Explain these comments on a Gary Does Solar video?

[Alan Ambrose]

In this recent video, there's a couple of comments that I'm not sure I quite get. Here's a link to the video:

 

 

Why Are The DNOs Limiting Your EXPORT And Even Your INVERTER SIZE?

 

https://youtu.be/Bvpl9pvg8zk?si=4rLhJ-me57Pcwabu

 

 

Here are the two comments (I've highlighted the relevant bits that were raising questions for me in bold):

 

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One detail - only grid tie need approval. If your system isn't capable of pushing power into the grid (that's not capable as opposed to "set to 0") then you sidestep it at the cost of no export revenue. Setting up a big non grid tie inverter and putting the house on that with the grid as an input (generator basically) lets you side step all the mess in the difficult cases. It's not usually the best option but if you are getting 3.6kW and especially if you are also refused G100 with a bigger inverter it's definitely worth doing the maths on houses where you want bigger batteries and inverters, and remember it also lets you avoid the MCS costs too. I am guessing plug in solar is going to make it even more of a circus especially if they got 250,000 G98s submitted the month it goes legal 😎 Our setup actually has some grid tie with grid tie batteries and solar, and some non grid tie with other batteries/solar that runs the heatpumps and some other bits. It was the only way to make this big old building work within the allowed G99.

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The inverter size limitation is to do with failure cases with export limitation. If they calculate that the export limit fails, and the resultant voltage would exceed legal upper limits at your house, and your inverter voltage shutdown protections also fails, then they impose a choice: 1. Stipulate Inverter size limits, 2. Provide a quote to the solar installer for reinforce the DNO’s network so that it can accept the higher inverter size (often many thousands of pounds). At my house, I have an 8kw inverter with a 5kw export limit. When exporting 5kw, the voltage is about 247V. So there is some headroom between the export limit and the upper legal voltage. There are two a get out clauses though: 1. Install a 3.6kW inverter, but with 7kW Maximum Power Point Trackers. That enables you to hookup 7kw of solar, and at maximum power: 3.4kw can be fed to a dc coupled battery, even though the AC output is limited to 3.6kW. Sunsynk offers such an inverter. 2. Don’t connect your inverter to the grid. DNO’s only have jurisdiction over connections to their network. They have no jurisdiction over off grid systems. You could have an 8kw+ inverter supplying your house off grid. Then you can choose whether your house is connected to the grid, or your inverter, using a changeover switch. There’s no opportunity for export, or charge up with cheap overnight electricity though.

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The reason I'm asking is that I'm planning on having a lot of panels and inverter power and self consuming as much as possible. I'm planning on over capacity so that I can make the shoulder seasons (i.e. spring & autumn) mostly self-consumption too. I don't really care about the export - I'm guessing the rates will continue to fall until it's a waste of time.

 

 

 

 

[JohnMo]

Lots of panels on a G98 inverter, massive overclock is the way to go. Easy no permission needed, just a G98 notification.

 

Self consumption is fine in theory, in practice difficult especially in the summer, you just end with loads of hot water you can't use. Just go with Octopus and pay £250 and get the export (wish I did it 3 years ago), East Suffolk you will generate tonnes of energy even with a 3.68kW export limits.

 

My advise, self install as many panels as you can to stay within the max voltage limits of your inverter, it's cheap, spend £250 to get with octopus. Export everything you don't normally consume.

[Dillsue]

10 hours ago, Alan Ambrose said:

 Setting up a big non grid tie inverter and putting the house on that with the grid as an input (generator basically) lets you side step all the mess in the difficult cases.

This is basically an off grid setup with the inverter taking one or more energy sources to power the house. Intended to use batteries and PV with a generator as a backup. In terms of the inverter generating anything, and being regulated by the DNO, it only generates power to supply the house as so far there's no grid connected. Now swap the generator input for a grid connection and as far as the grid is concerned the inverter is only a load but no generation capacity on the point where the grid is connected.

 

10 hours ago, Alan Ambrose said:

it  also lets you avoid the MCS costs too

MCS isnt required for any installation works. If the video is suggesting otherwise then take it with a pinch of salt

 

10 hours ago, Alan Ambrose said:

 DNO’s only have jurisdiction over connections to their network. They have no jurisdiction over off grid systems. You could have an 8kw+ inverter supplying your house off grid. Then you can choose whether your house is connected to the grid, or your inverter, using a changeover switch. 

As stated use a changeover switch to choose if your house is supplied from the grid OR from an off grid system that the DNO doesn't regulate.

 

What's your concern about what is said above??