grid tie inverter

[nwdiver]

The second post in that thread corroborates the 2,500W DC-DC rating.

With no source. And the photo of the DC-DC converter shows #2 wire which is only good for ~100A. Also mention of a 100A fuse. That's ~1200w.

I suspect the confusion is throughput vs conversion. The DC-DC converter also feeds others load but those loads aren't 12v powered.

 

[David99]

The DCDC converter is fused for 250 Amp. If we apply the 80% continuous load rule, we have 13.5 Volt at 200 Amp = 2700 Watt.

 

[nwdiver]

The DCDC converter is fused for 250 Amp. If we apply the 80% continuous load rule, we have 13.5 Volt at 200 Amp = 2700 Watt.

What's the source for that? I can't find anything even close to resembling an official spec sheet....

200A is A LOT of current. Any high resistance connections would get very hot very quickly.

 

[David99]

What's the source for that? I can't find anything even close to resembling an official spec sheet....

200A is A LOT of current. Any high resistance connections would get very hot very quickly.

Specification of DC-DC converter in Tesla Model S | Tesla

 

[AB4EJ]

Guys, correct me if I have misunderstood this but... I think it is possible to put in a grid-tied inverter, and add to your system a Tesla Powerwall. Even if you use an inverter that does not interface directly with the Powerwall, you can supposedly program the Powerwall to charge during the day and push its power out during peak demand period (in this case, the Powerwall is connected directly to the house main panel, just like the solar system inverter). This is a possible configuration, is it not?

 

[nwdiver]

Specification of DC-DC converter in Tesla Model S | Tesla

... not exactly the quality of source I was searching for...

If you manage to pull ~200A from the DC-DC converter please post about it... I would be very interested to find out if this is possible...

 

[miimura]

I couldn't find any conclusive proof. However, I did see this interesting thread on the RAV4 EV forum. This is the same Tesla DC-DC as a 2012-2014 Model S. When the cabin heater fails, it blows one of the 40A HVDC fuses. That's ~15kW and there are two 6kW resistance heaters and the AC compressor connected in addition to the DC-DC converter itself.

Toyota Rav4 EV Forum • View topic - Anatomy of The DC/DC Converter

 

[gavine]

Is this what the OP is looking to do?

 

[Ampster]

For power generation >4kW you really want voltage >200v. Radians operate at 48v. I have a 8kW grid-tie. If I wanted to generate 8kW with a Radian I'd need wire that could handle ~170A instead of ~24A.

I agree, but what inverters will work with a high voltage battery and be a back up when power is down? Solaredge? I am hoping that the new Outback will.

 

[nwdiver]

I agree, but what inverters will work with a high voltage battery and be a back up when power is down? Solaredge? I am hoping that the new Outback will.

Solar edge seems to have the best one... Fronius and SMA have HV battery backed inverters but I don't think they're available in the US yet. Outback has a new inverter called the Skybox that's supposed to come out next year but I couldn't find any specs... not sure if it's 48v or >300v....

 

[SageBrush]

I'm surprised PV (or more PV) is not the obvious choice for peak shaving.

 

[Ampster]

I'm surprised PV (or more PV) is not the obvious choice for peak shaving.

I thought the only way to do peak shaving was with batteries. With PV only one would only be able to do peak shaving during the day.

 

[Ampster]

Solar edge seems to have the best one...

I am waiting on the Skybox so I can compare the two. I should be able to use the Mate3 interface and Opticsre remote monitoring. Hopefully the Skybox operates on 240 AC like the Radian. If I recall the SolarEdge needs a transformer to do that. I wonder if that adds more loss? The SolarEdge price per Watt is attractive. The Radian was expensive and on top of that the Mate3 and the battery monitor plus a separate battery charger added almost $1000 to the system cost.

Your comments have been helpful as I am doing a system upgrade when my HOA puts on a new roof next year. It will be fun comparing the Skybox and SolarEdge.

 

[miimura]

I am waiting on the Skybox so I can compare the two. I should be able to use the Mate3 interface and Opticsre remote monitoring. Hopefully the Skybox operates on 240 AC like the Radian. If I recall the SolarEdge needs a transformer to do that. I wonder if that adds more loss? The SolarEdge price per Watt is attractive. The Radian was expensive and on top of that the Mate3 and the battery monitor plus a separate battery charger added almost $1000 to the system cost.

Your comments have been helpful as I am doing a system upgrade when my HOA puts on a new roof next year. It will be fun comparing the Skybox and SolarEdge.

I thought the Radian didn't need a separate battery charger because the generator input (non-grid-interactive) could be used as a programmable battery charger with appropriate Mate3 programming. Am I wrong there or does your battery charger have additional features I'm not considering? I do know that you need separate solar charge controllers to do MPPT directly into the batteries with a Radian system. Skybox is supposed to integrate it all together.

 

[SageBrush]

I thought the only way to do peak shaving was with batteries. With PV only one would only be able to do peak shaving during the day.

Oh .. I think I see.
I was thinking of peak hours, but you and presumably OP mean highest load. I'm still surprised that is not a daytime event

 

[miimura]

I'm surprised PV (or more PV) is not the obvious choice for peak shaving.

One interpretation is to eliminate usage (grid draw) during the peak rate period time window. For me, the Peak rate period goes until 9pm, so there's no way for solar to do that.

 

[SageBrush]

One interpretation is to eliminate usage (grid draw) during the peak rate period time window. For me, the Peak rate period goes until 9pm, so there's no way for solar to do that.

That thought occurred to me too, but I'm under the impression that most of the use in the late Peak rate period is due to summer A/C when people get home from work. That use can in part be moved to solar hours by time shifting the A/C use to cool down the home from ~ 4 pm and putting up some west facing panels. The home can also be cooled down a little more than usual during the PV hours

 

[miimura]

That thought occurred to me too, but I'm under the impression that most of the use in the late Peak rate period is due to summer A/C when people get home from work. That use can in part be moved to solar hours by time shifting the A/C use to cool down the home from ~ 4 pm and putting up some west facing panels. The home can also be cooled down a little more than usual during the PV hours

Yesterday was a sunny day and the solar output had a very smooth curve. It fell to 10% of max at 4:15pm and was below 4% from 4:45pm to dark. I have hills to my west, so once the sun goes down below the hill, there's only a little bit of scattered light generation.

 

[David99]

I did a first test run with a cheap 1000 Watt grid tie inverter. It went better than I expected. Attaching cables to the 12 Volt system is pretty easy from the 12 Volt battery. The car keeps the 12 Volt system perfectly stable. Unfortunately, all grid tie inverters I could find are for 22 Volt or higher. The one I used for testing starts at 10.5 Volt but to reach it's nominal power of 1kW it would need around 22 Volt. The car only provides 14.2 Volt which means the inverter maxes out at around 600 Watt. That's a little disappointing. But I cannot find an inverter that is optimized for 12 Volt and is grid tied. There are plenty of high power inverters available for 12 Volt, but none of them is grid tied.

Another interesting thing: I was expecting the car would have to be kept on for the DCDC converter to be on. During my tests I turn off the car to see what would happen. It shut off, and of course the high load from the inverter made the voltage drop right away. Within 2 seconds the car realized it and turned on the DCDC converter and kept it running. In other words, you can just park and lock your car and the grid tie system would not drain the 12 Volt battery at all.