Solar inverter vs micro inverter questions

A few weeks ago, on a different board, a poster explained the difference between ENPH micro inverters vs “traditional” inverters.
He was extolling why ENPH was a great investment.

Basically, inverters are the point at which DC electricity is inverted to AC. The AC is then input to a system that uses AC - most home appliances or “the Grid”.

Micro inverters change DC to AC at each panel, or perhaps a subset of panels. (Yes, there are pros for this arrangement - more granular control data for the solar panel array.)

Traditional inverters capture the DC from an whole array of panels.

My question: why did Musk/Tesla decide AGAINST micro inverters? At the time, it was suggested (IIRC) that Enphase owned “all” the valid patents, and Tesla/Musk didn’t want to pay for patent use.
But, is that the reason?

Electricity is stored in batteries as DC.
Micro inverters produce AC, which must be converted BACK to DC for battery storage (in Tesla’s Power Wall, or Megapack batteries).

Traditional inverters are in line AFTER the battery, inverting the DC current from the battery to AC for use in the home, or supply to “the Grid”.

Denny writes:
I’m also feeling very bullish on renewables, specially solar. For me the most attractive part is that unlike most energy sources, solar is becoming widely distributed which negates the power of governments and industries to operate monopolies. In energy like in everything else, distributed is a lot safer than central planning. Just see how the Fed can screw up the works – capitalistic central planning no better than Soviet 5 year plans. With the advances in battery technology the intermittency problem of renewables is being overcome. I had solar panels on my boat 25 years ago but that was too early in the adoption cycle. A quarter century later I’m convinced that solar has “Crossed the Chasm” which is an important milestone for investors as it reduces the risk considerably.…

Tesla Energy storage and arbitration requires BATTERY storage. Ie DC electricity. This is true for Tesla Power walls, and for all the other “home battery backup companies” and the other “grid scale battery storage/back up companies”.
Inverting at each solar panel to AC, requires another “inversion” back to DC for battery storage.
Tesla Energy Megapacks and arbitration is potentially a BIG revenue future source.

Right now, many states (apparently) REQUIRE solar panels to dump the captured energy to the grid.
A home owner CANNOT directly use the energy her system captured.
In the event of a blackout, rolling brown out, disaster power outage, etc, the solar panel OWNER is also without power.

This design requirement is supposedly due to “powerline worker safety”.
But, a switch IS available, that will automatically cut power supply from the panel array and battery back up, to the grid and thereby protect the workers, while maintaining power to the home owner.

IMO, the real reason is to prevent viable distributed energy, and “protect centralized energy providers” income streams.

Back to micro vs traditional inverters.
Micro inverters directly SUPPORT the “dump electricity to the Grid (Central energy providers)” plan.

Traditional inverters, in a system with battery-power wall storage, avoid the DC to AC to DC for battery storage, and supplies DC directly from the solar array to the battery. Traditional inverters therefore, directly support Distributed (home) battery systems.

The 2nd Law of Thermodynamics says that changing energy from one form to another causes loss of (usable) energy as entropy.
Does conversion between DC to AC cause a loss of usable energy?
And DC to AC to DC is a less efficient system?

Is a traditional inverter system more efficient for home battery storage than a micro inverter system?
And for the grid level battery storage systems?

For investment purposes, as solar panels on homes with battery-power-wall installations increase, will micro inverter use decrease?

I know 2 local, Texas small towns, that have 5 ha solar farms. I don’t see any mega battery storage units, with them.
For installations that merely supply electricty to the grid during active (daylight) solar energy collection, micro inverters might be more efficient?
But for installations that store electricity in batteries, traditional inverters are more efficient?



The 2nd Law of Thermodynamics says that changing energy from one form to another causes loss of (usable) energy as entropy.
Does conversion between DC to AC cause a loss of usable energy?
And DC to AC to DC is a less efficient system? – ralph

Twiddling with anything involves losses. Energy transmission has losses as well.

I don’t have the other answers you’re seeking.

Former RB and BL Home Fool, Supernova Portfolio Contributor & Maintenance Fool
He is no fool who gives what he cannot keep to gain what he cannot lose.


