diy solar

diy solar

Are micro invertors the future of residential installations?

ncsolarelectric said:
Personally, I think you are splitting hairs between authorities.
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Yes I am splitting hairs. It is important for me to know what my rights are and that is why I have researched this. California follows the same concept as the US Constitution. The legislature makes the laws (statutes). They have delegated some of that to the Counties and Cities. They have not delegated any of that lawmaking authority to the CPUC. It is just a Commission to regulate the IOUs. That may be different in your state or another country. In California the municipal utilities are not regulated by the CPUC because they are run by elected city officials. That is why I use the term IOUs (Investor Owned Utiities) for the entities regulated by the CPUC. Since those cities adopt the building codes they may very well have laws that govern zero export inverters. I do not know because I do not live in one of those cities. It all depends on where you are standing.
 
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Ampster said:
Yes I am splitting hairs. It is important for me to know what my rights are and that is why I have researched this. California follows the same concept as the US Constitution. The legislature makes the laws (statutes). They have delegated some of that to the Counties and cities. They have not delegated any of that lawmaking authority to the CPUC. It is just a Commission to regulate the IOUs. That may be different in your state or another country.
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So, you do not recognize the state-appointed authority of the CPUC or their authority to enforce the rules they set forth, because they are not "laws" set forth in statutes by the legislature. The CPUC's authority however was setforth in law by the legislature in 1911 and I just read is part of the CA Constitution. So they have the authority, they just can't throw you in jail for it. All they can do is cut off your power.
 
That is an important distinction.
(That, and whether or not they can impose fines.)
 
ncsolarelectric said:
So, you do not recognize the state-appointed authority of the CPUC or their authority to enforce the rules they set fort
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I am a law abiding citizen. I do not follow the advice of anonymous posters on the Internet without checking my assumptions.
I recognize the authority of the CPUC to enforce the rules that they set forth for the IOUs which they regulate. I have explained many times that the rules that the CPUC adopts, apply only to the three IOUs which they regulate.
 
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Ampster said:
I am a law abiding citizen. I recognize the authority of the CPUC to enforce the rules that they set forth for the IOUs which they regulate. I have explained many times that the rules that the CPUC adopts, apply only to the three IOUs which they regulate.
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But they have jurisdiction over "all" interconnections to the utility grid, not just those owned by IOUs. The CPUC and the state have delegated the authority to enforce interconnection rules to the general public through the utilities as shown in the slide I posted above.
 
Hedges said:
That is an important distinction.
(That, and whether or not they can impose fines.)
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That is correct. Have you seen any examples of the CPUC imposing fines on individuals? I have seen fines for the IOUs but not individuals. I have seen city building departments impose fines and red tag jobs when I worked for a material supplier. I had to have an approved building permit before PG&E would connect a new service panel. I have an acquaintance who is a solar installer who has taken SCE to the mat at the CPUC on a number of occasions. He has never had one of his clients fined by the CPUC.
 
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ncsolarelectric said:
But they have jurisdiction over "all" interconnections to the utility grid, not just those owned by IOUs.
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Not "all interconnections", as I mentioned above, the CPUC does not regulate Municipal Utilities in California. I do not know how those other interconnection policies are developed. That is not the topic of this dialog. There are fifty states and I have no idea what the rules are for the other states and thousands of local jurisdictions.. You could be correct in many states.
 
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Ampster said:
Not "all interconnections", as I mentioned above, the CPUC does not regulate Municipal Utilities in California. I do not know how those other interconnection policies are developed. That is not the topic of this dialog. There are fifty states and I have no idea what the rules are for the other states and thousands of local jurisdictions.. You could be correct in many states.
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In North Carolina, it is spelled out more explicitly. The NCUC has the same powers as those conferred upon the superior courts. They are in fact a law-making body in this state.

"The Commissioners and members of the Commission staff designated and assigned to serve as Hearing Examiners have full power to administer oaths and to hear and take evidence. The Commission renders its decisions upon questions of law and fact in the same manner as a court of record. A majority of the Commissioners constitutes a quorum, and any order or decision of a majority of Commissioners constitutes the order or decision of the Commission. The Commission has the same power to compel the attendance of witnesses, require the examination of persons and parties, compel the production of books and papers, and punish for contempt, as by law is conferred upon the superior courts."

