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Grid Connected Powerwall Design & Build
#11
(08-29-2017, 03:41 PM)Greg Wrote: For completeness, I've finished the build using these off the shelf batteries as shown below:



The system seems to work as it should, when I have excess solar, the inverter charges the batteries. When I have a load the inverter powers that load from the batteries up to 3kW, the rest is provided by the grid.

I'm just waiting on some 25mm² M6 crimps so I can shorten the battery cables and neaten that up a bit.

I'd recommend the system, not as neat as a Tesla Powerwall, but cheaper and has customisable capacity. Also I think the inverter is a good choice for anyone in the UK who already has solar with a FiT and wants to build their own powerwall to go with it. Either with off the shelf batteries or build your own batteries.

Looks good Greg. You went for the 7.2kWh (3) battery back setup?  What size is your solar array?  I’ll be interested to see how theism system works for you. With a view to perhaps head down this road myself in the future. I’m definitely limited as to choice given that I’m grid tied an I want retain my FIT payments.   Big Grin

Kenny
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#12
Thanks for the info KtB, I've followed the manual and put the max charge voltage at 53.2V (3.55V/cell) and min at 47V (3.13V/cell) so should be ok.

Kenny.j - Yes i went for 7.2kWh. Probably a bit more than required but I wanted it to be able to do more testing, last through rainy days (like today) etc. I have 3kWp of solar and tend to make 3kWh a year from it. One thing I've noticed so far is it isn't very good at handelling low loads. When the net load is <~80W it tends to not get involved and instead imports electricity from the grid. My nightime load is often that low, so it's a bit annoying that it doesn't supply it always from the battery.

Greg
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#13
.CT clamps are not that accurate especially at low currents is there any calibration options on the mass for the CT

Wow thats low usage mine hovers around 500w
4 kw grid tied system

20 kWh 12v lead acid (don't ask) off grid system used as a giant ups for my servers and network and to provide house power incase of power failure

10 kWh 48v lifep04 with 1.5 kw of solar on a mpp5048 mppt and a flatpack2 2000/48 mains charger. Grid tied with limiter to help even out the power usage at night 
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#14
(08-30-2017, 06:50 AM)Greg Wrote: Thanks for the info KtB, I've followed the manual and put the max charge voltage at 53.2V (3.55V/cell) and min at 47V (3.13V/cell) so should be ok.

Kenny.j - Yes i went for 7.2kWh. Probably a bit more than required but I wanted it to be able to do more testing, last through rainy days (like today) etc. I have 3kWp of solar and tend to make 3kWh a year from it. One thing I've noticed so far is it isn't very good at handelling low loads. When the net load is <~80W it tends to not get involved and instead imports electricity from the grid. My nightime load is often that low, so it's a bit annoying that it doesn't supply it always from the battery.

Greg
Hi Greg,

I like your choice of product but I can find very little information or reviews on the internet for the ME 3000SP.  It looks like a great compromise, I want to make up my own battery packs but want to keep it as mainstream as possible and as safe as possible. How long have you had it installed?  Just to be clear, your pick shows an inverter but I assume that was what you had before for your panels, the ME 3000SP was all you needed plus batteries?

Very tempted to join you with this setup.  Did you have any problems getting it installed?

Thanks, Kevin
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#15
Hi Gregg,

How are you getting on with your new setup! is it working as planned. Have you tried the app? I’m interested to know as having watched Robert Llewellyn’s Fully Charged review of the Tesla Powerwall 2 it’s well cool how you can monitor it all so beutifully on the Tesla app. I know very little if any other systems apps will be as cool and user friendly as Tesla’s but wondered if you’d tried this one?

Kenny
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#16
I really like the look of this setup as it appears to be the simplest and lowest cost way to add storage to PV. Spoke to Homeswitch and checked out the inverter/battery companies and they look pretty good so will likely buy a kit in next months.

Am interested in the cost saving over just having a PV array though. Just written some software to capture data from an Owl intution energy monitor and model the addition of storage. If anyone has done any calculations for their systems would be interested to know or compare notes.
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#17
(09-07-2017, 10:42 AM)7Racer56 Wrote: I really like the look of this setup as it appears to be the simplest and lowest cost way to add storage to PV. Spoke to Homeswitch and checked out the inverter/battery companies and they look pretty good so will likely buy a kit in next months.

Am interested in the cost saving over just having a PV array though. Just written some software to capture data from an Owl intution energy monitor and model the addition of storage. If anyone has done any calculations for their systems would be interested to know or compare notes.

I've done some analysis at 5kWh and 10kWh for my usage and the maths don't add up with any of the pre-built battery systems within the life of the batteries.  They just cost too much compared to my savings (in the UK).  If I have a larger battery bank of used cells the maths may start to work in my favour (at least for 6+ months of the year).

I'll dig it out and see if I can share it.

Kevin
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#18
It’s not just the maths for me, it’s about being somewhat self sufficient and not having to rely on “the grid” so much.  I think renewables are the future, we don’t need new nuclear power stations (think Hinckley point c).  The less demand we put on the grid the less they need to generate with fossil fuels. The power mix is getting better but as Asda say “Every Little helps”

That said, obviously the less its going to cost me the better ?
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#19
(09-07-2017, 02:43 PM)morrisok Wrote:
(09-07-2017, 10:42 AM)7Racer56 Wrote: I really like the look of this setup as it appears to be the simplest and lowest cost way to add storage to PV. Spoke to Homeswitch and checked out the inverter/battery companies and they look pretty good so will likely buy a kit in next months.

Am interested in the cost saving over just having a PV array though. Just written some software to capture data from an Owl intution energy monitor and model the addition of storage. If anyone has done any calculations for their systems would be interested to know or compare notes.

I've done some analysis at 5kWh and 10kWh for my usage and the maths don't add up with any of the pre-built battery systems within the life of the batteries.  They just cost too much compared to my savings (in the UK).  If I have a larger battery bank of used cells the maths may start to work in my favour (at least for 6+ months of the year).

I'll dig it out and see if I can share it.

Kevin
Hi Kevin, I'm in UK and my sums a year ago suggested a saving of £200 per annum so the payback time was much longer than the battery life but it was based on some very simplistic assumptions. Systems are now cheaper and batteries like Pylontech have 10 year plus life so thought I'd redo the calculations using an accurate model and with real data from the energy monitor. Electricity cost has gone up a lot in the last years and expect that trend will continue.

Don't think I can spend the time collecting hundreds of cells, testing them etc. etc. so if I'm going to add storage then it will need to be off the shelf.

Was also considering Economy 7 to charge the battery when there isn't much sun.

Cheers - Jim
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#20
(08-18-2017, 02:16 PM)Greg Wrote: Hi Wim, the plan is to control the inverter so that i charge the batteries from my current solar (off the 230V out of the SolarEdge) when i have excess energy (From 'the grid' from the MPP inverter's perspective). Then in the winter also top them up from cheap night time grid power. I will then power my house as much as possible when i don't have enough solar from the batteries and the rest comes from the grid. However it looks like i need a different inverter to do this. I think their 'Hybrid' inverters connected to a modbus energy meter can do what I'm wanting but they are about 4x the price...

I may also add some cheap pannels to charge the batteries from them directly as well in the future, but my current 3kWp should be enough most of the time.

The drawing was done in Microsoft Visio.

Greg

Any chance you wouldn't mind sharing the visio file?
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