advice on upgrading 24v to 48v

System

Hi,
I would be grateful if you could give me some advice. I have an off grid system:
24v outback vfx2430
2 x outback mx60
24v battery bank
I am in the process of interfacing a proven 2.5kw wind generator. I have built a diversion charge controller for 48v and this is charging a 48v battery bank.
My intention is to upgrade the outback inverter to an inverter charger at 48v. My inclination is to go with a sunny island 5048. This will mean the batteries are charged via my home made charge controller with the wind generator and via pv array (2.2kw) using the sunny island. I have a diesel generator for low output days.

I would really welcome your advice on planning the system. I am pretty clued up on the products and I am comparing other 48v inverter chargers. We have managed great with a vfx3024, but since I am going to have spend a heap on upgrading, I feel that the extra cost of the sunny island will mean that I will not have to reconfigure the system again in the future.


Regards,
Justin

BB.

Re: advice on upgrading 24v to 48v

Justin,

A couple questions... How much power do you want to use in a day (seasonally?), how large are your battery banks, and roughly where is the home (England, Spain, etc.)?

Generally, we like to match the batteries to the load (AH capacity around 6x average daily load--3 days of no sun, 50% maximum discharge for long life) and the charging current/power to be around 5-13% of the Battery 20 Hour capacity.

-Bill

mike95490

Re: advice on upgrading 24v to 48v

Do you have or plan any 240V gear (well pumps or such?) Different inverters either need transformers or an additional inverter to get the high voltage, and some can provide 240V directly (Xantrex XW series)

By

proven 2.5kw wind generator

is that a brand name, or you actually have a working wind gen ?

Solar Guppy

Re: advice on upgrading 24v to 48v

The Xantrex XW-6048 does everything the SunnyIsland can and a lot more for about 40% less in cost. This includes the feature of having GT inverters back feed with the new XW-6048 firmware 1.05.

I haven't tried it yet ...

http://www.global-download.schneider-electric.com/852575A6007E5FD3/all/41B2D3BC19AE2F83852576F000698E7F?OpenDocument&L=EN~EN~FR&p=7654&idxUrl=repositorySchneider\\index.nsf&XID=225305&XHOST=http://logi5.xiti.com/&HOSTIP=http://www.global-download.schneider-electric.com/&OTrSer=http://www.download.schneider-electric.com/

BB.

Re: advice on upgrading 24v to 48v

Proven Energy Wind Turbines?

-Bill

stephendv

Re: advice on upgrading 24v to 48v

Sunny Island vs. Xantrex price all depends on where you are, the SI is cheaper in europe and the Xantrex cheaper in the americas. I suspect Justin's from the UK since he's buying a UK made turbine.

The Sunny Island is a nice bit of kit, a bit more expensive than other 5kW inverters but then it does come with a built in battery meter and would allow you to do AC side coupling in the future if you wanted to.

You'll need a shunt between all other chargers (everything except the sunny island) and the battery. This is then connected to the Sunny Island so that it's battery monitor can work properly. The battery monitor (SoC meter) is quite sophisticated, it even takes the age of the battery into account and learns how to change the battery capacity with age. Without the shunt, it won't be able to calculate the SoC properly.

If you already have a working system then the sunny island would fit in exactly where the outback used to - the rest of the config would be the same, with the exception of it all being 48V.

mike95490

Re: advice on upgrading 24v to 48v

Solar Guppy wrote: »

The Xantrex XW-6048 does everything the SunnyIsland can and a lot more for about 40% less in cost. This includes the feature of having GT inverters back feed with the new XW-6048 firmware 1.05.

I haven't tried it yet ...

http://www.global-download.schneider-electric.com/852575A6007E5FD3/all/41B2D3BC19AE2F83852576F000698E7F?OpenDocument&L=EN~EN~FR&p=7654&idxUrl=repositorySchneider\\index.nsf&XID=225305&XHOST=http://logi5.xiti.com/&HOSTIP=http://www.global-download.schneider-electric.com/&OTrSer=http://www.download.schneider-electric.com/

So could I plug an inverter genset into my porch outlet at night in a storm, and backfeed the XW6048, and charge batteries (without going to the gen shed and fireing up thumper ) ?? (if the genset will sync with the existing 120V line, or would it need 240V to backfeed) That'd save me having to run another 200' of dedicated cable over the creek.

They do vary the XW's output to knock the GT inverter offline

Bummer for my genset.

