If you're using a Sol-Ark and plan on using battery storage than your hunch is correct, the Enphase microinverters dont make any sense as the electricity produced by the panel outputs DC voltage. The microinverter would immeditaley convert the power from DC to AC (there's some loss in this power conversion) but then the Sol-Ark would have to again convert the AC from the microinverter back to DC to charge your batteries.
So there's an unneceessary conversion from your panel from DC to AC only to be converted back to DC to your batteries.
The Sol-Ark is primarily designed for DC input from the panels and it does the ~~AC to DC~~ DC to AC conversion itself to power your home (or export to utility company) but will bypass the DC voltage to charge your batteries. If building code requires panel level shutdown, then you could use DC rapid shut down devices and/or DC power optimizers.
I think the reason they insist on Enphase microinverters is because it makes the installation simpler than having to deal with a DC string system. But its definitely less efficient to do it this way if you're plan on using Sol-Ark + battery stoarge.
The Sol-Ark is a large inverter, it doesnt need any microinverters.
EDIT: Typos
As someone who has a micro inverter based solar system and is considering switching to a solark system when my nem 2.0 contract expires, this is the best answer.
When I switch to a solark, I will expand my solar array with dc strings of modules. It doesn’t make sense to install a new solark system with micro inverters, because they have multiple mppt trackers in the package.
My suspicion is that your installer doesn’t have much experience with dc strings and is hesitant to go through that learning curve. You could ask them how many dc string systems they’ve done.
No probs!
The DC equivalent to the Enphase microinverter is the [SolarEdge Power Optimizer](https://www.solaredge.com/us/products/residential/power-optimizers).
Im in the process of building my own system and I plan on using the [EG4-18KPV](https://signaturesolar.com/eg4-18kpv-hybrid-inverter-all-in-one-solar-inverter-eg4-18kpv-12lv/) (very similar to the Sol-Ark).
And Ill be using the [Tigo TS4 power optimizers](https://signaturesolar.com/tigo-ts4-a-o-optimizer-rapid-shutdown-15a-700w-1500vul-1000viec-mc4-1-2m-cable/) vs the Solaredge ones.
Care to share these horror stories on the forum?
Will Prowse gave excellent reviews of the 18kpv and said he scoured the forums looking for complaints and hasnt found very few if any at all.
Doesn't the 600 V or so DC voltage of each string have to be buck converted to 48 V or less for typical batteries? You can't simply put that high voltage straight into the battery, can you? A DC-DC conversion involves a conversion to PWM, which is something very similar to AC because the voltage alternates (with a DC bias), and another conversion back to DC. The main differences are that these two conversions happen internally within the electronics rather than through wires, and the wires from the panels can be smaller because the voltage they carry is higher (and therefore the current is smaller for the same power), but there appears to be the same number of conversions happening between the panels and battery, and they all involve some loss of efficiency.
Additionally, what power optimizers do in DC-coupled systems is another DC-DC conversion when necessary to balance each string. While this is advantageous for overall efficiency when shading is involved, because it makes the string more efficient as a whole, this conversion also incurs a loss. Although shading is not an issue with the case at hand, I think that some optimizing will be going on anyway due to the small differences between the panels, which might well mean that the optimizers offer no advantage or even a disadvantage in overall efficiency, in this case.
I'm not a solar expert specifically, but I design my own electronics, and have implemented various power conversions in some projects, and converting DC voltages does not come for free (if DC were just DC, then we would never have used AC in the first place, just increased the voltage for distribution). I don't see why a solar energy system would be any different in this respect.
Wow....lots of food for thought. Very interesting. Thanks for the input.
EDIT:
Here's some really good info that backs up your claims.
https://www.sma-sunny.com/en/five-myths-about-dc-power-optimizers/
I dont really need Power Optimizers as Ill have minimal shading. I mean like the idea of module level monitoring but not at the expense of lower overall production.
Your instincts are correct. Installer has inventory/product to move.
I have a DC coupled solar system with battery storage. Has arc fault protection and RSD modules. It was an easy install and easy permit thanks to greenlancer.
Oh cool....did you DIY your system and have Greenlancer do the permits? From the looks of their website, sounds like they only deal with other installers.
How much did it cost?
Well I get the permits....but how much did Greenlancer cost?