The N. C. Utilities Commission Statutes are under Chapter 62 of the General Statutes.
Visit the North Carolina General Assembly Web Site to See the N.C. General Statutes.

"§ 62-1. Short title.
This Chapter shall be known and may be cited as the Public Utilities Act. (1963, c. 1165, s. 1.)"

In CA, the Public Utilities Act was passed in 1912 by the California Legislature.
 
It might be best to take all the "under the radar" legality discussion to its own separate thread and try to keep this more on topic to pros/cons of microinverters. Just a suggestion anyway for readers that are potentially interested in either.
 
Wet1 said:
It might be best to take all the "under the radar" legality discussion to it's on separate thread
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I agree, on other forums the moderators can do that. I apologize for dragging this on and do not expect our volunteer moderators do have to be the topic police. Even if they were inclined, the forum software may not make that easy to do.
 
I’m saving over half at panel level by doing DC to DC. Going to parallel two inverters, so I still have power if one needs repair.

My roof gets hot in summer, so I’d imagine the life of micro inverters may not be as great as advertised.

I will get less loss in conversion to my batteries with DC.

Same goes for an EV, if I get one in the future.

And I will still have Optimization and RSD of panels.

Just to add, micros would be clipping on my panels as they are 460W bifacials. May never see it, but the potential is there to produce over 500W per panel.
 
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Danke said:
I will get no loss in conversion to my batteries (or less) with DC.
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I would be curious what components you are using to do that? I presume your string voltage will be several hundred volts and the battery is a typical 48 volt nominal pack. Keep us informed as you proceed.
Danke said:
Same goes for an EV, if I get one in the future.
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That is an even bigger challenge because V2H is not mature and the hardware is expensive. My analysis on a similar issue concluded that if was more cost effective to buy another solar panel or two to compensate and just use a typical EVSE that could vary the current which the EV draws as the solar changes during the day.
 
Major efficiency losses, in my opinion.
Going from a DC solar panel, to AC on the roof.
Then from AC to DC , to store in a battery.
Then from DC to AC again, to use the power later.
 
timselectric said:
Major efficiency losses, in my opinion.
Going from a DC solar panel, to AC on the roof.
Then from AC to DC , to store in a battery.
Then from DC to AC again, to use the power later.
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I agree but there are tradeoffs for every situation. A lot depends on rate differentials which could offset some of that inefficiency. By using a hybrid inverter in self consumption mode I do not buy any power during the summer peak rate period. That rate is $0.53 per kWh. I can buy power back from the grid at 0.23 per kWh. There is some room in that spread for inefficiencies.
Assuming my solar lasts 20 years the cost of that system amortized over twenty years divided by the expected kWhs produced gives me a cost of 0.08 per kWh. I did not factor in losses but assuming 20 percent I am still less than $0.10 per kWh. My decision to go with micros was based on the simplicity of the install which I did with the help of some paid labor. I am not arguing for micros versus strings since I have had both. I am just saying that in my case it was a close match and one or two things tipped the decision . It all depends on where you are standing.
 
Hedges said:
If they try hard enough, they can build a system with half-cut panels and poor-MPPT algorithm string inverter to prove their point.
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I bet I could build a crappy micro system too, but what exactly is the point of that? They are in the premium solar PV space, so compare with premium string inverters, which simply don't work so poorly. This has been demonstrated time and again.

Their claims are false and misleading and I don't know how they keep getting away with it.

Hedges said:
Since Enphase' competition is primarily SMA and Fronius, to be fair the comparison should be an actual test with current models from those companies. Which is what NRG's video presented.
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Exactly.

Hedges said:
Given excessive over-paneling, which Enphase promotes because their inverters are lower wattage than many panels now available, I think string inverters come out ahead.
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Bingo.

Hedges said:
Many companies market their products with similar performance claims. Caveat Emptor.
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Sure, but at the same time people should expect such claims to be pointed out for the nonsense they are.

