They are pretty clearly targeting DIYers and enthusiasts who like tinkering with off-grid solar.

Grid-connected is an entirely different ball game. You will not see any open source projects there, or at least not any that anyone will want to use.

Let's think about why not. Anything grid-connected, you REALLY want a licensed electrician to plan and install. And competent electricians will NOT go anywhere near a piece of equipment that is not UL certified. A company producing equipment is NOT going to go through the expense of getting UL certified and then just release their design, PCB, and schematics for free.

And I want to be clear that I am a strong proponent of open source hardware, there are just certain situations where the incentives in reality just don't line up. This is one of them.

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hamdingers 7 hours ago | parent | next [-]

> Anything grid-connected, you REALLY want a licensed electrician to plan and install.

Have you heard of balcony solar?

It's a solar panel, a microinverter, and a standard wall plug. It doesn't need an electrician to install any more than anything else, you just plug it in. Outlets work both ways.

LibreSolar doesn't seem to be working on any inverters, but a complete open source system like this would be great.

https://en.wikipedia.org/wiki/Balcony_solar_power

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bityard 4 hours ago | parent [-]

If that wikipedia article is right, then balcony solar is not legal where I live (in the US). Here, we require a hard-wired, permanently installed automatic transfer switch that disconnects the solar generation from the grid when the mains power goes out. This is to protect line workers when working on downed lines.

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hamdingers 4 hours ago | parent | next [-]

It's probably coming soon for you, 30 states have bills announced or introduced legalizing plug-in solar and one (Utah) has already passed. They should be fairly uncontroversial.

Also, there's no need for a transfer switch in any grid-tied system, whether plug-in or hard-wired. Grid-tied inverters shut off automatically if there's no grid frequency to sync to.

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jacquesm 2 hours ago | parent [-]

That simply is a transfer switch that is built in.

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hamdingers an hour ago | parent [-]

What would it be transferring the load to?

"Transfer switch" refers to a specific kind of switch that transfers load between two sources. There is only one source (the panels) and one load (the grid) on a grid-tied inverter, so what you're saying does not make sense.

There are more complicated solar setups that do involve transfer switches, but they are not applicable to the balcony solar use case and remain uncommon even for hardwired rooftop solar.

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jacquesm an hour ago | parent [-]

In grid tied inverters with batteries the transfer switch can be built in to the inverter or it can be an external switch that the inverter talks to. Similar to how you would use one with a generator setup.

And indeed these are uncommon, mostly because they tend to be more serious devices. Victron and formerly Xantrex make nice ones, but the inverter alone probably costs more than a complete balcony solar installation.

For the solar balcony and more common rooftop solar setups there is only a simple disconnect, but both a transfer switch and a disconnect are the same thing: a (usually beefy) relay, but the transfer switch variety switches your house between the inverter and the grid whereas the disconnect just physically disconnects the inverters output. The downside of that setup is that if there is no grid but you do have solar that you still have no power.

Most of these wouldn't be able to power anything but the smallest installations anyway (300 W or so, typically), and don't have a battery to store any excess (as if there would be any...).

As soon as you add a battery it makes good sense to use the transfer switch: you can disconnect from the grid but the inverter can keep running to power your house and if you're lucky the solar will replenish it fast enough during the day that you can hold over for a while.

The big rooftop inverter that I have has a built in transfer switch but I'm not using it right now simply because I don't have a good way to route the wiring to and from the inverter. It is stuck in my garage with the main distribution panel on the other side of the house. In my old house in Canada that was all designed from scratch and there we had the house entirely off-grid with the transfer switch hooked to a genset if the power was out for longer than the battery could sustain us (48 KWh so that usually was good for a couple of days).

	▲	hamdingers 38 minutes ago \| parent [-]
		A disconnect and a transfer switch are not a same thing, "transfer switch" refers to a specific type of switch in a specific role as I have described. Conflating the two is incorrect and benefits nobody.

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jacquesm 2 hours ago | parent | prev [-]

99.9% of all inverters currently being sold has this functionality built in. That 0.1% remaining you will find in the second hand market and the bargain bin of Amazon.