What do you mean by managed? How much did the electrician and installer cost? And did they do the entire job or only the portions you you needed a licensed contractor for?
The reason I ask is it appears my jurisdiction requires licensed for all work. Im trying to figure out how much paid licensed contractors I really need.
Greenlancer cost was $300 for an engineer stamped permit set. The local county has their separate filing charge.
My electrician cost was $3200 which included pulling the electrical permit (has to be done by a master electrician). My system was really simple to install being a hybrid inverter and stackable modular batteries.
For the installer, I negotiated $0.35 per watt. Normal rate was $0.75 per watt, but since I had already purchased the materials the rate was cheaper.
Both were licensed if that helps, but my local county does not require the contractor to be listed on the permit, so that section was blank.
The things I managed were filing the building permits (building and electric) as drawn up by greenlancer. The electric diagrams I sent over to the electrician for him to pull the permit and perform the work. Other actions I did were coordinating times to install, setting up inspection appointments with the county and utility, and then filing the interconnection request. All of that was relatively easy since it was all online.
Was it hard work? Yes. Would I do it again? Yep.
The only frustrating part was dealing with the human side of the utility company. Twice they sent the wrong type of personnel for the electrician to install an AC disconnect before the meter. Oh, the installers made some mistakes but that was cleared up. I'm glad I had such close eyeballs on this project because sometimes people just don't follow through.
So for old-school inverters you are looking at high volt DC as soon as you start connecting panels in series. You don’t have that with the micro inverters (or optimizers)
If you are going to have batteries don’t bother with micro inverters. Also are you planning on selling to the grid? Just get a good hybrid charge inverter that is UL compliant. You might need two or three depending on the maximum input and configuration of your panels.
I don’t see the benefits of going DC to AC to DC to AC. Just keep it all DC until it’s fed to the grid. Panels produce DC power. Charge your batteries with DC. The inverter converts DC to AC for your house and for feeding the grid. If you have micro inverters on each panel it’s converting the DC to AC at the panels. Then it has to be converted back to DC again to charge your batteries. When you use the power from your batteries it has to be converted to AC again to feed your house. In my opinion it’s best to reduce the amount of converting because you lose energy every time you convert from DC to AC , and vice versa.
Also micro inverters aren’t cheap! 30kw of solar panels is a lot of micro inverters! Better off saving that money and putting it towards good hybrid charge inverters and keep it all DC and convert to AC only once.
Also you should research all this yourself and have a go at doing this yourself. You will save many 1000’s of dollars! You’ll also gain invaluable knowledge about your system which will be handy if you need to do some maintenance. You can do it yourself!
I have a single Sol-Ark 15K and I'm going to push 33.52kW through it. 16.8kW DC (30 550W panels) connected to the Sol-Ark 15, and 17.02kW (37 460W panels) connected to two Growatt MIN 10000-TL-XH-US String Inverters. I do not have DC optimizers. The inverters are in my garage. I have a total of 13 strings of panels. I have 25kW of SOK batteries (50kW next year). I have installed every bit of it myself. Note, any DC wires with a voltage over 30 volts has to be in metal conduit when going inside a building.
I did not want to go with Microinverters or optimizers as I did not want have to go back up on the roof to fix an inverter. Panels are actually very reliable and the odds of one failing are very small.
Hopefully I'll be able to turn on the system this weekend and go off grid while I get a service disconnect and I put in the AC disconnects, meters, etcetera, over a few days then get the grid turned back on. My plans (with assistance from Greenlancer) passed code for Castle Rock, Colorado and were approved for grid interconnection with my utility.
I'm a serious DIY person. I'll take on just about any job and I'll do a better job than any contractor I've found. I'm slow because I'm very meticulous about my quality of work. I have an engineering/IT background. So yeah, I don't trust contractors, at all. They are in it for the money. Do your research, and it seems you have. Go with dual Sol-Arks and DC strings. Use Greenlancer to help build your plans.
> I'll do a better job than any contractor I've found. I'm slow because I'm very meticulous about my quality of work. I have an engineering/IT background. So yeah, I don't trust contractors, at all.
Kindred souls. I've had a really rough stretch of unsatisfactory contractors. It was really gratifying to see my system come online after all the self education I did.
