Battery storage - existing solar

[NateHornblower]

So my power just went out and this prompted me to revisit something I've though about occasionally - battery storage for the house.

I'm curious how this works with a solar set up during a power outage. Without grid power, my solar isn't generating. Inverters are off and disconnect engaged. How would this all work with battery storage? Would solar still disconnect as it does today and house draw from battery? Would solar disconnect from grid but charge the battery & supply the house? Does this all depend on how the system is designed?

My energy storage thoughts are two fold - for power outages (3 in the last year) and lessening reliance on the grid. I'll be grandfathered in the SDGE TOU rate which benefits solar for 5 years, but peak time is going to shift to 6-11pm when solar isn't generating and when that time comes, my thought is to draw from battery during those hours. Of course, none of this has been evaluated from a cost benefit standpoint, just tossing around ideas. Battery storage prices will continue to drop over the next 5 years so those calculations aren't necessary just yet but I do want to get an understanding of the options and benefits.

Besides, a home generator seems so 1998

thx

[Mike90250]

If you have LOTS of household blackouts, and cannot fathom how to reset the blinking 12:00 on appliances, you may indeed want to spend $40,000 on replacing gear (you can keep your PV panels, but all the other gear is useless for batteries) to have a battery bank become a giant, solar charged UPS for your whole house. You will have to shut down most large loads (air conditioner, heat pumps, pool pumps, electric water heater. electric range) for the duration of the backout.
OR
If you know how to reset your clocks, and can stand to wait 5 minutes for an automatic backup generator to start and switch over, you could have power for about $12,000 and not have to replace batteries every 5 years.. Increasing the generator size means you could run the big loads, but will burn more fuel..
Your choice as to how much you want to spend

[Sunking]

I'm curious how this works with a solar set up during a power outage. Without grid power, my solar isn't generating. Inverters are off and disconnect engaged. How would this all work with battery storage? Would solar still disnnect as it does today and house draw from battery? Would solar disconnect from grid but charge the battery & supply the house? Does this all depend on how the system is designed?

Short answer isnot worth a damn. Firrrst thing you woul dhave to do is replace your Inverter and rewire your house. Then buy several hundred pounds of batteries that collect dust and get replaced in 5 years.

It requires a special Inverter called a hybrid. It has built in Battery Charger and Automatic Transfer switch that requires you to rewire your home. The ATS is only a small 60-amp Circuit. Your electrician needs to wire an Emergency Breaker Panel, you select a few circuits like to your fridge, a light or two, and an outlet. Everything else goes dark. For extended or over night outages requires a generator you input to the hybrid Inverter. The Inverter will turn on the generator to recharge the batteries.

Look if you want power during an outage, then buy a whole house generator, 200 to 550 gallon LPG tank, and ATS. No rewiring your house, and a lot less expensive. Like nothing ever happened. Your power goes out in hot summer, and you sit inside in cool comfort, and laugh at your suffering neighbors who do not have power for a week. Otherwise the only comfort you will have with batteries is cold beer in the fridge as that is about all they are good for. Who cares in winter, keep the beer outside while you freeze with no heat.

[NateHornblower]

Power outage coverage is a side benefit of energy storage. I'm clear I can buy a generator but the power doesn't go out that much. I'm exploring energy storage along with the side benefit of power outage coverage. NEM is going to be far less beneficial in 5 years in San Diego. Something like this:

https://www.greentechmedia.com/artic...t-a-40-reduced

Powerwall is similar - can wire to a sub panel of specific circuits or whole house depending on budget.

Perhaps what I meant to ask is - if one has energy storage, will the PV system still be able to charge the batteries in the event of a grid outage? Sounds like that could be done if an ATS is put in place.

[SunEagle]

Power outage coverage is a side benefit of energy storage. I'm clear I can buy a generator but the power doesn't go out that much. I'm exploring energy storage along with the side benefit of power outage coverage. NEM is going to be far less beneficial in 5 years in San Diego. Something like this:

https://www.greentechmedia.com/artic...t-a-40-reduced

Powerwall is similar - can wire to a sub panel of specific circuits or whole house depending on budget.

Perhaps what I meant to ask is - if one has energy storage, will the PV system still be able to charge the batteries in the event of a grid outage? Sounds like that could be done if an ATS is put in place.

No you will need a hybrid inverter which can also use your solar pv system to charge a battery . The standard string or micro inverter will not work if the grid goes down.

So now you have to decide to spend the big bucks for that hybrid inverter along with the batteries to handle your power needs during a grid outage. Or you can just use a generator the few times the grid goes down spend much less money for an emergency power source that will provide a lot more power then a set of batteries or even a Powerwall 7kWh system.

[Sunking]

All those micro-inverters have to go, a complete rewiring of your home and solar system. Either way requires a generator for extended or over night outages.

