NEDAP inverter with battery backup

[infinity]

Installed our first nedap system today, it has 4x12V 220Ah batteries for self use and emergency back up, its actually a very well made system, it can use the generated power to charge the batteries then discharge them at night supplying the home with power through the night!

Seems to work very well, so just thought id let anyone know who may be interested in this type of product!

 

[Worcester]

I thought with the Needap you had to replace the Solar PV inverter as well?

 

[wersolaruk]

Could you pm me some info on this infinity? Something I have looked into. Thanks

 

[Gavin A]

Installed our first nedap system today, it has 4x12V 220Ah batteries for self use and emergency back up, its actually a very well made system, it can use the generated power to charge the batteries then discharge them at night supplying the home with power through the night!

Seems to work very well, so just thought id let anyone know who may be interested in this type of product!

how does it know when to use generated power to charge the batteries, and when to discharge them?

and is it actually G83, so grid connected at all times, or does it switch the house / certain circuits off the mains and on to battery only?

If the latter, what's the script with the earthing sitution?

sorry for the 20 questions, but I've been through the install manual etc for those, and these were the sticking points for me, so I'm interested in what your experience was with them?

 

[infinity]

You install a nedap inverter which is designed for use with the battery system.

It will usually use all the battery allowance at some point in the night, it cycles 50% of the battery power.
Then tge following day it will trickle charge the batteries again only using generated power and any excess going to the house/ grid, once charged it will go into self use, you can define how much it allows to draw, we decided 2kw was ample as opposed to 3kw and draining the batteries quicker.
It is constantly connected to the grid and the batteries simply act as solar panels producing power for use, it monitors the house usage via a clamp at the incoming mains.

Once there is a power cut the relay (installed separately) switches the supply to a local out put on the inverter supplying up to 25A, this is then off grid but the earthing remains the same.
It has an extensive online portal and can be monitored remotely by us and Nedap in case of any faults/ errors etc.
I think for the price it's a great option for future proofing energy rises! And the battery usage also counts as generation through the meter!

 

[Gavin A]

And the battery usage also counts as generation through the meter!

Do you mean that the power from the batteries is fed through the generation meter?

Surely that would only be allowed if the power to charge the batteries were drawn direct from the panels, or from the inverter output before the meter... but if this were the case then it'd result in the battery charging, and potentially 2nd round of inverter losses before it was fed through the generation meter.

If the batteries are being charged from power drawn from after the generation meter, then fed back through the generation meter, I'm pretty sure that'd not be allowed (unless something's changed that I'm not aware of)

Thanks for the info / feedback, I've been trying to get my head around how it works for a while.

 

[SibertSolar]

Interesting thread, thanks. How does the Nedap handle situations where it might be necessary to change the earthing/Neutral arrangement when switching from grid-connect to off-grid mode? Are there consequences from a G83 point of view?

I'm struggling with the "battery usage being measured as generation" thing too, to be honest.

 

[wersolaruk]

Will it effect there annual sap calculation?

 

[Worcester]

Do you mean that the power from the batteries is fed through the generation meter?

Surely that would only be allowed if the power to charge the batteries were drawn direct from the panels, or from the inverter output before the meter... but if this were the case then it'd result in the battery charging, and potentially 2nd round of inverter losses before it was fed through the generation meter.

I'm waiting for infinity's response, though from my discussions with Nedap that was exactly how it worked.

So now you are adding a second generator to the system (albeit theoritically controlled so it is not generating at the same time) , however it surely MUST be G83 compliant / and or the separate relay must be? And also surely you MUST notify the DNO.

So this should need notification to the DNO (connecting a generator, primary power source - batteries) and so therefore needs a G83 stage 2 application for multiple generators at the same location.

We are also seeing refusals for G83 at > 3.68Kw/16A (which this could theoretically do) and the DNO is requiring the whole site to be re-configured to G59.

Nice and simple

 

[SibertSolar]

Frankly Gordon, if you are still managing to get any >16A/phase systems through without the DNO insisting on G59 settings then I'm amazed! ;-)

 

[infinity]

Yes the power from the batteries is fed through the generation meter, you are generating it after all.
After speaking with Nedap the assure us that it is G83 compliant along with the earthing arrangements which I have asked for further information on.
When in backup mode it has a seperate local output for power AC so it does not carry on as normal feeding power through the supply AC cable. The local output controls a relay in the inverter which you use to supply your own relay which switches the supplies from main grid to your local out put. So the inverter supply needs to be before the change over relay so the inverter does not see a voltage again once the backup switches in and incorrectly assume the grid is back on switching the relay back again.

 

[Gavin A]

I've just spent a couple of hours reading through every manual they have, and tbh I'm starting to be quite impressed - other than with the quality of the wiring diagrams and manuals themselves, which ain't brilliant.

I suspect that some of the dodgier results I've seen threads for relate to the systems being set up incorrectly, as it looks pretty complicated to set the system up to get the best out of it, and there are settings that could well result in the battery being charged during periods of no generation / from imported power.

As far as I can see, the batteries are charged from power drawn from the inverter, so on the generation side of the generation meter, meaning that it'd be right for the power from the batteries to then be fed through the generation meter. This will definitely lead to a loss in FIT eligible generation due to the losses in charging the batteries, but this could well be judged to be an acceptable situation if the increased self consumption resulted in a greater saving than the minor loss in FIT income.

It looks as if the power is fed via the standard grid connected inverter in self consumption mode while grid connected, and only run in stand alone mode when the grid is down if an extra relay is fitted to shunt the entire house to the back up power supply - ie isolating the house from the grid until grid power is restored.

There look to be other good control options such as controlling relays / battery charging based on import / export levels monitored via CT clamp rather than just by monitoring generation levels, which is one aspect that had concerned me.... I see the potential for using it to install bigger systems and then limiting the actual export to 3.68kW via battery charging, relay circuit, and then via the actual inverter MPPT tracking, which could be a bit of a holy grail type function for certain situations.

I think I'm starting to like this, though it's going to be a bit of a niche market, I've got a customer in mind that this could be brilliant for, and can think of a few other situations where I'd have liked to have been able to offer this option.

 

[Worcester]

GavinA, did you find out what happens to the earth as it switches grid connect / off grid?

Also we haven't had any export limitations put on yet, just flatly refused connection!

 

[Gavin A]

from the wiring diagram it appears to leave the suppliers earth connected, but also to supply an extra earth path through the inverter presumably to tie in with the negative side of the battery.

I suppose the logic might run that as there is no other connection to the grid, then the earth path to the grid is also redundant at that point until the grid connection is restored and the contactor cuts the grid power back in and the battery power out.