Tesla Solar inverters

[Garlan Garner]

Blocking diodes have a different function than bypass diodes.
Blocking diodes prevent reverse current flow (primarily useful when you have a panel connected directly to a battery).
Bypass diodes allow current to bypass shaded cells on a panel to prevent the shade from bringing down the whole string.

See my above posts....about the voltage drop per panel using bypass diodes. Its not merely a current drop per panel. Its also a voltage drop. The Voltage drop is immensely more important.

 

[Ampster]

I ran the wiring for our 240v A/C myself. There's no neutral wire. In what way would the A/C even be able to perceive that the power was unbalanced?

Perhaps he was referring to a 120 volt air conditioner. My 240 volt water heater doesn't have a neutral either.

 

[Garlan Garner]

Wait... what?

I ran the wiring for our 240v A/C myself. There's no neutral wire. In what way would the A/C even be able to perceive that the power was unbalanced?

I don't know how in the world you ran in 240 with no neutral wire. That's perplexing to me unless you are using the ground wire as a Nuetral to which …..I would rewire the whole house immediately.

Example:

If you plug in a 240volt Air Conditioner wall unit to 240V outlet that is connected to your power company...your AC would be 120VAC power on one wire ….then there would be 120VAC on the other wire...and back and forth - 120 times a second. The motor in the Air Conditioner can pull all the power it needs up to what circuit breaker limit you installed.
It could potential pull 30 AMPs on one wire and then switch to the other cycle and pull another 30 AMPs from the other wire. That would be great.

NOW. Lets connect our Solar panel strings.

Lets connect one inverter to one string and another inverter to another string. String 1 inverter one has enough panels on it to provide 10 amps of Power. String inverter has enough panels on it to provide 30 amps of power.
Will you be able to power your Air Conditioner unit? Answer: Yes as long as you are grid tied and the 10 AMP side can pull an extra 20 AMPs from your utility 60 times per second. Sure.

But as I stated in my above post: Don't ever try to go off grid with that kind of unbalanced system. It would be like trying to pedal a bicycle with one leg.....except that a motor of that type will probably vibrate the whole house - and would hopefully blow a circuit breaker or something before vibrating itself out of the window.

 

[Garlan Garner]

Perhaps he was referring to a 120 volt air conditioner. My 240 volt water heater doesn't have a neutral either.

Hey ampster….exactly. I was just posting the example of an Air Conditioner as you posted. LOL

How does your Water Heater know that there is 240Volts present without a neutral? The Neutral wire is the 0 line.

 

[Ampster]

I am not dismissing the importance of balancing between the two legs and neutral for 120 volt appliances. Years ago the neutral on my service drop failed and I noticed things were behaving funny. I was getting 180 volts on some plugs and 60 volts on others. Some 240 volt appliances with neutrals have some components that run off 120. For example the control board of my oven burnt up during that situation.

 

[Az_Rael]

I have to say with all honesty that Tesla's solar "sales" are horrible for more than one reason. First of all....its not a sale. Its a rent-forever system. Tesla should be ashamed at making people rent their systems.

Nah, they don’t do that anymore. 8 years ago when we first talked to Solar City that was true. But once Tesla bought them, they majorly scaled back the leasing programs.

I paid cash for my system, and Tesla Energy had zero heartburn with that. They never once mentioned a lease during the sales pitch. So my Tesla Energy/Solar City system is currently 100% owned by me.

 

[Garlan Garner]

Nah, they don’t do that anymore. 8 years ago when we first talked to Solar City that was true. But once Tesla bought them, they majorly scaled back the leasing programs.

I paid cash for my system, and Tesla Energy had zero heartburn with that. They never once mentioned a lease during the sales pitch. So my Tesla Energy/Solar City system is currently 100% owned by me.

Thanks... I thought that they not only leased the systems but also participated in taking a portion of the energy produced for the lifetime of the system.

 

[Az_Rael]

Thanks... I thought that they not only leased the systems but also participated in taking a portion of the energy produced for the lifetime of the system.

Yep, no more PPAs or other weird power agreements either. It was one of the reasons I picked them after Tesla bought them - I figured Tesla was changing them into a “good” solar company from the crappy one they were. Turns out there are still a lot of issues in the chain, so I can’t recommend them to anyone at this point.

I hope Tesla will eventually be able to turn them around though.

 

[Garlan Garner]

Yep, no more PPAs or other weird power agreements either. It was one of the reasons I picked them after Tesla bought them - I figured Tesla was changing them into a “good” solar company from the crappy one they were. Turns out there are still a lot of issues in the chain, so I can’t recommend them to anyone at this point.

I hope Tesla will eventually be able to turn them around though.

WOW!!!! That's good to know.

That's a step in the right direction for them.

No more PPA's WOW. That's great.

 

[wwhitney]

And its not a linear cost increase. a 10 gauge wire isn't just twice the cost of a 20 gauge wire. A 10 gauge wire can be 3 to 4 times the cost.

For the record, the AWG scale is logarithmic, and a difference of 3 in AWG means a ratio of (almost exactly) 2 in cross-sectional area. And at least in larger sizes (maybe #1/0 and above?), the cost will be nearly proportional to the cross-sectional area, but the current carrying capacity grows more slowly than cross-sectional area. [That is because it depends on both resistance (a function of cross-sectional area) and the rate of heat rejection (a function of surface area).]

