New program request to bypass Utility demand rates

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New program request to bypass Utility demand rates

Postby Coda555 on Mon Jul 01, 2019 11:27 am

I’m having an issue because my utility is not solar friendly. They have peak times from 1pm to 8pm in summer and 6am to 10am in winter. During peak times they have what is called demand charges where they charge you for the amount of demand you put on the grid during those times. It’s expensive $6 per KWh of demand. The only way to bypass this is to disconnect from the grid completely during those times. Which also means i cant sell to the grid either.

So I need to try and get ahold of an outback engineer or software specialist that can creat a program that allowed me to sell to the grid, but when the load exceeded the solar production it pulls from the batteries and not the grid. Then when the load is gone it recharges the batteries and resumes selling to the grid once the sell voltage has been reached. I’m in desperate need to overcome this. I’m loosing a crazy amount of solar production during these peak times and the utility changes the peak times from year to year. So next year it could be from noon to 9pm and that would hurt me even more.
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Re: New program request to bypass Utility demand rates

Postby Mike Curran on Tue Jul 02, 2019 8:57 am

I'm not experienced with the Radian's AC modes, but from reading the manual seems like a combination of grid-tied mode along with flex time schedule (disconnect during your peak cost periods) and load grid transfer (transfers to grid when needed based on AC loads or low battery voltage) might be a possible solution. Hopefully someone with experience using these options will chime in. - Mike
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Re: New program request to bypass Utility demand rates

Postby pss on Tue Jul 02, 2019 9:10 am

Mike is right. If you set up grid tied mode, your system will harvest maximum PV, sell to the grid when the load and battery voltage allows, then draw any power needed (clouds) when the PV drops and or the load increases (AC comes on). Imagine that you are grid tied. In the morning, the sun comes out and your batteries begin to charge from PV. Initially, your loads are powered from the grid. But say by 10-11AM, your batteries have received enough charge amps and voltage is high enough so that now, in addition to completing the battery charge cycle,some PV is directed to your load and grid use is decreased accordingly. After say another hour, by noon, your batteries are nearly charged, so the PV is directed to topping off the batteries (phase 3 of charge cycle), powering your loads and selling to the grid. Along towards say 4PM, the PV is dropping, so you may alternate selling and consuming from the grid. By 5PM, your PV is low enough that you would need grid power, but then you remember your batteries are 100% charged, so you disconnect from the grid to 8PM and run your loads on battery for 3-5 hours depending on the time of year. Then, when the rates drop, you just reconnect to the grid (all of this done with Flextime schedule and batteries are protected by draw settings so as to not be overly discharged). The Outback solution for avoiding high time of use charges works very well and is already fully mature and implemented.
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Re: New program request to bypass Utility demand rates

Postby Coda555 on Tue Jul 02, 2019 9:17 am

This is is a mode that allows the system to connect to the grid based on battery voltage with no sell capability. I need a system or mode that will allows me to sell to the grid without buying, but shifting loads to the battery when in grid tied mode. Another way of putting it would be like mini-grid mode, but with the ability to sell to the grid when the system sell voltage is met.
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Re: New program request to bypass Utility demand rates

Postby Coda555 on Tue Jul 02, 2019 9:22 am

I don’t think I understand this mode fully then. I don’t have to go through the full charge cycle because I have lithium iron batteries so once they reach their required voltage they can start selling right away. Right now I’m operating in grid-tied with grid use set to disconnect at 12:58pm and reconnect at 8:01pm. How would I set this up to be able to sell between 1pm and 8pm?

I have to stress that I can’t use any energy from the grid AT ALL WHAT SO EVER between 1pm and 8pm.
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Re: New program request to bypass Utility demand rates

Postby pss on Tue Jul 02, 2019 9:45 am

Do you have a Mate 3S, FNDC and Hub 10? They are not listed in your equipment list. First off, you should not disconnect from the grid at 12:58 or you cannot sell during the period of high PV. Set your disconnect to be say 5PM (I don't know where you are located) so you can sell up till 5PM. Set your sell voltage to say 52 and make sure your FM100's are set to be grid tied. And let us know if you have an FNDC.
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Re: New program request to bypass Utility demand rates

Postby Coda555 on Tue Jul 02, 2019 10:01 am

No FNDC it doesn’t work with lithium iron batteries. Lithium already had a built in BMS so I didn’t need the FNDC
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Re: New program request to bypass Utility demand rates

Postby pss on Tue Jul 02, 2019 10:25 am

Just trying to get a handle on your system to make certain there are no conflicting settings to sell and avoid using expensive grid electricity. So you should try programming your system as I have mentioned. That should minimize your expensive use period.
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Re: New program request to bypass Utility demand rates

Postby Coda555 on Tue Jul 02, 2019 1:05 pm

My system is Mate3s, two GS8048 inverters, eight altE KiloVault lithium iron batteries, two FM-100 charge controllers and a 9kWh PV array.
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Re: New program request to bypass Utility demand rates

Postby Coda555 on Tue Jul 02, 2019 1:47 pm

I still dont think this will work as it only allows connection to the grid when the battery voltage is low or the load is to big for the system to handle. I need it to be able to connect and sell when the batteries are full and stay disconnect when the load is bigger then the solar production so as not to pull any energy from the grid.
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