Higher voltage inverters

[niel]

i've been thinking that there may be a market for inverters that are above the standard value inverters of 12v, 24v, and 48v. you already have a controller that is capable of handling the higher battery voltages up to 93v and the higher battery voltages would also bring efficiencies better in line for the input to output ratios on the classic. i see guys with large systems having to parallel many strings of batteries for the larger inverter draws at 48v. this would make it more manageable. i know you're looking to have systems growable, but there may still be a market for inverters in the 4kw to 8kw range with higher battery voltages as an input option. how about super sized modules at say 72v or even 84v that are growable with increments of say 2kw? with the max of the classic sitting at 93v you can't double it like the 12-24-48 trend goes.

i know it presents a larger range of models to be engineered, but the higher voltages are best utilized as a starting point for most expanded applications. maybe the forum readers can input their thoughts on higher input voltage inverters that are expandable. i am seeing many inquiries on going higher than 48v for the inverter as people are getting it that the lower voltages aren't always cutting it for high power uses being they have to parallel battery banks to accommodate it and that gets messy at times.

[boB]

Niel, Midnite makes the Classic 250KS  that charges a
120V nominal battery bank up to 150VDC maximum.

There are 120V inverters out there.  Exeltech for instance
makes one in the states.  There are also some 120VDC inverters
made in Australia and down under.

I don't see us making a 120V DC inverter though in the near
future anyway.


boB

[niel]

yes, i'm aware of the exeltechs, but they also make standard inverters that are modular too so why are you delving into the modular aspects then? i did forget about the mks model, but i think there may be a market for modular in the higher voltage ranges for you guys. if you want people to go to exeltech then they could do so for all other models as well making it moot for you to go into it at all then with your same argument. up to you though.

[Halfcrazy]

With PV prices going the way they are I could definitely see say a 96v inverter. Wire size is now starting to hit us again like it did 20 years ago on 12 volt systems. It is nothing now to see a 24kw inverter system in a normal off grid system. That said it will be tough just do to listings etc.

Ryan

[ibedonc]

I am ready , I could do a 120 - 150 vdc inverter today , I have designed my own , but would like a off the self one
that does not cost so much , I have 40 120ah batteries right now and will have more , and 6kw of solar , I have been making my turbines at 100 -200v , with the cost of copper , higher volts off sets that cost , I work in a datacenter that runs 400vdc battery banks for UPS
you get more watts out of a turbine at higher volts , less lost

I am a friend of Tom W

[boB]

Hi ibedonc !   Welcome !  A friend of Tom's is a friend of ours !

What kind of inverter topology did you use on your inverter ?

I have heard of 400V UPS's for server farms and have seen large ones
but don't know what the voltage was.  One was an Emerson.

Good to see you here.

boB

[ibedonc]

I used a sinewave chip to supply the 60hz sine , crystal ref

used a current sink to create a triangle wave  and then a op amp to integrate into a PWM , that went to a H-bridge MOSFET using IR mosfet driver chips , pwm freq is 30khz

made my own low pass filter

so no cpu in my design
it works
I have run it off of a bank of 7ah gels with +- 200v

[laszlo]

Would you have a trace of your inverter's waveform? Also, what kind of conversion efficiency do you get with it?

[ibedonc]

I have to find the jpegs this was 3 or 5 years ago and I have not tested the eff yet

[mahendra]

i agree with the market for higher voltage inverts but i think guys like Bob have to initiate something like that ,i can safely say there is market in the Caribbean and South America since alternative energy is just catching on and prices are becoming affordable(slowly but surely) .48 volts max limits us here and its a major factor when setting up solar or wind systems.So definitely higher voltages inverters would be really nice.

[billvon]

i've been thinking that there may be a market for inverters that are above the standard value inverters of 12v, 24v, and 48v. you already have a controller that is capable of handling the higher battery voltages up to 93v and the higher battery voltages would also bring efficiencies better in line for the input to output ratios on the classic.

As an additional benefit, there will soon be a large number of 200-400 volt battery packs available as hybrids and EV's replace their battery packs (or are junked.)  Even a Leaf battery that has degraded significantly (say to 50% of its capacity) is still good for 12kwhr, and is designed to be fairly light, well protected and very high power output.

[boB]

As an additional benefit, there will soon be a large number of 200-400 volt battery packs available as hybrids and EV's replace their battery packs (or are junked.)  Even a Leaf battery that has degraded significantly (say to 50% of its capacity) is still good for 12kwhr, and is designed to be fairly light, well protected and very high power output.

Maybe those can be broken down into lower voltage and then paralleled ?

boB

[vtmaps]

Maybe those can be broken down into lower voltage and then paralleled ?

Don't these battery banks have BMS (battery management systems)?  If so, you would have to redesign the BMS to support the change in configuration.

--vtMaps

[boB]

Maybe those can be broken down into lower voltage and then paralleled ?

Don't these battery banks have BMS (battery management systems)?  If so, you would have to redesign the BMS to support the change in configuration.

--vtMaps

Yes and maybe the BMS isn't included ?

I think that if the batteries are worn out, they should be recycled.  Probably not worth all the hassle for
depleted batteries ?

boB

[billvon]

>Maybe those can be broken down into lower voltage and then paralleled ?

Perhaps - but a lot of the value of those packs is that they are monolithic, well protected and relatively safe.  Disassemble them and you lose those features.

>Don't these battery banks have BMS (battery management systems)?  If so, you would have to redesign the BMS to support the change in configuration.

I don't think you'd have to do much.  Those batteries are designed to accept charge/discharge at 4C rates so the BMS wouldn't get upset by the lower rates in RE systems.  Perhaps you'd have to spoof the CAN bus a bit.