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.

[pianotuna]

Hi,

volts only tell us the "pressure" Amps are what we wish to store.

bpounds wrote:


No, I meant volts. Amps were so low I don't remember, but basically nothing. It was barely past dawn.

The CC is an Epever Tracer AN 40, MPPT.

[pianotuna]

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

[bpounds]

BFL13 wrote:
"At 7AM this morning, we've got a little marine overcast today, I was getting 14v from the PV array (max at 40v). The battery was down to 12.6 after sitting all night. I'm sure the system will be hitting the batteries with 14.6 within the next hour or two"

I assume you meant amps instead of volts.

It makes a difference how to answer your question whether that 40 amp controller is MPPT or PWM. Your question is easy to answer either way but not both.

No, I meant volts. Amps were so low I don't remember, but basically nothing. It was barely past dawn.

The CC is an Epever Tracer AN 40, MPPT.

[BFL13]

"At 7AM this morning, we've got a little marine overcast today, I was getting 14v from the PV array (max at 40v). The battery was down to 12.6 after sitting all night. I'm sure the system will be hitting the batteries with 14.6 within the next hour or two"

I assume you meant amps instead of volts.

It makes a difference how to answer your question whether that 40 amp controller is MPPT or PWM. Your question is easy to answer either way but not both.

[Itinerant1]

bpounds I like to record what's happening in the system plus like what you're asking about, to see potential solar harvest at different locations boondocking. It easy with the setup I have using the Magnum remote display in the 5th wheel.
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

[bpounds]

I guess there just isn't a convenient way to do this. With a good ammeter I could check it at the PV connection point to the controller. Anything else, including using an inverter, is going to see some contribution from the battery bank. I didn't find anything in my other searches on the web either.

Not a big deal. All that really matters is getting the charge into the battery. My curiosity wasn't so much about whether the system was working, as it was about sun/clouds/shade in any given parking location. It would be kind of fun to look at the harvest on a given day, overcast versus sunny, intermittent clouds versus blue sky. You can still do that, but it will be skewed by whatever the batteries will accept at that particular moment, and always changing.

I turned the breaker off for the converter last night (I am always plugged in when stored here at home). I think I am going to leave that turned off as a norm, and rely solely on the solar for charging.

At 7AM this morning, we've got a little marine overcast today, I was getting 14v from the PV array (max at 40v). The battery was down to 12.6 after sitting all night. I'm sure the system will be hitting the batteries with 14.6 within the next hour or two.

[pianotuna]

Hi,

Do not disconnect the battery bank. You may let out the magic blue smoke from the controller.

A 300 watt inverter running flat out would represent a 30 amp load to the battery bank. While I prefer PSW (Vitron makes one for about $100) may find an MSW for 30 to 40 bucks. It is always nice to have a way to charge small devices, such as laptops.

bpounds wrote:

pianotuna wrote:
Hi,

If you have an inverter load it up and that will soon have the solar pumping out watts.

Now that makes sense. I'm not really planning on an inverter, at least not at the moment. Maybe a small one at some point to run entertainment.

[bpounds]

I musta misspelled EZ. 😉

[wa8yxm]

Is there an easy way to put a load on an electrical device

You will need. a bunch of standard surface mount switches (15 amp at 120 volt work fine) and light sockets (The common two screw mount procelin)

Some wire and a box full of 12 volt light bulbs (100 watt works well)

Heavy wire along the bottom goes to the switch. 12 ga or 14 ga from switch to lamp socket heavy wire along top back to controller. Matters not which heavy wire is _+ and which is -

Turn on switchs one at a time to add load in 10 amp steps

For smaller steps. Use smaller lamps.

[2oldman]

bpounds wrote:
Is there an easy way to put a load on the controller? With batteries disconnected obviously.

No, don't disconnect. Use an inverter load as mentioned, or let 'em run down.

You can figure the approximate output at around 80% of their rated capacity.

[time2roll]

bpounds wrote:

time2roll wrote:
If you are at the bulk or float voltage you are good to go.
If voltage is still rising (bulk) at 2pm your system is weak or something is wrong.

It is doing a fine job of that. But sitting in my driveway with full summer sun, so not very meaningful.

Best test.... go camping!

[red31]

if you can't figure out how to apply a load, yo can measure the panel's current directly with a ammeter with the panel disconnected from the controller.

[bpounds]

time2roll wrote:
If you are at the bulk or float voltage you are good to go.
If voltage is still rising (bulk) at 2pm your system is weak or something is wrong.

It is doing a fine job of that. But sitting in my driveway with full summer sun, so not very meaningful.

[time2roll]

If you are at the bulk or float voltage you are good to go.
If voltage is still rising (bulk) at 2pm your system is weak or something is wrong.

[bpounds]

azrving wrote:
"With batteries disconnected obviously. "

You may see smoke come out of the controller. I use a trimetric but victron and others are also available

I understand that you should not run the controller without batteries, but I was suggesting some other type of load in place of batteries. Perhaps using a pair of disconnects to switch between loads. A Trimetric would not do what I was hoping for.

pianotuna wrote:
Hi,

If you have an inverter load it up and that will soon have the solar pumping out watts.

Now that makes sense. I'm not really planning on an inverter, at least not at the moment. Maybe a small one at some point to run entertainment. We've become very comfortable camping without AC power, and I don't want to haul more than 2 GC batteries just to support an inverter. I think you are right though, that would be a way to test the system. I thought of just turning on every 12v device in the entire coach, but that still would not tax the 40a charge controller, or even the 30a that the solar array might be capable of on its best day. A good sized inverter would, then try to find enough AC gizmos to run for a while.

I was hoping someone had devised a simpler method. Haven't seen it done as of yet. Maybe something similar to a battery load tester?

I know it is kind of a silly curiosity of mine. And is due to the fact that I haven't been able to take it out camping yet. It won't matter once I have a little experience with the system.