Smart Solar Charging

[ridgebackpilot]

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.

Sponsored

 

[gryphon]

@ridgebackpilot FWIW, the NSC rate has jumped to over $0.08 since February, so you should do a bit better on your next true-up.

 

[ridgebackpilot]

@ridgebackpilot FWIW, the NSC rate has jumped to over $0.08 since February, so you should do a bit better on your next true-up.

Good to see, thanks! Last year I switched from PGE to my local community energy provider, Central Coast Community Energy. Their electrical generation rates are considerably cheaper than PGE's rates.

However, their published NSC rate is $0.047/kWH, which is lower than PGE's current rate. But if PGE is raising their compensation, maybe my local energy provider will have to follow suit!

 

[Blackpony]

This is a very interesting thread. I have two solar arrays, one that has been in operation (full year) since 2015 and it produces about 12.5 Megawatts of power per year. When I put it in the net mattering I had was 100% and I never had to pay an electric bill once it was up and running for a few months. At the end of each year I had a credit using about 12 Megawatts. In addition for every Megawatt generated we earned one SREC (Solar Renewable Energy Certificate) which are auctioned off to power companies that need to produce some amount of power from renewable sources. I believe that these will run out at some point but they are still being paid to me. That system has long ago paid for itself. Last year I put in a geothermal system and took out our oil powered heating, cooling and hot water system. So no oil cost going toward but I am using more electricity so I added another solar system that will produce about 17.4 Megawatts. But the net mattering rules have changed. Instead of 100% it is now 60% and, what is more, my existing system’s net mattering has also been reduced to 60% net metering based on monthly surplus production. In addition the new system does not earn SRECs but it does earn some form of incentive called Smart payments which is not nearly as generous perhaps a hundred dollars a month. While it may be possible to calculate what my yearly eclectic costs are going to be doing that is above my abilities at this point so I will wait for the year to end.

Of course I am charging my MME almost fully at home so that will be using power too and depending on my net generation it may cost me something. Finally, Eversource, our electric provider, increased the Kilowatt cost substantially in the middle of all this. But Eversource does not have a TOU factor and, like I said, net metering is based on monthly surplus. It will be interesting to see if I will have any costs going forward for my car electric costs. I will let you know when I know.

 

[DevSecOps]

I have a similar setup to yours except a bit more of everything. 39, 320W Silfab panels and 12, 370W Silfab panels totaling just under 17kW with a SolarEdge 11.4kW inverter. 4 PowerWalls and like yours they are also set to self-powered so they take over when there's no solar production.

I installed the Emporia Vue Energy monitoring system and two Emporia EV chargers (one on each side of the garage for connivence). The chargers are hard wired and set to the 48 amp setting so they will charge the car at max if need be. Like Lee mentioned, I have them set to charge the car ONLY with "excess solar". The EV charger constantly varyies the charge amperage depending on excess solar production. If I'm using more power than it's producing or there's a temporary cloud cover, the EV charger pauses. If I need the car to charge at full amperage instantly at any time, I can tell it to do so and it will charge at the max 48 amp setting. Also, the charging amperage can easily/instantly be adjusted on the app.

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.

 

[Jppumper]

I want to have a powerwall, but the thought of the cost scares me as a retiree. Each battery about 20k or more plus the panels and other equipment sounds like 100k

 

[ridgebackpilot]

I want to have a powerwall, but the thought of the cost scares me as a retiree. Each battery about 20k or more plus the panels and other equipment sounds like 100k

Don’t overestimate the cost. Panels aren’t as expensive as Powerwalls and other batteries.

In many places, the grid can act as your battery. The main advantages of having your own battery storage are load shedding (to draw from the grid only during off-peak hours) and emergency backup for your home.

 

[markboris]

I want to have a powerwall, but the thought of the cost scares me as a retiree. Each battery about 20k or more plus the panels and other equipment sounds like 100k

$20K for the install of ONE PowerWall is very high. Three years ago Tesla installed 3 of them including their Backup Gateway and the total with labor was just under 25K. At that time there was a 30% federal tax credit and that knocked a good chunk off. Back in March, I ordered a fourth PowerWall from Tesla's website and 10 days later it was delivered to my home. $8415.50 total cost with tax and delivery. I installed it myself along side the other three, provisioned it and I'm the happy camper. There is still a 30% Federal tax credit so again I'll get a good chunk back.

 

[DevSecOps]

I want to have a powerwall, but the thought of the cost scares me as a retiree. Each battery about 20k or more plus the panels and other equipment sounds like 100k

Most people who purchase Powerwall's don't realize how much money they are throwing away. We have a thread that's blown up where people are complaining about $800 a year for Bluecruise but they tuck their tail to solar installers.

