Comment by toomuchtodo | Hacker News Reader

Comment by toomuchtodo | Hacker News Reader

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Perfect comment on the topic. With that said, newer inverters do have “grid fault ride through” capabilities where they will continue to operate during excursions from nominal operating windows, and some regulators are more hip to it than others.

https://www.iso-ne.com/static-assets/documents/committees/co...

https://www.solarpowerworldonline.com/2019/03/smart-inverter...

Grid forming inverters (versus the traditional grid following) are at the finish line of being proven, and paired with distributed storage providing ancillary services (including frequency response), regulators simply need to be dragged to the present to solve for this (distributed energy orchestration, rapid system segment isolation and recovery during transient events [“self healing” for the marketing folks], etc). This is one of those tug of wars between very conservative regulators and a quickly innovating industry (DER power controls).

https://www.energy.gov/eere/solar/articles/powering-grid-for...

https://www.nrel.gov/news/features/2020/renewables-rescue-st...

https://www.nrel.gov/docs/fy21osti/73476.pdf

https://www.eia.gov/todayinenergy/detail.php?id=50176

The Enphase IQ8 is now in general release, and is grid-forming.

During sun, a site can island with perfect 60Hz AC power from the ASIC-driven IQ8. No battery –– and certainly no grid –– needed.

I spec’d my 21kw system with IQ8+s for this reason. It’s future proofing distributed generation by being software defined (Enphase’s Ensemble system). Highly recommend them to anyone considering residential solar, and go for as big of a system as you can (and your utility will allow, if they limit based on usage history; tell them you’re buying an EV if necessary).

We ended up with 16kW and solar edge stack. 16kw was about all we could fit on the roof. Was a nightmare getting Xcel to approve it. Took them 2 months. We have 20 kWh of battery to buffer and back us up in the case of extended outages. It is a nice system. Anything over 10k in Colorado requires a lengthier approval process.

We also moved the house entirely to heatpumps. They practically sip energy for cooling.

Excellent choices!

It is kind of fun :)

Consider the peak power of the panel vs the maximum power of the microinverter... My very small p.v. if converted to microinverters from string inverters would be FAR LESS productive due to the maximum power limit of the microinverters, surely they allow "free" panels, mixed with any orientations, many different numbers, even different kind of panels, but they cut much the output to a point they are IMVHO interested only if you can't make chains due do shadows / physical location issues...

No, these days microinverters aren't the bottleneck. The IQ7 can handle up to a 460 W module, with 366 VA output. The IQ8 can handle up to a 540 W module, with 384 VA output. 97.6 efficiency.

Mh, from Enphase catalogue in my country (France) I do not see such data, the IQ8 are not on sale here and IQ7 variants arrive at maximum at 315 VA for the IQ7X-96-2-INT witch is the top performer on sale here. Anyway, it's still less than classic string inverters even if they give "resilience" and "installation freedom"...

Do you have any battery storage? How well do islanded microinverters handle startup surge on electric motors, or is it the case that you need a 20kw+ array to handle a refrigerator cycling on?

No battery storage. 1:1 net metering with my utility. 21kw array is about 30% over what we’d need for annual consumption, but (Q Cell) panels were the smallest component of total system cost and they help keep the attic 5 degrees F cooler. Also, I’m required to carry $1M in liability insurance for anything over 10kw. Even if I have credits forever I want to maximize production to offset utility natural gas generation during daylight hours. Not needed but installed a soft start on the 4 ton AC condensing unit for longevity and to reduce start surge. I will likely add battery storage in the future when it declines in cost for outages.

The system is not yet configured to support solar only utility disconnected operation due to supply chain issues (additional components, rush to PTO), so I cannot speak to surge start capability of the IQ8+ micros in island mode.

Every IQ micro and battery you add adds more ability to deal with current surge requirements. On my 8.5Kw system with 30KwHr of Enphase LFP batteries, I can handle turning on AC when I have full sun and partially charged batteries without going to the grid.

AC is a difficult load. Get the inrush current here: https://www4.enphase.com/en-us/support/faq/how-support-hvac-... and you will be able to figure it out.

Your refrigerator will be fine. Its locked-rotor amperage requirements are small compared to AC.

This made me think "What about SMA Solar, they are supposed to be a technology leader?"... and yes, they do have all the grid stabilization features (and an island feature in at least some models, not mentioned there):

https://www.sma.de/en/partners/knowledgebase/sma-inverters-a...

Interesting. Can it sense when the grid is present, and can it match phase?

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