Great video. I learned something new. Especially the AC coupled portion. As an off grid guy, I never fully understood the AC coupled path and advantage. Now it makes more sense. Like adding the hybrid to an existing solar setup.
I'm just starting to learn about solar and this is the most informative video that I have found that really helped me understand what I'm doing with all the different components. Thank you so very much!
I've done both over the years but these days I far, far prefer DC coupling because you have less electronics up on the roof. In the old days you had no electronics on the roof at all but these days regulations typically require per-panel rapid shutdown, so there has to be something up on the roof per-panel to do that. But the equipment is dead simple and unsophisticated compared to micro-inverters. Generally speaking, maintenance on DC coupled systems is far, FAR easier and far less expensive because the equipment most likely to break is at ground level and doesn't require partial disassembly of panels up on the roof. DC coupled systems are cheaper to install and cheaper to maintain. Another big advantage of DC coupling is that you don't need to wiggle the line frequency around during a blackout (UL1741SA) to regulate AC micro-inverters. It can just stay locked at 60hz. And there are fewer voltage overshoots and undershoots with variable loads. -Matt
One thing I didn't hear mentioned about AC, and the reason AC was chosen over DC for transmitting power over distance, is AC's ability to efficiently move power over longer distance with lower losses. This allows you to move your panels farther away from your home/load and not have the power loss due to wire length.
@@matthewwakeham2206 DC will require more step-up transformers to account for losses in the line. I don't think solar will deliver high enough DC voltage to matter...could be wrong..wouldn't be the first time
The efficiency of transmission is primarily a function of voltage, not whether something is AC or DC. AC is actually a bit less efficient than DC. The reason AC is used for most short-haul transmission lines (less than a few hundred miles) is that it is a lot easier to step-up and step-down an AC voltage than a DC voltage. However, for transmission lines longer than a few hundred miles, AC must be phase-synchronized (often multiple times), which is more costly and DC winds up being the most cost effective. So very long distance transmission lines these days tend to be DC.
It seems like the major down side to AC coupling is price. I've seen several videos where it is claimed that "power optimizers" are now longer necessary with today's modern panels. If power expansion is the goal it would seem like two hybrid DC coupled inverters would offer all the benefits compared to a combination AC coupled + DC coupled. IMHO.....I've never been a fan of microinverters. They are the most expensive path and the redundancy benefit is a double edge sword. The probability of failure go up at the same time.
I always learn something new from these videos. Can you do a video on which microinverters work best with different wattage panels? Also my grid tied SolarEdge inverter and SolarEdge optimizers were not cheap. I would prefer to utilize the optimizers and ditch the inverter for the 18kpv and add EG batteries. Our local power outages are getting ridiculous and this grid tied set up is starting to really wear on me. I would still like to back feed to the grid but their control over my 24/7 power use needs to come to an end. “So my question would be if the SolarEdge optimizers will work for me with the 18kpv and minus the SolarEdge inverter. Also if I doubled my array and added micro inverters to that section of panels would this work well”?
I have a very similiar setup but would like to be able to use the solaredge to AC couple to my EG4 inverter system after disconnecting from the grid during a grid down event
Researching solar installation. Correct me if i am wrong, but the whiteboard has grid to the main load/panel to the inverter. Should it not be grid to inverter to main load/panel?
I am curious how much power you actually lose in total with Panel to Inverter DC to AC, then Inverter to Battery AC to DC, then Battery to Inverter for actual use in the home Is it possible that one kWh of power harvested by the Solar Panels only produces 80% of one KWh by the time it is used in the house ?
It adds up. Actually it multiplies. You take each stage's efficiency and you multiply them all together. So, for example, if a micro-inverter is 98% efficient and the AC battery charger is 95% efficient and (when discharging the battery) the DC-AC inverter is 92% efficient, you get: 0.98 * 0.95 * 0.92 = 0.857 = 85.7% end-to-end efficiency. Also, these efficiencies are actually quite variable and depend a lot on how much power is actually being transmitted. Higher efficiencies are possible with higher-voltage topologies... for example, a Tesla Megapack has a round-trip efficiency of (I think) somewhere around 93%. Generally speaking, having more conversions is bad but some conversions are worse than others. Reducing the voltage tends to be quite efficient while boosting voltage is less efficient. DC-to-AC can be made fairly efficient while AC-to-DC is less efficient. And output regulation also matters. Micro-inverters can hit 99% efficiency if they have something (like the grid) to push against, primarily by not regulating their output as well as an inverter powering house appliances would have to regulate its output. The trade-off is that a micro-inverter can easily overshoot and cause the line voltage to increase beyond specs if it doesn't have anything to push against. -Matt
The conversion losses in a AC coupled system is 3% more than a DC coupled system. Typical DC coupled will loss around 6% during the entire process, it can store up to 3% higher efficiency than AC coupled systems. That is huge impact on a commercial/utility scale eco system but residential…. Fractional IMO. DC is ⚠️ high voltage ⚡️ unsafe. Why should your solar be at voltages 300-600v when there’s a better and safer alternative but question the conversion loss over safety 🔥? So you lose 3% big deal safety should be the priority. RSD devices help yes but that’s a separate component added in conjunction with your single point of failure inverter that micros have integrated. All homes run off 240V.. not 600V why should your solar be different.
