Poll: What inverter is best to use
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Singel hybride inverter
16.67%
2 16.67%
Multiple hybride inverters
25.00%
3 25.00%
Single inverter
16.67%
2 16.67%
Multiple inverters
41.67%
5 41.67%
Total 12 vote(s) 100%
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Aim high, 100 KWh powerwall
#1
This project started end 2017 and only a few things where know.

1. Build with 18650 cells which I salvage from broken packs.
2. Aim for 2 times my highest measured daily use, which is 48 KWh. This means a target pack of 100KWh, as the future also will have an Electric car and Motorbike planned.

In the past years some basics are came up.
3. Max load for my house is estimated between 10 and 15 Kw.
4. I do not want to ballast the batteries more than 0.5C. This means I need at least 30 KWh before I start connecting to the net.
5. Battery packs will be 14S80P which makes an average of 5 KWh per pack. They are with electronics about 30 Kg and that is easier to handle and replace. Pack size is 560mm*400mm*<70mm. The ideas is to place them on the long side.

The first 5 Kw is packed, other are underway, See picture. The pack on the back is a 7S160P. This was my practice pack and I used cells that are not deemed right (low capacity or less than 90% of original capacity) for my Powerwall and is used for charging my E-Bikes. Currently I have >14 KWh packed. This is without a couple of smaller packs and the 7S160P Which I builded to test idea's. I have a steady stream of batteries coming in and currently have tested or are in testing another about 6 KWh on cells and more to come early next years. The expectation s that I will start hooking up somewhere end 2019.

I am not sure with what kind of BMS I will start working and what kind and size invertor I am going to use. I was thinking a Hybrid inverter, any advice is welcome.
Menno
Using 7S80P pack. Building 14S40P packs.
"Tell me, and will I forget. Show me, and I may remember. Involve me, and I will understand." Confucius 450 BC
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#2
What do you have running that pulls 48kWh per day? I'd first take a look at that and see if you can reduce it. Then you wouldn't need such a huge powerwall.
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#3
I said my peak load is 48 kWh a day. My average daily use in winter is about 20. But with a could southerly wind, everyone home, some washing to be done, use of the sauna it just start going up and up. My annual use is about 8000 kWh with a 350 sqr meter house (3500 square foot), a swimming pool, spa, and 2 Sauna's. And we are with four. All runs on electricity. So I covered most of reducing my use.

There is no real issue with the size of the Powerwall. It is just a pet project to build and I will also run my future car and motor bike from it. I have the space, however it is not that big. I got my cells for free. So I just aim high. It is like a road trip, is it how you come to there and not the destination. I learn a lot, reduce the impact on the environment in the mean time. With keeping my house warm it gives me a real warm feeling.

Thank you for thinking with me. If I needed to buy the batteries is would have been very expensive.
Menno
Using 7S80P pack. Building 14S40P packs.
"Tell me, and will I forget. Show me, and I may remember. Involve me, and I will understand." Confucius 450 BC
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#4
I’d just move into a smaller house..
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#5
Better to overbuild for capacity than to underscale. I agree.

You hot water I would see about converting to on demand, if you can (if not already done). The units are LOT better than they were 20yrs ago. For your sauna's, I would see another way of heating them other than thru electricity, or at least primarily through something else. Perhaps you can use evacuated tubes to produce hot water for the sauna (and also for the house if enough). This would go for the spa as well. Evac tubes will work to heat the water drastically, and even works in 0C weather because of the way they work.

For the Pool and Spa, I would have load limiters so that you can't run the Pool/Spa pumps while dryer/water-heater are running or other heavy loads. And vice versa. But have overrides if needed. That way you won't have 4 heavy load devices running at the same time pulling over 5kW of power at once
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#6
(11-30-2018, 10:36 PM)camthecam Wrote: I’d just move into a smaller house..

Great, we not we like our house. I am not building because I need, I am building because I can.

(11-30-2018, 10:38 PM)Korishan Wrote: Better to overbuild for capacity than to underscale. I agree.

