Solar Panel Question ....

[Windrat]

[QUOTE=markopolo;111073]Booster covered it: Match Imp (current or amps) for panels in series & match Vmp (voltage) for panels in parallel.

I must be running the most mismatched ever set of panels. Solid 100 watt 20 volt + Flexible 100watt. 18 volt + 2 30 watt Colman 24volt All parallel to a single controller. With all panels flat on my roof with some shade from ac and rootop storage box. I am getting high numbers at 560 Wh north of the 49th. So I think you should be getting more yield

5DCF69F2-7360-4085-8D1B-C7BC3424243C.jpg.

[themexicandoctor]

Are you saying that you have 360 watts?

This is what I got yesterday (in shade for 2 hours);

Saturday 540
Friday 670
Thursday 490

[themexicandoctor]

Got to love Victron!

Do those figures seem more in line?

Of course when the fridge goes in I am expecting my draw to increase along with a similar curve in yield & that yield to have absorbed all of the demand & more when the sun is uut, its hotter & the fridge taking up the excess that is normally lost.

On Theory of course.

What do you think of those numbers, are they more accurate & in line with what I am supposed to have.

There have been rare days when using the inverrter in perfect sea level conditions throughout the day where I have seen highs of 900 plus to a high of 980.

[Windrat]

Originally Posted by themexicandoctor

Are you saying that you have 360 watts?

This is what I got yesterday (in shade for 2 hours);

Saturday 540
Friday 670
Thursday 490

Nope only 260. watts 2x100. 2x 30:

[DaveBad]

Just another explanation:

https://www.youtube.com/watch?v=JfzT8u205co

[Nic7320]

If you're mixing different size panels or different manufacturer's panels, a good solution is to use two separate but smaller controllers. The Victron 20 amp, 100 volt controller is a good choice, and is only about $150 each.

It has a switchable DC output with a history page, reporting the last 30 days of power draw, which can tell you a lot about critical loads such as DC refrigerator. Victron's larger controllers, those over 20 amps, omit this feature.

This became valuable as I didn't know my fridge was shutting off due to low voltage, but the history page alerted me when I checked it. The history page also details how much more power it needs on a hot day. All on all, it's a very useful feature.

[themexicandoctor]

I am going to talk again with my Guru - it would appear, based on that last video, that in fact Series is best with two different wattagw panels.

Or am I missing something?

NIC, are you saying that I need to buy back my Victron 15/75 Bluetooth unit (or purchase a new one) & connect it to the 80 watt panel, in parallel?

Or is that feature only available on the Victron 20amp unit?

[Nic7320]

If you have both a 15 amp controller and a 30 amp controller, then you can use one on each panel. And yes, the 15 amp controller has a DC output with the history page accessible via Bluetooth if you need that feature. But the output is limited to 15 amps.

[themexicandoctor]

NIC,

Do you have mismatched panels?

Do you have two controllers?

Does that video mean even though I believed that I saw an increase in watts produced, at a voltage level, I was getting less valuable yeild?

I usually just give all this to my Guru & have him work it out, that last video was a slap in the face.

Bottom line; it says if I dont go through the expense of 1. paying someone to wire them in series 2. I either add another $150 Victron & pay to have that done or 3. I just cut the connection to the 80 watt unit?

Does that sound accurate?

So as to the two controllers of I went that way of buying anothrr Victron 75/15, would I be able to, or not be able to, track the fridge usage or would it just give me the yield from the 80 watt but no history?

I have an email & a call into my guy who has now retired & I don't blame him. I might ask him to describe here exactly the thinking behind his theory.

As it is, as part of adding the Victron 30/100, I gave him my 75/15.

The guy as I said is an Electrical Genius, I paid him $500 to rewire everything because another quality rv guy but without the Electrical background had two negatives/earths with the dual batteries & it was throwing off the BMV712 - he was reluctant to add the 80 watt but I was so enthused at the idea of perfect batteries & free power I had him choose the panel versus adding another Go Solar unit as he felt his purchase was a better product.

I am sure he chose wisely & installed as such.

[themexicandoctor]

Originally Posted by Nic7320

If you have both a 15 amp controller and a 30 amp controller, then you can use one on each panel. And yes, the 15 amp controller has a DC output with the history page accessible via Bluetooth if you need that feature. But the output is limited to 15 amps.