Good point to be considered. However 120v is just as dangerous as 500v . The tiny current that will stop your heart can be generated by even lower voltage. I worked with 480v for years and my experiences while part of those circuits was no more painful than the 120v shocks. Higher voltages save money because the lower current makes components and wires much smaller for the same power.
I agree that the 3% conversion loss is insignificant considering how inexpensive solar panels have become. In a 10 KW solar array,that’s just one 300 watt panel. I’m gravitating toward moving the whole system to a power shed and letting the house panel simply see it as it if were a grid connection. I already am totally done with panels on the roof of the house because of the fall hazard. Also,if it’s not a square surface clear of vent pipes,the installation has a Frankenstein appearance.
Many dc to ac conversions and vice versa generate very high levels of dirty electricity, which are very dangerous to human health. DC coupled systems are simpler and require fewer inverters so it should produce less dirty electricity.
It depends on what your goals are. DC tied via string to inverter and batteries, you’re more efficient with the energy than with a micro-inverter. You also have less moving parts and fewer single points of failure. Safety of DC vs AC is funny because in all likely scenarios, the systems are shut down; typically, if installed to code/spec, this will be a non-issue. Full disclosure, I have a 12kWH DC coupled system with 20kWH of battery from QCells. Their systems just work.
Great video. I learned something new. Especially the AC coupled portion. As an off grid guy, I never fully understood the AC coupled path and advantage. Now it makes more sense. Like adding the hybrid to an existing solar setup.
Excellent Job!!! Easily the most informative video on this subject I have ever seen!!!💥🤘
I'm just starting to learn about solar and this is the most informative video that I have found that really helped me understand what I'm doing with all the different components. Thank you so very much!
I hope she’s a millionaire; well-deserved, great clarity
I've done both over the years but these days I far, far prefer DC coupling because you have less electronics up on the roof. In the old days you had no electronics on the roof at all but these days regulations typically require per-panel rapid shutdown, so there has to be something up on the roof per-panel to do that. But the equipment is dead simple and unsophisticated compared to micro-inverters.
Generally speaking, maintenance on DC coupled systems is far, FAR easier and far less expensive because the equipment most likely to break is at ground level and doesn't require partial disassembly of panels up on the roof. DC coupled systems are cheaper to install and cheaper to maintain.
Another big advantage of DC coupling is that you don't need to wiggle the line frequency around during a blackout (UL1741SA) to regulate AC micro-inverters. It can just stay locked at 60hz. And there are fewer voltage overshoots and undershoots with variable loads.
-Matt
Thanks Kelly that’s a great comparison video!
One thing I didn't hear mentioned about AC, and the reason AC was chosen over DC for transmitting power over distance, is AC's ability to efficiently move power over longer distance with lower losses. This allows you to move your panels farther away from your home/load and not have the power loss due to wire length.
Dc is more efficient over longer distances as i understand it. New high power grid interconnectors tend to be high voltage dc.
@@matthewwakeham2206 DC will require more step-up transformers to account for losses in the line. I don't think solar will deliver high enough DC voltage to matter...could be wrong..wouldn't be the first time
The efficiency of transmission is primarily a function of voltage, not whether something is AC or DC. AC is actually a bit less efficient than DC. The reason AC is used for most short-haul transmission lines (less than a few hundred miles) is that it is a lot easier to step-up and step-down an AC voltage than a DC voltage. However, for transmission lines longer than a few hundred miles, AC must be phase-synchronized (often multiple times), which is more costly and DC winds up being the most cost effective. So very long distance transmission lines these days tend to be DC.
@@junkerzn7312 Guess I should have paid better attention in Power Systems
Excelent Video 👍👍👍👍💪
It seems like the major down side to AC coupling is price. I've seen several videos where it is claimed that "power optimizers" are now longer necessary with today's modern panels. If power expansion is the goal it would seem like two hybrid DC coupled inverters would offer all the benefits compared to a combination AC coupled + DC coupled.