Cheers, Wayne

 

[wwhitney]

I don't know how in the world you ran in 240 with no neutral wire. That's perplexing to me unless you are using the ground wire as a Nuetral to which …..I would rewire the whole house immediately.

A straight 240V circuit (e.g. for an EVSE) has no need of a neutral conductor. Everything functions normally without any circuit conductor being grounded. If you're under the impression that "electricity wants to return to earth," that's a fallacy.

Cheers, Wayne

 

[Ampster]

No more PPA's WOW. That's great.

But there are plenty of them still around. Last year my daughter bought a home with a Solar City PPA on it. I tried to convince her to have the seller take it with him buy she didn't want to jeopardize the under listing price they got. Her next window of opportunity is in 2 1/2 years when she can buy the system at fair market value. The worse part is that the seller, who had a Tesla, was on a tiered plan which she inherited and the solar has not reduced her bill. If she switches to TOU now she will have to pay the cumulative charges which are just starting to be reduced from the summer production. My point is not only was the PPA from Solar City a bad value proposition but there was no advice about the best rate plan.

 

[deonb]

I don't know how in the world you ran in 240 with no neutral wire. That's perplexing to me unless you are using the ground wire as a Nuetral to which …..I would rewire the whole house immediately.

I can rewire the house all I want, but my air conditioner still only has an L1, L2 and Ground wire.

Are you saying that is unsafe? It's a brand new GE air conditioner. Are they all unsafe? OMG! Is that why GE's stock price tanked??

 

[deonb]

But as I stated in my above post: Don't ever try to go off grid with that kind of unbalanced system. It would be like trying to pedal a bicycle with one leg.....except that a motor of that type will probably vibrate the whole house - and would hopefully blow a circuit breaker or something before vibrating itself out of the window.

When I was in school I was taught that the current in a series circuit is the same throughout.

Now granted it wasn't a very good school and I was paying more attention to the cute blonde in front of me than the teacher, so what do I know.

 

[Shygar]

No it doesn't come down to cost.

You keep saying that. And that's just NOT TRUE.

It comes down to what people want ( value ).

Remember you are posting this in a TESLA forum. TESLA cars are far more expensive than most other cars in their individual classes and there is a huge waiting list to get them.
It comes down to value not cost. It comes down to what people are willing to pay for. That's value. People are willing to pay for the value of Tesla Cars EVEN THOUGH they are more expensive....otherwise if it were all about cost....the waiting list would be at the Nissan Leaf doorstep...or the Chevy Bolt doorstep. Those 2 cars are cheaper than a Tesla, however Tesla is surpassing their sales even though Tesla's are MORE EXPENSIVE.

Autopilot / Summon / Electric Motor Power / Saving the Environment / Super Charging / Sexy Look - all contribute to value ( and are more expensive than other cars.

It doesn't come down to cost. It can't be any clearer. People will pay for value even if the price is higher. There are people in this thread indicating that if Tesla would have offered optimizers...they would have bought them - even though they are higher priced. Click my progress link below and look at my progress chart....and show me a string inverter monitoring service that can monitor per panel like that. Show me string systems that can perform full MTTP per panel optimization. That's value.

IMHO....a customer that choses String over optimizer hasn't been educated as to what power optimization is. Most people just say "I want solar" and don't want to get down into the weeds as to what their options are.

Lets slow down the cheaper rhetoric because its just not true. This is a Tesla forum...not a cheaper forum. Value is the truth.

I'd say the difference is that I expect my solar system to generate me money, so cost is a big factor. But at this point I'm not expecting my Model 3 to generate me money. I will pay more for a higher quality solar system if it's going to last longer, but ultimately it has to make me more money than I spent, otherwise I would unlikely do it.

 

[nwdiver]

I'd say the difference is that I expect my solar system to generate me money, so cost is a big factor. But at this point I'm not expecting my Model 3 to generate me money. I will pay more for a higher quality solar system if it's going to last longer, but ultimately it has to make me more money than I spent, otherwise I would unlikely do it.

Yep... no such thing as a luxury kWh. Just a clean kWh. If they're both clean I'll take the cheapest one.

 

[cwied]

Yep... no such thing as a luxury kWh. Just a clean kWh. If they're both clean I'll take the cheapest one.

I think the analog to "luxury" in this case is limited space. For roof-mount installations you may not have the ability to easily add a panel, so you'd be willing to pay more per kWh to get the output you want with the same number of panels as the most cost-efficient system.

 

[Shygar]

I think the analog to "luxury" in this case is limited space. For roof-mount installations you may not have the ability to easily add a panel, so you'd be willing to pay more per kWh to get the output you want with the same number of panels as the most cost-efficient system.

Solar driveway?

 

[Garlan Garner]

I think the analog to "luxury" in this case is limited space. For roof-mount installations you may not have the ability to easily add a panel, so you'd be willing to pay more per kWh to get the output you want with the same number of panels as the most cost-efficient system.

One such Luxury is per panel monitoring.

Another Luxury is varying string lengths.

Another Luxury is the ability to use whatever panel you want wherever you want. Mix and match Panels on the same string...

 

[Garlan Garner]

Solar driveway?

There ya go... Great idea.

Lets put in Solar Driveways. No problem with parking your car on it and shading it. Small panel here and a big panel there. No problem.

Now...if I can only get my driveway to tilt 22.5 degrees to the south for optimal sunlight...… I'll worry about that later. LOL