Would you please go into a bit more details - or even show the code? You have just outlined EXACTLY what I would like to do with our hot water tank, but I donlt really know how. I have some arduinos and some electrocnic skills - just not enough to pull this off by myself safely.This is a bit niche but I programmed an Arduino to poll the serial port of my easun inverter.
The Arduino can obtain all the operating voltages/currents etc since 1 second ago.
The program monitors the PV array voltage to ensure it is high enough. Then it gently loads the inverter to test if there is any spare energy to divert to a 1.2 kw hot tank element.
Whenever the generated PV watts exceeds the inverter output watts by 30 watts the Arduino begins to increase the firing angle of a triac connected to the hot tank heater element.
As long as the battery remains charging or is fully charged the Arduino keeps diverting power to the heater.
This way the hot tank is boiling hot by about noon on a decent sunny day.
There are a number of critical parameters that drive the Arduino logic but it works well. As a bonus I can display how many kwh were used per day and how much solar kwh was generated.
There is also a long term watt meter display that can log up to 9999 kwh.
next step is to log all this to an openlog based SD card data logger. Or run a raspberry Pi/ Banana Pi data logger.
would you consider an east-west array? I'm at 53 degrees north and get 12 hours of PV power from May-Sept with a SE/NW arrayIm in the same boat as many.. I have a larger system and im. Usually full by noon. Now i need to dump into hot water heater, and AC in the summer. Im waiting on my solar Assist to come in and already have a raspberry pi. Just setting it up is the challenge.. Lol
Similar to your situation I get very little usable solar energy from November to February. The inverter gets switched to UPS mode for these four months. Let's just say blackouts are no longer a worry ?I only have 4.5hr window from November to February. Im facing south. I've had to build my system for that short window.. And I'm WAY too big this time of year.
If i could maybe add a second Hot water heater and use it for storage to keep from drawing from the batteries at night.
Maybe even a passive water heater..
@SunFarmerDoes anyone know how to use the dry contacts on an EG4 6000EX inverter to trigger a dump load?
As described in the pathetic manual, the dry contacts seem to be for starting a genset to recharge the battery, the opposite of what I want. According to the manual, with the inverter set to SBU, the contacts will engage when the battery voltage drops to 46V and disengage when voltage reaches 54V. The manual also states that when the battery type is set to "EG4" the values for programs 20 and 21 will been shown as a percentage, but it shows voltage. It's stupid errors like this that make me suspect of how much of the rest of the document is incorrect. But I digress...
Thanks in advance for any input.
No, the grid tie connection goes through a series of tests, which includes synchronization and testing that its really a connection to a solid power source. Anything is possible, but a simple spoof is not going to do it.If so, I wonder if there is any way to spoof it? Maybe a couple of megaohm resisters to couple the sinewave, but not any current.