NIC,

I had a Victron MTTP 75/15 on the previous set up but it seemed overpowered.

Gave that to Guru.

And asked him to buy & install the Smart Victron 30/100 only to find after a couple of hours being unable to connect that he had made a mistake of buying the non-smart version.

MANY PEOPLE ON-LINE MAKE THE SAME MISTAKE.

Purchased the bluetooth dongle & its from that dongle that I printed out the data shot/history.

[Nic7320]

Yes, I have two Victron MPPT 20/100 controllers going to two different kinds of panels. Each goes to a panel string (wired in series) from two different manufacturers. One has four Renogy 100 watt polycrystalline panels and the other controller goes to four HQST 100 watt monocrystalline panels.

It gets the job done.

[themexicandoctor]

You have 800 watts of Solar?

What make, model & type of fridge did you add?

And on review of your other posts, it appears my present controller will work as far as history but that I need another controller just for the measly 80 watt panel which was the last unit I could fit on the roof.

I could add some more flexible, stick on units but then they too would have to be wired in series as well.

[themexicandoctor]

And if I am understanding everyone, are these three options accurate;

To resolve my issue I can;

1. pay someone to re-wire them in series?

2. I either add another $150 Victron Controller & pay to have that wired in? (there isn't much space available at all in the electrical area).

or 3. I just cut the connection to the 80 watt unit because its dragging my 170 down?

[themexicandoctor]

And are Watts unimportant compared to Volts?

[Nic7320]

Yes, I have 800 watts on a 24 foot class C RV. I run two chest type chillers, one is a Whynter FM452, which fits between the front seats and is used as a freezer, and an Iceco VL60S which sits behind the passenger seat and used as the refrigerator.

I still have the propane fridge in the RV, but use it as another pantry.

I will probably add more solar panels. The goal is to be able run an air conditioner 100 percent from solar. But that's also going to require a very efficient mini split AC. And it's got to be quiet. The one that came with the RV is terribly loud.

Energy is all about collecting watts and the hours of operation. Collecting power takes place over the useful hours of sunshine (i.e. sun-hours, which are usually 5 or 6 hours per day in North America), and the product of watts and hours gives you energy, which is measured in watt-hours. Power is measured in watts, energy is watt hours.

Another goal here is to have an adequate margin of battery energy stored, so a day or two of cloudy weather is not a problem.

[themexicandoctor]

Originally Posted by Nic7320

Yes, I have 800 watts on a 24 foot class C RV. I run two chest type chillers, one is a Whynter FM452, which fits between the front seats and is used as a freezer, and an Iceco VL60S which sits behind the passenger seat and used as the refrigerator.

I still have the propane fridge in the RV, but use it as another pantry.

I will probably add more solar panels. The goal is to be able run an air conditioner 100 percent from solar. But that's also going to require a very efficient mini split AC.

Energy is all about collecting watts and the hours of operation. Collecting power takes place over the useful hours of sunshine (i.e. sun-hours, which are usually 5 or 6 hours per day in North America), and the product of watts and hours gives you energy, which is measured in watt-hours.

So the goal here is to have an adequate margin of battery power stored, so a day or two of cloudy weather is not a problem.

This part I understand.

With a 24 footer you have an abundance of space available.

Hopefully tomorrow my Guru will educate me as to what he did to mitigate the mismatch - I just didn't have that much space, maybe a 100 watt at most.

I have since removed that MaxxAir cover, too much shadow.

Are my three options accurate?

[Nic7320]

A fourth option is to replace your small panel with one matched to your larger panel -- if you have enough space. Now that I see your rooftop, that's not going to work.

Look for panels that best fit your roof. You might try three panels that use all your roof width. I selected mine based on the distance from the AC and roof vents to the edge of the roof. The 100 watt panels were a good fit.

One more option is to use deployable panels on the ground. I did that when I had a class B van with very limited space on the roof. The trick is where to store them when traveling. I found a slot behind the spare tire carrier that worked.

[themexicandoctor]

The fourth wouldn't work or I would have already done that with the issue being size - no more space.

So my other three options were accurate?

[themexicandoctor]

I posted a photo - zero room.

[Nic7320]

I see enough space for three rectangular panels if you mount them sideways.

If your panels are wired in parallel, look for a wye connector on the roof where your wires combine. Then it's easy to isolate the smaller panel just by disconnecting one MC4 connector.