IMHO.....I've never been a fan of microinverters. They are the most expensive path and the redundancy benefit is a double edge sword. The probability of failure go up at the same time.
I always learn something new from these videos. Can you do a video on which microinverters work best with different wattage panels? Also my grid tied SolarEdge inverter and SolarEdge optimizers were not cheap. I would prefer to utilize the optimizers and ditch the inverter for the 18kpv and add EG batteries. Our local power outages are getting ridiculous and this grid tied set up is starting to really wear on me. I would still like to back feed to the grid but their control over my 24/7 power use needs to come to an end. “So my question would be if the SolarEdge optimizers will work for me with the 18kpv and minus the SolarEdge inverter. Also if I doubled my array and added micro inverters to that section of panels would this work well”?
I have a very similiar setup but would like to be able to use the solaredge to AC couple to my EG4 inverter system after disconnecting from the grid during a grid down event
@@magnumcj wish they had these inverters back when I got my install done 🤷🏼♂️
Researching solar installation. Correct me if i am wrong, but the whiteboard has grid to the main load/panel to the inverter. Should it not be grid to inverter to main load/panel?
I am curious how much power you actually lose in total with
Panel to Inverter DC to AC, then
Inverter to Battery AC to DC, then
Battery to Inverter for actual use in the home
Is it possible that one kWh of power harvested by the Solar Panels only produces 80% of one KWh by the time it is used in the house ?
agreed, would like to see some data about how much power is lost in the conversion process
It adds up. Actually it multiplies. You take each stage's efficiency and you multiply them all together. So, for example, if a micro-inverter is 98% efficient and the AC battery charger is 95% efficient and (when discharging the battery) the DC-AC inverter is 92% efficient, you get:
0.98 * 0.95 * 0.92 = 0.857 = 85.7% end-to-end efficiency.
Also, these efficiencies are actually quite variable and depend a lot on how much power is actually being transmitted. Higher efficiencies are possible with higher-voltage topologies... for example, a Tesla Megapack has a round-trip efficiency of (I think) somewhere around 93%.
Generally speaking, having more conversions is bad but some conversions are worse than others. Reducing the voltage tends to be quite efficient while boosting voltage is less efficient. DC-to-AC can be made fairly efficient while AC-to-DC is less efficient.
And output regulation also matters. Micro-inverters can hit 99% efficiency if they have something (like the grid) to push against, primarily by not regulating their output as well as an inverter powering house appliances would have to regulate its output. The trade-off is that a micro-inverter can easily overshoot and cause the line voltage to increase beyond specs if it doesn't have anything to push against.
-Matt
Do you have a solar for dummies or Solar 101 video?
The conversion losses in a AC coupled system is 3% more than a DC coupled system. Typical DC coupled will loss around 6% during the entire process, it can store up to 3% higher efficiency than AC coupled systems. That is huge impact on a commercial/utility scale eco system but residential…. Fractional IMO. DC is ⚠️ high voltage ⚡️ unsafe. Why should your solar be at voltages 300-600v when there’s a better and safer alternative but question the conversion loss over safety 🔥? So you lose 3% big deal safety should be the priority. RSD devices help yes but that’s a separate component added in conjunction with your single point of failure inverter that micros have integrated. All homes run off 240V.. not 600V why should your solar be different.
Good point to be considered. However 120v is just as dangerous as 500v . The tiny current that will stop your heart can be generated by even lower voltage. I worked with 480v for years and my experiences while part of those circuits was no more painful than the 120v shocks. Higher voltages save money because the lower current makes components and wires much smaller for the same power.
I agree that the 3% conversion loss is insignificant considering how inexpensive solar panels have become. In a 10 KW solar array,that’s just one 300 watt panel. I’m gravitating toward moving the whole system to a power shed and letting the house panel simply see it as it if were a grid connection. I already am totally done with panels on the roof of the house because of the fall hazard. Also,if it’s not a square surface clear of vent pipes,the installation has a Frankenstein appearance.
Many dc to ac conversions and vice versa generate very high levels of dirty electricity, which are very dangerous to human health. DC coupled systems are simpler and require fewer inverters so it should produce less dirty electricity.
It depends on what your goals are. DC tied via string to inverter and batteries, you’re more efficient with the energy than with a micro-inverter. You also have less moving parts and fewer single points of failure.
Safety of DC vs AC is funny because in all likely scenarios, the systems are shut down; typically, if installed to code/spec, this will be a non-issue.
Full disclosure, I have a 12kWH DC coupled system with 20kWH of battery from QCells. Their systems just work.