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diy solar

Dutch PowerWall live and kicking

Reiver

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Jan 1, 2022
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After some time experimenting with solar, battery and grid tie........here it is: my first Solar LFP PowerWall.

It's live now and feeding back to the grid - to the home.
 

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My 8 S battery setup is based on Liitokala 90 AH.
The second pack is in backorder. We would like to build 4.5 KWh config.
 

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The monitor is simple + via Bluetooth + via Wifi.
 

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The black Grid Tie inverter is configurable and we can select the power we feed back to the house.
The temporary inverter to generate 48 Volt from this 8 S battery pack is needed for this Grid Tie Inverter. With the installation of the 2nd battery pack we will not use it.
 

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Full picture inside the PowerWall enclosure.
 

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This is the basic design and there is still work in progress like double temparature safety check of the battery pack, emergency shut off......and others.
 

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First results are very nice:
 

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Ultimate goal is to store energy when the Sun delivers and deliver back via the grid tie inverter during night. Solar setup is now: 3 x installation in total 3,5 KWh. Storage of energy is forecasted to be at 4 - 4.5 KW in total and during night for 6 - 10 hours 400 watt continue.
With this I'm not using the grid during daytime when sunny and not at night because of this PowerWall feeding back to the house!

DutchGuy.
 
That is cool, I was hoping to do something similar at smaller scale since the net metering is ending soon in NL. I did not fully understand the specs of your installation. You have 3,5KWh of solar? you mean 3,5KW? You forecast your consumption to be 4,5KW? You mean 4,5KWh per day? And then the 400W continued during the night (sounds quite a lot for the hours when everybody is sleeping).

How do you regulate what you use from the batteries and what you send to the grid? (Specially when referring to different consumption levels between day and night?) I only know of inverters that can be regulated at a constant discharge rate analogically; can yours match real time consumption?

Also curious about knowing if you made this project for fun or because you do see a payback as the net metering disappears in NL.
 
Solar panels are 3,5 KWh
Total storage is 4,5 KW (16 S setup with 90AH cells)
Principle is simple: charge onze sun is shining (not fully optimized yet) and feedback to the house during night (goal is 400 Watt per hour = currently our average use without cooking/ wasmachine/ magnetron and other heavy load).

This project is a result of many years experimenting with deep charge battery/ AGM battery/ 18650 battery packs. Extra safety measures are taken to install this cabinet in the house (garage). Fully build with Aliexpress products but very well selected to avoid issues. Costs are 1000 USD and with the current energy prices (0.45 USD per KWh) the ROI is 3-4 years.
 
This is the daily charge power; as you can see the charge power is stabilizing since the PowerWall was running for 2 weeks at 150Watt per hour for 6 hours per night.
So we need approximately 1 KW to store in the battery to get back 6 x 150 Watt = 900 Watt energy -> very nice first results!!
 

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This is the daily feedback power to the house. Yes it's lower than the 150 Watt per hour since the inverter 24 Volt to 48 Volt is consuming some power in this Test Config.
So basically the input is 1 KW per day and the output is 0,7 KW per day.

Once the 2nd battery pack is received (end january) then it's more effficient.
 

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