I see that there are a number of inverters that allow for battery input voltages from 80V up to 495 Volts, so batteries can now be added in series instead of parallel.

The charge/discharge current is limited to 50A which makes for small diameter DC battery cabling.

What other benefits would using a HV inverter provide?

Is this the way inverters a re going to move?

At higher voltages, buck and boost circuits have to do less to output 230V sine waves. Also, you are closer to the string voltages, so smaller conversion and less losses.

A 40A 100V Mosfet transistor is substantially more expensive than a 20A 400V Mosfet.  The so called I^2*R (I squared R) losses get out of hand at high currents.  48V is good for 5KW.  Over 5KW the currents get a bit high.  However, do not mention this to an electronic engineer that has to design a 120KW inverter for an E-vehicle.  300 or 400V is no sweat for silicon.  At 1000V things become a bit more difficult.  In the past, very few components where available for 1000V and up.  The biggest problem is personal safety.  High voltage is bad enough, but DC high voltage, that is unforgiving.

I think we will see a lot of technology advances in this domain.  That is one reason I wouldn't invest in a very expensive inverter now.  Somehow I wonder if the E-car and the household inverter will find some common ground.  Some sort of system integration.  For instance, if you have access solar energy, you can dump that into your car.  So it would make sense to have compatible voltage busses, etc.  Imagine, in future you might "tank up" your E-vehicle at a fast-charge installation, and then drive it home and connect it to your home inverter to feed from the car battery.  LOL.

Due to E-cars fast rise and the resulting production volumes, it is likely to pull down the power electronics costs.  Even a small E-vehicle has an 80KW inverter.  Most have 120+ KW inverters.  And we think an 8KW inverter is big.

12 minutes ago, Modina said:

Somehow I wonder if the E-car and the household inverter will find some common ground.

Pretty much all modern Euro market EVs come with V2G support for exporting/importing/managing power.  But you do need an EVSE with an 800V inverter to integrate it into your house.

@JustinSchoeman Using your car as a mobile battery pack sounds very appealing. I found a video on Youtube of a guy using his Nissan Leaf to power his house inverter by connecting  the High Voltage DC connector to the MPPT controller on his houses inverter. The Nissan has a 480V battery pack so as long as the inverter can handle 480V it does not appear to be a problem apart from having to have the car switched on 🙂 .

EVSE's are REALLY expensive at the moment but I think it is a matter of time till normal household inverter comes with a connection for your EV built in as standard.

i am considering a high voltage deye 20kw inverter - it needs 160-700V batteries though which are rare...seems like a much better answer than normal voltage kit...given losses (97% efficiency for HV v 60% for LV)

No idea where you get 60% efficiency for an LV inverter.  Most are 95% plus.

5 minutes ago, JustinSchoeman said:

No idea where you get 60% efficiency for an LV inverter.  Most are 95% plus.

ok - that helps.. saw it on a LV v HV comparison...

is the HV to AC V only 2% more efficient that LV to AC V?

 

Just now, craig shaw said:

ok - that helps.. saw it on a LV v HV comparison...

is the HV to AC V only 2% more efficient that LV to AC V?

 

Low-voltage batteries are 60% efficient, whereas high-voltage batteries are 97% efficient.

This means when you own a low-voltage battery you have to spend 40% more electricity to charge your battery.

https://firstenergy.co.za/high-voltage-vs-low-voltage-batteries/

 

is this wrong

 

6 minutes ago, craig shaw said:

Low-voltage batteries are 60% efficient, whereas high-voltage batteries are 97% efficient.

This means when you own a low-voltage battery you have to spend 40% more electricity to charge your battery.

https://firstenergy.co.za/high-voltage-vs-low-voltage-batteries/

 

is this wrong

https://greeneconomy.media/low-voltage-vs-high-voltage-power-backup-system/

 

 

 

and this one:

he battery round-trip efficiency is the round trip DC-to-storage-to-DC energy efficiency of the storage bank, or the fraction of energy put into the storage that can be retrieved. Typically it is about 80%. HOMER assumes the storage charge efficiency and the storage discharge efficiency are both equal to the square root of the round-trip efficiency.

 

source - https://www.homerenergy.com/products/pro/docs/3.11/battery_roundtrip_efficiency.html

 

 

Amazing. My 48V RTE always measures ~90%.  But then, I am not trying to manufacture a market for HV equipment.

uok..why do they say HV systems are more efficient then.. voltage conversion losses 230v to 48v and then back again? plus voltage of PV higher and then reduce to 48v again...conversion & heat losses? possible?

