How to justify more battery purchases

[dougbert]

The batteries would probably provide better value

My argument (with myself) goes like: -

• I want XYZ.
• I have the $$$
• I buy XYZ
• Madam notices (if I'm unlucky)
• I buy Madam gold (she's Thai, they always want gold).

QED

bump wife limit first, then your limit

 

[dougbert]

I need to buy an EV as a "dump load".

I am adding a second 14-50r outside that is only ON after:

• battery is full
• water pre-heater is at 125degF, 100 gallons

So I can:

• now charge the EV I don't have yet

 

[jeff.lankford]

The batteries would probably provide better value

My argument (with myself) goes like: -

• I want XYZ.
• I have the $$$
• I buy XYZ
• Madam notices (if I'm unlucky)
• I buy Madam gold (she's Thai, they always want gold).

QED

Years ago, I bought a sports car (midlife crisis purchase, I guess).

Once of the first things I did after buying the car was to buy my wife a track day to drive the car at a local racetrack (Road Atlanta). That worked well to smooth over the purchase. It also somehow became more her car than mine...

 

[Brucey]

The batteries would probably provide better value

My argument (with myself) goes like: -

• I want XYZ.
• I have the $$$
• I buy XYZ
• Madam notices (if I'm unlucky)
• I buy Madam gold (she's Thai, they always want gold).

QED

Make it seem as tho xyz is for madam...take gold gift, spend on more batteries.

 

[SparkyJJO]

bump wife limit first, then your limit

Unless the bank account limit hits back.

 

[Zwy]

We had 58Kwh in the house and could go 5 days by not running optional loads like the dishwasher, washing machine or dryer. Added a heat pump water heater ahead of the propane water heater and do shut it down if extended cloudy days are forecast. I've since added the Luyan box to the battery bank and that will get us over 6 days. Now I've changed out some B grade cells that were not matched and this allowed me to use more of the operating range of the battery, both on the high and low end.

Usually after 6 days we get some sun, this winter was the exception, it went on for 3 weeks. I can't control that but we used less than 200 Kwh for the past year from grid.

I have now added the shop system and it has 114Kwh of battery and I did install a circuit to transfer power from shop to house and vice versa using Chargeverters. That has worked out well. The majority of loads in the shop is during the day, the house more at night. Yesterday I added a few Kwh to the house system from the shop and that was enough to get us to this morning which is clear skies.

One needs to analyze when the majority of loads will be placed on the system and plan accordingly. More panels for daytime loads and more battery if loads are during non daylight hours. But for cloudy stretches, one should have at least 3 to 4 days of battery in case backup power went down. In your case, you chose generator backup. The cost to run the generator needs to be compared against the cost of batteries for a scenario of grid down. If one DIY's the batteries and builds a large bank, the costs can come down quite a bit. I don't have the total figures down yet, but the shop 114Kwh bank was about $12K for cells and BMS's with screens and the $200 cabinet. It takes almost 30 Kwh per day just to run the lights in the shop and come summer, the air conditioning will be on. With the recent rate increases from the utility, the utility bill just for the shop would be over $900/month. I will still have the meter charge and what Kwh are used by the air compressor, but that might run for less than 1/2 an hour per day during the busy season. This time of the year I might not run it for several days. I could add a smaller air compressor just to keep the tank topped off for those times I only need a small amount of air power.

At $800/month, how long does it take to get the $12K back? About 15 months but one must also take into account the hours during the day PV supplies loads. I do need that reserve however during the night as air conditioning is run 24/7 during the summer months. In the shoulder seasons, I run the heat pumps in the shop instead of the propane condensing boiler so I will gain some of that $12K back sooner.

 

[wpns]

install a circuit to transfer power from shop to house and vice versa using Chargeverters

How does that work? Two CV or carry one back and forth?

 

[pollenface]

The ROI on this stuff doesn't always make sense. It's often more about convenience/independence rather than saving money.

100% agree with this, also it can be a hobby, somewhere to direct your mental energy and focus on, it is for me anyway...

 

[Zwy]

How does that work? Two CV or carry one back and forth?

Two CV, one on each end. Covered in the shop build thread under this post. I'm still having problems with the Shelly smart plugs connection, will have to move the access point. I think the steel cabinet is blocking the wi fi.

 

[ksmithaz1]

I need to buy an EV as a "dump load".

