Solar panels with micro inverters

[JanVlietland]

After completing my domoticz adventure viewtopic.php?t=42719 I'm now venturing into solar energy. My requirements for this next step are as follows:
* Solar panels combined with microinverters: maximizing energy efficiency at the panel level.
* Integrating with a home energy storage system (battery): to cover energy usage in the night
* No internet/cloud connection or dependency: Ensuring local control and data privacy.

After som preliminary research I explored the brands: Enphase, APsystems, Hoymiles, SolarEdge, Tsun, SMA, Autarco, Omnic, Deye and Sungrow. Among these, only a few seem to offer microinverters with an API (via a gateway) and/or a Zigbee interface for local control:
* APsystems (Zigbee enabled)
* Hoymiles (sub 1GHz protocol, still figuring out connectivity)
* Deye (Powerline/Wifi/Zigbee, connectivity details under review)
* Sungrow (gateway includes a lan interface, still figuring out local control possibilities)

However these brands (at least) seem to expect their systems to be connected to their respective cloud. This is a dealbreaker for me. I want to avoid internet dependency due to concerns over potential hacking, vendor lock-in, or even supplier bankruptcy. My energy system should remain fully under my control. My energy system should be fully under my control.

Objectives:
- Offline Functionality: Has anyone in this forum successfully implemented an offline solar setup with microinverters? Ideally, the system should already support MQTT or allow easy integration.
- Real-Time Energy Pricing: I'm also looking for energy suppliers that publish real-time prices. This will enable the system to make intelligent decisions about whether to feed power to the grid or store it in the battery. Given that this setup needs to last 25+ years, the Dutch salderingsregeling will be a thing of the past long before then.
- In-Depth Resources: Recommendations for forums or communities that dive deep into solar energy technology and integrations are highly appreciated.

Thank you in advance for your insights and advice!

[waltervl]

For Dutch energy pricing look at the Enever integration. Also has prices of the next day per hour so you can plan on forehand.

For solar inverters, non of my (not mini) inverters need an internet connection to produce energy. Internet mostly needed to monitor. You can also monitor the energy production with external energy (kWh) meters that can communicate with Domoticz (zigbee, S0, wifi).

And if you do not have partial shade on your solar panels during the day there is no need for mini inverters, you better use the normal inverters. The extra costs are hard to earn back.

[JanVlietland]

That is great information Walter. Thank you! I have added the Enever integration and will request a access token.

At second thought I indeed also do not have partial shade. What type of inverters do you have since you imply multiple, but not mini.

Indeed I want to use Zigbee enabled power monitors and connect them to Domoticz via mqtt, like my other zigbee devices.

Do you have a battery? In fact I still need to understand how switching is done between battery and the energy provider, based on delivery and prices.

[waltervl]

I have 3 sets of solar panels as I bought every 2 years an extra set. 1700, 1900 and 3600 Wp. I have 2 Goodwe DNS and one Omnik inverter. Omnik is bankrupt but the inverter still works fine. The Goodwe DNS inverters can be monitored directly but that needs something extra. I monitor them through the cloud.

For power monitoring you can use zigbee power clamp meters like https://www.zigbee2mqtt.io/devices/PJ-MGW1203.html

I don't have batteries and also not plan to install them soon as it seems financial totally not interesting. You hear now stories about earning a lot of money by using smart pricing algoritms but it already seems to be regulated down by the power companies as they don't want the fluctuations on the net. I also have a PHEV car and heatpump and an old fashioned turning power meter. And I guess in the end only in the summer I could use a battery to charge my car in the evening with the solar energy stored in my battery. The winter I use too much electricity for my solar setup to cover. If I want to use a battery to cover this I will need a huge one.....

[BazemanKM]

Sessy battery is Dutch and has an Domoticz plugin: viewtopic.php?f=65&t=42865
For car charger: https://gathering.tweakers.net/forum/li ... 2#80869032 Smart EVSE

[gizmocuz]

"No internet/cloud connection or dependency: Ensuring local control and data privacy."

It's great to also have a cloud environment to check the status/logs.
Updates for your system to support new features like 0 return on the grid by disabling a certain amount of microinverters etc

Enphase is (in my opinion) a good systeem, can also work without an active internet connection.
You can take control of your own system, so only the data is logged to Enphase, and boy what are they interested in 'your' data!

Now talking about batteries, these days you can buy multiple brands, some even have a paid subscription to let it know when to charge/dischange.

