter. I expect the cost differential in labor to replace a roof-mounted micro inverter vs. a wall-mounted inverter would be substantial. This may factor into the overall system availability if a homeowner opts to not replace a single failed micro inverter right away.
I have also heard the opposite case to hold true for certain (primarily government) installs where the budget to purchase the PV system is available, but the budget for O&M down the road is zero. In this case, it is expected that the system output degrades gradually over time with individual component failures, versus a complete system failure should a central inverter fail with no budget for repairs.
I do find this installer's claims of having failures on 100% of their installed microinverter systems to be hard to believe. This seems like an outlier to me, not in line with anecdotal evidence that I am hearing from other installers. However, I'm not an expert in reliability, so I'm not going to get into it.
I have also heard the opposite case to hold true for certain (primarily government) installs where the budget to purchase the PV system is available, but the budget for O&M down the road is zero. In this case, it is expected that the system output degrades gradually over time with individual component failures, versus a complete system failure should a central inverter fail with no budget for repairs.
I do find this installer's claims of having failures on 100% of their installed microinverter systems to be hard to believe. This seems like an outlier to me, not in line with anecdotal evidence that I am hearing from other installers. However, I'm not an expert in reliability, so I'm not going to get into it.
Claiming that today's micro-inverters---which use mixed-signal ASIC technology to operate at 96% efficiency and deliver utility interactive and wireless networking capabilities---is anything like the microinverters of the 1980's is absurd.
The rate of evolution in microinverters is faster than string inverters in every dimension (from performance and reliability to cost and features), which is the whole point of why end-customers are so interested.
I would hope that the rate of micro evolution is progressing as they have a ways to go to catch up with string inverters. They aren't as reliable, they aren't as efficient and they aren't as cost effective as string inverters for larger installations. It baffles me to hear about 600kW to 2MW micro installs. I find it hard to believe that those LCOE/ROI works out in favor of the customers, and I have yet to be proven wrong. I would be happy to sell people 4000 SB240's, but I feel compelled to warn against it for multiple reasons, mainly, because it doesn't make sense. Micros just aren't there- yet.
Also, I think you need to reread the article as he never tried to compare micros from 30 years ago to the ones today. He only mentioned that they have been around a long time.
The rate of evolution in microinverters is faster than string inverters in every dimension (from performance and reliability to cost and features), which is the whole point of why end-customers are so interested.
I would hope that the rate of micro evolution is progressing as they have a ways to go to catch up with string inverters. They aren't as reliable, they aren't as efficient and they aren't as cost effective as string inverters for larger installations. It baffles me to hear about 600kW to 2MW micro installs. I find it hard to believe that those LCOE/ROI works out in favor of the customers, and I have yet to be proven wrong. I would be happy to sell people 4000 SB240's, but I feel compelled to warn against it for multiple reasons, mainly, because it doesn't make sense. Micros just aren't there- yet.
Also, I think you need to reread the article as he never tried to compare micros from 30 years ago to the ones today. He only mentioned that they have been around a long time.