I have an M215 based GT system and was playing around with a battery based system. I took an EPever charge controller, 24V battery, a few random solar panels and a spare M215 inverter.
The solar panels would charge the battery (first LA, then lifepo4) via the epever 30a charge controller. I then put the charge controller into nighttime switch mode where the epever would turn on a load for a specified period of time at after sundown/befroe sunrise. The load was the spare M215. It would run for 2-3 hours pulling current from the battery. The epever performed low voltage/overvoltage duties also. It was a way to shift some of my solar production to the nighttime hours. It still had all the benefits and flaws of a GT system, but time shifted. No grid down power, but also no islanding issues and met UL. It is my coarse understanding that the enphase batteries do essentially the same thing, but the IQ8 and some brains replace the epever and M215.
A couple of questions:
1. Has anyone else created a similar system?
2. I had a lot of trouble communicating with the epever, often it would not take my parameter changes. Anyone have a similar problem and solution?
3. Working with the M215 was tricky. I let the smoke out of a few of them. It makes sense, but was still a problem. If you connect them directly to a 24v battery, they will short and let the smoke out. I had to connect it in series with an NTC termistor to limit the inrush current. Usually over time the NTC wold crack and die. I didn't know how much limitation the M215 needed. I eventually combined it with a timed switch, which would go closed after 90 sec or so. That helped, but looked even more Rube Goldberg. I am assuming that the M215 is expecting a solar panel, which has naturally limited current. The battery looks like an infinite current source and blows something. Once it determines that is is 24v and starts running MPPT on it, then it calms down and only takes what it needs. It would be nice to have a little more information on how to not let the smoke out of a M215. Has anyone designed a better solution to working with a GT inverter expecting solar, but running it with a battery instead?
4. Has anyone tried this with a IQ7 or even better an IQ8 or similar inverter? If the IQ8 could be used as an inverter charger with battery, grid and PV input/output that would be useful. It seems like that is exactly what they are doing in their battery, with the inclusion of a transfer switch for grid forming and such. ATM I don't want grid forming. Just a battery agnostic scaleable MPPT/inverter/charger.
rearden
The solar panels would charge the battery (first LA, then lifepo4) via the epever 30a charge controller. I then put the charge controller into nighttime switch mode where the epever would turn on a load for a specified period of time at after sundown/befroe sunrise. The load was the spare M215. It would run for 2-3 hours pulling current from the battery. The epever performed low voltage/overvoltage duties also. It was a way to shift some of my solar production to the nighttime hours. It still had all the benefits and flaws of a GT system, but time shifted. No grid down power, but also no islanding issues and met UL. It is my coarse understanding that the enphase batteries do essentially the same thing, but the IQ8 and some brains replace the epever and M215.
A couple of questions:
1. Has anyone else created a similar system?
2. I had a lot of trouble communicating with the epever, often it would not take my parameter changes. Anyone have a similar problem and solution?
3. Working with the M215 was tricky. I let the smoke out of a few of them. It makes sense, but was still a problem. If you connect them directly to a 24v battery, they will short and let the smoke out. I had to connect it in series with an NTC termistor to limit the inrush current. Usually over time the NTC wold crack and die. I didn't know how much limitation the M215 needed. I eventually combined it with a timed switch, which would go closed after 90 sec or so. That helped, but looked even more Rube Goldberg. I am assuming that the M215 is expecting a solar panel, which has naturally limited current. The battery looks like an infinite current source and blows something. Once it determines that is is 24v and starts running MPPT on it, then it calms down and only takes what it needs. It would be nice to have a little more information on how to not let the smoke out of a M215. Has anyone designed a better solution to working with a GT inverter expecting solar, but running it with a battery instead?
4. Has anyone tried this with a IQ7 or even better an IQ8 or similar inverter? If the IQ8 could be used as an inverter charger with battery, grid and PV input/output that would be useful. It seems like that is exactly what they are doing in their battery, with the inclusion of a transfer switch for grid forming and such. ATM I don't want grid forming. Just a battery agnostic scaleable MPPT/inverter/charger.
rearden
