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Hybrid Inverters & Grid Passthrough

Mark1988

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Joined
Sep 6, 2021
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Hi All,

I'm based in the UK and would like to buy a Growatt hybrid inverter to run a 2-4kW solar array together with a 5-10kWh battery bank in the 'grid support' mode, i.e. solar / battery first then the grid. I'm specifically looking at the SPF 5000ES model (5kW).

Right now my grid connection is 100A x 230V = 23kW so the question is, what happens if I need more than the 5kW provided by the inverter? Can the inverter be wired in to take the extra power needed directly from the grid while still using solar / battery first?

Thank you,
M
 
Right now my grid connection is 100A x 230V = 23kW so the question is, what happens if I need more than the 5kW provided by the inverter?
That Growatt model is an off-grid inverter. Any circuits supplied by the inverter's output are limited to the output capacity rating of the inverter, including in utility line mode when AC input is passed through to AC output.

If you attempt to draw more load than the inverter is capable of supplying the inverter's overload protection will kick in and shut the inverter down.

To be able to supplement the inverter's output with grid supply requires a grid-tied inverter, which operates in parallel with the grid and not in series with the grid like the off-grid inverter does.

Or alternatively separate your home's circuits such that the off-grid inverter is unlikely to be overloaded while other circuits are left connected to the grid only and are never supplied by the off-grid inverter.
 
Hi, thanks for clarifying that up for me. I suppose the 3rd option is to buy another unit or two and put them in parallel to get to a more reasonable 10-15kW... however, since each unit consumes around 60W this makes this approach rather unfeasible.

A few other questions if I may:

1) Are there any good grid-tied hybrid inverters in a similar price range that you would recommend?
2) How do I know if a hybrid inverter is of the off-grid or grid-tied type?
3) Do grid-tied inverters pass through any extra grid power that might be required OR do I need a separate device for that?
4) I don't intend to export any power back to the grid but would I need to inform my energy company that I'm installing a grid-tied inverter?

Thank you for your help,
M
 
1) Are there any good grid-tied hybrid inverters in a similar price range that you would recommend?
I'm not familiar with the options available in the UK. I'm in Australia. Others may be able to chime in. But I'm sure there will be plenty of choice from major brands in the industry. Fronius, SMA, Delta, ABB, Goodwe, SolarEdge, Sungrow, and so on. Then there are those more targeted at DIY like Victron.

2) How do I know if a hybrid inverter is of the off-grid or grid-tied type?
It will be stated in the specifications.

3) Do grid-tied inverters pass through any extra grid power that might be required OR do I need a separate device for that?
Grid tied inverters don't "pass through" power from the grid. They operate in parallel with the grid.

4) I don't intend to export any power back to the grid but would I need to inform my energy company that I'm installing a grid-tied inverter?
The regulations concerning installation of small scale generation systems vary the world over and they vary across regions within each country so I can't comment on the requirements in your specific case/location. You need advice from someone with relevant knowledge in your area.

Usually the local electricity distribution authority/company will have a section on their website about solar PV / small scale generation connection approvals.

A rule of thumb / litmus test to have an inkling as to whether you'll probably require approval is whether the system can energise any circuit still connected to the grid. Just because it is export limited to zero does not necessarily meet that standard (e.g. if the export limiting is done via current clamp measurement). Typically (but not always) systems not requiring approval are those in which the circuits being supplied are completely isolated from the grid.


Your comments and questions make me think you are putting the cart before the horse.

I suggest stating what it is you want to achieve by adding a solar PV / battery system. Is is to save money, is it for backup power with the grid goes down, is it to go off-grid, just want to have a new hobby? No reason is right/wrong, but it affects the path taken.

Once that's clear then the process to identify suitable technical solution/options to pursue becomes clearer.
 
Thanks for this, that's very helpful. Yes, I guess you could say that. I suppose I'm still trying to get my head around various options etc.
 
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