Anyone working toward Off Grid

[creeky]

Randen, does SMA not have a solution for this? They have an inverter designed to go directly from PV to load.

[gasstingy]

It was my understanding when I read about the new SMA inverter that does PV direct to load in an outage, that it only does this within a very narrow parameter up to a max output of 1500w as I recall.

If I were to go through the effort, and I may one day do this, I'd just use an SMA Sunny Island {or 2 so I'd have 240v available} and probably a Leaf battery or two. I currently have a Sunny Boy 5000 on my larger array, so it'll work nicely with it.

[stevehull]

Randen,

When I spoke of balancing it was not to balance the two 120 legs - rather it is production vs load balancing.

You can't just connect a PV panel/inverter up to an appliance (even if 240 V). An inverter is neither a current or voltage source.

Power has to go somewhere and most inverters simply go dead if the output load is not appropriate. Or there is smoke . . . .

This is why I spoke of the need for an intelligent dump load. In this case (imagine full noon sun) and the appliance load is < production power.

A lot of people in the utility offices watch this VERY carefully and are constantly bringing production up and down on and off line to meet ever changing hourly grid power needs. They have strict voltage, current and frequency limits they need to keep the grid within. Some of this is automated, but there is ALWAYS a power engineer in each generation station on 24x7 to either add or strip load - manually if need be.

Load balancing is not easy. One way to do it is to combine batteries and PV panels and THEN do the AC conversion. The maximum from the batteries is always > than load. But this is also expensive.

I am not aware of an inverter (no battery storage) that just with PV panels and the inverter has an associated output that can connect to a dump load (240 V resistance element in water tank for example) that can balance production load and dump automatically.

I would sure like to see one!

Steve

[gasstingy]

Originally Posted by stevehull

You can't just connect a PV panel/inverter up to an appliance (even if 240 V). An inverter is neither a current or voltage source.

I am not aware of an inverter (no battery storage) that just with PV panels and the inverter has an associated output that can connect to a dump load (240 V resistance element in water tank for example) that can balance production load and dump automatically.

I would sure like to see one!

Steve

Cherry picking part of your response to Randen about what I mentioned in my previous post. Please take a look at this and pay attention for the part about: Innovative Secure Power Supply provides daytime power during grid outages

- See more at: SUNNY BOY 3000TL-US / 3800TL-US / 4000TL-US / 5000TL-US / 6000TL-US / 7000TL-US / 7700TL-US

Best as I can tell just a single 120v outlet.

Mark

[creeky]

I'm trying to track down a used leaf battery pack and wondering how to charge it. I can repurpose the cells and charge with my Morningstar controllers (40v). But I wondered if I could use the A.C. charger that's built in along with a SMA inverter.

Then use the high voltage DC (360v) with the new SMA inverter and use it to provide AC to my off grid location. The price of that new inverter (under 1,500 US) is quite attractive.

Any thoughts and ideas?

[mejunkhound]

FWIW
my cabin is off grid but only am there 3-5 nights a year.

4 kW genset for power tools

microhydro of about 400 W from small stream and crossflow turbine and custom gear driven generator. Have 1kW inverter, could have a 50 or so kWhr batterybank that would be float charged from the hydro if I wanted, but no need. 400W enough for everything except power tools.

[mejunkhound]

3742.1



Have most of turbine welded up (pic), need to get the bearing supports welded up next, etc.

Grandsons did some of the welding, lots of technique for them to learn yet.

I'll let them drag the 200 ft of sch 80 surplus pvc conduit thru the woods for the penstock, will try to remember to take pic of that when we install

the old chevy 2.8L flywheel gear will drive a starter pinion and the generator at about 4000 RPM.

it.

I forget how to insert an image without having it on the web ?

[Redmohawk]

Originally Posted by mejunkhound

3742.1



Have most of turbine welded up (pic), need to get the bearing supports welded up next, etc.

Grandsons did some of the welding, lots of technique for them to learn yet.

I'll let them drag the 200 ft of sch 80 surplus pvc conduit thru the woods for the penstock, will try to remember to take pic of that when we install

the old chevy 2.8L flywheel gear will drive a starter pinion and the generator at about 4000 RPM.

it.

I forget how to insert an image without having it on the web ? Attachment 6981

From what I've built in the past , I'd go with direct drive 3 phase gen instead of geared , you'll loose valuable energy through the gears at that sort of step up could be 20% . Noise and wear will also be an issue long term.

For a cheap 3 phase gen look into Fisher n Paykel washing machine motors as a gen, 3 phase at 450v AC at 1000 rpm is no problem for low loss long runs .

[randen]

The thread has gotten a little diluted and terribly side tracked. Let’s get this back on track
I had posted some progress on “ticking all the boxes”

The project thus far has the pergola finished and producing power ( 4 kw ) The power was directed through a high voltage charge controller charging the old Nimh battery pack ( 390 volt ). 29 kWh

The old battery pack has been removed as it developed internal shorts (catastrophically)

A newer battery pack is being sourced

The last week or so has been busy to finish installing the remaining 7 Kw of solar panels on the roof. The Dynoraxx system was used. Very nice system.

My testing of a high voltage inverter solution was unsatisfactory therefore the development of a 2 phase high voltage inverter has begun

Randen

[creeky]

I thought I'd share a pic of one off grid system I helped build this summer.



This is 3kw of solar and 18kw of Volt based lithium with SW Schneider inverter and 600/85 solar controller. I call it the sweetheart.

This fella is running his large cottage; Electric hot water etc and charging his electric car (Leaf), off of solar. I know. Volt batteries. And a Leaf car. Kind of funny.

It really is about load management and smarter building. His cottage is well insulated. Takes advantage of a hillside for earth tempering of hot and cold weather. Yet in most other respects it is similar to a normal tract home.