Grid Connected Powerwall Design & Build

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Greg

New member
Joined
Aug 14, 2017
Messages
10
Hi There,

I've recently been looking at making a power wall for my home. I currently have 3kWp of solar on the roof grid connected through a SolarEdge inverter getting paid for generation.

I'd like to add a battery to this system so that during the day I can charge my pack up and then when the sun goes down, I can power my house. I also have an Economy 7 meter which means that during the night my electricity is half price, so during the winter I can charge the pack up over night when electricity is cheap and then use it in the daytime.

I'm planning on buying new cells as I haven't got the time/patience to hunt down enough second hand batteries. I will probably buy 1000 LG MH1 or Samsung 33G cells which come in at 2 - 2.30 per cell including shipping. I will make 64P packs giving 64P14S final solution (I'm using the rest of the cells for some smaller packs). So it will be about a 9kWh pack.

I have been looking at using the PIP-HS 5048 inverter for this project, but i can't work out if it will work? Can someone who has used this inverter help? The arrangement I'd like to have looks like the circuit diagram shown below:


image_eknoyb.jpg


What I'd like to be able to do is use an emonPi energy monitor to monitor my generation/usage and control the PIP-HS 5048 to either charge the batteries or discharge depending on the load. Is this possible? I'm imagining I write a PI controller in the emonPi that gives a power demand to the PIP-HS 5048 based on the current load.


As you can see I also plan to use the Batrium BMS as many others do.

I would very much appreciate some advice on this build. From what I understand about the PIP-HS 5048 this isn't possible, however when I emailed the supplier they said it was... I think I need to put all my loads on the output of the inverter. However this would limit my usage to 5kVA as the inverter is rated at that. I have a 10kW electric shower so that wouldn't work.

It looks like there are other products out there that would work (SMA etc) but they are 2k+ compared to the 488 of this PIP-HS 5048.

Regards,

Greg
 

KtB

New member
Joined
Jul 31, 2017
Messages
22
Greg said:
Hi There,

I've recently been looking at making a power wall for my home. I currently have 3kWp of solar on the roof grid connected through a SolarEdge inverter getting paid for generation.

I'd like to add a battery to this system so that during the day I can charge my pack up and then when the sun goes down, I can power my house. I also have an Economy 7 meter which means that during the night my electricity is half price, so during the winter I can charge the pack up over night when electricity is cheap and then use it in the daytime.

I'm planning on buying new cells as I haven't got the time/patience to hunt down enough second hand batteries. I will probably buy 1000 LG MH1 or Samsung 33G cells which come in at 2 - 2.30 per cell including shipping. I will make 64P packs giving 64P14S final solution (I'm using the rest of the cells for some smaller packs). So it will be about a 9kWh pack.

I have been looking at using the PIP-HS 5048 inverter for this project, but i can't work out if it will work? Can someone who has used this inverter help? The arrangement I'd like to have looks like the circuit diagram shown below:


image_eknoyb.jpg


What I'd like to be able to do is use an emonPi energy monitor to monitor my generation/usage and control the PIP-HS 5048 to either charge the batteries or discharge depending on the load. Is this possible? I'm imagining I write a PI controller in the emonPi that gives a power demand to the PIP-HS 5048 based on the current load.


As you can see I also plan to use the Batrium BMS as many others do.

I would very much appreciate some advice on this build. From what I understand about the PIP-HS 5048 this isn't possible, however when I emailed the supplier they said it was... I think I need to put all my loads on the output of the inverter. However this would limit my usage to 5kVA as the inverter is rated at that. I have a 10kW electric shower so that wouldn't work.

It looks like there are other products out there that would work (SMA etc) but they are 2k+ compared to the 488 of this PIP-HS 5048.

Regards,

Greg

If you are not worried about using the power if/when the grid goes down then a grid tie inverter with limiter may be a simpler option. This can be used in conjunction with your existing inverter.You can then run this at night or all the timeto supply power to the house from you battery bank. Or have a split system as Ido which is part grid tie with an off grid inverter for the odd occasion the grid is down and to act as a giant ups for critical loads
 

Greg

New member
Joined
Aug 14, 2017
Messages
10
Thanks KtB. Yes, I'm not worried about grid outages. I can't remember the last time we had one here. Which grid tie inverter do you use?
 

wim

Member
Joined
Apr 6, 2017
Messages
556
Like howyou arethinking... as youi did not have the patience to collect laptop battery's and test them... ( a do have 6 of them :p )
I did a build with all new cells to get a quick start, maybe expand later with used cells.
My "old" grid tie inverter is still connected to make some money, the new installation is off grid ( in Belgium it is not cheap anymore to feed into the grid )
Are you going to add solarpanels to charge your battery or are you only chargewith grid ac? (those pip's dohave a solar input )
Maybe load sharing is something to look into.

