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The BYD B-Box can help households and businesses to slash their electricity bills by storing the output of their rooftop solar panel systems for use in the evening, when household electric appliance demand tends to rise. The B-Box can minimize the amount of solar energy that is fed back to the grid, as well as the impact of costly electricity tariffs.“The B-Box series offers a wide range of renewable power capabilities to meet light to heavy electrical load usage, off-grid or on-grid, single-phase or three-phase applications.” said Julia Chen, Global sales director, BYD Batteries. “Ideally, the B-Box can be integrated to a fully sustainable energy-independent enterprise or lifestyle, enabling its users to reduce reliance on electricity from fossil fuels.
BYD Cabinet with IP55 Rating 0-955BYD is the world’s largest manufacturer of rechargeable batteries

Those three letters stand for Build Your Dreams and apparently their dream was to build a battery box and sell it for storage in grid-tie solar systems because that’s exactly what they’re doing with their B-box battery systems.
There are 2 product lines – the High Voltage1 (HV) and Low Voltage (LV) B-Boxes, each in a variety of storage capacities.
The one most likely to be used for home energy storage is the B-Box LV Residential, which comes in 4 sizes.  The smallest being the B-Box 2.5 with 2.45 kilowatt-hours of usable storage and the biggest, the B-Box 10 with 9.8 usable kilowatt-hours.
The B-Box batteries pack more power per kilowatt-hour of storage than almost any other system.  BYD batteries are lithium iron phosphate, which is the safest lithium chemistry. 

BYD has confirmed a retail price for the B-Box 10 - $9,950 including GST

BYD is huge

BYD is a massive Chinese company headquartered in Shenzhen, a city of 12 million immediately north of Hong Kong.  Many people have not heard of BYD despite it being bigger than Tesla2. 
BYD has around 220,000 employees and a market capitalization of about $22 billion.  

BYD manufactures batteries, LED lights, solar panels, trains, and monorails.

They don’t just produce more batteries than Tesla3, they produce the most rechargeable batteries in the world.  
bbox2 BYD-568

B-Boxes Use The Safest Lithium Battery Chemistry

The B-Boxes’ batteries are lithium Iron Phosphate.  This is the safest lithium chemistry as it is very difficult to get these batteries to overheat and undergo thermal runaway, which is where they uncontrollably raise in temperature and catch fire.  Thermal runaway is also known as “venting with flame”.
If someone tells you lithium iron phosphate batteries are immune to thermal runaway, that’s not true.  They simply  haven’t tried hard enough.  However, as they need a temperature of over 480 degrees to suffer thermal runaway they are much safer than those dangerously unstable lithium batteries we use in our phones and laptops.  

Chinese electric cars normally use LiFePO4  (lithium iron phosphate) batteries and not the higher performance NMC (lithium nickle manganese cobalt) batteries used by Tesla and others.  This makes Chinese electric vehicles simpler and cheaper –  although with reduced performance.
But it does mean China is getting a lot of practice producing lithium iron phosphate batteries which I believe will soon become the cheapest and best for stationary storage.

The B-Box LV Residential Needs An Inverter

The B-Box LV Residential is not just a battery. 
For your money you get lithium iron phosphate batteries, an IP55 rated powder coated steel cabinet, and a battery management system.  This is a lot better than just a stack of batteries, but it will need a compatible multimode (hybrid) inverter to work.
BYD says compatible inverters are SMA, GoodWe, SolaX, and Victron.   We have been told more compatible inverters will be announced soon.  Since BYD is a huge company, I think there is an excellent chance this will actually happen.
The correct inverter will allow DC coupling to solar and backup power during blackouts.

These Are High Power Batteries

The B-Boxes have high power output.  As far as I know it is only exceeded by the German-made BMZ ESS3.0.  The continuous power B-Boxes can supply is equal to their nominal storage capacity.  This means the B-Box 10 can give 10.24 kilowatts of power continuously and go from fully charged to flat in a little over 57 minutes. That’s very impressive.
Their peak power is also excellent.  They can give twice their continuous output for 3 minutes which is far better than most batteries and long enough to boil the kettle.

When off-grid, it is also useful for starting pumps, air conditioners, and other devices with electric motors.
High power output means less electricity gets drawn from the grid when household demand is high or, if used off-grid, it managing loads is easier.  
Unfortunately, just how much power the B-Box can supply and how rapidly it can charge is limited by the inverter it is attached to.

