Electronics > Power/Renewable Energy/EV's

What exactly are dubious grid tie inverters for?


I came across a load of these things while browsing ebay and amazon:

It's a grid-tie inverter. It looks dubious. There are a lot of them available, low-cost and with no mention  of G83 certification, and all having a nicely non-regulation-complient IEC connector for output so that any uncertified DIY enthusiast can plug it in - and with a convenient 'finger death hole' if the islanding protection isn't fast enough.

So what are they actually for? I'm not the most knowledgeable on wiring regulations, but I know that you can't just shove energy into the grid without notifying the operator, and somehow I don't imagine they'll be too happy about having something like that hooked up. Even if it does promise islanding protection. As much as I would like to stick that in my garage and see power bills drop slightly... no. A lot of them don't even have a manufacturer brand!

Are these things sustained entirely by shady bodge installers and hobbyists who are happy to disregard any rules? Or are the requirements a lot more lax than I thought, and it's actually somehow legal to plug that thing in to the grid?

David Hess:
In some cases, a "temporary" installation has more regulatory leeway than a fixed installation so these are popular with do-it-yourselfers and hobbyist who have only a small solar array and with people in jurisdictions where grid tie inverters are effectively unlawful.

It is not difficult to implement islanding but it would be nice if standards approval could be relied on.  By default, most grid tie inverters will disconnect on AC power loss just to protect themselves and cannot operate as a stand alone inverter.

--- Quote from: blueskull on October 10, 2017, 06:24:01 am ---In a lot of countries, selling to grid is cheaper than buying form grid, so illegally backfeeding saves more money than install a proper dual direction meter.
--- End quote ---

Or the utility company uses the law as a stick to prevent legitimate installations and further rent seeking.

So there really is no legal role for these? Not only are they not G83, but wiring regulations also prohibit connecting any generating device using removable cabling. There is simply no situation I can find in which it is legal to operate such a device. Hobbyists just get away with it because the grid operator isn't going to notice.

I was hoping there would be some sort of exception for micro-scale, maybe <1KW, but... nope. Not that I've been able to find.


--- Quote from: Codebird on October 10, 2017, 06:18:37 am ---Are these things sustained entirely by shady bodge installers and hobbyists who are happy to disregard any rules? Or are the requirements a lot more lax than I thought, and it's actually somehow legal to plug that thing in to the grid?

--- End quote ---
They are not legal in most countries, the mandatory UK rules are here:
People just buy them and hope they will slip through the net by not being a large problem (including several users on here) which is a risky investment when it could be cut off at any time. Given the constantly falling cost and second hand availability of compliant inverters its not worth the risk, the majority cost of many installs is the labor and paperwork.

At the risk of having opprobrium heaped upon me I would take issue with several of the points raised.
First of all the unit does have islanding protection (stated in the ad). Secondly if someone is idiotic enough to do as suggested they get what they deserve!

Fortunately we do not live in a country such as Australia where I believe it is illegal to install Ethernet cables in ones house!

These units whilst being fairly unreliable are no worse than many other items of semi-consumer equipment sold on Ebay and elsewhere such as SMPS units etc. Anything directly connected to mains requires a modicum of common sense to ensure safety and it is impossible to regulate and control the world to protect stupid people from the inevitable.  Such control also affects the freedom of choice for the majority and results in higher cost, taxation etc to pay for it so I personally am definitely against it.

As a matter of fact I am one of those that does run a self installed grid tie, I informed my DNO and they have no problem with it.

I recall there was another discussion regarding safety with over excited commentary regarding a DPST switch with one pole on each side of a transformer. It is a matter of fact that DPST switches meeting reinforced insulation requirements exist and providing the wiring also meets this requirement there is no safety problem.

Excessive excitement or over indulgence in safety and regulation serves no purpose IMOP.


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