Solar Panels and Battery Backup

[Fmc]

nowhere for the excess power to go if you have no grid and no battery storage. no way to compensate for fluctuation in solar output.

Solar system needs a battery...if your grid tied with no battery storage then the grid is your battery...but in that scenario you lose power when the grid loses power.

Curious why a transfer switch would not detect the power out and keep a home powered via solar without the battery. There is more to it since solar does not work without battery during an outage.

Sponsored

 

[emoore]

Curious why a transfer switch would not detect the power out and keep a home powered via solar without the battery. There is more to it since solar does not work without battery during an outage.

What is the transfer switch transferring to without a battery? It’s an open circuit. I’m guess its too much power to leave it open on the strings and I don’t think most arrays can short strings and dump the energy as heat.

 

[3wisemonkeyz]

Any decent solar provider will give you a good ROI if you are looking at 10 years out. Always buy the system, don’t lease.

Backup battery use case is really for power outages. Everything else is gravy and you will not make up the battery cost in any savings. Just won’t compute. So, it comes down to how the power is in your area. In the Bay Area part where I am, we lose power maybe once a year for a few hours. Doesn’t make sense to spend $15k to keep power on for that short amount of time. Especially when a couple 1500kw battery generators can keep throngs going very easily and you can use you R1 to recharge them quickly. If you live where power is not as reliable (hurricane, snow, ice, excessive heat in an area where power gets flexed), the use case for battery backup is way way better. So….just think about your current power situation and how often you need your own power.

Tell me more about this 1500kw generator option - what’s an example model you would use? I’ve been considering battery backup but it seems silly not to take advantage of the Rivian battery I already have, even if as a hack, until V2H is an option.

 

[NY_Rob]

Curious why a transfer switch would not detect the power out and keep a home powered via solar without the battery. There is more to it since solar does not work without battery during an outage.

One problem is, without a battery to stabilize voltage and current you're at the mercy of sun vs clouds. I see my system (43 panels) putting out 12kW under full sun, then the next min clouds roll past creating shadows, blocking the sun and now I'm only putting out 2kW.. imagine what that would do to your home's electronics experiencing constant brown-outs then back to full power then another brownout a few min later?

 

[Hereforthesnacks]

Tell me more about this 1500kw generator option - what’s an example model you would use? I’ve been considering battery backup but it seems silly not to take advantage of the Rivian battery I already have, even if as a hack, until V2H is an option.

Haha. Crap. I was typing too fast. I meant 1500W. Sorry. But I have a couple Jackery’s. They are great. You can run a fridge, internet, TV, computer, whatever you want. Here is a 3000W one that can run heavy appliances and you can get it on sale for $1200-1300. https://a.co/d/9wCfcYy

This bad boy is currently on sale for $2800 and has solar and an extra battery. https://a.co/d/2kDnbJy

If you don’t often have power outages and just need to keep things going for a bit once or twice a year, you can easily do it for less than $3k. Nothing beats battery backup since it’s seamless and auto charges with solar, but the math doesn’t work for me.

I also like the Jackery (and other brands) because you can take it with you on the trail or camping so it has a use outside of backup.

Just my 2 cents

 

[Electrified Outdoors]

Curious why a transfer switch would not detect the power out and keep a home powered via solar without the battery. There is more to it since solar does not work without battery during an outage.

A transfer switch works great to disconnect the grid but that's not the only issue. What makes it work is the ability for power to travel in both directions when your connected to the grid.

What I really like about Tesla is that it can also charge your EV battery with excess production as well.

Solar power production can vary a lot during the course of the day. With no battery and no grid there is no place for excess energy (which changes with demand peaks and valleys) to go. The things in your house would be turning on and off on their own, be subject to damaging brownout, and when the sun goes down it would still be a blackout situation.

In the case of a location where power goes out infrequently and the owner only wants to offset grid energy usage then battery storage is not needed.

If you want to use the solar to power your home during an outage you need battery storage. When the grid is down the battery provides a stable and constant power output to your home while using excess production to replenish the battery.

If you look at your homes energy use there are peaks and valleys. There are also spikes. Its not possible to provide reliable power without some type of battery (either grid or home battery storage).