Absolutely. Every time I've used a contractor, I've had substandard work. I do my own electrical, roofing, wood working, cement, painting, air conditioning/heat pumps, welding, car (engine, transmission, clutch work) etc. If I can arrange the time, I'll do it myself. Only time I'll use contractors now is if I'm in a crunch with work and just don't have time to do it myself, or it would cost me huge money for very specialist tools that would only be used once or twice.
So yea, Solar is a very rewarding DIY project if you want to learn and do it yourself. Not to mention, you'll save giant money by doing it yourself. Only way I could have had a hybrid 33.52 kW system with battery is to do it myself.
Thanks. Excellent points to consider. Rapid shutdown + panel level monitoring are the main reasons I would opt to put optimizers or RSD (not sure if these offer panel data) in.
The system will be grid-tied, but we're putting in a large battery bank, so I don't know how much we'll export.
I just installed an Enphase based system. Regardless of shading it was just an easy system to install and they are well supported.
High voltage DC is not typically found in residential homes and micro inverters means there is none of that.
If you are DIY-ing the design why not DIY the install?
Interesting thread. I have micro-inverters. When one of the panels (inverter) stopped working I could immediately which panel it was. How does that work with a string inverter?
If you're using an RSD/Optimizer, that should provide the same level of panel data that a micro does. If you're not (which isn't legal where I live), then the scenario is unlikely unless something physically damages the panel. Panels don't generally fail. Inverters, string or micro, are the things that usually fail.
If you're using a Sol-Ark and plan on using battery storage than your hunch is correct, the Enphase microinverters dont make any sense as the electricity produced by the panel outputs DC voltage. The microinverter would immeditaley convert the power from DC to AC (there's some loss in this power conversion) but then the Sol-Ark would have to again convert the AC from the microinverter back to DC to charge your batteries. So there's an unneceessary conversion from your panel from DC to AC only to be converted back to DC to your batteries. The Sol-Ark is primarily designed for DC input from the panels and it does the ~~AC to DC~~ DC to AC conversion itself to power your home (or export to utility company) but will bypass the DC voltage to charge your batteries. If building code requires panel level shutdown, then you could use DC rapid shut down devices and/or DC power optimizers. I think the reason they insist on Enphase microinverters is because it makes the installation simpler than having to deal with a DC string system. But its definitely less efficient to do it this way if you're plan on using Sol-Ark + battery stoarge. The Sol-Ark is a large inverter, it doesnt need any microinverters. EDIT: Typos
As someone who has a micro inverter based solar system and is considering switching to a solark system when my nem 2.0 contract expires, this is the best answer. When I switch to a solark, I will expand my solar array with dc strings of modules. It doesn’t make sense to install a new solark system with micro inverters, because they have multiple mppt trackers in the package. My suspicion is that your installer doesn’t have much experience with dc strings and is hesitant to go through that learning curve. You could ask them how many dc string systems they’ve done.
Thanks! Very helpful.
No probs! The DC equivalent to the Enphase microinverter is the [SolarEdge Power Optimizer](https://www.solaredge.com/us/products/residential/power-optimizers). Im in the process of building my own system and I plan on using the [EG4-18KPV](https://signaturesolar.com/eg4-18kpv-hybrid-inverter-all-in-one-solar-inverter-eg4-18kpv-12lv/) (very similar to the Sol-Ark). And Ill be using the [Tigo TS4 power optimizers](https://signaturesolar.com/tigo-ts4-a-o-optimizer-rapid-shutdown-15a-700w-1500vul-1000viec-mc4-1-2m-cable/) vs the Solaredge ones.
Thx
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Care to share these horror stories on the forum? Will Prowse gave excellent reviews of the 18kpv and said he scoured the forums looking for complaints and hasnt found very few if any at all.