I build my own system, bought a good battery (14.3 kW) for ~2200€, and am using Victron equipment.
Victron is great, you can control it the way you want, but they have also an ESS mode that does everything for you.
If you go to my personal Github project page, you find my implementation complete with all code/scripts you need in Domoticz.

Enphase can be monitored directly with Domoticz
Victron supports MQTT and with this (See my repo) you can connect/control it with Domoticz

Mind you, this is for advanced users, sure it can be a 'set it and forget it' solution, but it probably needs some more tweaking

There are tons of information to be found on the internet about batteries, and I suggest watching all of them (for instance the video's of 'off grid garage')

You also have to decide if you want a 1 phase of 3 phase system

The Victron multiplus also has a backup output, for a 3 phase system you want to have 2 cables of 6mm2 (5 wires) going to your battery, one cable for input, the other for output.
You also need to decide where to connect your microinverters.

If you are not good with electricity, you do need to hire someone that connects everything for you. a DC system with >70A is very dangerous.

For a car charger, Alfen Eve Single Pro Line, this is also the one that for example Essent is providing.
You can find good second hands on Dutch marktplaats from users that left Essent.
Native support in Domoticz as well. Nice about these things is they do support a backend for business users, and you can program them to use with for example your watch that supports NFC (no needs for cards or tags, aldo you can use your bank card if you wish)
It supports load balancing.
And I have integrated it into my system because when you charge your batteries, and you want to charge your car (at 01.00am for example because of the price), you do need to stop charging your batteries or fuse could blow)

[Toxopipo]

You can use the panels of solarEdge or similar products. I bought a cheap DAH solar set https://cjxsolar.nl/products/plug-play-zonnepanelen-set. They work pretty well with a unit that connects to wifi reporting the data to some server. However, I found out that you can get the data directly from the unit using Domoticz. In the add hardware section choose “SolarEdge via lan interface” find the IP of the solar unit and use it here and add either port 80, 2221 or 2222. Press “Add” and your solar panels will show up in the “Utility” section of Domoticz.

[solarboy]

Using SMA here which isn't a micro inverter system but is cloud free using the sma modbus plugin and smahub (sma2mqtt). You can also use sbfspot with cloud upload disabled. Working well so far and the hardware is very high quality. I shall be adding a Sunny Island + Pylontech LifePo soon.

[psubiaco]

Maybe I'm answering very late.
Just to say that I'm using microinverters from Hoymiles, that have an high efficiency inverter with 1-2-4 MPPT (so each solar panel is optimized), with OpenDTU (but you can also check OpenDTU-Onbattery) that is a board with ESP32 + 865MHz RTX to communicate with Hoymiles microinverter.
When you configure OpenDTU to send MQTT messages to Domoticz (MQTT AutoDiscover), Domoticz automatically create devices. Also, OpenDTU has a nice web page with all info about each module and inverter output.
A bad thing for Hoymiles microinverters is that when voltage raise above 253V, it disconnect and restart (you can limit by a Domoticz automation, of course, but it's not the best solution): to enable automatic power limiting (Volt Watt Droop) you need a Hoymiles DTU device to program the grid profile increasing the voltage limit to 264V or similar.

[FireWizard]

Good evening @psubiaco,

You wrote:

A bad thing for Hoymiles microinverters is that when voltage raise above 253V, it disconnect and restart (you can limit by a Domoticz automation, of course, but it's not the best solution): to enable automatic power limiting (Volt Watt Droop) you need a Hoymiles DTU device to program the grid profile increasing the voltage limit to 264V or similar.

I think this is according to international standards.

The standard IEC60038 specifies that in case of a nominal voltage of 230V, the voltage may vary -10%/+10%.

+10% means that the maximum allowed voltage is 253V. If inverters would not switch off, the grid voltage would become higher than 253V.
As manufactures has to make their equipment to resist that 253 V, it could happen that equipment will be damaged.
Although their tolerance is much bigger than that 10%, inverters should limit their output voltage to 253 V.

Just for your information.

Regards

[psubiaco]

+10% means that the maximum allowed voltage is 253V. If inverters would not switch off, the grid voltage would become higher than 253V.

