I'm a student in Norway doing market research on grid sensing technology. I am wondering; What's the most annoying or costly thing about running your PV/battery system right now?
a quick chat (video/phone) just send me a dm here!
Everything gets used anonymized. Thanks a lot in advance!
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Longer version:
In addition, I'm curious about:*
Curtailment: How often does it happen to you, and do you know whether it's your own installation or something the grid operator imposed? How hard is it to figure that out or get compensated?
Battery control: How do you/your system decide when to charge/discharge? Do you manage it yourself, does your own energy management system handle it automatically or is it outsourced to a third party (aggregator/direct marketer)? Do you use dynamic prices or forecasts to avoid curtailment or discharge during price peaks?
1800W PV, SE and SW 75°. Charges lead acid battery 24V about 7kWh. Surplus power into Boiler. Inverter 22-500W, zero export via openDTU onbattery. Shelly meter receives epex data and controls Boiler (230V side), charger, export. Additional script overrides when voltage, frequency exceeds limits. A system description is also found here . A fully charged Battery is good for 2-3 days. No other external control (yet).
AT regulations do not allow yet for "balcony system" to profit from epex controlled import or export. May change next year
one thing i forgot is that there is a curtailment in the form of exporting max 60% of the total PV power into the grid. This applies to relatively new systems, the rules here have changed several times over the years.
It does however not really matter to me, 1. because i have an east-west facing system (less midday peaks) and 2. because i can shave the peaks by charging the home battery and the EV.
This regulation actually makes a bit of sense, incentivising systems designed for self-consumption
interesting! Especially the 60% cap. Curious to learn more:
The cap sounds like a fixed design limit, separate from the dynamic grid-operator curtailment you mentioned earlier as not really working in practice. Is that so?
Have you ever experienced that a real-time signal from your grid operator/direct marketer cutting export beyond your own 60% limit? If so, how often, and could you tell it apart from your own system's normal behavior?
How do you know your inverter is respecting the 60% cap correctly?
Thank for replying Some follow-up questions if you feel like it 1. The voltage/frequency override script: roughly how often does it trigger in a typical month? When it does, how can you distinguish whether it's your own installation or something happening on the grid? 2. Was "zero export" mainly a way to avoid grid-operator registration/curtailment rules, or more about cost/simplicity of the build itself? 3. Even with the boiler as a dump load, do you ever still hit a point where generation exceeds what battery+boiler+EV can absorb, and the inverter has to cap output anyway?
We have a new PV system, live since Nov. 2025. The regulatory process really is a pain in the ass, knowbody knows exactly all the details, even the VNBs don't, the electricians don't - its more educated guessing (just my opinion). We had to look over 1 year for an electrician willing to re-use our old electric compartment (Zählerschrank, ZS). Others want to completely replace it by new regulations costing easily 5000 Eur. Finally we found one how did it for 1000 Eur. Old ppl or such who don't care get ripped-off, either by PV-companies (Solarteure) or electricians. Some have difficulties with their energy provider (EVUs, VNBs), we didn't - so far.
Battery is controlled via BMS, the hybrid inverter and myself. I designed the whole system myself, getting lots of information here from the forum - thanks for that, guys! - and on the internet. I did lots of the electric wiring for the pv-modules on the roof to the inverter in the cellar - all in all more than 150m of cables. I took me half a year to plan and organize everything and another half year to do what was needed.
battery control is an ongoing task if you want to optimize it. Many ppl don't care much, i guess. They rely on default settings (coming with the battery and/or the inverter).
We also didn't apply for any governmental support program /financial support due to too much regulations and complications. We also modernized and improved the insulation of our roof beforehand - without any support program. To apply for you need an extra appraise and have to observe minimum insulation layers thickness we couldn't technically achieve (without setting complete new windows in the roof layer). Otherwise the whole procect costs would have rised enourmously without paying out in terms of insulation. Germany is master of burocracy - probably 1. place in the world - and it gets worse and worse.
1.The 60% cap is just simply an export limit in the inverter. It does require a power meter (typically connected via Modbus), to see the current energy export.
