Smart Solar Charging

[ridgebackpilot]

I just came across this intriguing system. Hope it looks as interesting when it's for sale.

https://enteligent.com/dc-coupled-dc-evses

Sure would be nice to avoid the loss of efficiency involved in converting DC solar power to AC and then back again to charge our EV batteries!

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[markboris]

I just came across this intriguing system. Hope it looks as interesting when it's for sale.

https://enteligent.com/dc-coupled-dc-evses

That does look interesting. I've been so happy with my Emporia Energy Monitor system and EV chargers that when they come out with their V2X Bi-directional charger next year, I want to be first in line.

 

[Jppumper]

Thanks everyone. I am getting a lot of solar info from this thread.

BTW, in the news locally, a homeowner along Florida's west coast had a problem with his insurance company. They would not renew his homeowner's insurance because he had too many panels on his roof. It was a larger home that could be completely off the grid. The insurance company thought that too many panels were a fire hazard. Once he came to an agreement that he would disconnect some panels, they renewed his policy.

 

[Maquis]

Thanks everyone. I am getting a lot of solar info from this thread.

BTW, in the news locally, a homeowner along Florida's west coast had a problem with his insurance company. They would not renew his homeowner's insurance because he had too many panels on his roof. It was a larger home that could be completely off the grid. The insurance company thought that too many panels were a fire hazard. Once he came to an agreement that he would disconnect some panels, they renewed his policy.

Did it name the insurance company?

 

[Jppumper]

Did it name the insurance company?

I don't remember. It was a couple of months ago and I'm 70, lol

 

[Maquis]

I don't remember. It was a couple of months ago and I'm 70, lol

I understand….I’m just a few years behind you!

 

[DevSecOps]

Thanks everyone. I am getting a lot of solar info from this thread.

BTW, in the news locally, a homeowner along Florida's west coast had a problem with his insurance company. They would not renew his homeowner's insurance because he had too many panels on his roof. It was a larger home that could be completely off the grid. The insurance company thought that too many panels were a fire hazard. Once he came to an agreement that he would disconnect some panels, they renewed his policy.

It could be that they over panelled which is fairly common to account for cloudy days and losses and normally done to about 30%. Maybe the insurance company wasn't too happy about them exceeding the inverter limits?

 

[markboris]

It's interesting how so many people are doing it this way. I took a totally different approach.

- I don't send anything back to the grid, ever.
- I have a 24k propane generator that serves as backup to the main house and additional buildings
- I only have 10kW in panels (ground mount)
- I have a 12kW inverter
- I have 30kW in batteries
- My main house isn't served by solar at all.
- Secondary building (office/workshop) is served by grid, solar, and generator

My inverter is set to use solar and battery simultaneously if the draw is more than solar can provide. Then I just replenish the batteries when the car is done charging via solar.

I use Sense, Home Assistant and Solar Assistant to monitor the batteries and if they don't get replenished fully then I'll just pull from the grid at midnight, which is our cheapest rate ($0.09), to replenish them.

The difference I guess is how fast you want your car to charge. If you work from home or are retired or have multiple cars I guess the trickle charge variable rate thing could work just fine, but if you need the car to charge quickly what would you do? In this case, I just pull from the batteries and let solar top them back off. I'm also not completely reliant on batteries as a backup for power loss since all the buildings are covered by the generator.

Hey Todd, we have some differences for sure but also some similarities. I think both of our goals are the same and that’s avoid having to pay our utility company.

I do send power back to the grid because during winter months when we might get a week of rainy days, I may need to pull power from the grid. I want to make sure I have a credit when I get my yearly true up and so far, that’s been the case.

Like you, my solar and batteries simultaneously power my home if the draw is more than solar alone can provide.

My batteries are set to discharge whenever there is not enough solar and never charge from the grid.

I'm retired and have multiple cars. My MME rarely has a low SOC so it charges fairly fast with excess solar only. If I need to charge faster, the batteries are more than capable of doing this and solar will charge them back up.

You live in an area where the noise from a generator probably wouldn’t bother neighbors but I’m not as lucky. While it was definitely a more expensive way to go, I decided on batteries so I could not only use them as a backup but also as a power source charged by solar.

 

[markboris]

While we’re showing off solar apps, here’s my Tesla app illustrating my solar production and MME charging using most of that solar power. Since the Powerwalls are fully charged, the small amount of excess solar power is being sent back to the grid.