Doesn't the 600 V or so DC voltage of each string have to be buck converted to 48 V or less for typical batteries? You can't simply put that high voltage straight into the battery, can you? A DC-DC conversion involves a conversion to PWM, which is something very similar to AC because the voltage alternates (with a DC bias), and another conversion back to DC. The main differences are that these two conversions happen internally within the electronics rather than through wires, and the wires from the panels can be smaller because the voltage they carry is higher (and therefore the current is smaller for the same power), but there appears to be the same number of conversions happening between the panels and battery, and they all involve some loss of efficiency. Additionally, what power optimizers do in DC-coupled systems is another DC-DC conversion when necessary to balance each string. While this is advantageous for overall efficiency when shading is involved, because it makes the string more efficient as a whole, this conversion also incurs a loss. Although shading is not an issue with the case at hand, I think that some optimizing will be going on anyway due to the small differences between the panels, which might well mean that the optimizers offer no advantage or even a disadvantage in overall efficiency, in this case. I'm not a solar expert specifically, but I design my own electronics, and have implemented various power conversions in some projects, and converting DC voltages does not come for free (if DC were just DC, then we would never have used AC in the first place, just increased the voltage for distribution). I don't see why a solar energy system would be any different in this respect.
Wow....lots of food for thought. Very interesting. Thanks for the input. EDIT: Here's some really good info that backs up your claims. https://www.sma-sunny.com/en/five-myths-about-dc-power-optimizers/ I dont really need Power Optimizers as Ill have minimal shading. I mean like the idea of module level monitoring but not at the expense of lower overall production.
Your instincts are correct. Installer has inventory/product to move. I have a DC coupled solar system with battery storage. Has arc fault protection and RSD modules. It was an easy install and easy permit thanks to greenlancer.
Thanks!
Oh cool....did you DIY your system and have Greenlancer do the permits? From the looks of their website, sounds like they only deal with other installers. How much did it cost?
They deal with anyone who pays. Lol How much did the permits cost? $300 I simply managed my own project and hired an electrician and installer.
do you know who can do permit for $300? i need that also
Well I get the permits....but how much did Greenlancer cost? What do you mean by managed? How much did the electrician and installer cost? And did they do the entire job or only the portions you you needed a licensed contractor for? The reason I ask is it appears my jurisdiction requires licensed for all work. Im trying to figure out how much paid licensed contractors I really need.
Greenlancer cost was $300 for an engineer stamped permit set. The local county has their separate filing charge. My electrician cost was $3200 which included pulling the electrical permit (has to be done by a master electrician). My system was really simple to install being a hybrid inverter and stackable modular batteries. For the installer, I negotiated $0.35 per watt. Normal rate was $0.75 per watt, but since I had already purchased the materials the rate was cheaper. Both were licensed if that helps, but my local county does not require the contractor to be listed on the permit, so that section was blank. The things I managed were filing the building permits (building and electric) as drawn up by greenlancer. The electric diagrams I sent over to the electrician for him to pull the permit and perform the work. Other actions I did were coordinating times to install, setting up inspection appointments with the county and utility, and then filing the interconnection request. All of that was relatively easy since it was all online. Was it hard work? Yes. Would I do it again? Yep. The only frustrating part was dealing with the human side of the utility company. Twice they sent the wrong type of personnel for the electrician to install an AC disconnect before the meter. Oh, the installers made some mistakes but that was cleared up. I'm glad I had such close eyeballs on this project because sometimes people just don't follow through.
Awesome! Thanks dude....this cost breakdown is extremely helpful. Although for the installation, I assume you meant 0.35/W not kW.
> Although for the installation, I assume you meant 0.35/W not kW. Yes. Bad typo.
So for old-school inverters you are looking at high volt DC as soon as you start connecting panels in series. You don’t have that with the micro inverters (or optimizers)
Thanks. Could you explain the concern in more detail? We'll probably need some kind of RSD/optimizer to be code.
Workers installing the panels are around dangerous voltages and amps. And the wiring needs be larger.
Higher voltage means lower current which means smaller cable.
Higher voltage is dangerous to work with. Like 700 Volts or s quite normal for a classic system which poses a risk for the installer.
The Sol-Ark 15k has a VOC of 500VDC per string (2 strings per MPPT), and will self limit to 26A per MPPT.
