What's the best Home Energy Storage option for retaining domestic stored solar power in preparation for power cuts?

Quick question please @Transparent.

Yaming Electric have replied with the following message:

Please could you explain why 12 pairs of terminals (24) are required for 6 cables?

Thanks

@dnshorto 

I don’t think that switch diagram is correct @dnshorto 

The part we were looking at is a 3-position switch, but their diagram shows only 2-pos.

Here’s the diagram from their website for the switch we’re interested in and then adapting:

So this shows 6 stacked wafers. I’m a bit surprised they did it that way because a cam (moving contact) is surely able to connect either to one fixed contact or a different one as it turns. You don’t need two wafers to achieve the same result.

So the way I’d expect them to do it would look this this:

Even if they don’t have wafers which do this, they should at least understand that the diagram shows a change-over switch.

My diagram shows 6 wafers, each with three numbered terminals.

Terminal 2 connects to terminal-1 when the switch is in position-A;

and to terminal-3 when the switch is in position-B.

It’s a different switch. 2 position isolator. 

Now it’s my turn to be confused.

I thought you were looking for a switch which could connect a ‘source’ to one of two possible options.

There are two locations where one might be required to switch a ‘source’ either to the Growatt grid-connected inverter, or else to the proposed off-grid inverter:

• PV Panels
• Storage batteries

In any event, the device I’ve described in the table above has a centre-off position and will therefore act as an isolator as well.

Crossed wires @Transparent . If you check back, the switch I am at present trying to source is the 6 Pole isolator which you recommended where the 6 solar panel 4mm cables arrive. The changeover switch, which I will also need to source,  is to connect the battery either to the Growatt, or to the off-gris inverter, which doesn’t need to be 6 pole. If I understand the message from Yaming Electric correctly, as soon as they read that I am looking for an isolator, they realised that a 2 position switch was preferable. As you remarked in an earlier post, their customer service is amazing!

@dnshorto 

So it’s a big thumbs up for Yaming Electric and the excellent customer service of Chinese business

and a wake-up call    for me, because I got wires crossed, which is always a bad sign when we’re discussing electrical safety

Let’s have an initial look at the Solis SOL-5K-RHI-48ES-DC inverter which you’re considering @dnshorto. I have a few points which will need investigation.

The Solis inverter you are considering only has the briefest overview of its features on the Segen website. You must go to the website of the Chinese manufacturer to obtain the detailed specification and installation manual.

Even so, the feature overview raises a couple of issues:

You might think that the battery compatibility isn’t a problem for you because your four existing batteries are Pylontech. However, it might constrain your choices if you decide in future to operate both on-grid and off-grid storage simultaneously.

You would also want to enquire if a purchase of an existing unit would allow future upgrade to a wider range of batteries. After all, it may be that the design does support further batteries, but that the way in which this is achieved has not met the standards required for regulatory approval in the UK. The question needs to be asked.

Secondly, you might think that the matter of having more than one Solis inverter isn’t a problem either. After all, you intend only one of these to be grid-connected, and the new one to be used as a hybrid.

But the crunch issue is the emphasis on the word hybrid in the warning which Segen have published.

Might it still be a problem to have two Solis inverters connected to the grid, even if only one of the two is designated as a hybrid?

Furthermore, this Solis inverter model does not operate within the normally-accepted definition of a hybrid unit. It is actually capable of exporting back to the grid in addition to export in-house using its “AC backup” connector.

Under the rules agreed with the Electricity Networks Association (ENA), you would therefore have two grid-connected Solis inverters, both with grid-export capability. This applies even if you have the mechanism (and intention) to only operate one at a time.

Your G99 site approval will need to be updated to reflect this.

You might also find that the Solis hybrid inverters are not on the list of approved devices for grid-connection for this very reason.

So you have some further investigation to do even before we turn to look at the manual and installation instructions in greater detail.

Thanks @Transparent . The 6 pole isolator is on order, £23 with tax. Delivery early January:

The plan is to install it in its own enclosure just where the 6 leads emerge along with lightning protection, then take the leads on to a separate string combiner enclosure. This is because of space restrictions in my particular layout. However, I still don’t know why it seems to have twice as many terminals as it needs!

So I would welcome your input on putting the surge compression modules, plus fuses?, on order from FEEO . There is such a bewildering array of choices.

