EEVblog 1502 - Is Home Battery Storage Financially Viable?

Running through the numbers to see if home battery storage is viable on my home.
And comparing Tesla Powerwall, Enphase IQ Battery, BYD LVS, and Greenbank battery pricing.

00:00 - Is Home Battery Storage Financially Viable?
00:45 - Energy consumption & production numbers
03:25 - What about hot water?
04:30 - Am I 100% grid-independent?
05:18 - How much does electricity cost?
06:10 - What size battery and what budget?
07:07 - 5 year or 10 year payback?
07:35 - What size battery?
08:34 - Battery storage price comparison.
10:01 - AC Battery. Tesla, Enphase.
10:40 - DC battery hybrid inverter storage
12:26 - Do I get blackouts in Sydney?
12:54 - DYD LVS battery
13:19 - CHEAP Greenbank battery
14:25 - Does a cheap battery pay for itself?
15:11 - Feeding Enphase microinverters into a Hybrid inverter?
17:17 - Longevity, Maintenance, Peak power, and depth of discharge all determine battery life.
18:44 - Conclusion

Support the EEVblog on:

Buy anything through that link and Dave gets a commission at no cost to you.

Donate With Bitcoin & Other Crypto Currencies!
#ElectronicsCreators #Solar #batterystorage

[johnwest]

I found comparing grid power costs to my own PV power costs was silly. Instead of spending a lot of money on a backup generator for emergencies I have my PV/battery system that requires almost no maintenance. And for the years I lived in an RV my PV panel /battery energy system was priceless. A friend told me that PV panels simply didn't pay for themselves. I replied that he wouldn't say that in the dead of winter at a campsite in the national forest. ANY money I put into the system just made my life better, and it saved me over $1000 a month in rent. So the RV and the PV/battery system entirely paid for itself in the first 2 years, ALL of it. So it's entirely a situational thing, as you mentioned.

[JBoya]

We have a Tesla system, Solarroof and Powerwalls. We got it to do 2 things. First, ensure we had power all the time. We have 3-5 power shutoffs per year some lasting upwards of 18 hours, and since we work from home, no power means no work and associated billings. Second, to reduce our power costs. The system has done very well at both.

The system has pretty much removed our electrical power bill. We used to pay upwards of $600 USD/mo. in the summer. Now we usually only pay the minimal connection fee amount, about $12/mo. And as far as backup goes, we have not lost power, even when the neighborhood is out. We usually just get a message in the app that says the grid is down. And we verify this by looking out the windows and see the lights are out at in the neighborhood. We usually don't even see our lights flicker.

[ksolar]

I have lived off grid for quite a while and I have learned that the word battery can mean several different methods, some are electrical in nature however the larger ones are usually water, air, and even larger ones are large tank batteries for sweet crude oil, I like the idea of heat storage, as far as the electrical devices that I use most are one off which I have repurposed from other devices and redesign their power supplies to a softer mode to the lightest power usage needed, as an example instead of using one Pelletier device at 12 volts I will connect to in series and run them using the load control on the solar charge controller.

[rilosvideos]

It really depends on so many parameters you didn't (and probably can't take) into account - so its all kind of a milkmaid bill in the end. You can't predict daily solar power, charge cycles, energy consumption - its all an average attempt and a prognose of the future behavior. It will pay off in good conditions and won't in the worse ones. But you have good chance that it will in the end!

[eddwhite]

Even though the feed-in tariff is a pittance, if you factor it into the calculations it reduces the yearly saving to ~$1170. Because you're no longer selling the excess energy to the grid and instead storing it in a battery, then you need to subtract that loss of revenue from the savings made on your electricity bill. I still think the battery system is a good way to go, as feed-in tariffs only seem to be going down, so I don't think you can rely on it for long term investments like this.

[MikkoRantalainen]

1:15 The price of electricity here in Finland is about 38 cents/kWh right now and some estimates put the price over 50 cents/kWh before the end of the year already. It used to be about 6 cents/kWh only a year ago! Everybody thinks this is just temporary market error but nobody knows for sure.

As far as I know, in 2021 any plant that had estimated costs above 55 EUR/MWh was cancelled for not being profitable. If end of the year estimates are actually correct, any power source with price less than 500 EUR/MWh is going to be profitable!

[erbse]

You could take a small 5kwh battery to power the house if your electric car is on its way and install a system that takes the energy from your parked car. Then you would have a 60+ kwh battery at no additional cost other then the setup. (Hyunday Ioniq 5 has a 58 kwh battery with bi-directional output of max 3.6 kwatts)

[sokolum]

Lithium Iron Phosphate is way to go to have a grid/house battery. And i would buy 12~15kWh, a bit overhead will have less stress on your batteries and better live span, in my opinion.

[rootbox]

These hybrid inverters are "whole house" too as they can measure the energy in and out of the total house and make decisions based on that to for example charge or discharge their battery. A transfer switch like you showed could also be handy

[raymondcasso]

Wow... about time this made sense. I've been off-grid for 4 years now and I paid $2000 usd for a 10kw lifepo4 24v battery plus $800 usd for a hybrid inverter. Best purchase so far!

