can the house draw from solar and battery at the same time using a hybrid invertor

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sanjaymistry42

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Hi

Looking to install solar PV with storage. I am trying to understand the best type of invertor to get. As I work from home a lot and have usage throughout the day I want to ensure that I am making the most out of my generated electricity.

My driver is to be able to pull from the solar and battery if my draw is more than the solar is producing at any given time. Essentially I want to stay off-grid as much as I can

Can a Hybrid inverter do this, or would I need to go for a AC coupled system?
 
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I would think most will allow this. though inverters do have a max output and if you exceed this, then grid draw will occur no matter how much you have stored in the battery. Best thing to do is read the manual of the inverter that you are looking at fitting.
 

revor

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Yes you can certainly my system does and presume is pretty standard. From what I have my gleamed from my system how much you can draw from the battery will be dictated by the battery and inverter capacities. On my 6kW system I can draw up to 5 kW from the battery so if during the day run a heavy load e.g. shower then it will take all solar top up with battery and then from grid if not enough. We have a game in our house "beat the grid" so we aim to use power without taking from grid. This time of year we are most days running at 99% self sufficiency a v, dull day and it drops. We have an induction hob and have learnt not to switch on full straight away but ramp up as although there is enough solar and juice in the battery a sudden power up can cause a spike of usage from the grid. Ramping up avoids this. That is our system not all will be same I guess.
 

Chrisbee

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As a user, here is my experience.

I'm at home all the time and had 4.5kwp of panels, a Solis 3.6Kw hybrid inverter and 4.8Kwh of Pylontech lipo batteries installed in February.

Every morning the battery starts empty. (Actually 20% state of charge to look after the batteries).

All draw is from the grid untill the sun comes up.

The power from the panels grows until the middle of the day and then dies down over time until sunset. Any clouds moving across, cause big dips in output. So you can see there can be peaks and lulls randomly throughout the day.

The inverter is constantly prioritizing where our power comes from, by the second. If the panels are producing more than we're using then all our draw comes from the panels and any excess is charging the batteries.

If there's a dip in production then the batteries take over and supply us until the sun comes out again. That's assuming there is some charge in them.

Most days this mix of use carries on and the batteries are full by the time the sun goes down and we get a few more hours from the batteries. On the best days we're still running from batteries when we go to bed. But that's not often.

The inverter can only provide up to 3.6Kw. So if draw goes above that, the extra, and only the extra, comes from the grid.
 

Andy1733

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Chrisbee. Please excuse my ignorance
If you use the battery storage in the evening is the grid constantly recharging the batteries until you go to bed then once the battery's are topped up they are ready for the next day. Or do you use the grid in the evening and run the batteries down and charge then on low tarriff over night?
I am fitting very similar setup. Same inverter. 4k panels though ordering 2x 5000 (9.6kw) pylontech
 

Chrisbee

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Hi Andy1733

It's fully automatic. The batteries only receive a charge from the solar panels, they effectively "mop up" every scrap of excess production whenever panels are producing more than we're consuming.
Then they fill in the gaps when solar production is less than we're using.

On a bad day, today is a good example, they get little or no charge and are of no help.

On a good day which has been the majority of days since install, there is enough excess that while going up and down through the day, they end up full by sunset and seamlessly supply us until they're down to the set 20% where the system protects them by swinging back to using the grid.

In reality there are times when the house is using some solar and some battery at the same time, or some battery and some grid. The system is constantly doing it's best for us.

Right now the house is using 560W. The miserable drizzly weather means the panels are only making 220W. Somehow the batteries have got up to 24% charge so are supplying the 340W difference. So a brighter period earlier today is effectively supplying some power now, via the batteries.

I'll see if I have a screenshot of the inverter display and/or the monitoring app.
 

Chrisbee

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OK, sky just got brighter so solar generation has gone up, house is running from panels and batteries are charging.

Sorry it's not the best photo. But here panels are producing 1.55Kw, batteries are charging at 0.9Kw and we're consuming the rest. (Often the numbers don't quite tally with each other but are always very close).

Smart meter is also reading 0 from grid, which is the whole point.

IMG20220516101017.jpg
 

Andy1733

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Thanks Chris. Does that mean you don't charge your batteries via the grid? Only from solar?
 

Chrisbee

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Sorry, that was your question. No the batteries never take anything from the grid.

(Oh, just remembered, it sometimes takes a very brief charge from the grid. From observation it looks like if it spots that batteries have gone to 19% charge in the middle of the night it tops them up to 20%)

I think there are settings to use the inverter in backup mode, where it keeps the batteries above a set charge level to cover power cuts, charging from grid if necessary. But I'm not sure I understand how that would work.
 

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