On the inverter questions, Pylontech 48v battery is exactly what it would be linked to, and it would be the only HYBRID Solis inverter on the site, so there didn’t seem to be a problem. I downloaded the data sheet for the range (3kW to 6 kW) from the Chinese manufacturers, Ginlong Solis, but could do with some help in checking its suitability. The model number I first quoted (SOL-5K-RHI-48ES-DC) was specifically off-grid, but there didn’t seem to be an exact match from the data sheets list and the models below are clearly grid-connectable. 

Datasheet

Model Name RHI-3K-48ES-5G RHI-3.6K-48ES-5G RHI-4.6K-48ES-5G RHI-5K-48ES-5G RHI-6K-48ES-5G

Input DC (PV side)

Recommended max. PV power 7 kW 7 kW 8 kW 8 kW 8 kW

Max. input voltage 600 V

Rated voltage 330 V

Start-up voltage 120 V

MPPT voltage range 90-520 V

Max. input current 11 A / 11 A

Max. short circuit current 17.2 A / 17.2 A

MPPT number/Max. input strings number 2/2

Battery type Li-ion / Lead-acid

Battery voltage range 42 - 58 V

Battery capacity 50 - 2000 Ah

Max. charge / discharge power 3 kW 5 kW

Max. charge / discharge current 62.5 A 100 A

Communication CAN

Output AC (Back-up)

Rated output power 3 kW 5 kW

Max. apparent output power 4 kVA 6 kVA

Back-up switch time <20 ms

Rated output voltage 1/N/PE, 220 V / 230 V

Rated frequency 50 Hz / 60 Hz

Rated output current 13.6 A / 13 A 22.7 A / 22 A

THDv (linear load) <2%

Input AC (Grid side)

Input voltage range 184-264 V

Max. input current 26.1 A

Frequency range 45-55 Hz / 55-65 Hz

Output AC (Grid side)

Rated output power 3 kW 3.6 kW 4.6 kW 5 kW 6 kW

Max. apparent output power 3.3 kVA 4 kVA 4.6 kVA 5.5 kVA 6 kVA

Operation phase 1/N/PE

Rated grid voltage 220 V / 230 V

Rated grid frequency 50 Hz / 60 Hz

Rated grid output current 13.6 A / 13 A 16.3 A / 15.7 A 20.9 A / 20 A 22.7 A / 21.7 A 27.2 A / 26.1 A

Max. output current 15.7 A 17.3 A 23 A 23.9 A 26.1 A

Power Factor >0.99 (0.8 leading - 0.8 lagging)

THDi <2%

Efficiency

Max. efficiency >97.5%

EU efficiency >96.8%

Protection

DC reverse-polarity protection Yes

Short circuit protection Yes

Output over current protection Yes

Surge protection DC Type II / AC Type II

Ground fault monitoring Yes

Integrated AFCI (DC arc-fault circuit protection) Yes (1)

Protection class/Over voltage category I/II

General Data

Dimensions (W*H*D) 340*510*250 mm

Weight 18.3 kg

Topology High frequency isolation (for battery)

Operating ambient temperature range -25 ~ +60°C

Ingress protection IP65

Cooling concept Natural convection

Max. operation altitude 2000 m

Grid connection standard G98 or G99, VDE-AR-N 4105 / VDE V 0124, EN 50549-1, VDE 0126 / UTE C 15 / VFR:2019, RD 1699 / RD 244 / UNE 206006 /

UNE 206007-1, CEI 0-21, C10/11, NRS 097-2-1, TOR, EIFS 2018.2, IEC 62116, IEC 61727, IEC 60068, IEC 61683, EN 50530, MEA, PEA

Safety/EMC standard IEC/EN 62109-1/-2, EN 61000-6-2/-3

Features

DC connection MC4 connector

AC connection Quick connection plug

Display 7.0"LCD color screen display

Communication RS485, Optional: Wi-Fi, GPRS

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I have emailed the UK importers in Bootle to see if they can help.

@dnshorto 

Why is this so complicated ? I thought I wanted battery storage etc too, until reading this.

I agree @juliamc . Battery storage is straightforward and I would highly recommend it for stored solar power when the sun isn’t shining. The complications arise when trying to prepare for future power cuts, when our grid-connected solar systems are designed to shut down, leaving us in the dark and cold. It is building an OFF-Grid facility for back-up which introduces the complications. Without the wisdom accessible on this Forum I doubt if most of us would contemplate even considering the challenge!

@dnshorto