Hey,
I would like to use my solar power more controllable. In Sommer where there is plety of Sun I would like to gnereate a flow where the energy should go first
direct consumer if needed.
In Batterie if empty or isn´t full.
In heating rod for water storage.
If there is more energy available I would like to sell to grid to my max allowed 4,44 kwp
For 3: Did you guys have experiances with good systems, e.g. MY-PY Solutions or Shelly Systems to controll the heading rod. Is there maybe a good supported to directly connect in VenusOS.
For 4: How can I create a flow, if there is like 5kw selling to grid how can I dynamicly limit it with the opendtu like to 4,44kw
The Last days were partical very cloudy and I generated with my solar in the day 8kwh, thats not much. Other Days I generated like 35kwh, thats enought for my devices directly and charge my batteries. But overwall I dont know what to do. Increase the Panels and connect it directly to the DC Rail and install another 1,5 kw on AC or just wait an buy the power
MY Setup:
3x MP2 5000/48v
VM-3P75CT
Batteries (30kwh): 6x Pytes E-Box-48100R-C 100Ah 51V LiFePO4 Batterie
Cerbo GX MK2
Kraus&Naimer KA63B.T904.VE2.F437
6kwp Solar (west/east) Hoymiles HM600/HM800/HM1500
OpenDTU
The ESS ist connected to my Power Distribution Panel via AC In1
In Emergency i can switch to ac out1 the complete Power Distribution Panel
This is very doable with ESS settings and then node red for hot water (i have setup systems that do use a shelly switch to activate via node reds http node).
ESS will cover this by default
ESS will also cover this. Solar is used then battery (until below grid setpoint) then grid.
This i prefer to setup in node red but I have heard of people using assistants but personally i find node red more flexibile.
if(SoC > x && (PV - loads) > y){
return 1; //have function node flow into a switch or http node to activate the shelly via http api or you could even do the http request in this function if you prefer
}else{
return 0; //same situation to turn off the shelly
}
You can customise the if statements further and to be honest you might want to add a buffer. ie if hot water turns on you might end up in a loop of the hot water turning on and usnig too much so node red turns it off again. So i suggest adding a buffer in your node red code to stop it turning on and off repeatedly. Either a buffer in terms of watts used/battery drawn or even just a time delay.
Same for question 4 use node red to dynamically change export limit however in the events battery is full you might need to find another solution to ramp down power output, this is more difficult on AC coupled system. DC would be automatic.
In regards to your question about expanding it really depends on your goals in my opinion ie self sufficiency, financial, environmental or a bit of them all.
If you want just more offgrid I personally follow this logic/sizing.
If you’re using a lot during the day then I tend to get AC coupled to cover that. Then go DC coupled for the ease of automatically reducing if you have a grid limit.
In general I find panels are much cheaper than batteries where i live so if space is available I put as many panels up as possible rather than increasing battery.
Hey Matt,
thanks for your response. Which Hardware is for heating often used, or doesnt it matter really. I think i have an 1 1/2 inch thread.
I only have ac inverters from Hoymiles, at least at the the moment now
In Expanding i already purchased 2 600W inverters for 4 Panels. I could get panels for 36€ 400W each. I would place them on a very small shed with 2x1 Panels frame and the other 2 panels diy mount it to a wood wall.
I would like to setup a small array with 2 String a 5 Module → WINAICO WST-400GX-P3 FULL BLACK and mppt
The most expensive there is the frame underneath and accessories like the MPPT, string cable, connectors, DC Cable. When I am purchasing the panels I have the feeling the car ride (1,5 hrs one way) is more effort than the panel price itself. So I would thing getting more is rather more effectice, than driving a second time.
I have the feeling purchasing a bit more panels increase my rentability of my Batteries/ System a lot. Maybe is a dynamic ESS also good for me, but I am scared of the hight prices in Winter. Also the static fixed fee from the local power company (transfer fee) is at the moment static. I would thing it is much more affortable if its dynamic. I charge my batteries at night when there is enough offshore/onshore power instead of use an power plant far away.
thanks
Sounds like an interesting system you’re designing. It really depends on your area/electricity prices. Personally where I live the dynamic ESS tariffs aren’t very common or cost effective. In my area I’m actually better off using an electric car tarrif, with just a standard solar export tarrif.
So i charge the house battery (and car) for very cheap overnight in the winter and use that during the day as my solar probably only cover 10% in the winter.
In the summer however I can cover car and house usage from PV.
SO for me using a simple schedule charging setup in ESS settings is sufficient.
Its definitely worth planning it out/pricing it all.
I personally do it in excel.
List out the options and do some cost analysis.
On my personal DIY projects I strive for 5 year pay back period.
Personally for me I enjoy being offgrid/self sufficient as much as possible however price very much is a factor. I’m off-grid most of the year however getting completely off-grid makes my return on investment closer to 15years.
That price sounds really good to me but not sure if that’s just because they’re expensive where I live.
In regards to the water heating I use a standard hot water tank immersion heater. They’re relatively common in my area. Then i simple attach the shelly smart switch to the input (check the ratings of course first).