[billjohnson]

Nice video Dave. One thing you also need to consider is your best and worst solar days combined with worst and best home usage - not just average for the seasons. For example, if you have many days in the summer where your solar is pumping but your house load is light, that energy can't all get saved with your battery system - you will hit max state of charge. At which case you still have to give back to the grid (at your lower feed-in rate). But if you then have rainy days where you need more power than the battery could have banked, you have to get that from the grid at your higher consumption rate. If it turns out you have an overall surplus, that's not a big deal. But you really need to look at your daily worst cases to size the battery - not just average within the seasons. Otherwise your calculations are giving you a best case, and you'll be 'clipped' by your battery state of charge in reality and not achieve that.

Seems super easy to have many days where your solar provides more than 10kWh surplus over your home usage (which would be your 0-100% battery SOC for a 10kWh battery) - and that extra energy can't be banked by the battery and goes back to your current grid feed in/out pricing. And conversely, on a rainy but high consumption day, you won't get your battery charged to last through the night - so need power from the grid. If you do a day to day analysis, you'd probably see that both these scenarios happen fairly often, and you have to either go with a bigger battery - or just factor in the grid in/out cost for those daily over / under consumption scenarios.

And also, when sizing the battery, you also want to consider how far you want to dip down. Battery life is extended if you aren't cycling 0-100%, so you generally want to oversize capacity to account for that as well.

I think in your case a battery system is a tough call. You probably won't reclaim your expenditure if you figure a 10 year life on the batteries. Unless you have some incentives in your area to help with the price. If you have time-of-use billing, or zero credit for feed-in, then a different story.

[horsreseauquebec]

Nice analysis, thanks! I live off more or less 8 kWh usable, off grid (14 kWh SiO2 total). I like when the batteries go full, then the charge controllers will lower the input for float stage. Then I can turn on more loads such as boiling water or cooking. The charge controllers will instantly adjust and pull the exact quantity of required power, you can see the stats of the load by looking at the difference of the input before/after! Going off grid requires a lot of optimization and compromises, let's call it degrowth.

[Speed]

Having a battery bank with solar panels is a no brainer. I have 4 server rack batteries that store 20k Kilowatt hours. Cost me $9500 U.S dollars. I'm 100% grid independent. BEST money I have ever spent.

[ctechbob]

Not sure what Heat Pump water heaters you have down under, but I replaced my 50 gallon (190 Liter) electric resistive heater with a heat pump model in April. According to my records I'm using a smidgen less than 1/4 the electricity to heat water. Bonus is that it pulls moisture out of the garage, and keeps it a bit cooler out there as well. Best case scenario for me. The heater sits in the garage, and I'm in the Southeast US, so it gets HOT out there. Plenty of heat to pull from the air and pump into the water. Highly recommend!

[AntonioCunningham]

Power in my neighborhood used to go out once every 2 months or when it's stormed. I got tired of looking out of my window doing one of these blackouts and seeing the next door neighborhood have power. So I went out and bought a few power stations.

The following year the power company buried the power cables in my city.

Now the power only goes out twice a year.

However I'm still glad I bought my power station because over half my power usage is now from solar power.

[EngineersFear]

I noticed that a fair share of energy that I used to pull from the grid was down to pulling energy at the wrong instant (clouds) or the solar not providing sufficient power. So now with the battery system I can bridge those cloud gaps and boost the solar system on high power loads. So it's not just night and day that matters.

[jonathanrees]

Here in South Australia we have all been (forcibly with no options) moved off flat rate charges - so we now pay off peak, shoulder and peak. All properties get/got a smart meter when solar is installed so easy for the suppliers to do this. Expect this will come to NSW over the next year? This will significantly increase your bills. There is so much BS re the grid - solar power distributed across the network actually lowers grid cost, and improves reliability. Current best feed in I have been able to get is 7.5cents - which is straight forward theft, maybe a class action against the AEMO? Tesla 13.5Kw battery has cost me $11, 529.00 (actual cost). Went to this solution because of install options and location. This is currently working as part of the Tesla virtual power plant - which I can leave at any time, but does give additional rebates and extends battery warranty if you stay on the plan. Waiting to see what real costs are.

[drstefankrank]

Did I miss something in the video? On long summer days you generate way more than your battery can store and you are only using a fraction of it during the short night. The next day starts with a pre filled battery already. So you are going to export the excess most of the time. In winter it's hardly possible to fill up the battery to store enough for the longer night. Especially if you got a heat pump that needs the most energy during these cold days.
I created a battery simulator from my hourly data on my sold/bought values of my main meter for the last >400 days and came to the conclusion that no matter what size of battery I buy at this time, I get ROI dates of around 15 years. As soon as I get <10 years, I think about it again.

[hojnikb]

I'm so happy, that we have yearly accumulation of solar production in our country.
Whatever you produce during the year gets fed into the grid (minus what you can use urself at the moment) and that MWh then transfers to the next year. So if you size your solar panels right, so the yearly total production is equal or higher than your yearly consumption, you're pretty much golden and you have almost free electricity. Grid is really the best kind of battery there is.

[_general_error]

The viability of batery storage lies in self-sufficiency - if the grid goes don;t for whatever reason, you still can fill up those batteries with your solar panel.