Home solar plus battery question

Accomodation, House and Garden
1
Hi, my partner and I have been interested in home solar power (photovoltaic) for a long time and this year we had a system installed on our house. The system includes a battery that, when full, can take care of our power requirements through the night. In the last month we've averaged more than 90% self-sufficiency.

However, we've noted that sometimes the power coming down from the solar panels is being split between going to the battery, the house and the grid. Given how little remuneration we get for sending power to the grid it's a bit annoying our system does not prioritize filling the battery BEFORE exporting power to the grid.

I understand that the ... not sure how to express this ... flow rate (?) of power to the battery is limited to 5 kW, and we have definitely seen it hit that on sunny mornings and on those occasions the excess power heads on out to the grid - which is fine. What bothers me a bit is when the battery is only receiving about 2-3 kW and the rest is heading out the door (so to speak).

Today it was really cloudy and the battery only managed to get two thirds full. At the same time the system exported about 5 kWh to the grid ... and I'm thinking ... huh, I would much prefer to have that power go to my battery.

Anyone else see this happening? Is this normal and can things be adjusted?

Cheers,

DKH

2
EKZ (Zurich) raised their price to the grid to CHF0.09/kWh on January 1.

Presumably the control system you are see what charge is sent where does not have the ability to adjust this - with an app for example?

3
Hi, do you mind me asking how much the battery was ? We have the panels but sell to the grid right now, we were told a few years ago getting a battery wasn’t worth it at current prices but they were falling rapidly, am wondering if now might be the time.

4
we're in the process of deciding on photovoltaic panels, and other renewable energy sources + isolation. To my understanding it is still not interesting to invest in a battery. A better payback would be having an EV and charge it with your panels during the day.

5
When you signed up for this deal did it include a commitment to provide a minimum amount to the grid? Read your contract.

6
This makes sense to me too assuming the grid some how invested in the installation? Was that the deal?

7
Just disconnect it from the grid.

Tom

8
Sometimes there are solar subsidies, and sometimes those subsidies come with conditions.

9
Some years ago, friends did this. Within days there was an inspector from the grid supplier knocking at their door, having come to demand their pound of flesh.

10
To AbFab: we are with Primeo Energie and I think we only get CHF 0.015/kWh. Correct, the app doesn't give us the kind of control that would solve my issue.

To keyboardandmouse: We got a 15 kWh Huawei battery (LUNA2000-15) for CHF 8910.

To bowlie/markalex: We did not sign up with any kind of deal with the local provider. We just went with SelNET (we are in the Basel area). We have no expectation of getting our money back by going full solar, it's just something we wanted to do and we can afford it. Likewise with the battery.

To sonnenhund: yes, we are getting a couple of solar subsidies from the local gemeinde and the canton (I think), but nothing from the energy provider. we should get about 30% of our outlay costs back in this way.

To Tom/doropfiz: hmmm ... disconnect from the grid? I mean, it's definitely an interesting idea. Even if we had such a switch I could flip at will (I mean, we don't right? That's not normally a thing, right?) I'm just too damn lazy.

The money isn't the issue. Is electricity in Switzerland expensive? I don't know. It's not too expensive for us is about all I can say. We didn't do this to necessarily save cash. We just feel that we are in a position to "contribute" to getting energy in a renewable way and we have this interest in solar power. We ditched oil heating last year and replaced it with a heat-pump system. We don't own a car, we have our own garden, etc, etc ... ours is a privileged situation to be sure and we're lucky to have the means and opportunity to indulge.

I'm just interested in figuring out how the battery charging thing is controlled. Why does some power *sometimes* get diverted to the mains grid when it could be going to my battery?

The only constraint I'm aware of at this stage is that the battery can absorb no more than 5 kW, so when we are getting e.g. 10 kW from the panels I can see how the excess can go towards the grid. It's just ... weird ... when we are getting e.g. 3 kW from the panels on a cloudy morning and watching some go the battery and some go to the grid. But as I said, this only happens sometimes. Sometimes all the power not going to the house, goes to the battery and only a trickle is going to the grid. It's inconsistent. It makes me think that the local grid might have some kind of need and will occasionally take a toke from our panels? I dunno ...

I'm trying to figure out what the correlating variables might be, but I've drawn a blank so far. Just asking if any of you have had a similar experience.

Thanks for your input so far though. Interesting.

DKH

For those interested, it's 17 kWh of solar panels (building integrated).

11
How do you know where the electricity is going? Is there some sort of app your running that is telling you this is the case?

If that is the case, find out who developed the app? They may know the answer to your question?

Just a wild idea...

12
To monitor things we were advised to use a particular app (FusionSolar) and it tells us how much power we are getting from the panels, how much is going to the house, how much is going to the battery (or coming from the battery to the house) and how much power we are exporting to (or importing from) the grid.

We also get daily information in kWh about yield, consumption, export to grid, import from grid.

Anyway, I think I might have already an answer to my question. Our system includes two inverters, could it be that only one of them is connected to the battery? I'll keep digging.

DKH

13
Aaand ... yes, it seems that only one of our two inverters is tied into the battery. This very likely accounts for what we're seeing. Anyway, cheers for the feedback.

DKH