You hot water I would see about converting to on demand, if you can (if not already done). The units are LOT better than they were 20yrs ago. For your sauna's, I would see another way of heating them other than thru electricity, or at least primarily through something else. Perhaps you can use evacuated tubes to produce hot water for the sauna (and also for the house if enough).  This would go for the spa as well. Evac tubes will work to heat the water drastically, and even works in 0C weather because of the way they work.

For the Pool and Spa, I would have load limiters so that you can't run the Pool/Spa pumps while dryer/water-heater are running or other heavy loads. And vice versa. But have overrides if needed. That way you won't have 4 heavy load devices running at the same time pulling over 5kW of power at once

Hot water is done by hotwater panel. in winter time it will be topped up between 4 and 6 in the morning. The wash machine runs only from 11pm. Mostly drying of the wash is done outside. Only on rainy days the heatpump drier start automatically after finishing the washing. The spa normal goes on only after midnight. use of the Sauna is not that often but is still uses a lot of power.

I am interested in the possibilities of the load limiters, good idea, so I can prevent some items to run when e.g the heatpump is running or cooking.
Menno
Using 7S80P pack. Building 14S40P packs.
"Tell me, and will I forget. Show me, and I may remember. Involve me, and I will understand." Confucius 450 BC
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#7
How are you going to charge the pack ? Solar + Wind ?

15kW inverter - get a toroid based unit and check the no-load power use as this can be very significant with some units and use 5kWh per day. Custom tuned inverters can be around 30W standby or less for a 15kW unit (not on pulsed standby). You might be able to get away with a 10kW unit depending on how long the overloads above 10kW last or build your own inverter and just put the transformer in an oil bath, just like a standard commercial distribution transformer and you can then run it at a higher loading for longer.

In one regard the battery is the easy bit.
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#8
(12-01-2018, 12:54 AM)completelycharged Wrote: How are you going to charge the pack ? Solar + Wind ?

15kW inverter - get a toroid based unit and check the no-load power use as this can be very significant with some units and use 5kWh per day. Custom tuned inverters can be around 30W standby or less for a 15kW unit (not on pulsed standby).  You might be able to get away with a 10kW unit depending on how long the overloads above 10kW last or build your own inverter and just put the transformer in an oil bath, just like a standard commercial distribution transformer and you can then run it at a higher loading for longer.

In one regard the battery is the easy bit.

Charging will be Solar, and maybe on low priced night energy. Currently I only have an estimate of max use. Did some measurements already and probably can go with 10 kW. All depent of the time and height I have peaks above that. Any examples you can send a link from are very welcome.

Yes the battery from some point the easy bit, but also a lot of work. Smile
Menno
Using 7S80P pack. Building 14S40P packs.
"Tell me, and will I forget. Show me, and I may remember. Involve me, and I will understand." Confucius 450 BC
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#9
Well, at least you got your loads sorted out Smile

Load limiters would monitor your current draw. You'd have a monitor on each power cable and a relay would be used to fully disconnect a circuit if another circuit is running. That's my understanding of how they work, anyways.
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Certified 18650 Cell Reclamation Technician

Please come join in general chit-chat and randomness at Discord Chat (channels: general, 3d-printing, linux&coding, 18650, humor, ...)
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#10
Most of the hours of work goes into the battery, but the rest of the system is usually the more tricky bit.

These are the types of inverter board I plan on using to build my own and oil bath cool the toroid. I still need to find one that is closer to 15kW continuous rated (right FET's, QTY and board design). I have seen the boards and just trying to find out who actually makes them.

http://s.click.aliexpress.com/e/BrUq2Uo

The transformer ends up being the largest part of the cost of an inverter due to the additional cost of the high shipping weight and can be well over 50% of the inverter price.

In regards to solar I would try and put as much solar out as possible (more than you need for the peak of summer) because in winter/spring/autum that is when every kW of capacity really counts. I would estimate 15kW of solar as an absolute minimum (summer maximum of 4:1 - i.e. 4kWh for every 1kW of capacity) and probably closer to 25kW to make the most in the shoulder and winter months with some excess in a couple of months in summer, which an EV will soak up.

Try and heat the pool direct from the solar output as this could then reduce the battery size and use the pool as a thermal store or dump load for the solar.
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