Testing potential solar harvest?

[bpounds]

Now that I have a solar installation up and running, and it's working great BTW, I feel a little under informed at times. For example, at any given point in time, what is my array capable of harvesting with current sunload? All I can see is what my batteries will accept at their SOC at that moment.

Is there an easy way to put a load on the controller? To somehow make it "gimme all you've got Scotty". With batteries disconnected obviously. Or do we just assume our array can do XYZ based on panel specs?

I feel like I won't ever see what the system can actually do, without discharging the batteries way down and then hitting the solar switch, and even then it is only a short term metric.

[red31]

epever PC software makes cute plots, never figured out to save the data.
hers's bulk/abs early morning charging tiny 7ah AGM via epever's PC software.

[CA_Traveler]

bpounds wrote:
I'm impressed with the time you guys put into your spreadsheets. I assume you pull that out of your Morningstar charge controllers.

Yes, the Morningstar MSView software logs and creates a CSV file and the rest is done in Excel.

[Itinerant1]

I'm using all Magnum equipment, readings come from the the me-arc50 mounted inside the trailer. The Lifepo4 battery readings have their own display for monitoring.

[bpounds]

I'm impressed with the time you guys put into your spreadsheets. I assume you pull that out of your Morningstar charge controllers.

So far I am really happy with the Epever Tracer MPPT. I don't think it does realtime logging. I know it accumulates a value for watts collected. I'm not sure over what time period, and if it ever resets or rolls over. It's not a value that interests me.

It came with an MT-50 remote monitor which I mounted inside the coach, using RS485. The main monitor screen tells me the important stuff, and also is a better method of adjusting settings in the controller, than the controller front panel. I also kept my old volt meter as a second opinion, and it has the added value of reading in hundreds of a volt. Sounds silly, but I find that extra digit useful.

It has optional modules to do Bluetooth and WAN connections. Based on reviews I've read, I'm not sure they have the bugs worked out of those. And it was super easy to pull an RS485 cable over to the trailer control panel wall.

At about $190, it does everything I value. I think it is a good buy, as long as it doesn't blow up.

[Itinerant1]

I like those graphs to see production through out a days use I wish my system had that option.

[CA_Traveler]

Here's a graph where I used house loads to gain the maximum solar output.

What makes the graph work for me is that my controller when connected to a PC will log CC input and output volts and amps and many other parameters.



Click here for the thread. This graph was posted to show the positive effects of bypass diodes in solar panels and frankly to dispel a lot of incorrect posts concerning shadows on panels.

But it does show the maximum solar output for the morning sun.

[CA_Traveler]

bpounds wrote:
I think a load tester would do it, sort of. I won't do that. The inverter load would be the closest thing to a designed in tester.

Clearly what I was asking about is not practical on an off-grid system.

Consider a grid-tied solar system. That array is going to be putting out full capability, based on available sun load, at all times. What power your home is not consuming will feed the grid. You can look at that inverter monitor at any time and see the full capacity at that moment. The grid is like a battery that is always hungry, never fully charged. The panels are always harvesting all the sun available, and that can be monitored. Cannot do that off-grid.

Other than panels there is almost nothing in common between grid tied and RV solar so I'm not going down that route.

[Itinerant1]

bpounds wrote:
I think a load tester would do it, sort of. I won't do that. The inverter load would be the closest thing to a designed in tester.

Clearly what I was asking about is not practical on an off-grid system.

.... Cannot do that off-grid.

Like most things it comes down to cost and importance.

In this excel sheet you can see charging/ discharging current, battery state with other misc info. This would be at maximum what the solar is producing at the moment while charging or maintaining batteries and covering loads. In theory what you originally asked about potential of solar production?

DC Display readings

[bpounds]

I think a load tester would do it, sort of. I won't do that. The inverter load would be the closest thing to a designed in tester.

Clearly what I was asking about is not practical on an off-grid system.

Consider a grid-tied solar system. That array is going to be putting out full capability, based on available sun load, at all times. What power your home is not consuming will feed the grid. You can look at that inverter monitor at any time and see the full capacity at that moment. The grid is like a battery that is always hungry, never fully charged. The panels are always harvesting all the sun available, and that can be monitored. Cannot do that off-grid.

[CA_Traveler]

You must be able to determine both amps and volts from your CC to know how much power is coming from the CC. Volts times amps equals watts. Volts by itself doesn't answer you question.

You can use a battery load tester to provide additional load, which will lower the battery voltage regardless of battery charge state.

You can use a hydrometer to measure SOC and can be useful in helping to determine how the charge is progressing.

But nothing beats knowing CC amps and volts and measured on the CC input eliminates CC losses.

[bpounds]

BFL13 wrote:
You compared the 14 with the 40 and your controller is a 40 amper. So it was not volts! Morning battery voltage (no charging) would be 12.x, rising during the day to 14.x with solar charging.

No, I made a point of saying the PV were putting out 14V. Not the charge controller. I'm wired series/parallel, and the PV is usually at 38-39V once the sun is up. It was intended to make the point that the sun was not yet up.

That it happened to be 14 was just coincidence, as was the 40.

[BFL13]

You compared the 14 with the 40 and your controller is a 40 amper. So it was not volts! Morning battery voltage (no charging) would be 12.x, rising during the day to 14.x with solar charging.

Hard to follow what you are talking about. 😞

With MPPT in Bulk the amps on the array to controller wiring will be Imp. Volts will be Vmp. Not to be confused with "amps to the battery", which is entirely a different thing.

[Itinerant1]

pianotuna wrote:
Hi,

All I see is a blank sheet.

Itinerant1 wrote:

Here are recordings from last years all boondocking 24/7/365, note I have Lifepo4 batteries so they charge quicker with extra power going to rv fridge or other 120v items through the inverter.If you're interested.
2017 PV system/ boondocking

When you open it at the bottom there are tabs to open. I just opened with my phone from the link.

[bpounds]

Yeah, I was borned, but it wasn't yesterday. I'm clear on the V-A thing. I only mentioned the 14v to note the very low light level at the time.

Seems about half the responses didn't understand the question.