Willing to engage a subject matter expert to determine what can be done. We live in Costa Rica and ordered a system to deal with the 100± voltage drops and outages we have every 24 hours.
We engaged to solve this and requested:
Specified an active system (not passive)
Line conditioning
Battery backup for a couple hours
Solar ready (for future)
After install we noticed the surge protectors and small UPS units in the house continued to click and beep all night. Realized the install was a passive system and it was switching back and forth all the time. Huge issue because these Multiplus II units are designed to last an average 10k transfers so they were headed for failure in less than 6 months!
The installer took some responsibility and installed AIMS Power battery chargers. So we have stable power in the house now because the battery chargers convert AC to DC and charge the batteries. The Multiplus II units are set to inverter only (DC to AC) so no more switch transfer wear.
Looking for ideas on what can be done to turn these pieces into our original intent. The issues now are:
Electric bill has doubled due to losses from the double inversion.
No longer Solar ready.
No option to return excess power to utility if we add Solar.
Option to add an auto start generator also went away because the Multiplus units are set to inverter only.
I’m thinking an actual line conditioner up front and changing the Multiplus units back to passive settings might workee. Most of our power issues are voltage drops and the outages are normally only seconds so a quality line conditioner would absorb most. My concern is that there would still be an excess number of transfers so I would be replacing Multiplus units frequently.
The MultiPlus synchronizes to the grid voltage/frequency and passes that through.
It doesn’t and it can’t change the voltage/frequency.
If the voltage/frequency jumping to much it will disconnect and reconnect after the values are back to normal.
I guess the best you can do is to build your own grid and change the batteries with normal chargers.
You can still add PV via MPPT or PV inverter to reduce the grid usage but you will not be able to feed back energy to the grid.
You can configure a relay to only switch on the charger if the SOC of the battery goes below a certain level and only charge to a safe level.
How is your solar sized? Will it be enough to cover loads and charge batteries? If so then you could just move off grid.
If you are not at that point yet, you could set up some programming with either smart switches and node red or remote switching of the chargers so they only charge when needed, not all the time. Or set them so they only partially charge )with a voltage setting to sustain them preveting them from becoming empty) and solar finishes them to full.
Your other option is some pretty big AVRs on the output of the inverter to correct voltage for loads. This is probably the only option that will allow grid feedback and suits your ‘line conditioning’ requirement. If you install them on AC in they may cause issues with ESS.
But if your grid is that unstable then the idea of grid feedback, while noble, is not worth the wear and tear on your own equipment.
So you bring up two possibilities I am considering. Neither solve all my issues but they would mitigate the monthly bill:
Add Solar panels to reduce the utility power being drawn by the batteries chargers during the day.
Turn the chargers off during the day when electricity cost is almost double the nighttime rate.
That second option sounds good but would deep cycle the battery bank and shorten its life. I may try it manually one day just to see how low the batteries get, then decide.
Still willing to tear this apart and start over if there is a way to get what I originally wanted.
Placing line conditioning on the output side of the inverter is not a solution. First that would leave the inverters switching many times a day and cause a short life span, and second the power coming out of the inverter is already being controlled for voltage and frequency.
If a dedicated line conditioner were installed it would be first in line from the utility, then the multiplus inverters in passive (failover) mode. I know the conditioners will cover voltage drops and that is most of our daily utility issues. We still have actual outages however so the inverters would have more transfers (and hence shorter life) than a normal install.
Also working this from the utility side. Trying to get a price to run the high tension line closer and install a transformer. Right now we are running about a 10% loss just from the service line size and distance.