I can't put enough in them. Maybe I should just drive around more? The problem is EV's are very efficient around town. I only drive around 40 miles round trip (or less) every day. GF even less. I don't even charge up every day. I need to work on a bitcoin miner like some other folks on this forum.

 

[wpns]

Two CV, one on each end. Covered in the shop build thread under this post. I'm still having problems with the Shelly smart plugs connection, will have to move the access point. I think the steel cabinet is blocking the wi fi.

Nice! I'm using Shelly Pro devices, which have Ethernet and DIN rail mount, and other great features, for controlling my HVAC minsplits, but for the CVGC input contactor coils I just use this USB dual relay, so I can do on/off/auto control of the signal between the inverter "generator dry contacts" and the contactors:

Amazon.com

Did I mention I really dislike WiFi for anything important?

 

[Zwy]

The Shelly work good in the house. I prefer running CAT5 for many things but for something simple like the Shelly plugs it is easier to just use wi fi.

 

[MattMan119]

Make it seem as tho xyz is for madam...take gold gift, spend on more batteries.

Oh I need a new battery to store extra power to use drawer anytime you like dear… (nice I will try it)

 

[Brucey]

Oh I need a new battery to store extra power to use drawer anytime you like dear… (nice I will try it)

Exactly. Oh darling, you want more than a 5 gallon bucket of hot water for a bath? I just need another pallet of panels, you know these crap upstate winter solar conditions...

 

[EPicTony]

I have been thinking about this very thing lately. I have 71kWh of battery. Usually enough for 2 or 3 days when it gets cloudy in Ohio. These Ecoworthy rack mount battery can be had for $1850 for 2 including shipping. Giving me about $82kWh of battery. (About a 15% increase)
With the tax credit and depreciation for office use the $1850 goes down to maybe $1100. I don't know when to draw the line on batteries where enough is enough. I have more than enough PV so no issues there.

 

[dougbert]

I have been thinking about this very thing lately. I have 71kWh of battery. Usually enough for 2 or 3 days when it gets cloudy in Ohio. These Ecoworthy rack mount battery can be had for $1850 for 2 including shipping. Giving me about $82kWh of battery. (About a 15% increase)
With the tax credit and depreciation for office use the $1850 goes down to maybe $1100. I don't know when to draw the line on batteries where enough is enough. I have more than enough PV so no issues there.

when you no longer wake up in the middle of the nite with the sweats - then you have enough

 

[SomethingAppropriate]

I was more talking about justification to myself.

This is easy

I have a very simple check list.
Do you want it?
Can you afford it?
Have you been thinking about this for over a year?

 

[MattMan119]

This is easy

I have a very simple check list.
Do you want it?
Can you afford it?
Have you been thinking about this for over a year?

I can live with 2 of them anyhow.. the year thing is a bit excessive… more like day or two?

 

[EPicTony]

This is easy

I have a very simple check list.
Do you want it?
Have you been thinking about this for over a year?

Well I have only been thinking about it for a couple of weeks but I'll have a look at your check list. Thanks

 

[SomethingAppropriate]

more like day or two?

need great discipline!

Of course, it all about the money. 5k is a bit for me so...a year it is

 

[455dan]

I have always heard it is better to do something and apologize later...and ask forgiveness... and the key is just ordered them and be surprised when they show up.... amazing, I didn't order it, look, they don't have my name on them... hint use your middle name.

It's funny, the wife was like You Need to get More batteries if the inverter will not cover at least a full day or two if the grid goes down, so I ordered the third battery and installed it and she says- I thought you bought another battery ?

I said i did and that makes three, she says why did you only get one more? and I said well they are not exactly cheap, and she says well how much is just one? I say $3600 plus shipping.... Should have seen how big her eyes got.

On the batteries, she Can't complain -since she said to do it without asking how much they cost, hehe. I do see why advice is just buy more panels because they are cheap, which is good advice.

 

[Brucey]

It's funny, the wife was like You Need to get More batteries if the inverter will not cover at least a full day or two if the grid goes down, so I ordered the third battery and installed it and she says- I thought you bought another battery ?

I said i did and that makes three, she says why did you only get one more? and I said well they are not exactly cheap, and she says well how much is just one? I say $3600 plus shipping.... Should have seen how big her eyes got.

On the batteries, she Can't complain -since she said to do it without asking how much they cost, hehe. I do see why advice is just buy more panels because they are cheap, which is good advice.

Oh thats when you give her the 5kWh price even though it's 14-16kWh.