Dave Angelini

Re: advice on upgrading 24v to 48v

Mike you are wild and crazy! I like your "backfeed style" but... oh yea, really enjoyed the pix!
Now get back to the trench. Might as well just put an extra 2 inch pvc in there with a rope. There is always another wire!

System2

Re: advice on upgrading 24v to 48v

I am in the uk.
Sunny island looks a good choice
What about my diversion load controller - there is not much intelligent controll of the charging - basically the wind generator output is rectified and into the tteries. There is a 3 stage loading applied using voltage monitoring relays. I may have the choice of putting the wind generator output through one of the mx60s to have a bit more intelligent battery charging.

Any comments welcomed.

mike95490

Re: advice on upgrading 24v to 48v

jhinshel wrote: »

I am in the uk.
Sunny island looks a good choice
What about my diversion load controller - there is not much intelligent controll of the charging - basically the wind generator output is rectified and into the tteries. There is a 3 stage loading applied using voltage monitoring relays. I may have the choice of putting the wind generator output through one of the mx60s to have a bit more intelligent battery charging.

Any comments welcomed.

Whatever you put your wind gen thru, it needs to have 100% extra capacity. And a robust diversion load or dump load that does not rely on a cooling fan. Too many systems get fired on a windy night when a 1KW turbine has been putting out 2KW because the controller gets cooked and can't handle the storm load. And that boils your batteries all night while you sleep.
When you can't regulate the wind, the turbine overspeeds and trashed it bearings.

System2

Re: advice on upgrading 24v to 48v

I have up to 6kw diversion loads that will run from the batteries through the inverter. I am concious that there needs to be a dump load run direct from the wind generator output. This requires a 48v (dc or 3 phase) heater element rated around 3kw. I am keen to have a 3 phase air heater in order to do this. I'd be grateful if anyone could suggest how to do this cheaply.

Justin

stephendv

Re: advice on upgrading 24v to 48v

Solar Guppy wrote: »

This includes the feature of having GT inverters back feed with the new XW-6048 firmware 1.05.

SG, do you have any details on how this works? Would be great if they use the same frequency shifting technique that SMA use so that Xantrex and SMA GTIs and sunny islands and 6048's are interchangeable.

mike95490

Re: advice on upgrading 24v to 48v

jhinshel wrote: »

I have up to 6kw diversion loads that will run from the batteries through the inverter. I am concious that there needs to be a dump load run direct from the wind generator output. This requires a 48v (dc or 3 phase) heater element rated around 3kw. I am keen to have a 3 phase air heater in order to do this. I'd be grateful if anyone could suggest how to do this cheaply.

Justin

I'd have diversion load #2, be a motor to wind up the brake on the windmill.

Toss a handfull of 1,000 W 120V water heater elements into a "stock water barrel" I guess you would need 3 paralled, to give a 1,000W load at 48V

BajaGringo

Re: advice on upgrading 24v to 48v

I have a wind/solar setup working well down here in Baja, Mexico. I use several heating elements as my diversion load and I agree that you should oversize the dump = 3X rated turbine output wired in parallel so that in case one fails you still will have a big dump load available. I also suggest you install a good turbine braking system where you can stop the turbine for maintenance and repair as well as consider fuses and lightning protection.

I am using a ColemanAir diversion / charge controller and really like the performance as well as easy wiring setup. It is a hybrid and can handle solar panels as well although I prefer to use a Xantrex MPPT for my panels.

Coleman Air C440-HVA Diversion / Charge Controller

Solar Guppy

Re: advice on upgrading 24v to 48v

stephendv wrote: »

SG, do you have any details on how this works? Would be great if they use the same frequency shifting technique that SMA use so that Xantrex and SMA GTIs and sunny islands and 6048's are interchangeable.

They do vary the XW's output to knock the GT inverter offline ... it is also UL approved as this released software, not some beta version. Should work with any UL1741 inverter , not just Xantrex GT inverters

stephendv

Re: advice on upgrading 24v to 48v

Awesome! I guess though, that if it's compatible with all GTIs, then it must either knock them offline, or keep them online, but they can't vary their output like the sunnyboy's can. Anyway, still a handy feature.

stephendv

Re: advice on upgrading 24v to 48v

stephendv wrote: »

Sunny Island vs. Xantrex price all depends on where you are, the SI is cheaper in europe and the Xantrex cheaper in the americas.

I'm enjoying a delicious hat & mayo sandwich right now. Just stumbled on a Spanish wholesaler who has the Xantrex XW inverters for less than the retail price in the US! Don't know how or why, maybe some sort of perfect currency exchange storm. Justin if you're interested pm me and I'll send you the details.