diy solar

diy solar

An Enphase Ensemble Installation

We had some >60 mph gusts here the other day for quite a while and up to 19" of rain in some areas (looks like we got ~17"). Looks like all the panels are generating properly. But once the roof isn't so slick (tomorrow?) I'll head up to check everything out. 99% humidity and tree limbs all over the place.
 
Wow, your panels should be nice and clean ;-)

Good to hear it all held up. Hope your inspection goes well. Be very careful on a wet roof.

We got over a day of heavy overcast and rain, but it really was not enough water to clean them. So my first two days of the next billing month look bad. I had to use over 17 KWHs of grid power. But it is noce and sunny and topping up the battery bank again.
 
Whew... harder to get up on the roof than last year. ; -)
The nice thing about two stories high is the roof isn't buried with limbs and leaves like the yard.

Everything looked good... except I found the base of a stainless T-bolt with the shank snapped on the roof, only saw the tiny thing as it was shiny and today is sunny. I checked all of the clamps and they all seem tight...so no idea where it came from. Possibly it was just under the array from installation and got blown out from under. It does look like the shank was more twisted off than snapped. So all good I guess, making power anyway. ?
 
svetz said:
Enphase has announced their EV chargers... but not bidirectional yet like they talked about earlier in the year (SolarEdge demoed theirs in Las Vegas). You can read about it at https://enphase.com/ev-chargers/home
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The main issue with bidirectional EV charging is that the car has to support it. Very few have the hardware to do it, and even less have software support. The typical J1772 connector was never intended to allow reverse power. The high power pins go the the input of an AC to DC charger in the car. The charger would need to also act as an inverter. I think this is what Hyundai/Kia has done to support a 120 volt 15 amp output. With many companies switching to the NACS (Tesla) connector, it may open the door for this to be easier.

It looks like most EV's are going to start supporting it in the 2025 model year. And since the hardware is there, Tesla says they will be able to do it on all models with a software update.
 
solar8484 said:
This is incorrect as least for current Tesla 3/X/Y.
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All of the block diagrams I have seen for the NACS charging setup shows a physical contactor between the battery and the connector. When the car switches to DC fast charge mode, this contactor directly connects the battery to the large AC/DC power terminals of the plug. This allows DC fast charging at over 300 amps. Due to that high current involved with DC fast charging, I highly doubt they use a diode or other semiconductor device that would not allow reverse current flow. If this is correct, there is no reason that power couldn't flow the other way. So hardware wise, I don't see a reason that it couldn't work. The problem is the software needed to turn on the contactor to power a load going out.

The same thing is basically true for CCS and CHAdeMo cars. You need to tell the ca to turn it on.

One possible issue, that I doubt, is that the BMS load current sensing wouldn't work. Obviously the car can measure the charge current coming in, and it can measure the load going to the motor/drive unit. And the drive unit can also have power go either way, since it does do regen braking. I would expect that all of the battery current, in or out, all goes through the same shunt. So that should not pose an issue.
 
I think it's unlikely that the BMS sensing will be busted. Are these sensors (specifically the one on the charger path) inherently directional or something?

I have heard in a couple of places that recent Teslas have very aggressive bean counting of the current balance on the HVDC bus, so it's not that easy to steal power. But this should be fixable with a hardware change.

Another thing I've worried about with EVs (but not in Teslas b/c it's 400V class) is the ones with 800V architecture. I own one (Ioniq 5), and I don't know if the onboard 400V->800V DC-DC converter works in both directions. It only needs to work in one direction for its original purpose of backwards compatibility with 400V DCFC. Dunno if the first set of bidirectional CCS hardware is going to work up to 800V or just 400V. It would most likely be harder (initially) to find DIY hardware for 800V than for 400V.
 