The problem I have with such bogus claims is it reduces trust in everything else they say. Enphase have no need to perpetuate false claims.

They have an excellent product which should be sold on its merits.
 
Danke said:
I’m saving over half at panel level by doing DC to DC. Going to parallel two inverters, so I still have power if one needs repair.

My roof gets hot in summer, so I’d imagine the life of micro inverters may not be as great as advertised.

I will get less loss in conversion to my batteries with DC.

Same goes for an EV, if I get one in the future.

And I will still have Optimization and RSD of panels.

Just to add, micros would be clipping on my panels as they are 460W bifacials. May never see it, but the potential is there to produce over 500W per panel.
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Microinverters are tested to operate at 85C, well above roof temperatures and they are still warranteed at that temperature for 25 years. SIC Diodes are amazing! The junction temperatures can approach 200C.
 
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timselectric said:
Major efficiency losses, in my opinion.
Going from a DC solar panel, to AC on the roof.
Then from AC to DC , to store in a battery.
Then from DC to AC again, to use the power later.
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Enphase IQ Battery 3T, 89% Round trip efficiency (AC to Battery to AC)
Enphase IQ8A efficiency 97.6% (PV to AC)
Overall: 89% x 97.6% = 86.86%

Compared to Victron
Victron charge controller 96% or 98% (PV to DC)
Victron Inverter 94% (DC to AC)
Overall: 98% x 94% = 92%

Compared to AIMS Power
Charge controller 98.5% (PV to DC)
LF Inverter/Charger 88% (DC to AC)
Overall: 98.5% x 88% = 86.68%

Victron is more efficient, but it isn't grid-tied like Enphase. AIMS has very efficient MPPT charge controllers, but their LF inverters have high losses due to the LF transformer having significant core losses.

IMO, the Return on Investment (ROI) is more important than efficiency or autonomy. An off-grid system offers no financial benefit when the batteries are fully charged, everything in the home is powered and there is still sunlight on the panels that isn't being harvested for use. A grid-tied system takes that extra energy from the sun that wasn't being used and converts it into cold, hard, cash. At $0.53/kWh @Ampster is paying that's way more important than efficiency.
 
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ncsolarelectric said:
Microinverters are tested to operate at 85C, well above roof temperatures and they are still warranteed at that temperature for 25 years. SIC Diodes are amazing! The junction temperatures can approach 200C.
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We will see over the next 25+ years how the harsh environment affects them. Where I live we can get to -40 to +40 C with snow and rain.
 
In my opinion, they only halfway make sense for grid tied systems. Which I don't want anything to do with.
The grid is only going to get less reliable and more expensive. I'm running as fast as I can, in the opposite direction.
 
ncsolarelectric said:
Enphase IQ Battery 3T, 89% Round trip efficiency (AC to Battery to AC)
Enphase IQ8A efficiency 97.6% (PV to AC)
Overall: 89% x 97.6% = 86.86%

Compared to Victron
Victron charge controller 96% or 98% (PV to DC)
Victron Inverter 94% (DC to AC)
Overall: 98% x 94% = 92%

Compared to AIMS Power
Charge controller 98.5% (PV to DC)
LF Inverter/Charger 88% (DC to AC)
Overall: 98.5% x 88% = 86.68%

Victron is more efficient, but it isn't grid-tied like Enphase. AIMS has very efficient MPPT charge controllers, but their LF inverters have high losses due to the LF transformer having significant core losses.

IMO, the Return on Investment (ROI) is more important than efficiency or autonomy. An off-grid system offers no financial benefit when the batteries are fully charged, everything in the home is powered and there is still sunlight on the panels that isn't being harvested for use. A grid-tied system takes that extra energy from the sun that wasn't being used and converts it into cold, hard, cash. At $0.53/kWh @Ampster is paying that's way more important than efficiency.
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My power company only pays $0.04kWh (for 10 years, no increase with inflation) if you pay huge fees and built a system up to 120% of your previous year usage, no larger than 20,000kW.

Not worth it for me, even though my system has the ability to sell back.

I am building a larger one than what is allowed because I want to have power in the winter months.
 
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