Any interest in something like this?

[2strokeforever]

It figures out how much excess solar power you have and will "talk" to anything that will accept a 0-5v signal, or a PWM signal. SSR, VFD, ect.
It will throttle your load to use as much power as possible, but back off instantly once something wants the power, turn on the kettle, charge controller kicks into bulk, panels get shaded ect.
It only uses power that would otherwise be wasted. perfect for water heating, AC, irrigation pump ect

Your load can be off of the panel voltage, off the battery voltage, or plugged into the AC out of your inverter.
I am currently using one with a VFD drive to run my redneck air conditioning.

This version will do from 80 to 1000v, if there is enough interest I will consider selling them and possibly make a low voltage version after I finish the updated High voltage version.

 

[Craig]

Interesting concept. but I cant help but wonder what those very large guage wires are attached to that wont fry an arduino. I'm not criticizing just curious.

 

[Ampster]

I have a lot of that functionality with my SolArk and my Emporia Energy Monitor which charges my EVs from excess solar. In my situation all my loads are 120 or 240 volts so I don't need all that extra complexity.

 

[2strokeforever]

Interesting concept. but I cant help but wonder what those very large guage wires are attached to that wont fry an arduino. I'm not criticizing just curious.

The arduino is connected to the vfd 0-5v in
The big wires on the left power the unit (it has 2 isolated power supplies on board to not share any grounds with the high voltages)
They are big because im not interested in having a tiny wire spliced into a 550v 30+ amp Dc directly off the panels, I want it to be tough in case it gets yanked on.

Nothing in the picture uses more than a few milliamps, I just used the wire I had at the time that was convenient as this is the prototype, not a finished product.

 

[2strokeforever]

I have a lot of that functionality with my SolArk and my Emporia Energy Monitor which charges my EVs from excess solar. In my situation all my loads are 120 or 240 volts so I don't need all that extra complexity.

Interesting, I havent heard of those.
Does it work off grid, or only with grid tied based off of current flow direction?
Does it talk to the sol ark or MPPT, or work only off of current sensors?

I am hoping I have something unique, since it only needs the panels and a load controller.
Here are 2 pwm load controllers I am also testing, the top one is rated at 200 amps continuous at 12 to 80 volts.
I just need to start casting the heatsinks and hopefully I can find a 10kw 48v heating element to go with it.

 

[BenQ]

I’m wondering if your device would be just the thing to power a sand battery off of…

On a slight tangent, I just spent $80 on a 48v DC to 12v DC converter advertised as 720 watts of output but it only has 360 watts of output before the voltage sags to a voltage too low for my equipment (11v). You got something that’ll stop that sag?

 

[Ampster]

Does it work off grid, or only with grid tied based off of current flow direction?

The Emporia Energy Monitor works off grid.

Does it talk to the sol ark or MPPT, or work only off of current sensors?

No, it does not talk to the SolArk. It gets its data from current sensors.

 

[2strokeforever]

The Emporia Energy Monitor works off grid.

No, it does not talk to the SolArk. It gets its data from current sensors.

Is there current sensors on the charge controllers ?
I cant understand how it can figure out how much excess solar is available just off of measuring current alone when off grid.

You got something that’ll stop that sag?

No, when buying Chinese electronics I divide ratings by 2, that usually gets you more realistic results.

 

[SamDeleted]

It figures out how much excess solar power you have and will "talk" to anything that will accept a 0-5v signal, or a PWM signal. SSR, VFD, ect.
It will throttle your load to use as much power as possible, but back off instantly once something wants the power, turn on the kettle, charge controller kicks into bulk, panels get shaded ect.
It only uses power that would otherwise be wasted. perfect for water heating, AC, irrigation pump ect

Your load can be off of the panel voltage, off the battery voltage, or plugged into the AC out of your inverter.
I am currently using one with a VFD drive to run my redneck air conditioning.

This version will do from 80 to 1000v, if there is enough interest I will consider selling them and possibly make a low voltage version after I finish the updated High voltage version.

So it can monitor excess DC solar , and control an AC device ?


Or is it only for DC equipment ?

 

[Ampster]

I cant understand how it can figure out how much excess solar is available just off of measuring current alone when off grid.

Let me clarify. I may not have understood which, "it" your were referring to. The Emporia Energy Monitor works off grid, but there is no "excess solar" when off grid. I use the energy monitor for a lot of circuits. Emporia also makes an EVSE which uses the Energy Monitor data to set the charging rate of my 'EVs based on what is being exported and it changes the charging rate accordingly. . When the grid is down and I need to charge one of my EVs I use a separate EVSE connected to my essential loads panel and reduce the charging current so I do not draw down my batteries. It is a rare ocurrance that I have to do that.

 

[SamDeleted]

Is there current sensors on the charge controllers ?
I cant understand how it can figure out how much excess solar is available just off of measuring current alone when off grid.

Very interesting I was wondering if something like this existing, you'll have to forgive all the questions.. ?


How does it monitor excess solar ?

When my batteries are full , the SCC throttle down the panels to a very low output , surely very similar situation to when there no sun out

So how does your clever little box tell the difference between low production & throttled production?

