Solar Panels and Battery Backup

[NY_Rob]

That rate definitely helps with the value of solar. We currently pay $0.10241/kWh (for the first 1,400 kWh) and $0.11077 after that, plus a $14.23 customer charge, so any system we install will take a long time to pay off.
I thought about going without batteries, but my Wife wants us to have them for outages. We typically have a few of them ever year (lasts for a couple of hours mostly).

That's a tough one since your rates are so low. For me it was a no-brainer because I've owned this house since 1991 and my utility rates have more than doubled since then and have gone up every year without fail.

At your rates, it would take me around 13 years to break even... IDK if I would have gone with solar at that point.

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[md2023]

Does your utility have net metering? PG&E is net metering. So they just add up what you used and what you generated and bill you at the end of the year. It’s also time of use, so if you charge your battery when it’s sunny and peak cost, you actually are losing out because you are storing expensive energy.

With a setup like that, the only way to save is to charge the battery off peak, ironically pulling cheap power from the grid, and then discharging it during peak only so you are using lower cost energy during peak cost time. With costs here, you can probably save a little. But that’s a lot of work on the batteries and Tesla has warned me that the batteries will not last more than 10 years using them like that, which kills the cost benefit for me. 3 batteries is about $20k and I can maybe save $5-7k with load shouldering in 10 years.

Unfortunately, we do not have net metering. We are paid a flat rate for the power we send to the grid, regardless of the time of day. We receive a $10/month credit if we charge our vehicle at night (or via solar). My system uses solar to power my home and charge the battery. The battery gets charged up and run down (to 10%) on a regular basis. I only pull from the grid when neither solar nor battery is supplying enough power.

 

[md2023]

We based our decision to purchase solar on the environmental impact, followed by cost. After that, and along side it, were guesses and random considerations such as expected increase in energy costs over time, future regulations/incentives and other minor conveniences such as battery back up for outages. If I could have comfortably afforded it at the time I would have included 1 or 2 more batteries.
If the only consideration was financial, then it would have essentially been a toss-up and prob not worth it. But it wasn't and we are generally happy with the decision.

 

[Hereforthesnacks]

Unfortunately, we do not have net metering. We are paid a flat rate for the power we send to the grid, regardless of the time of day. We receive a $10/month credit if we charge our vehicle at night (or via solar). My system uses solar to power my home and charge the battery. The battery gets charged up and run down (to 10%) on a regular basis. I only pull from the grid when neither solar nor battery is supplying enough power.

Oh wow. That really changes the calculus!

 

[Hereforthesnacks]

We based our decision to purchase solar on the environmental impact, followed by cost. After that, and along side it, were guesses and random considerations such as expected increase in energy costs over time, future regulations/incentives and other minor conveniences such as battery back up for outages. If I could have comfortably afforded it at the time I would have included 1 or 2 more batteries.
If the only consideration was financial, then it would have essentially been a toss-up and prob not worth it. But it wasn't and we are generally happy with the decision.

Yeah, I’m with you. When we design our next house (when!!!), it will have tons of solar and several batteries. Would love to be connected to the grid just in case, but essentially never use it.

 

[Tikiman71]

Does your utility have net metering? PG&E is net metering. So they just add up what you used and what you generated and bill you at the end of the year. It’s also time of use, so if you charge your battery when it’s sunny and peak cost, you actually are losing out because you are storing expensive energy.

With a setup like that, the only way to save is to charge the battery off peak, ironically pulling cheap power from the grid, and then discharging it during peak only so you are using lower cost energy during peak cost time. With costs here, you can probably save a little. But that’s a lot of work on the batteries and Tesla has warned me that the batteries will not last more than 10 years using them like that, which kills the cost benefit for me. 3 batteries is about $20k and I can maybe save $5-7k with load shouldering in 10 years.

This is exactly the strategy that we are using in San Diego on a grandfathered net-metering plan with the original installation in 2012. Two years ago we added a NeoVolta battery, which is LFP rather than lithium ion, and is more robust in terms of daily discharge cycles. Safer too. We switched to a time of use EV plan to charge the Rivian and NeoVolta from the grid during super off-peak hours.

The battery is programmed to top off charge from the grid at super off-peak/midnight at $0.13/kWh, then we use the battery and solar all day, and begin selling power back to SDGE during peak use time at $0.43/kWh. We are currently accumulating several hundred dollars in credits that will be used during less than optimal solar production months later in the year and for increased upcoming Rivian charging.

Our system is fairly small due to a funky roofline and skylights, but we jammed 15 modules up there totaling 4kW. The NeoVolta battery works great for us, had a better physical form factor for our tight installation, the safer LFP chemistry, and was from a San Diego based veteran owned company with excellent customer service. Total cost over the years for the entire system after incentives was about $24K, and it has generated $20K in power thus far and provided power during outages maybe 2-3 times. Saving money was not our primary motivation for the installation, but it is working out favorably for our situation.

It is so frustrating to attempt to decipher and make sense of all the power company shenanigans and ways they try to de-incentivize solar. Having a good installer and manufacturer who knows how to strategize and design a system to work for you, in your situation, and regionally with your power provider is key.

 

[PaythePiper]

Fair question. $44K. I'm 4 years into an 8 year break even. As electricity rates rise the remaining 4 years will shrink. Being your own power source with two EVs is very satisfying.

Sounds like you made a great decision. Power is still fairly cheap in AZ, but I don’t expect that to last

 

[blacknight]

That's a tough one since your rates are so low. For me it was a no-brainer because I've owned this house since 1991 and my utility rates have more than doubled since then and have gone up every year without fail.

At your rates, it would take me around 13 years to break even... IDK if I would have gone with solar at that point.

Yep, that's exactly our issue and why I need material cost to drop a bit before my Wife and I can decide to commit. We both do really want to go solar though... Once we get our R1T, charging for free will be great, and having additional power stored will be awesome. One day...

 

[PavilionSolar]

If you have natural gas connection get a home generator, cheaper and more reliable, especially since the use case is small.

Sorry but this suggestion is an absolute waste of money. Battery is a better investment but don't get a huge one. Eventually (hopefully) Rivian will have V2H option. In the meantime, regardless of not having net metering, solar literally pays for itself.

 

[PavilionSolar]

Wonder why systems without batteries can't just be diverted off the grid and just to the house, in-case of grid being down etc?

They actually can be. The new enphase iQ8 microinverters do just this. No battery required.

 

[iansriv]

They actually can be. The new enphase iQ8 microinverters do just this. No battery required.

Very interesting! I have those in my solar set up. My system is grid tied. How would this work? Cheers.

 

[Fmc]

They actually can be. The new enphase iQ8 microinverters do just this. No battery required.

Is your avatar real? If so what’s your setup? Off-grid? Inverter? Otherwise cool pic.

 

[Fmc]

Very interesting! I have those in my solar set up. My system is grid tied. How would this work? Cheers.

https://enphase.com/installers/microinverters/iq8/sunlight-backup

i go back and forth on if battery is worth it. When the power goes out in south La it could be days and no amount of battery would keep me up and running and also with wholesale net-metering and no TOU there is not much rate arbitrage for me to take advantage of.

 

[ndmiller]

Sorry but this suggestion is an absolute waste of money. Battery is a better investment but don't get a huge one. Eventually (hopefully) Rivian will have V2H option. In the meantime, regardless of not having net metering, solar literally pays for itself.

been through 20+ hurricanes in Florida and for 14 years it wasn’t but hey I’m sure your solar will work with no sun for days.

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