Sol-Ark 15k setup: How to use my 60+ kWh battery bank to offset my energy bill?

[Braebyrn]

I've had the 15K for a while now grid tied. It was hooked up too bunch of 12 volt light acid batteries until recently. I just built four EEL BATTERY do-it-yourself battery boxes with JK BMS inside. I have one 15 kWh box hooked up to the 15k and working in closed loop. The other three will be online in the next week or so.
Peak shaving, time of use, not sure where to set my Sol-Ark 15k.
We don't have a sell back agreement with the utility, but I would like to use some of the battery power to offset the utility bill.
Does anybody have it setup like this and if so what are your settings?

 

[DIYrich]

Time of use periods and prices? Average use during peak period?

 

[teal95]

Is it feeding a separate, dedicated breaker panel or is tied back into your main panel? I have mine feeding a separate panel and set to "limit to load". I believe the current sensors that it came with are intended to be put on the grid input if you're on a single breaker box and can then also use "limit to load", probably with a few other setup changes.

 

[Supervstech]

How much solar do you have? And what is the orientation?

 

[Braebyrn]

Time of use periods and prices? Average use during peak period?

There is no time of use periods or prices yet. They just have a pilot program going for some customers who signed up for it. I am getting prepared. Peak periods are typically from 7 a.m. to 10 a.m. and 5 p.m. to 8 p.m. on weekdays is what the utility put on their website.

 

[Braebyrn]

Is it feeding a separate, dedicated breaker panel or is tied back into your main panel? I have mine feeding a separate panel and set to "limit to load". I believe the current sensors that it came with are intended to be put on the grid input if you're on a single breaker box and can then also use "limit to load", probably with a few other setup changes.

Teal95, we set it up like Sol-Ark 15k instructions show and have it going from the grid to a fused disconnect then to the 15k and then to the main panel as intended. Current sensors are installed and working. It is set at "Limited to Home" now. It would have been better had we installed a bypass panel if the 15k were to quit working.

 

[Braebyrn]

How much solar do you have? And what is the orientation?

Supervstech, We have eleven 335w Sunpower panels facing East and 27 facing West. Total 38 x 335 = 12,730

 

[Vigo]

The possibilities are probably ultimately limited by how its wired to the house. If it can cover the entire house's overnight consumption (ie house never pulls more than 15kw at night) then the simplest thing would be to start there. I dont know any details of your house but with 60kwh of battery and 15kw of inverter, 12kw of solar, you should be able to cover the majority of your consumption with the system you've built and knock your utility bill down by more than half. Again these are just guesses since i dont know anything about your house.

The reason i bring up the wiring is because if you have loads that you know the inverter/batteries/solar can and cannot cover, you can segregate them to always be grid powered or always be inverter powered, etc. But rewiring that way may not be a better option than just allowing for the possibility of a second inverter if the first is unable to carry the full house load.

 

[DIYrich]

There is no time of use periods or prices yet. They just have a pilot program going for some customers who signed up for it. I am getting prepared. Peak periods are typically from 7 a.m. to 10 a.m. and 5 p.m. to 8 p.m. on weekdays is what the utility put on their website.

Charge from Solar, and use power between 5p-8p, and 7a-10a.

If you have a large price difference between peak and off-peak, then you charge from grid overnight for use during 7-10am. and top up (what solar doesn't do) at 4pm going into the 5pm-8pm peak time.

Allow for 10% charging loss, which is why you want a large price differential.

 

[Braebyrn]

The possibilities are probably ultimately limited by how its wired to the house. If it can cover the entire house's overnight consumption (ie house never pulls more than 15kw at night) then the simplest thing would be to start there. I dont know any details of your house but with 60kwh of battery and 15kw of inverter, 12kw of solar, you should be able to cover the majority of your consumption with the system you've built and knock your utility bill down by more than half. Again these are just guesses since i dont know anything about your house.

The reason i bring up the wiring is because if you have loads that you know the inverter/batteries/solar can and cannot cover, you can segregate them to always be grid powered or always be inverter powered, etc. But rewiring that way may not be a better option than just allowing for the possibility of a second inverter if the first is unable to carry the full house load.

Vigo, I am not in the spirit to do any more modifications to the wiring at the moment. Maybe in the future. I like your idea of using the battery overnight. That is a start for me.

 

[Braebyrn]

Charge from Solar, and use power between 5p-8p, and 7a-10a.

If you have a large price difference between peak and off-peak, then you charge from grid overnight for use during 7-10am. and top up (what solar doesn't do) at 4pm going into the 5pm-8pm peak time.

Allow for 10% charging loss, which is why you want a large price differential.

DIYrich, My utility charges the following right now:
No peak or off peak rates. (Pilot program started recently though).
Electricity Tier 1 (First 600 kWh Used) $0.113278 600 kWh
Tier 2 (Above 600 kWh Used) $0.132695 621 kWh
I used 1221kWh for the month of January.