17 minutes ago, craig shaw said:

uok..why do they say HV systems are more efficient then.. voltage conversion losses 230v to 48v and then back again? plus voltage of PV higher and then reduce to 48v again...conversion & heat losses? possible?

perhaps only 2-4% difference - only resistance?

32 minutes ago, craig shaw said:

uok..why do they say HV systems are more efficient then.. voltage conversion losses 230v to 48v and then back again? plus voltage of PV higher and then reduce to 48v again...conversion & heat losses? possible?

The difference in the conversion voltage does not play such a big role as the differences in value. 

HV is more efficient - but you are talking about max 5% or so. Mostly due to DC distribution losses. The basic architecture stays the same, as the HV systems still use an HF transformer for isolation - it is just 1:1 instead of 1:8 ratio.

HV does tend to become cheaper from about 15kW though - you need a lot of copper, and a lot of parallel switching devices to move that sort of current around efficiently.

9 minutes ago, JustinSchoeman said:

HV is more efficient - but you are talking about max 5% or so. Mostly due to DC distribution losses. The basic architecture stays the same, as the HV systems still use an HF transformer for isolation - it is just 1:1 instead of 1:8 ratio.

HV does tend to become cheaper from about 15kW though - you need a lot of copper, and a lot of parallel switching devices to move that sort of current around efficiently.

 

9 minutes ago, JustinSchoeman said:

HV is more efficient - but you are talking about max 5% or so. Mostly due to DC distribution losses. The basic architecture stays the same, as the HV systems still use an HF transformer for isolation - it is just 1:1 instead of 1:8 ratio.

HV does tend to become cheaper from about 15kW though - you need a lot of copper, and a lot of parallel switching devices to move that sort of current around efficiently.

thanks - yes - i am looking at 2x12kw or 1x 20 or 30kw inverters (3 phase). but the larger ones need HV batteries which are a bit more scarce for now - but if it works better it may be worth it in the long run..

I think one needs not only look at the voltages etc. One needs to consider your loads. The HV inverters to me make a lot of sense for some large 3 phase loads like bore hole pumps that require cold start surge and inductive loads. The HV machines make heaps of sense due their transformer architecture. The smaller LV especially Sunsynk and Deye are transformerless in design. 

Yes the HV batteries are scare but they make a lot of sense and the copper losses are much less. Prices are actually similar HV vs LV. Thats for FreedomWon anyways, i cant comment for the others, I only install these both HV and LV.

11 hours ago, Steve87 said:

The smaller LV especially Sunsynk and Deye are transformerless in design. 

They are actually not transformerless - the transformers are just high frequency variants (at least for the battery bidirectional inverter section).  The high frequency HV inverters (some Sunsynk are HV, as well as GoodWe etc.) use the same topology - but the windings differ.

15 hours ago, Steve87 said:

I think one needs not only look at the voltages etc. One needs to consider your loads. The HV inverters to me make a lot of sense for some large 3 phase loads like bore hole pumps that require cold start surge and inductive loads. The HV machines make heaps of sense due their transformer architecture. The smaller LV especially Sunsynk and Deye are transformerless in design. 

Yes the HV batteries are scare but they make a lot of sense and the copper losses are much less. Prices are actually similar HV vs LV. Thats for FreedomWon anyways, i cant comment for the others, I only install these both HV and LV.

so a 20kw HV inverter with HV (160v plus) battery and loads of PV makes more sense than normal (LV 48V) sense in the long run?

On 2023/07/10 at 9:31 PM, Steve87 said:

I think one needs not only look at the voltages etc. One needs to consider your loads. The HV inverters to me make a lot of sense for some large 3 phase loads like bore hole pumps that require cold start surge and inductive loads. The HV machines make heaps of sense due their transformer architecture. The smaller LV especially Sunsynk and Deye are transformerless in design. 

Yes the HV batteries are scare but they make a lot of sense and the copper losses are much less. Prices are actually similar HV vs LV. Thats for FreedomWon anyways, i cant comment for the others, I only install these both HV and LV.

steve- what is the smallest freedomwon HV battery pack (eg more than 160/180v but lowest Kwh)?

Hi @craig shawall depending on the voltage of the inverter. 

Try the Pylontech H2 Powercubes. I have the H2 batteries connected to a Goodwe 10 kW EHB inverter. 

 

ah.. good thanks.. i mentioned pylontech … some forum member said better to get 1xhv as series connection an issue..doesnt seem to be as greenrich, deye, and pylon do that…

Pylontech is Half C. So if you want to pull 20kW from the Deye inverter continuously you need 40kWh worth of Pylontech Batteries. Not trying to rubbish them, just saying you need to know that this is not a 1C lithium battery.