First, bidirectional NACS standard is not a thing. Not even in draft form. Since this thread is in the context of the Enphase charger which also does not yet have any specific supported EV model. Not even the existing EV models that officially support bidirectional charging. So, any claim that bidirectional charging would work on the existing Tesla's with the Enphase charger is really speculations on speculations. Tesla has never said bidirectional charging would be available for existing Tesla's much less doing it with only a software update. The idea that Tesla would simply rely mainly on the BMS for protection with third-party equipment is a non-starter. This is not some server rack battery. Blowing some FET's in the Tesla BMS because some random third-party equipment screwed up would mean very expensive repairs since the battery pack would need to be removed. If Tesla ever supports bidirectional charging they would likely put in additional protective HW that's would cheaper/easier to replace. Also, power HW is not the only HW change likely required based on what happened with the support for CCS charging. New ECU module is required and not compatible with all generations of existing Tesla's. This is all before we even talking about why Tesla won't do any of it due to business reasons like not killing its Powerwall business or help a competitor like Enphase.
 
Interesting.

What kind of Power HW do you think they would want to add on the path?

Wouldn't it be simpler than switching OBC to bidirectional? Or having to deal with DC-DC conversion as a 800V car has to do?
 
Many possibilities ... Tesla is a big fan of e-fuse so I would expect them to use that at the very least. Probably also dedicated surge and arc fault protection too. Maybe even a bidirectional DC-DC converter. I doubt they would make bidirectional OBC a standard item but it could be an option but that would take additional space and weight for something not used often. More likely they would create their own external bidirectional DC chargers as they already make many chargers. In any case, Tesla is unlikely to do any of this for existing Tesla's anytime soon due to business reasons. For new models, it's a different story. The Cybertruck is designed to provide V2H but only via Tesla equipment. It's unlikely any third-party bidirectional DC chargers (including Enphase) will work with it.
 
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FWIW, I'm not a Tesla owner so this is more for educational purposes for me.

solar8484 said:
Tesla is a big fan of e-fuse so I would expect them to use that at the very least.
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Where else do they use the e-Fuse?

I guess you're saying that EV manufacturers in general should put any components that can be nuked by V2X in a readily serviceable location.

There could be some market pressure for Tesla to do some of this stuff.

Lucid is shipping (or will soon send early access units) a bidirectional DC DC (? not sure about architecture ie DC vs AC, but I believe they have a 800V traction battery so they anyway need an onboard DC-DC for compatibility with 400V infra) setup for buddy (rescue?) charging between EVs. There's not much difference between a bidirectional DC DC capability on a car for buddy charging, vs DC coupled V2X.

Bidirectional OBC (well, I don't know if it's literally bidirectional OBC, but there's a 20A inverter in one of the modules) is on E-GMP cars already. For 230V markets this works OK as a 3000W V2H/V2L. I'm bummed that it's 120V only in the US, haven't tried it on my car yet.

If there are Tesla solar competitors that have V2X then there would be pressure for Tesla to roll something out. And they already have the expertise/pressure on external suppliers on the power conversion part of the external DC-DC charger.
 
Tesla loves e-fuse. Tesla cars don't have a traditional fuse panel with field replaceable fuses. Instead e-fuse is used throughout Tesla cars.
 
It's much easier to access/replace modules with e-fuses than the battery pack. Still it's not as easy and cheap as replacing traditional car fuses.
 
Updated the OP with November's numbers and spent some time plugging stuff into my spreadsheet to start figuring out my average rate for the year. FPL cost of power went up in November by 1.4¢/kWh. So, although I made less power, I actually saved more money than last month.
 
svetz said:
Updated the OP with November's numbers and spent some time plugging stuff into my spreadsheet to start figuring out my average rate for the year. FPL cost of power went up in November by 1.4¢/kWh. So, although I made less power, I actually saved more money than last month.
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Same thing happened here with So Cal Edison. They had another rate hike, and it shortened my break even time by over a year. Of course it does not really make or save me any more real money, but if I didn't have the solar panels, I would be paying out more money.
 
Working on the rates for 2023 in the OP and ran into something I don't understand. I'll have to call up the power company to see what they say, but it looks like my equity charges are double a non-solar home per kWh.
 
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