Btw, like your diagram, what are you using to draw it?
 

Greg

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Joined
Aug 14, 2017
Messages
10
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
 

wim

Member
Joined
Apr 6, 2017
Messages
556
Greg said:
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
I think it is bestto replace the solaredge with a hybrid inverter and be done with it, (there are timers in the hybridmpp inveters to charge only at night and much more)...anything else is going to be a pain to contol/speak with each other.
If you are a wizard with microcontroller and so, i am sure you can manage... :)
 

KtB

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Joined
Jul 31, 2017
Messages
22
Greg said:
Thanks KtB. Yes, I'm not worried about grid outages. I can't remember the last time we had one here. Which grid tie inverter do you use?
I have theseGTIL2 2000w v2.
Mike on here has quite a few videos about the same one Iuse.
 

Greg

New member
Joined
Aug 14, 2017
Messages
10
Thanks for your thoughts guys, I've been looking into this more myself. I think that this grid tie inverter would be the best solution:

https://midsummerwholesale.co.uk/buy/sofar-storage/sofar-me3000sp.html

It's designed to be used with existing solar systems and comes with CTs to measure production and consumption and controls the charge/discharge acordingly. It can also be programmed to charge at night to a certain level when electricity is cheaper. So I was starting to look if the Batrium BMS could talk to this inverter when I then found this kit:

http://www.homeswitch.co.uk/sofar-solar-9-6kwh

I can't decide if I should just buy this with the batteries or make my own battery! The cost isn't a massive difference As I'm using new cells the total cost of making my own 9.4kWh battery with a Batrium BMS would be ~2700 plus the inverter comes to 3300 which isn't much different to the ready made kit...
 

Greg

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Joined
Aug 14, 2017
Messages
10
For completeness, I've finished the build using these off the shelf batteries as shown below:


image_ylwybl.jpg


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 25mm 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.
 

KtB

New member
Joined
Jul 31, 2017
Messages
22
Greg said:
For completeness, I've finished the build using these off the shelf batteries as shown below:


image_ylwybl.jpg


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 25mm 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.
Having got hold of a couple of the pylontech batterys that where dead.I would recomendthat you make sure that the voltages for charge and discharge are defiantly set up correctly. They only have 15 lifepo4 cells in them not the usual 16 for 48v and if they shut down due to undervolting they lockout and you cannot start them up anymore to even charge them.

This is why the ones i got didn't work anymore :)


image_zxlflg.jpg
 

Kenny.j

New member
Joined
Aug 23, 2017
Messages
7
Greg said:
For completeness, I've finished the build using these off the shelf batteries as shown below:


image_ylwybl.jpg


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 25mm 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 backsetup? What size is your solar array? Ill be interested to see how theism system works for you. With a view to perhaps head down this road myself in the future. Im definitely limited as to choice given that Im grid tied anI want retain my FIT payments. :D

Kenny
 

Greg

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Aug 14, 2017
Messages
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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
 

KtB

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Jul 31, 2017
Messages
22
.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
 

morrisok

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Joined
Sep 3, 2017
Messages
9
Greg said:
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 theME 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
 

Kenny.j

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Joined
Aug 23, 2017
Messages
7
Hi Gregg,

How are you getting on with your new setup! is it working as planned. Have you tried the app? Im interested to know as having watched Robert Llewellyns Fully Charged review of the Tesla Powerwall 2 its 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 Teslas but wondered if youd tried this one?

Kenny
 

7Racer56

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Joined
Sep 1, 2017
Messages
2
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.
 

morrisok

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Joined
Sep 3, 2017
Messages
9
7Racer56 said:
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 usageand 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
 

Kenny.j

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Aug 23, 2017
Messages
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Its not just the maths for me, its about being somewhat self sufficient and not having to rely on the grid so much. I think renewables are the future, we dont 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 ?
 

7Racer56

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Sep 1, 2017
Messages
2
morrisok said:
7Racer56 said:
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 usageand 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 yearago 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 hasgone up a lot in the lastyears 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
 

David Pesce

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Sep 2, 2017
Messages
6
Greg said:
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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