Every conversion from Dc to AC you will have a loss. For people that a battery back up system at home than the micro inverters would be a problem. Also, while having one inverter is nice, especially if it is not on the roof. It also gives you one point of failure. Of course you could have more batteries and more inverters to spread out the point of failure but that comes at an additional cost. What I plan on doing is have the micro inverters and put all my electricity directly into the grid. Than have a Ford Lightning and use it as my battery back up if the grid goes down. Supposedly you can run a house for 3 days on a Ford Lightning and up to 10 days. Of course that all depends on what you are powering and if your Ford Lightning at the time is fully charged.….


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To go from DC to AC you use an inverter, from AC to DC you use a rectifier.

To go from solar panel or battery to grid you need an inverter or micro inverters.

To charge batteries from the grid you need a rectifier.

To charge batteries from solar panels you need neither but a device to prevent overcharging.

They are all black boxes to me, I just know what they do, not how they do it.

Denny Schlesinger


My installer told me Tesla was making their own inverter but I couldn’t wait. He said once they do it will be easier and better.

My powerwall system works well. House is solar powered. Heat pumps (4) cool the house. Add heat in winter but I love my two wood stoves. Car is solar powered. I charge in the afternoon. 12 panels and one power wall.

Model Y is a dream. House system and car was 90 grand.


PS. We as a country need to make the cost of going electric more affordable. Tax breaks? Carbon tax? I don’t know. Taxpayers will be spending trillions on climate change. So pick your poison. Now I’m waiting for the California smoke to come over the canyon country.


This is nothing new. The transition to electric lighting (from gas lights or kerosene lamps) took decades. A major investment was required in each household.


So does that mean no help from the politicians needed? OK, then we leave it to capitalism. So far Elon is the only one who has delivered. I haven’t sold any shares since I bought in 2016. I’m rooting for the others but have very little confidence.

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I’m rooting for the others but have very little confidence.

For EVs to succeed there needs to be more than one provider. The thing is that while most automakers focus on the cars Tesla is focusing on the machines that make the cars like Henry Ford focused on the assembly line to make cars cheaper. It’s going to be a tough race for both incumbents and startups so I have to agree with the lack of confidence sentiment.

I started buying Rivian (RIVN) for covered calls now that the craziness has been squeezed out of the stock’s price.…

Amazon is backing Rivian and buying their delivery vans. It might be an easier market than passenger cars and pickup trucks. Rivian’s hurdle is cash flow.

Denny Schlesinger

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So does that mean no help from the politicians needed?

“Needed” is a strong word. Congress has many methods to accelerate a new technology they find attractive. That can be done with tax incentives, grants, low interest loans, etc, etc.

Economics is the fundamental driver. If a technology makes sense economically it will be adopted and grow.

Of course Congress can also make competitive technologies expensive or illegal.

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Coal, oil, and natural gas received $5.9 trillion in subsidies in 2020 — or roughly $11 million every minute — according to a new analysis from the International Monetary Fund.

Explicit subsidies accounted for only 8 percent of the total. The remaining 92 percent were implicit subsidies, which took the form of tax breaks or, to a much larger degree, health and environmental damages that were not priced into the cost of fossil fuels, according to the analysis…

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Does that list of subsidies include the oil depletion allowance?

Does that imply those who mine minerals should not be compensated for depletion?

Would you extend that idea to depreciation allowances on capital improvements?

Does that imply those who mine minerals should not be compensated for depletion?

Do you get compensated for your depletion as you age? Depletion compensation is political pork! All they should get is depreciation and amortization for money invested.

Denny Schlesinger

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State-funded financial incentives to buy electric cars in Germany will be reduced next year after an agreement within the governing coalition, people familiar with the discussions told Reuters.

The incentives, or premiums, paid to buyers of electric cars will expire completely once an allocated sum of 2.5 billion euros ($2.53 billion) is spent, according to the government sources.

Under the plan, first reported in the Handelsblatt newspaper, premiums for purely electric-powered vehicles priced below 40,000 euros ($40,488) will fall from 6,000 euros currently to 4,500 euros at the beginning of next year, and to 3,000 euros over the course of 2023.…