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balanced ac-load

Solar along with the grid to supply AC loads


Is it possible that PV can run the AC loads or at least contribute to the grid supply. Today for example, plenty of sunshine and a full battery. the PV chargers only letting through 5w, while its taken average 200w to run the AC loads. An ideal scenario would possibly be. Solar tops off the batteries first thing in the morning, then between solar and battery storage the AC is run for the day, Only using the grid in the evening's to help with the short fall of power. Is this looking for to much from the system ? We are using two MPPT, 250/100, 150/35 along with two multis.Screenshot_20230118_140414_Chrome.jpg

tighernan asked
tighernan answered ·

2 Answers

Multiplus Compact Pump Motor Startup

I have a Multiplus Compact and need to know how it handles a pump motor that has 5 x the normal load during startup but just for a fraction of a second.

rogeremeadows asked
klim8skeptic answered ·

1 Answer

Dumpload – Hot Water – Legionella, Efficiency ?

I am still in the planning phase of an off-grid system (MP II + AC-coupled Fronius or Fimer + LiFePO4 battery), reading for months now all relevant infos.

Using a hot water boiler as a dump load in case of excess PV inverter power sounds attractive, otherwise that power would just be lost (because the MP II would throttle down the solar PV inverter when the batteries are full).

But it does raise a few issues :

a) Legionella

Most water boilers (at least in France) take a long time to heat up, depending on volume of the boiler and capacity of the heating element (anywhere from 1,5 up to more than 5 hours).

During summer this may not be an issue : provided the solar system is correctly dimensioned there will be plenty of excess PV inverter power over the day and the water heats up to the temperature configured on the water boiler (typically a mechanical thermostat in simple boilers), say 55+ C.

However during winter this is rather unlikely and water may be heated up to e.g. only 35 C. That´s a perfect temperature for legionnella bacteria colonies to grow (growth range : 25 – 45 C). You won´t be taking a shower at 35 C, so you will need some means to increase the temperature (e.g. gas heater). Unfortunately, while showering the water temperature gets increased to e.g. 55C in the gas heater for only a very short time, not long enough for legionella bacteria to die, which takes 5-6 hours @ 55C and still more than 30 minutes @ 60C).

You would have to heat up the water to 70 C for the legionella bacteria to die instantly. But that takes a lot of extra gas ….. and so you would loose the energy saved by means of the dump load, possibly even more.

Legionella is not wide spread in western Europe, but if not recognised and treated early on potentially very dangerous.

All this makes me wonder if a boiler dump load is a sensible solution. Any comments ?

b) Efficiency : AC Thor, SoC

Heating water electrically is not very efficient, but who cares about efficiency if that electricity would otherwise be lost ….

The My-PV ´AC Thor´ is a technically clever solution, but rather expensive (because you also pay for a lot more functions which you will never use in a ´dump load only´ scenario, a fancy LCD which you will never look at again once the system is correctly up and running, data logging, etc). IMHO technically it may be the best, but no pay back in a reasonable time frame.

Switching on the boiler via the relay built into the MultiPlus II based on SoC is a standard feature at no extra cost, except for boiler, piping, cabling and RCD. But it will eat some battery capacity and if for example you switch on at 99% SoC and off at 95% SoC it will likely take a very long time for the boiler to warm up (switching on-off-on-off- ….), with the potential risk of the (literally) tiny problem mentioned under a) …..

All this makes me wonder if it is not far better to save the money otherwise spent on a dump load solution and put it in the budget for larger battery capacity.

Any thoughts / comments ?

rvicev asked
rvicev commented ·

1 Answer

3-phase load shedding on AC-Out-2

Hi there,

I'm trying to configure load shedding using relay assistants for AC-Out-2 on a 3-phase Quattro-II system. AC-Out-2 shall be dropped on all three phases/Quattros as soon as a device goes into an overload alarm or when a pre-alarm exists for several seconds.

For this I configured the wizards shown in the screenshot. However, a test with Overload Pre-Alarm on one phase did not drop AC-Out-2 of all or even the affected phase.

What am I doing wrong?

Many thanks in advance!


phtr asked
phtr commented ·

1 Answer

Load sharing - Mulitplus or Easy solar

Hi There, based in the UK. I'm thinking to use the Multiplus-II or Easy solar-II unit to charge a 15khw battery during the off-peak hours and reuse the battery to supply the house during the day, using the ESS, Parralelle grid function. Assuming I fit a 5kva variant. If the house load is over and above the output of the MP unit, will it share the load with the Grid. ie. Let's assume the house load is 10kw, can the MP supply 4kw and the grid 6kw or would the MP shut down and allow the grid to supply all 10kw of load.

elliot330 asked
ejrossouw commented ·

2 Answers

Autotransformer balancing

Does the autotransformer balance the output and the input 120 lines, or just the output, or just the input? I'm confused!

brianv asked
Mike Dorsett answered ·

1 Answer

Nulleinspeisung mit Phasenkompensation mit Gavazzi EM24 an MultiplusII 48/5000/70 single phase mit Pylontech Akku

Hallo Community, ich habe eine Frage bezüglich meiner Anlagenplanung.

Ich möchte gerne meine zukünftige PV Anlage (4,8 KWp) über den WR Multi+II 48/5000/70 + MPP150/100 und Cerbo GX mit 4 Pylontech 2000er Akkus einphasig (L1) ans bayrische Stromnetz mit dem EM24 durch Ausnutzung der Phasenkompensation anschließen. 63A Hausanschluss.

Es soll keine Einspeisung erfolgen. ("Nulleinspeisung")

Vorrangig sollen die Akkus nur über PV geladen werden und bis ca. 50% Entladung Phasenkomensation machen.

Soweit ich gesehen habe benötige ich dazu eine moderne Messeinrichtung mit Zweiwegezähler und Stammdateneintragung.

Ich habe Fragen bezüglich eines Netzausfalls.

- Was passiert im Fall der Notstromversorgung bei Netzausfall auf den kompensierten Phasen ? Wird dann nur noch L1 notstrombedient ? Wie hoch wäre dann die max. Belastung auf L1 ?

Oder wird nur die AC-Notstromdose (critical) des WR z.b. für Hausbeleuchtung oder Pumpensteuerung für eine Heizung bedient ?

- bei normalen Betrieb mit Kompensation liegt die Spannungsdifferenz zwischen den Phasen bei 400V. Wie reagiert der WR bei Netzausfall und was wird passieren wenn das Netz zurückkommt bezüglich der Hausfrequenz.

Ich freue mich auf ein feedback

prosolar24 asked
prosolar24 commented ·

2 Answers

Autotransformer Unbalanced when on shore power

I have been racking my brain over this one. I have this exact setup:

2x Quattros set up in split phase and the Autotransformer after the inverters to balance the 120v loads. When inverting, I am seeing nearly perfect balance between L1 and L2. On shore power it is all over the place. Is there a chance the neutral return is taking a different route via one of the ground wires and somehow bypassing the Autotransformer? Would that cause this? Any ideas where to look? I have used my clamp meter and do show some current flowing over the various ground wires in the RV. If I temporarily remove a ground it does not seem to help though. I am at a loss. I am connected to a shore power that only has a 30 amp limit across each phase and one Inverter always seems to start assisting before the other phase. It would be nice to use the Autotransformer as intended and get the most out of the shore connection we have.


jetwire asked

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