How to add batteries & more PV

[pudding]

Ah sorry, thats not on there. It's attached to the Solis, now Sunsynk inverter. In the photo, below the inverter you have the AC isolator to the mains, the black DC isolator to the new PV array, and then the battery disconnector.

[openspaceman]

So like this picture?



Have you looked at how the sunsynk can apparently run islanded like Nowty talks about, off its battery? Keeping the rest of the array alive in the absence of the grid.

Useful in the event of load shedding which may occur though never experienced since 1972.

[pudding]

Yeah exactly like that, just with the DC isolator in between the inverter and panels.

No not looked into that at all. But when we were installing, we had the grid AC isolator off and the inverter was still up and running from its batteries, so seems like it certainly does it automatically, although we didn't test it or look into it further, as we were concentrating on the earth leak initially and getting it all up and running.

[Oldgreybeard]

The Sofar runs happily without a grid connection, and I suspect most of them are the same and are powered by the batteries. I've only recently wired the EPS up on ours, running a small, separate, consumer unit that runs the lights, the well pump, the sewage treatment pump and a bank of sockets. Not had to try it in anger yet, but it seems to work OK.

We tend to get a handful of power cuts every winter, the winter before last we were without power for about 18 hours one day, which was a bit of a nuisance. We keep a camping stove handy for when this happens, but the last long power cut meant we ran out of water and the with the sewage pump not working we couldn't flush the toilets. Knowing my luck, not I've got the backup system working we probably won't have a power cut for years . . .

[Joeboy]

The Sofar runs happily without a grid connection, and I suspect most of them are the same and are powered by the batteries. I've only recently wired the EPS up on ours, running a small, separate, consumer unit that runs the lights, the well pump, the sewage treatment pump and a bank of sockets. Not had to try it in anger yet, but it seems to work OK.

We tend to get a handful of power cuts every winter, the winter before last we were without power for about 18 hours one day, which was a bit of a nuisance. We keep a camping stove handy for when this happens, but the last long power cut meant we ran out of water and the with the sewage pump not working we couldn't flush the toilets. Knowing my luck, not I've got the backup system working we probably won't have a power cut for years . . .

OGB, I fitted a 200 ltr water tank over here in Turkey back in the day. Up at highest point in Upper floor eaves. It's a horizontal tank with a ballcock on the top inlet. So far, so normal. On the bottom port (header pressure fed from the tank itself) I have a 1 way valve inline T'd off of the same line feeding the ballcock. Pressure fails (grid water goes off) and the 1 way valve opens feeding the home with 200 ltr supply at about 0.5bar. The water meter incoming to the home acts as a non return valve so we don't dump the tank to the village. Worth a thought?

[Oldgreybeard]

Unfortunately our house is "room in roof" so there is no head available, plus any gravity roof tank presents issues with water treatment, so really needs disinfection. Our water supply comes from a deep well, via a pump that pressurises a 100 litre pressure vessel in the well house, and that feeds water at about 3 bar to the house. The well pump turns on and off automatically, depending on the pressure in the pressure vessel. There are filters, plus a UV disinfection unit in the well house, so the water fed up to the house is potable.

We have about 50 litres of water available from the pressure vessel with the pump off, as pressure vessels only hold about half their capacity as water. I could fit a larger pressure vessel and gain a bigger buffer, but we're still limited by the sewage pump, so with no power we can't flush the toilets or run much water down the drain.

Now we have back up power there shouldn't be a problem, as both pumps can run as normal. They don't use a lot of power, each is around 650W, but they only run for short periods of time.

[Joeboy]

Unfortunately our house is "room in roof" so there is no head available, plus any gravity roof tank presents issues with water treatment, so really needs disinfection. Our water supply comes from a deep well, via a pump that pressurises a 100 litre pressure vessel in the well house, and that feeds water at about 3 bar to the house. The well pump turns on and off automatically, depending on the pressure in the pressure vessel. There are filters, plus a UV disinfection unit in the well house, so the water fed up to the house is potable.

We have about 50 litres of water available from the pressure vessel with the pump off, as pressure vessels only hold about half their capacity as water. I could fit a larger pressure vessel and gain a bigger buffer, but we're still limited by the sewage pump, so with no power we can't flush the toilets or run much water down the drain.

Now we have back up power there shouldn't be a problem, as both pumps can run as normal. They don't use a lot of power, each is around 650W, but they only run for short periods of time.

Sounds

[Umski]

No problem, attached is the schematic I made for our install, only thing thats changed is that we used a Sunsynk rather than a Solis inverter, and that uses a CT clamp extended by CAT6 cable directly to the inverter, rather than the meter on the diagram.

Then I've attached a picture from today, showing how the CT clamp is measuring the total attempted export from both old and new PV arrays, and sending that signal to the Sunsynk inverter, which is then feeding in a total of 4.6kW into the batteries, rather than just the 2.8kW generated by the panels directly connected.

Thanks for sharing this, this is similar to what I had in mind to expand my existing FiT 4kWp - however it wasn't clear to me if a hybrid will still factor in the existing output of PV - reason was that Sofar ME3000 which has no DC PV input seems to utilise 2 CT clamps (maybe the PV one is just to measure rather than make use of). I would like to have an EPS function so that rules out the Solis AC (cheapest option). Second was having some future proofing in being able to add more PV in the future i.e. just using it with batteries for the timebeing. So that leaves the Solis hybrid or Sunsync hybrid, both similarly priced) - I think those will do what I want by limiting export and charging the batteries? Second thing (sorry to hijack thread) - if the grid goes down, it seems others are saying that the hybrid will keep working from the batteries? I thought that was the premise of the EPS loads? Otherwise my existing old PV inverter would think that there is a 'grid' and start generating again? Am I barking up the wrong tree?! Last question, what purpose does the Accrel meter serve - is that in place of the Solis/Sunsync measuring the import/export itself and hence using RS485?

Thanks!

[openspaceman]

Second thing (sorry to hijack thread) - if the grid goes down, it seems others are saying that the hybrid will keep working from the batteries? I thought that was the premise of the EPS loads? Otherwise my existing old PV inverter would think that there is a 'grid' and start generating again?

I too am interested in this as if the hybrid does stay running and provides a 50Hz signal to the existing inverter then how does it prevent the existing inverter back feeding the grid, with potential serious consequences for someone working on the high voltage side of the substation/pole transformer? I thought there would have to be an automatic changeover between the grid and the consumer unit.

Looking through the threads I think poor planning on my part means I will need a third inverter for my additional solar panels because my current battery is AC coupled.

[marshman]

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