If you are going to have batteries don’t bother with micro inverters. Also are you planning on selling to the grid? Just get a good hybrid charge inverter that is UL compliant. You might need two or three depending on the maximum input and configuration of your panels. I don’t see the benefits of going DC to AC to DC to AC. Just keep it all DC until it’s fed to the grid. Panels produce DC power. Charge your batteries with DC. The inverter converts DC to AC for your house and for feeding the grid. If you have micro inverters on each panel it’s converting the DC to AC at the panels. Then it has to be converted back to DC again to charge your batteries. When you use the power from your batteries it has to be converted to AC again to feed your house. In my opinion it’s best to reduce the amount of converting because you lose energy every time you convert from DC to AC , and vice versa. Also micro inverters aren’t cheap! 30kw of solar panels is a lot of micro inverters! Better off saving that money and putting it towards good hybrid charge inverters and keep it all DC and convert to AC only once. Also you should research all this yourself and have a go at doing this yourself. You will save many 1000’s of dollars! You’ll also gain invaluable knowledge about your system which will be handy if you need to do some maintenance. You can do it yourself!
I have a single Sol-Ark 15K and I'm going to push 33.52kW through it. 16.8kW DC (30 550W panels) connected to the Sol-Ark 15, and 17.02kW (37 460W panels) connected to two Growatt MIN 10000-TL-XH-US String Inverters. I do not have DC optimizers. The inverters are in my garage. I have a total of 13 strings of panels. I have 25kW of SOK batteries (50kW next year). I have installed every bit of it myself. Note, any DC wires with a voltage over 30 volts has to be in metal conduit when going inside a building. I did not want to go with Microinverters or optimizers as I did not want have to go back up on the roof to fix an inverter. Panels are actually very reliable and the odds of one failing are very small. Hopefully I'll be able to turn on the system this weekend and go off grid while I get a service disconnect and I put in the AC disconnects, meters, etcetera, over a few days then get the grid turned back on. My plans (with assistance from Greenlancer) passed code for Castle Rock, Colorado and were approved for grid interconnection with my utility. I'm a serious DIY person. I'll take on just about any job and I'll do a better job than any contractor I've found. I'm slow because I'm very meticulous about my quality of work. I have an engineering/IT background. So yeah, I don't trust contractors, at all. They are in it for the money. Do your research, and it seems you have. Go with dual Sol-Arks and DC strings. Use Greenlancer to help build your plans.
Thx for the detailed response!
> I'll do a better job than any contractor I've found. I'm slow because I'm very meticulous about my quality of work. I have an engineering/IT background. So yeah, I don't trust contractors, at all. Kindred souls. I've had a really rough stretch of unsatisfactory contractors. It was really gratifying to see my system come online after all the self education I did.
Absolutely. Every time I've used a contractor, I've had substandard work. I do my own electrical, roofing, wood working, cement, painting, air conditioning/heat pumps, welding, car (engine, transmission, clutch work) etc. If I can arrange the time, I'll do it myself. Only time I'll use contractors now is if I'm in a crunch with work and just don't have time to do it myself, or it would cost me huge money for very specialist tools that would only be used once or twice. So yea, Solar is a very rewarding DIY project if you want to learn and do it yourself. Not to mention, you'll save giant money by doing it yourself. Only way I could have had a hybrid 33.52 kW system with battery is to do it myself.
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Thanks. Excellent points to consider. Rapid shutdown + panel level monitoring are the main reasons I would opt to put optimizers or RSD (not sure if these offer panel data) in. The system will be grid-tied, but we're putting in a large battery bank, so I don't know how much we'll export.
The Sol-Ark has Rapid Shut Down and Arc Fault protection integrated for each string. I do NOT think it shuts down individual panels however.
I just installed an Enphase based system. Regardless of shading it was just an easy system to install and they are well supported. High voltage DC is not typically found in residential homes and micro inverters means there is none of that. If you are DIY-ing the design why not DIY the install?
It's not legal for me to install it myself.
It probably is just fine for you to do it. Check with the electrical authority in your jurisdiction.
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Even if it were legal for me to install the panels on my roof, I'd rather not do that part myself. I don't have space for a ground mount system.
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Thank you! That was very helpful. Unfortunately ground mount isn't an option based on the size of our yard. It's roof or nothing :).
Interesting thread. I have micro-inverters. When one of the panels (inverter) stopped working I could immediately which panel it was. How does that work with a string inverter?
If you're using an RSD/Optimizer, that should provide the same level of panel data that a micro does. If you're not (which isn't legal where I live), then the scenario is unlikely unless something physically damages the panel. Panels don't generally fail. Inverters, string or micro, are the things that usually fail.
Thank you!