 

[3wisemonkeyz]

Haha. Crap. I was typing too fast. I meant 1500W. Sorry. But I have a couple Jackery’s. They are great. You can run a fridge, internet, TV, computer, whatever you want. Here is a 3000W one that can run heavy appliances and you can get it on sale for $1200-1300. https://a.co/d/9wCfcYy

This bad boy is currently on sale for $2800 and has solar and an extra battery. https://a.co/d/2kDnbJy

If you don’t often have power outages and just need to keep things going for a bit once or twice a year, you can easily do it for less than $3k. Nothing beats battery backup since it’s seamless and auto charges with solar, but the math doesn’t work for me.

I also like the Jackery (and other brands) because you can take it with you on the trail or camping so it has a use outside of backup.

Just my 2 cents

thanks. Ive actually being eyeing EcoFlow with the smart panel and right now they have 15% off with code DL15 which makes it almost $1k cheaper than Costco

https://www.earthtechproducts.com/ecoflow-delta-pro-ultra-12kw-shp2.html

 

[Hereforthesnacks]

thanks. Ive actually being eyeing EcoFlow with the same panel and right now they have 15% off with code DL15 which makes it almost $1k cheaper than Costco

https://www.earthtechproducts.com/ecoflow-delta-pro-ultra-12kw-shp2.html

I’ve heard good things about EcoFlow.

 

[MDH]

19/month, but what did your system cost you?

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.

 

[md2023]

Having a full battery and solar allows me to charge my R1T at 48 AMPS (or close to it). Without the battery, solar is almost never enough on its own.

 

[md2023]

A transfer switch works great to disconnect the grid but that's not the only issue. What makes it work is the ability for power to travel in both directions when your connected to the grid.

What I really like about Tesla is that it can also charge your EV battery with excess production as well.

Solar power production can vary a lot during the course of the day. With no battery and no grid there is no place for excess energy (which changes with demand peaks and valleys) to go. The things in your house would be turning on and off on their own, be subject to damaging brownout, and when the sun goes down it would still be a blackout situation.

In the case of a location where power goes out infrequently and the owner only wants to offset grid energy usage then battery storage is not needed.

If you want to use the solar to power your home during an outage you need battery storage. When the grid is down the battery provides a stable and constant power output to your home while using excess production to replenish the battery.

If you look at your homes energy use there are peaks and valleys. There are also spikes. Its not possible to provide reliable power without some type of battery (either grid or home battery storage).

And in particular when charging your Rivian, solar is rarely enough. I try to charge during peak sun, with a full back up battery (I keep a minimum of 10% for power during outages) also adding to power. The Rivian pulls form both solar and the back up battery.

 

[blacknight]

My Wife and I would love to get solar + battery backup installed at our house. Unfortunately, we live in a state that isn't very EV and solar friendly, so incentives are limited and there aren't many contractor options, so they tend to sandbag their estimates. I'll need the price for dollar to drop quite a bit before we can seriously consider it =\

 

[NY_Rob]

^ if you don't have frequent power outages, you might consider going without the batteries which are consumable products and very, very expensive to initially buy and replace down the line.

Thankfully our power here is very reliable so no batteries for me which brought my break-even point on the system down to 6.5 years.

Jan 2025 will mark the 6 year point for my system, right now I'm at 5years 9months and you can see my stats below. FWIW- we pay $0.25/kWh here, I've produced $23,942 worth of electricity since Jan 2019.

 

[Hereforthesnacks]

And in particular when charging your Rivian, solar is rarely enough. I try to charge during peak sun, with a full back up battery (I keep a minimum of 10% for power during outages) also adding to power. The Rivian pulls form both solar and the back up battery.

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.

 

[blacknight]

^ if you don't have frequent power outages, you might consider going without the batteries which are consumable products and very, very expensive to initially buy and replace down the line.

Thankfully our power here is very reliable so no batteries for me which brought my break-even point on the system down to 6.5 years.

Jan 2025 will mark the 6 year point for my system, right now I'm at 5years 9months and you can see my stats below. FWIW- we pay $0.25/kWh here, I've produced $23,942 worth of electricity since Jan 2019.

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).

Sponsored