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repparw 8 hours ago | parent | prev | next [-]

Could the inverse process work? Design, then (crowdsource?) pay for UL certs? Don't know the process for certification, but in the software side, I've heard from foss projects asking for money for, e.g, security audits

	▲	jacquesm 6 hours ago \| parent [-]
		Theoretically, yes. But in practice you need to bake certification requirements into the design or it will never pass.

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jacquesm 8 hours ago | parent | prev [-]

Bollocks. I've been making grid connected hardware for decades, there is nothing magical about any of that. You just need to be careful, use proper fusing and you need to know how to read the electrical code.

Competent electricians are licensed professionals who (1) stand to make money on selling gear and (2) have customers that hire them simply because they don't want the hassle or the liability. Obviously a licensed professional is not going to install your home brew inverter, but at the same time if you can design a homebrew inverter you probably don't need a licensed professional anyway.

I've rewired lots of homes and have never had an issue with any of this and designed my first inverter when I was 17 to power my room when my betters decided I should go to sleep and cut the power.

This stuff is not magic. If someone designs a modern open source inverter I'm definitely going to build and install it. Fortunately insurance companies here are reasonable: if your homebrew device wasn't the cause of the mishap then you are still insured.

The one thing they are very strict about is gas, because there is no such thing as a 'fuse for gas'. But if you've properly designed and fused your gear then it should be no less safe than any other grid connected device, even if the magic UL or TUV mark isn't there.

The big one is EMI, that can be hard to get right and you need some gear for this, which is why it pays off to pool the money for an open source design to be certified. And once certified of course the design is 'type approved' and frozen, so you can't change any of the hardware without going through recertification. This is expensive, but if you don't do it every other week should still be well within the means of a properly set up open source project.

Why the fearmongering? It's not as if we're 12 here.

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hn_acc1 6 hours ago | parent | next [-]

>Bollocks. I've been making grid connected hardware for decades, there is nothing magical about any of that. You just need to be careful, use proper fusing and you need to know how to read the electrical code.

I would say that rules out about 80-95% of DYI users.

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jacquesm 6 hours ago | parent [-]

This is 'hackernews', not 'consumersRus'. Though on odd days you might think differently.

	▲	relaxing 6 hours ago \| parent [-]
		And even days. And twice on Sundays.

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mcbishop 3 hours ago | parent | prev [-]

> Why the fearmongering?

The main concern is exporting to a downed grid that line-workers are trying to restore.

	▲	jacquesm 3 hours ago \| parent [-]
		If you can design and build your own inverter I would take it as read that you know how to read code and know how an actual inverter should function: If you're grid connected and see valid phase on the input for a certain amount of time of matching phase and measuring voltage you can provisionally connect at exactly that phase and voltage but without injecting power. After that you are allowed to slowly ramp up your output by leading the phase (while raising the voltage within certain limits) as long as you observe the effect that you have on the grid. If the grid phase drops away or there is any other anomaly (such as a voltage drop or rise of more than x V/s you are required to immediately disconnect, there are many other disconnect requirements but that's the main one with respect to line worker safety. Three disconnects within a short period of time = no reconnect attempts for a much longer time. If the situation persists that's a failure and you are no longer allowed to connect to the grid until there has been an intervention and an inverter reset. If your inverter is of the islanding variety then the rules are slightly different, then the transfer switch only gets energized when you match voltage and frequency but in the meantime the (usually battery backed up) inverter can supply local consumers. By the time you come up with the idea of rolling your own inverter you have either become familiar with the requirements (which differ from region to region, and which in a properly designed inverter are mostly a matter of tweaking firmware parameters) or you will have to do so because you realize your responsibilities. Anybody up for this kind of project will with a high degree of likelihood have the required knowledge because that knowledge is a lot simpler to acquire than the knowledge to build an inverter that isn't going to result in you being laughed out of the room when your EE buddies come look at your creation. I would expect you to do a better job than 95% of the imported ones that I've taken apart and which all had massive shortcuts taken, good enough to pass first inspection and a year into warranty, not good enough for long term safe deployment. This ranges from unsuitable connectors, low quality inductors, even lower quality relays, undersized FET boards, insufficient cooling, bad cast aluminum housings, in general bad housings (not rodent and/or insect proof) and so on.