[solar pete]

Things seem a bit different over there. Short answer is SK and the others are right about most things. Here in Oz we can get a 10kW/hr battery (LG CHEM) installed to a existing solar system IF the system is large enough to charge that battery during winter and they already have a inverter like a SMA or Fronius, you can then add Victron charge controller and sundry electrical equipment and labor ( might be a lot of labor, re-wiring and sub panels and all that jaz) might run you about 15K and then you have about 9kW/hrs of use when dark or no sun or blackout. You can use that up pretty quick

[J.P.M.]

Things seem a bit different over there. Short answer is SK and the others are right about most things. Here in Oz we can get a 10kW/hr battery (LG CHEM) installed to a existing solar system IF the system is large enough to charge that battery during winter and they already have a inverter like a SMA or Fronius, you can then add Victron charge controller and sundry electrical equipment and labor ( might be a lot of labor, re-wiring and sub panels and all that jaz) might run you about 15K and then you have about 9kW/hrs of use when dark or no sun or blackout. You can use that up pretty quick

Pete: curiosity on my part - how much electricity does the average Australian household burn through in a year ?

Thanx.

[Sunking]

Things seem a bit different over there. Short answer is SK and the others are right about most things. Here in Oz we can get a 10kW/hr battery (LG CHEM) installed to a existing solar system IF the system is large enough to charge that battery during winter and they already have a inverter like a SMA or Fronius, you can then add Victron charge controller and sundry electrical equipment and labor ( might be a lot of labor, re-wiring and sub panels and all that jaz) might run you about 15K and then you have about 9kW/hrs of use when dark or no sun or blackout. You can use that up pretty quick

Lotta If's Pete. We can do that here to, but it makes no financial common sense.

[solar pete]

Pete: curiosity on my part - how much electricity does the average Australian household burn through in a year ?

Thanx.

Howdy, acording to this ( https://www.platinumelectricians.com...-average-home/ ) its about 18kWh per day so about 6500 kWh per year. The battery thing is starting to gain traction here, its not quite economically viable as yet, but for a lot of people that does not matter, they just want some power on hand when the grid goes out

[J.P.M.]

Howdy, acording to this ( https://www.platinumelectricians.com...-average-home/ ) its about 18kWh per day so about 6500 kWh per year. The battery thing is starting to gain traction here, its not quite economically viable as yet, but for a lot of people that does not matter, they just want some power on hand when the grid goes out

That number is approximately a bit greater than half the U.S. annual average residential usage. I kind of thought it might be. That would mean it's a lot easier A$ wise to make a dent in what an Aus. POCO supplies as a % of total usage. If battery storage is perhaps finding it a bit easier down under, that may be part of the grease on the rails. It costs less upfront to offset a smaller load. Maybe just as much or more /kWh storage, but the up front hit will be less, and so easier to swallow for those who want a better shot at reliability.

[Bala]

A lot of people install grid connect systems that have no chance of giving them a ROI, they lose money. People will buy battery storage for the same reason.

They are led to believe that it will save them money. People cant do their own math and research, the sales people tell them what they want to hear.

I have stand alone and people think I dont have a power bill. Well I dont have a monthly bill but I will have a big one soon when my batteries die. I also have generator running costs, dont have aircon and certainly dont use 18kwh a day,

[SunEagle]

Howdy, acording to this ( https://www.platinumelectricians.com...-average-home/ ) its about 18kWh per day so about 6500 kWh per year. The battery thing is starting to gain traction here, its not quite economically viable as yet, but for a lot of people that does not matter, they just want some power on hand when the grid goes out

Wow. I thought I had a low usage for my home with a daily average of 40kWh.

I expect my new home which will be smaller and without a pool pump will use a lot less then my current home. Then I can look into getting a solar pv grid tie system.

[bcroe]

Wow. I thought I had a low usage for my home with a daily average of 40kWh.

I was usually under 10KWH a day, now that all the phantom loads are fixed. But when the propane
furnace needs to run, my average went up to 13.7 KWH per day. None of that applies since I switched
to electric instead of propane heat. Bruce Roe

[SunEagle]

I was usually under 10KWH a day, now that all the phantom loads are fixed. But when the propane
furnace needs to run, my average went up to 13.7 KWH per day. None of that applies since I switched
to electric instead of propane heat. Bruce Roe

My 3 big users are the pool pump, AC and cloths dryer. I at least switch out my water heater to solar back in 2010 so one of the big 4 has been eliminated.

I have also replace all my incandescent and tube fluorescent lighting to LED or CLF. Based on my data I have reduced my average daily consumption from about 72kWh back in 2010 to 40kWh.

Biggest problem is getting my adult daughter and my wife to turn off lights and fans as well as keeping the thermostat above 77. Those two seem to use much more than any vampire loads I have.