Hey Michael, thought I would share yesterday's energy figures. Since you are familiar with the Tesla app, thought I would post these instead of ones from the Emporia app.

Yesterday I was out with my parents most of the day so I didn't have the A/C set as cool as I would have if I were home. It was still running quite a bit though as it was 90+ yesterday. I also didn't charge my car so there wasn't as large of a power draw as there would have been if I were home.

Home Usage:

Solar Generation

Powerwall Discharge

Net Grid Use

 

[DevSecOps]

I do send power back to the grid because during winter months when we might get a week of rainy days, I may need to pull power from the grid. I want to make sure I have a credit when I get my yearly true up and so far, that’s been the case.

That's the way most people do it. I don't have an interconnect so it's impossible for me to send power back. I really wonder how long before they don't give any credit for power. Seems like it's headed that way.

The only reason I charge the batteries from the grid is basically the same reason you send power back. During the winter I can charge the batteries from midnight to 6am using my EV credit rate, then I can draw from those batteries during peak hours when the sun doesn't shine.

I draw way more power than most people in this area due to the workshop and I never have excess with the EV and batteries. Maybe one day, if I add another array, I'll consider sending some back to the grid.

 

[markboris]

That's the way most people do it. I don't have an interconnect so it's impossible for me to send power back. I really wonder how long before they don't give any credit for power. Seems like it's headed that way.

The only reason I charge the batteries from the grid is basically the same reason you send power back. During the winter I can charge the batteries from midnight to 6am using my EV credit rate, then I can draw from those batteries during peak hours when the sun doesn't shine.

I draw way more power than most people in this area due to the workshop and I never have excess with the EV and batteries. Maybe one day, if I add another array, I'll consider sending some back to the grid.

I didn't know you couldn't send power back to the grid.

Yes I think you are right and down the road, I am betting we won't get any credit for power we send back to the grid. On a different subject, last year I participated in the Tesla Virtual Power Plant program that California and PG&E have and earned just over $400 supplying power to the grid from my batteries during last summer. They pay $2 per kW which doesn't sound like a lot but it sure did add up. I did not sign up this year for it yet and not sure I will. I did not like not having full control of my Powerwalls while you are on the program.

 

[DevSecOps]

I didn't know you couldn't send power back to the grid.

Yes I think you are right and down the road, I am betting we won't get any credit for power we send back to the grid. On a different subject, last year I participated in the Tesla Virtual Power Plant program that California and PG&E have and earned just over $400 supplying power to the grid from my batteries during last summer. They pay $2 per kW which doesn't sound like a lot but it sure did add up. I did not sign up this year for it yet and not sure I will. I did not like not having full control of my Powerwalls while you are on the program.

Without an interconnect you can't send power back. It's a safety issue mostly. If there's a power loss (i.e. lines down) they don't want a bunch of batteries back feeding downed wires. Same goes for generators and thus why ATS' are required. If you program the inverter to send zero back then it's not an issue and you can use power during line loss.

$2 per kW is amazing. Our buy back rate is $0.074.

 

[markboris]

It could be that they over panelled which is fairly common to account for cloudy days and losses and normally done to about 30%. Maybe the insurance company wasn't too happy about them exceeding the inverter limits?

SolarEdge inverters use to have a maximum of 155% over provisioning so with my 11.4kW inverter I could have 17.1kw of panels (I currently have 16.9kw of panels). Now they are updating the firmware in their inverters to allow 200% over provisioning.

 

[markboris]

Without an interconnect you can't send power back. $2 per kW is amazing. Our buy back rate is $0.074.

No, the $2 per kW is not what PG&E pays to buy back my excess solar on a daily basis. They pay me $.088 for that. The $2 per kW is what they pay me during specific high power demand events and that power must come from my Powerwalls, not my solar. It is a special program between Tesla and PG&E.

 

[ridgebackpilot]

No, the $2 per kW is not what PG&E pays to buy back my excess solar on a daily basis. They pay me $.088 for that. The $2 per kW is what they pay me during specific high power demand events and that power must come from my Powerwalls, not my solar. It is a special program between Tesla and PG&E.

I also participate in Tesla's Virtual Power Plant, and made several hundred dollars last summer when I sent power back to the grid at $2/kWH during declared grid emergencies. It's a great program with more than 5,100 participants. I'm told they avoided activating the peaker plant at Moss Landing last summer because of all the power we sent back to the grid!

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