 

[Sennen]

With 12Kw of solar I'm guessing bringing in a peak of about 65-75KW/h/day minus your usage during the solar day, that's how much you can charge during the day (your current export number minus efficiency)
I see two paths.
1. Figure out your net export and have that as your battery capacity as you can only charge as much as you don't use
2. Go nights free and charge/use from grid at night and battery the day with solar assist (I don't 100% know how to set this up in Time of Use (can guess), but I'm sure someone's done it)

 

[Vigo]

Im not familiar with the 15k settings but im pretty sure on my growatts it would simply be selecting the right 'source priority' setting to make it use grid power first, but then also use the 'ac input time' setting to 'block out' all the time that i wanted it to run off of battery. Maybe ill go dig through the 15k manual but i do try to avoid getting excited over things i already know i dont want to spend the money on.

 

[DIYrich]

Since you don't have a Sell Back agreement, and have a flat/tiered rate, set the sol-ark to maximize self-consumption. You want to:
1) Use as much PV as you can as it is generated.
2) Store any excess in the battery (if you have an electric water heater, you can dump excess PV there).
3) Use battery to make up any deficiency
4) only then take from the grid.

Limit power to Load (or Home if you have CT's and load before the grid input).
Under Time of Use, leave Charge and Sell blank, and put BATT% to 0%.

Page 31:
General description:
a. Uses batteries to reduce the power consumption during user defined periods.
b. Energy Priority: 1. Solar PV Power | 2. Batteries (down to programmed discharge V or %) | 3. Grid Power | 4. Generator.

If you have Time of Use rates and/or Sell Back, then the calculus is a little different.

 

[Hedges]

DIYrich, My utility charges the following right now:
No peak or off peak rates. (Pilot program started recently though).
Electricity Tier 1 (First 600 kWh Used) $0.113278 600 kWh
Tier 2 (Above 600 kWh Used) $0.132695 621 kWh
I used 1221kWh for the month of January.

Those rates are so low that PV and battery wasn't going to save you money.
Considering whatever you've already bought is sunk cost, can try to reduce what you pay the utility.

Is a sell back (net metering) agreement available, and if so on what terms/rates?
How much do you consume during summer and winter?
If you have a kWh surplus in summer and deficit in winter, net metering would let you use grid/utility bill as a "battery" to save power for winter.

As was mentioned, you can try to use what you produce, PV direct plus stored in battery, to avoid buying from utility.

If consumption exceeds production or storage, you may be able to "buy" low from your PV panels (while running house on cheap electricity, then sell high during peak rates. That lets you use more kWh than you produce.

 

[Braebyrn]

I went into settings and selected time of use, energy use equals battery priority. I started the battery use at 3:00 p.m.

 

[Sennen]

The "Sell" is Sell from Battery. "Charge" is charge from grid. Battery first feeds battery before loads from solar (house might be powered from grid while battery charges) Here's my settings to charge when possible. I have % set to 40 (expecting bad weather, live in Texas, who knows if power will remain) normally have it set to 20%


If we have truly crappy weather where power keeps flickering on and off, I'd probably set the system to charge from grid. I, however, have the solar buyback, not nights free.

 

[beastman]

DIYrich, My utility charges the following right now:
No peak or off peak rates. (Pilot program started recently though).
Electricity Tier 1 (First 600 kWh Used) $0.113278 600 kWh
Tier 2 (Above 600 kWh Used) $0.132695 621 kWh
I used 1221kWh for the month of January.

You are so lucky. Here in CA (ev2a rate plan) on PG&E is .62c kwh 3pm to 10pm and .43c 10pm-12am; .27c kwh 12am to 3pm. With 8kw of solar in 2023 we still had a 4k true-up bill. Prices are supposed to go up another 10-20% in the next 18 months according the PUC. So my bill is probably going to be 4x of your bill; maybe more. Time to move I guess. Hard to do with a business and kids in school. Maybe time to about cut the cord w/ the utility and invest another $20k into pv and storage. That's about the only way this makes sense to live here.

 

[Braebyrn]

You are so lucky. Here in CA (ev2a rate plan) on PG&E is .62c kwh 3pm to 10pm and .43c 10pm-12am; .27c kwh 12am to 3pm. With 8kw of solar in 2023 we still had a 4k true-up bill. Prices are supposed to go up another 10-20% in the next 18 months according the PUC. So my bill is probably going to be 4x of your bill; maybe more. Time to move I guess. Hard to do with a business and kids in school. Maybe time to about cut the cord w/ the utility and invest another $20k into pv and storage. That's about the only way this makes sense to live here.

Wow. I never thought of it that way. It will probably end up that way here. Hydroelectric is abundant here, and wind energy. But that bill you get each month would cut bigtime into most families budgets!