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Grid Connected Powerwall Design & Build
Hi guys, I have been away for two weeks but just got back, I shall share a quick update and try and answer some of your questions.

An updated circuit drawing of the system as installed is shown below:

The origional visio file I have uploaded to Dropbox for those who wanted it:

So far it has been working generally well. Since installed i've only imported on average 1.8kWh/day of electricity which is probably mostly due to my 10kW electric shower and the three of us that use it each day, so not too bad really. It still doesn't do a great job when the net load is <80W which will also acount for some of this usage.

In terms of affordability calculations, I've estimated that I will save ~£200 on my electricity bill each year which doesn't quite cover the cost over 10 years. However I also have now changed tarriff from EDF to Solarplicity. The great thing about their tarriffs is that there is no day rate. So you only pay for the energy you use, which in this case is very little. So the combination of adding these batteries and changing tarifs to Solarplicity results in an estiamted saving of £326. This however includes ~£70 saving on gas too due to no day rate on the new tarriff. The electricty saving of the combined batteries and new tarriff i estimate to be £250 a year, so getting close to paying for it over 10 years.

The app... is a bit poor really. I think it has the potential to get much better, it has all the data needed, just doesn't present it in a very nice form. Personally I'd like to get access to the data directly which I haven't tried yet but might be possible. On the app you can plot lots of different variables: grid power, battery power, energy used, voltages, currents etc. I have taken some screenshots and put together a view of the two main screens below for you to see:


In the plotting part at the bottom, you can only plot one thing at a time and the week view is always from Monday-Sunday rather than the last 7 days.

Let me know if you have any more questions,

Kenny.j likes this post
As i can see you have the solaredge inverter without optimisers?
Here we have the HD version and then it not possible too hook on a battery at 48VDC....
2018 SolarEdge brings a new version.

Do you have photos from inside the inverter?
I have a Solaredge SE3000 inverter with 10 P300 optimisers as shown on the drawing...

You can't hook a 48V battery to the solaredge inverter which is why I have the Sofar ME3000SP inverter to connect the batteries to the AC as shown in the drawing.

Photo of the Sofar ME3000SP Inverter insides:

Photo of the Solaredge SE3000 inverter insides:

Photo of the Pylontech US2000B Plus battery inside:

mormor1971 likes this post
Hello Greg, I'm in almost exactly the same situation with a 4kW SolarEdge inverter with 16 245W solar panels with micro-inverters on each panel. I've had them for almost 3 years now and so far they have generated 12MWh in total so 4MWh a year which happens to be 1/2 of my total electricity use over the last 3 years. They have saved me around 600£ a year. 

I've been looking at adding a battery to that solution but if you want to do this and be integrated with the SolarEdge there's a lot of other stuff that you have to buy too so I've shied away from that. A quick sum came in a more than 2k£ just for the additional hardware and then there's the HVDC packs which are not cheap either!

I'm in the process of recycling 18650's but only gotten about 550 so far and I must admit I am very tempted to just buy new cells instead due to the work overhead of collecting, ripping apart, testing and recycling the reclaimed cells, as you can skip most of that process with new cells.

I've been looking at various other ways to integrate a battery backup and decided that a AC-tied system would be the simplest so when I read about the inverter you found I was quite happy as that fits the bill exactly and it's not 3k£!

In your talks to the manufacturer did you discuss the option to add more DIY battery packs and do you know how much happens inside the 2k5Wh battery packs, and could you not simply add more cells in parallel to one of those packs's battery pack?

I know about not mixing chemistries so it would have to LiFePO4 cells but that's not a issue as they are a lot safer and should last a fair bit longer, especially as the battery pack increases and you use less of each cell's capacity which helps to extend the lifecycle a lot...
Any updates on the performance of your storage system, `i,m looking to buy the ME3000SP inverter, how is is running, reliabilityetc... and info / review on the inverter greaty appreciated.

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