You're right.
The problem on Hoymiles inverter is that it's configured by default, for EU market, with a grid profile that:
* reduce power linearly when voltage is between 253 and 264V
* turn off inverter when voltage is above 253V for more than 10 minutes.
So, in Spring when sun is high, temperature is low and electricity usage is low, Voltage is often at 253V with inverter at full power.
To modify these parameters on Hoymiles (Increasing 253 limit or decreasing the voltage to get inverter power limiting, the original Hoymiles DTU device (that communicates by 863MHz to the inverter) is needed, because OpenDTU is not able to change those parameters.

[waltervl]

That your inverter reaches 253V is the result of low capacity on your public grid. In my street the grid supplier installed a new transformer, after complaints of a neighbour, reducing the voltage on sunny days from 250V to almost stable 230V.

Using voltages higher than 253V seems to limit the lifetime of devices in your home.

So increasing the voltage to even 264V is definitely not advised. And your neighbour a little bit further on the line need to go even higher.....

[psubiaco]

In my street the grid supplier installed a new transformer, after complaints of a neighbour, reducing the voltage on sunny days from 250V to almost stable 230V.

Yeah, a transformer with a variable secondary coil that stabilize the 230V voltage is a good solution, but when 100% of energy in the country comes from wind+solar (in sunny Sunday, in Italy), a way to store excess energy is needed (electric cars, BESS, green hydrogen, ...).
In Italy only few electricity suppliers have hourly tariffs.... most tariffs depends from the montly average price of energy for 3 time slots (23÷7, 7÷8 + 18÷23, 8÷18) and some tariffs are flat (you can consume energy at any time, paying always the same tariff), and this is very bad because it does not encourage users to consume energy when it costs less.
Since Feb 2022 (Ukraine war) I changed the automation (lua script) that manages the heat pump to reduce consumption and export energy during the peak hours (from 7 to 9 and from 18 to 21), to "help" the electricity grid, but this should be done by everyone, not only by me!
I've wrote in https://www.creasol.it/en/support/domot ... c-forecast all info about scripts to download ENTSO-e prices and compute the solar production forecast, very useful information to control the heat pump and other loads.
It's a pity that in LUA script it's not possible to update a counter device with further values (prices and solar production for tomorrow, hour by hour): only dzVents permits to do that.

How about the Netherlands and other countries electricity tariffs?

domoticz_entsoe.png (337.91 KiB) Viewed 834 times

[FireWizard]

Hello @psubiaco,

You asked:

How about the Netherlands and other countries electricity tariffs?

In The Netherlands we had (or still have) a system, which subsidized the installation of solar panels.
This subsidized system will end at 01-01-2027.
It means that if you buy and install solar panels, you do not pay VAT over the equipment and installation.
You also can (could) return the energy to the grid en you may deduct this amount from the energy you consume from the grid.

This is very efficient for the user, because what you produce on sunny days, you may consume at night or what you produce in summer, you may consume it in wintertime. However, as said this comes to an end. As up to now the Return on Investment was approx 5-7 years, it will become 15-20 years. You can imagine that the market for solar panels has collapsed and several suppliers of solar panels only has gone bankrupt already.

A second phenomena, we are faced with since about 2 years, is that energy providers are going to charge you, if you return energy to the grid.
They encourage you to use the energy, your solar panels produce, yourself. So that requires an "electricity consumption strategy".

What you pay, depends on your contract and your energy provider, so it is very difficult to compare the providers.
In fact, a so called "dynamic contract" is the contract, where you don't pay for returning energy to the grid.
A dynamic contract follow the stock market price for electricity..

For the time being (until 01-01-2027) you will receive more for your kWh, in spite of the "return fine", but after that date, we will see, what the best solution is.

As I have micro inverters (Enphase) as well, I am considering to disable inverters in case of to much production. It is crazy, I know, but I have to protect my wallet. This will depend on how easy I can access the API and to disable individual micro-inverters.

The future will learn.

Regards

[psubiaco]

Thanks for informing me about NL.
I understand: if you promise your citizens that all you produce in Summer you'll get back in Winter for free, you're doping the photovoltaic market!
We did the same in Italy in 2006-2012, with a very high revenew on each kWh produced (don't care if that energy is exported to the grid, or consumed).
Now you have negative prices during the day, as shown in the picture below (electricity price in NL today), and the solution is store that energy in vehicle or house battery, and make new storage systems (battery, water, green hydrogen, ...) and try to export this energy to other countries.

Istantanea_2025-04-02_15-15-39.png (38.59 KiB) Viewed 706 times