I have 30kW of LiFePO batteries that I paid $11k for (before the fed rebate) (link). That's the equivalent of $40k worth of installed Powerwall's at today's pricing. The only thing Powerwall's have going for them is their sleek looks, but it's not worth the 400% price hike IMO (or 36 years of Bluecruise at $800 a year). Solar panels you can buy used for about $60 a panel instead of $400 through a solar company. The title of the thread says "Smart" but I don't think there's anything smart about paying for Powerwall's - to each their own though.

If you go the DIY route (yes, you can get a tax credit for DIY as well) you can easily install a very powerful system for under 20k, before rebates. I understand that not everyone is up to working with a bunch of high voltage DC, but solar installers are some of the biggest crooks out there.

 

[Rt1AWD]

That's crazy! $300K liability insurance just to connect to the grid?! Talk about a disincentive to install rooftop solar...

... or to connect to the grid

 

[markboris]

Most people who purchase Powerwall's don't realize how much money they are throwing away. We have a thread that's blown up about people paying $800 a year for Bluecruise but they tuck their tail to solar installers.

I have 30kW of LiFePO batteries that I paid $11k for (before the fed rebate) (link). That's the equivalent of $40k worth of installed Powerwall's at today's pricing. The only thing Powerwall's have going for them is their sleek looks, but it's not worth the 400% price hike IMO (or 36 years of Bluecruise at $800 a year). Solar panels you can buy used for about $60 a panel instead of $400 through a solar company. The title of the thread says "Smart" but I don't think there's anything smart about paying for Powerwall's - to each their own though.

If you go the DIY route you can easily install a very powerful system for under 20k. I understand that not everyone is up to working with a bunch of high voltage DC, but solar installers are some of the biggest crooks out there.

Agree with you the PowerWalls are very expensive and yes I did pay a lot for them but I'm one of those people that wanted that sleek system in my garage and like the ease of setting up and choosing my options through their app. Not saying it can't be done any other way since I know you can do the same thing but it's what I wanted. My total cost after federal tax credits which I have no problem taking advantage of, was $23,450 for 54kW of batteries, backup gateway and labor.

 

[DevSecOps]

Agree with you the PowerWalls are very expensive and yes I did pay a lot for them but I'm one of those people that wanted that sleek system in my garage and like the ease of setting up and choosing my options through their app. Not saying it can't be done any other way since I know you can do the same thing but it's what I wanted. My total cost after federal tax credits which I have no problem taking advantage of, was $23,450 for 54kW of batteries, backup gateway and labor.

It helps that you installed them yourself. Any solar related labor is normally blown way out of proportion because they lure people with the word "rebate". That rebate money is baked into their profits.

I agree with you the sleek look of Powewall's is nice, but I have my setup in a room of a secondary building where I could care less what it looks like. All the app functionality I have as well, and much more than what Tesla offers.

Anyone looking to DIY solar hit me up in DMs, I've done way too much to talk about here and there's a lot of amazing resources out there.

 

[ridgebackpilot]

Agree with you the PowerWalls are very expensive and yes I did pay a lot for them but I'm one of those people that wanted that sleek system in my garage and like the ease of setting up and choosing my options through their app. Not saying it can't be done any other way since I know you can do the same thing but it's what I wanted. My total cost after federal tax credits which I have no problem taking advantage of, was $23,450 for 54kW of batteries, backup gateway and labor.

If you ever sell your home, I suspect your Powerwall-based system will have a far higher resale value than some DIY system thrown together with whatever the builder could afford. It’s never particularly smart to be penny-wise and pound-foolish.

In this thread, however, “smart” isn’t a reference to the sage advice we all get here but rather to the connected nature of the Emporia charger and similar systems that help us obtain maximum value from our solar charging!

 

[DevSecOps]

If you ever sell your home, I suspect your Powerwall-based system will have a far higher resale value than some DIY system thrown together with whatever the builder could afford. It’s never particularly smart to be penny-wise and pound-foolish.

Solar resale values are calculated by the amount of energy saved. Every dollar saved is equal to $20 in resale value. It has nothing to do with the type of system. DIY systems are perfectly legal in California and I don't consider saving 10's of thousands to be foolish. If aesthetics of a Powerwall are worth 400x the price to you then that's your choice. The person I replied to didn't think it was worth it, so I gave him other options.

Perceived wealth shaming is a bad take - saving money doesn't mean people can't afford more.

 

[SpaceEVDriver]

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

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

Sponsored