Remote control to switch and dim devices by the grid operator is "being rolled out", but like many things these days (in my opinion) it is way too ambitious complex and expensive. Also this requires smart meters and only about 6% of german households have those.
Your PV Installer should configure the inverter correctly. In reality, my inverter had updates which did a reset on some of these parameters. Since i am monitoring this via Home Assistant, i noticed quickly and fixed it. The grid operator could always look at your annual export reading and complain about too high exports - in theory. However, i dont even export much any more, since we have the EV. My amortisation is mostly through self consumption, i can look up the exact number if you want
Grid Voltage never triggered. Grid Frequency <49.9Hz triggers sometimes but only for very short periods (1-5 seconds). >50.1Hz triggered in summer when price was extremely negative, but the epex routine had switched to consumption anyway
Zero export ist most cost effective due to network cost per kWh. Due to new regulations I want to cap power from network to <2kW because each kW above 2 increases the basic price for a month.
It needs about 5-6 consecutive days no clouds in summer to fill boiler and battery into limiting PV current - or 3 days when I'm away. These occasions let me (a) do 90° washing and (b) do battery desulfatisation (voltage about 33V for 1-2h, monitoring all components). The washing machine is usually filled from boiler.
epex coupling for now is experimental / hobby (15m max) until regulations allow me to use that economically. Goal is to find a vitual power plant aggregator who is also interested in small instalations. Prices for tier 1, tier 2 reguation is attractive, see here
and austria and switzerland have some different regulations as far as i know, also compensation is different. This also makes it more complicated for international inverter manufacturers as they have to meet all the regulations in every country.
@energystudent.Norway : would you mind sharing your final research here? Is it a master thesis or similar?
@paddy72 To answer your question: I'm in my 4th year of my Master's in engineering, and this research is part time work alongside my studies. It won't be published publicly, but the challenges you're all describing are useful input for where new technology could help.
@tageloehner The frequency triggers more than voltage for you, that's a good data point. And the part about wanting a VPP aggregator that also accepts small installations is actullay some of the gap I'm trying to map.
Based on what you know of your local grid, are there specific situations where you think better real time monitoring is missing today? Could be voltage or phase imbalance, faults that take a while to locate, or capacity checks when new solar/EV connections are approved?
I compared manually the measurements of inverter, shelly, and online frequency. Differences negligible. In the script I use the shelly values. For voltage and frequency good enough. Frequency is the one measurement you need a very good idiot to break
Regulation:
calculate desired power to inverter.
Voltage limits can override (last mile)
Frequency limits override (whole network)
publish to inverter
Fast response is 0.5-1.5s, zero export 2-4s. That needs a bit of tweaking the shelly: Its internal measurement cycle is 0.5s, but official functions publish every 2s. I catch the trigger for new measurement and do my own calculation and publisher.
Makes sense, thanks. But right now you only see the grid from your own single point. Have you ever wanted to compare your readings against another point, like a neighbor's system or somewhere else on the feeder, to figure out if something you saw (a voltage dip, a frequency event) originated at your place or somewhere upstream on the grid? Or has that never really mattered in practice?
A frequency event is always european network wide, or our cuntry's network does a level 1 380kV disconnect / resync test (about once a year). Voltage? I'm about 100m away from the transformer ...
I think for true variable pricing I should get variable tansport price and load information from the provider.They are already building such a system but it is only available für a fee and only for systems >10kW with selected systems through their respective cloud systems, like Deye, Fronius, Apha Innotec, Audi/BMW/VW. No public available data.
so: never.
Some follow-up questions if you feel like it 
1. The voltage/frequency override script: roughly how often does it trigger in a typical month? When it does, how can you distinguish whether it's your own installation or something happening on the grid? 2. Was "zero export" mainly a way to avoid grid-operator registration/curtailment rules, or more about cost/simplicity of the build itself? 3. Even with the boiler as a dump load, do you ever still hit a point where generation exceeds what battery+boiler+EV can absorb, and the inverter has to cap output anyway?
