Sol-Ark 15k TOU/Grid Sell Clarificaiton

[sryan2k1]

Hey All,

We're in the initial stages of planning a grid-tied ~8kW system and a EG4-LL-S rack for my parents house who are looking to save a bit on energy but really gain some reliability from the grid.


Both of us like Sol Ark's inverters and will likely settle on a 15k. I had some questions on the TOU settings, which I see are common, the manual and posts on the forms have it a bit confusing.



Net metering went away in Michigan a while ago so we want the system to maximize self consumption, and grid sell only after the batteries and home use is covered.


It sounds like we'd enable Grid sell, Limited power to Home, and TOU for all hours/days, with the batt% set to ~25%, and on the battery setup set the shutdown limit to 0-5%

With excess solar this would (should?) charge the batteries/power the home first, and any leftover will go to grid sell.

Without excess solar the system will pull as much as it can from the batteries, until ~25%, supplementing from the grid as needed.

In a grid failure the circuits connected to the load terminals will be powered until the batteries get to the shutdown percentage (0-5%)

Leaving all the charge/sell boxes unchecked in TOU will prevent the batteries from being charged by the grid or being discharged by the grid.


Seem correct?

 

[2TrevorJ]

All of your conclusions are correct. It works exactly as you described.

 

[DIYrich]

It sounds like we'd enable Grid sell, Limited power to Home, and TOU for all hours/days, with the batt% set to ~25%, and on the battery setup set the shutdown limit to 0-5%

If you "limit power to home", the 15k will limit PV production. It will not sell-back to the grid.
"Grid Sell" is correct. It will sell excess PV to the grid.

In a grid failure the circuits connected to the load terminals will be powered until the batteries get to the shutdown percentage (0-5%)

Batt Setup -> Discharge -> Shutdown: voltage or SOC% when inverter will shutdown when grid is down (0-5%)

Leaving all the charge/sell boxes unchecked in TOU will prevent the batteries from being charged by the grid or being discharged by the grid.

See page 37 of the Manual for "Time of Use (using batteries during peak power times), particularly "Power Source Priority". You want the following Power Source Priority 100% of the time:
1. Solar Panels | 2. Batteries (programmable % discharge) | 3. Grid (control when grid charges) | 4. Generator

Page 36 has the parameters:
On Grid Param -> Limiter Tab
Grid Sell: Check the box (allows selling to the grid), and 15000
Limit power to home: unchecked (this is used for Grid Zero)
Limit power to Load: unchecked (this is used for Grid Zero)
Time of Use: Check the box to enable
Time: all time periods
Power: 15,000 (max power from battery during that time period)
Batt: 25% (battery voltage/% at wich the system will limit using for home from the battery, The 15k will drain the battery until reaching that percent/voltage)
Charge: uncheked (don't want to charge from grid. Note: "PV will always charge to 100%")
Sell: unchecked (don't want to use battery to sell to grid).

 

[sryan2k1]

If you "limit power to home", the 15k will limit PV production. It will not sell-back to the grid.
"Grid Sell" is correct. It will sell excess PV to the grid.

That is directly opposite of what the owner manual, and others on the forums have said, which is why it's confusing. I believe you are incorrect.

Page 28 of the manual says

Limited Power to Home + Grid Sell: This mode will NOT limit solar production. In this mode, the inverter delivers power to the
“LOAD” terminal (essential loads panel) + unlimited power to the “GRID” terminal (main service panel AND grid). The Sol-Ark will
monitor grid sell back and load consumption simultaneously (with +/ - 3% error from CT sensors). The CT sensors MUST be installed.
See section 2.8 “Limit Sensors” for proper external CT placement

The wording is confusing but it's my understanding that "Limited power to home" means that "if I don't have excess solar, the house gets priority", and other posts on the forum seem to confirm that, if grid sell is on and LPTH is off the inverter will end up pushing power into the grid over powering the house in some situations. This obviously only applies if you have something connected to the load terminals and not just backfeeding the main panel via grid.

 

[Oldphile]

@sryan2k1 Do you have any home loads between the meter and the grid terminals of the Sol-Ark? If not, just use Limited Power to Loads.

Utility meter----Ac disconnect-----CTs------Home Loads------Sol-Ark------Critical Loads panel

 

[sryan2k1]

Yes, both an electric water heater and a 4 ton AC that they don't want backed up during a grid outage, and will stay on the main panel.

I'm less concerned about the physical wiring, but the limiter setup. To get maximum self consumption and grid sell it seems (barely) the consensus is that Grid sell, Limited power to Home, and TOU must be enabled.

 

[DIYrich]

That is directly opposite of what the owner manual, and others on the forums have said, which is why it's confusing. I believe you are incorrect.

Page 28 of the manual says



The wording is confusing but it's my understanding that "Limited power to home" means that "if I don't have excess solar, the house gets priority", and other posts on the forum seem to confirm that, if grid sell is on and LPTH is off the inverter will end up pushing power into the grid over powering the house in some situations. This obviously only applies if you have something connected to the load terminals and not just backfeeding the main panel via grid.

They updated the manual.

I'm thinking they use the TOU "Sell" column to determine when it is ok to sell back to the grid. Or, it is saying that if you have "grid sell" checked, then it ignores Limited to Home.

 

[sryan2k1]

TOU Sell is when you want it to sell battery power to the grid, not excess solar.

If you don't have grid sell checked it won't export anything.

However it's unclear in the manual and posts here make it sound like if you want grid sell, and you don't also have "limited power to home/load" enabled the inverter will in some situations export to the grid instead of charging the batteries (when in reality you want it to export to the grid only when everything else is satisfied)

 

[Tulex]

My 15K absolutely sells back extra solar to grid with "Grid Selling" unchecked, "Limited to Home" checked, "Solar Sell" checked and not using time of use.

 

[Tulex]

If I want to use the batteries 24/7, limit PV to not sell to grid but always charge batteries, do I just set Time of Use to sell at all hours and:
Only limited to home checked
Solar Sell unchecked
Battery First checked

 

[DIYrich]

My 15K absolutely sells back extra solar to grid with "Grid Selling" unchecked, "Limited to Home" checked, "Solar Sell" checked and not using time of use.

Where is the "Solar Sell" setting?

 

[Tulex]

Right under Work Mode

 

[DIYrich]

Right under Work Mode

What screen is that on?

 

[Tulex]

On the pc app, it's in system work mode

 

[DIYrich]

On the pc app, it's in system work mode

What settings show up on the inverter screen when you set it on the PC app? Feature not available ftom the inverter screen? What app are you using?

 

[Tulex]

What settings show up on the inverter screen when you set it on the PC app? Feature not available ftom the inverter screen? What app are you using?

To be honest, I can't find on the inverter where that would be. I'm using Sol-Ark's Powerview.
There's also a setting in Solar Assistant called "Solar export when battery full". I checked that but it didn't change the setting in Powerview. I then unchecked it and changed the setting in Powerview, but that didn't change the setting in Solar Assistant, so either it's not the same thing, or it's not communicating that command.