B-Box LV Residential: Size, Weight, And Weather Resistance

The B-Box LV Residential is not a small battery system. 
It is 173 cm tall, 62 cm wide, and 32 cm deep. 
That’s about the height and width of a refrigerator, but only around half the depth.  It doesn’t matter whether it is the B-Box 2.5 or the B-Box 10, the cabinet size is the same.  Weight starts at 100 kg for the B-Box 2.5 and increases in steps of 35 kg until the B-Box 10 comes in at 205 kg.
This means that, while I am a little taller, I’m not sure I could beat the B-Box 7.5 in a fight because it has a slight weight advantage.
I also have to admit the B-Box cabinet is a lot less sexy than the Powerwall 2 case.  But if you find yourself concerned over which battery enclosure is the most sexy, or indeed find them sexy at all, perhaps you should seek professional help.  I know I have.
The cabinet’s Ingress Protection rating is IP55, which means it is suitable for indoor or outdoor installation.

Operating Temperature Range Could Be An Issue

BYD’s brochure states the B-Boxes have an operating temperature range from 0 to 50 degrees.  If this refers to the temperature of the battery itself, then this makes it suitable for installation anywhere in New Zealand.  Even if the air temperature occasionally drops below freezing, the thermal mass of the batteries will prevent them doing the same.
But the B-Box warranty document says that in order for the warranty to apply:
“4.7  The ambient temperature during the operation of the product must not exceed 0 ℃ ~50 ℃ temperature range…”
This is very different, because ambient temperature refers to the local air temperature which means the only capitals where it could be installed outdoors are Darwin, Brisbane, and probably Perth7.  The other capitals are too cold in winter, as is central Australia.
Fortunately, lithium iron phosphate batteries are quite capable of safely operating if the ambient temperature is below zero, provided the battery isn’t.  So I think it is likely BYD will drop the word “ambient” from their warranty, or at least they will if they want to sell many B-Boxes here.
While lithium iron phosphate batteries are more resistant to deterioration caused by heat than other lithium batteries, it is still a good idea to install it out of direct sunlight.
The B-Box has no fan and no active cooling system.  The BYD brochure says it is “nature cooled” which is a term I don’t approve of because it makes me think tuis will come and fan it with fern fronds or bees will gather at its grates and blow air into it with their wings.
As there is no active cooling there is no fan which means it should be completely silent.  If it does make noise then you probably have a problem.  Maybe a lock picking possum has moved inside.  But you can expect any multimode inverter you attach to have a mild hum.


One piece of information BYD doesn’t offer is how efficient their batteries are.  I presume this is because it is nothing special.  The round-trip efficiency of a lithium iron phosphate battery is typically around 92%.  This means for every 100 kilowatt-hours of energy put into the battery 8 kilowatt-hours will be lost.  A small amount of energy will also by lost by its multimode inverter, so the overall efficiency might be around 89%.

Higher Voltage And Professional Versions

In addition to the B-Box LV Residential there are two other types – the B-Box HV and the B-Box Professional.

The B-Box HV Needs A Sunny Boy Storage

The B-Box HV has a built in DC converter which means it can accept a higher DC voltage than other B-Boxes.  The drawback of this is the only way it can be connected to a home at the moment is with a Sunny Boy Storage battery inverter.  While this will allow it to be AC coupled to any home regardless of what kind of inverter the rooftop solar system has8, it limits both charging and discharging of the B-Box HV to 2.5 kilowatts.  As the smallest B-Box HV has a continuous power output of 5.6 kilowatts, this means the Sunny Boy Storage won’t even be able to provide half its potential continuous power.
There are 5 B-Box HV models.  The smallest has 5.26 kilowatt-hours of usable storage, while the largest has 9.47.
Like the B-Box LV Residential, it can be located indoors or outdoors, but its casing is considerably sexier and looks like an electronic beehive.

BYD B-Box Energy Storage-23

The B-Box Professional – Do Not Get Wet

The B-Box Professional is very similar to the B-Box LV Residential, but its capacity can go one step larger.  Also, its cabinet is black and squat and probably the sexiest of the lot.
Unfortunately, with an enclosure protection rating of IP20, it can only be located indoors and cannot be exposed to water at all.
At 88 cm tall, 60 cm wide, and 51 cm deep, it takes up more floorspace than the other two types.

Current Generation are exclusive suppliers of BYD battery storage in New Zealand.
Please contact us for further information
Thanks to Solar Quotes Australia for an easy to understand, non biased report.
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