 

[2strokeforever]

So it can monitor excess DC solar , and control an AC device ?


Or is it only for DC equipment ?

My contraption monitors the panels directly, it dosent talk to the mppt, it doesn't matter where you take the load from.
I have tested it by:
taking the load from the panels directly.
taking the load from the 48vdc (its not drawing from the battery, just the charge controller).
taking the load from the 240vac out from the inverter.

When taking the load from the 48v or the inverter there is a very slight lag when you turn on a heavy load, It might draw a few amps from the battery for under 5 seconds as the mppt "catches up"
The opposite happens when you turn off a heavy load, the dump load dosent throttle up for a few seconds.
It has to be slightly slowed or it will oscillate.
If its controlling anything with a motor it also has to be slowed since motors dont rev up instantly and I dont want it to keep commanding more throttle thinking the power is there when in reality the vfd and motor havent caught up yet.

If pulling off the solar DC its recalculating many thousands of times per second and there is nothing left on the table.

 

[efficientPV]

This monitors excess solar power by looking at array voltage. When voltage exceeds power point it proportionately diverts just enough directly from array to drop the array voltage back to power point. I use multiple of this control on separate water tanks and they are given priority based on set voltage. In a grid tie system that has zero export it would work the same. It could be connected to a battery, but I don't see the wisdom of that.

When taking energy from the PV array DC, energy not stored in a capacitor bank is lost. With a battery just, PWM will work.

 

[SamDeleted]

My contraption monitors the panels directly, it dosent talk to the mppt, it doesn't matter where you take the load from.

Really cool and very interesting,


How does it monitor when there's no load on the panels ?

 

[2strokeforever]

This monitors excess solar power by looking at array voltage

Looks like my idea isnt too unique... I like the way you silkscreened the capacitors negative, I might start doing it that way

It could be connected to a battery, but I don't see the wisdom of that.

if running the load on the AC side its nice to know battery voltage so if the mppt is off and array volts are high it dosent drain the batteries

 

[2strokeforever]

How does it monitor when there's no load on the panels ?

voltage and panel temperature, like anything electrical, more load = voltage sag.

 

[SamDeleted]

voltage and panel temperature, like anything electrical, more load = voltage sag.

I see very interesting, are they for sale ?

 

[2strokeforever]

I see very interesting, are they for sale ?

Eventually thats the plan, but being a one man operation running a separate business that pays the bills I can only work on this in my spare time.
I dont really want to sell it unless its 100 percent, If I am going to build a brand I want to earn the reputation of being rock solid.

 

[efficientPV]

I don't see the wisdom of running things off a battery when they will run directly off array voltage, save several conversion losses, not use expensive battery or inverter resources and leave battery in a lower state of charge. You can also continue diverting without fear of never fully topping off batteries.

This design was in response to several installers who had been burned by techluck when he wouldn't repair units which had failed. techluck has a very failure prone power supply sensitive to voltage spikes. I was sent one where every semiconductor had failed except the protection device. My board has no microprocessor that will go out of production with proprietary code, uses only common socketed IC's and even the FET are screw terminal mounted. The power supply is practically immune to lightning spikes. Ideal for an installer willing to learn the system as it is consumer repairable. If I die, they are not totally out of luck. I love micros, but solar is a technology desert.

 

[2strokeforever]

I don't see the wisdom of running things off a battery when they will run directly off array voltage, save several conversion losses, not use expensive battery or inverter resources and leave battery in a lower state of charge. You can also continue diverting without fear of never fully topping off batteries.

All of the above except the part about batteries is true, I already have the oversized inverter and while not the perfect 99% efficiency the other option is to not use the power at all for a zero percent efficiency. (or turn on my in floor heating in the summer)

My setup will not divert any power away from the batteries, if the batteries will take a charge they have priority. (except for a few seconds when a heavy load kicks on)
My crusty old mystery mutt collection of used lead acid and agm batteries sit at 100% SOC all day long, usually about 1 amp going into the batteries, despite the air conditioning drawing 5kw for most of the day. It certainly took some effort to tune the PID.

Running directly off of the panels is the way to go if it will work for you, no doubt about that.
The problem is it dosent work great for much other than water heating.

I am working on a buck converter that will power the 310v dc bus of whatever inverter you want, theoretically the best way, but the downsides are quite obvious.
It needs a High voltage array, Its not going to be cheap or easy to build, requires you to hook up to the hv dc bus of your appliance , most dont have a nice set of terminal blocks waiting for you.

So I really would like my 5kw air conditioner inverter to be powered directly off of the panels, and am working towards that, but that is quite complex so in the meantime though not the theoretical best way I am running it thru the mppt and inverter.

This isnt a one size fits every situation gadget that makes yours obsolete, but it does work well if you are in my situation where I have an excess of mppt and inverter capacity and want to easily make use of that power in a poorly insulated trailer in the middle of summer.

I imagine you chose a middle of the road temp coefficient and the pot adjusts the voltage setpoint?
There is certainly benefits of keeping it simple, reliable, and easy to fix like you have done.

Since I am in canada where the temp varies from -40c to 40c I made the temp coefficient calculate out exact.