Solar - How much charge do you get? Is this about right?

[Wissel]

Today I moved our van to the other side of the warehouse we have been parked at during lockdown. The side that gets the sun

This was the first day I've gotten an accurate reading of what are solar really does (since upgrading last year). But I've no real idea if it's performing well or not, so wondered what others may get?

My setup is 3 x 180w panels in series, connected to a Victron 100/50 MPPT. The panels are flat.

I'm in Cheshire and it's been more sunny than cloudy today, I moved the van at 11am (ish) to the sunny side, I had no shadows until about 6.30pm.

Total solar yield for the day was 1.84kw.

I'm pretty happy with this as I use between 1 - 1.4kw battery power per day, and it's only the end of March.

But is this a fair performance?

Are others getting more/less/similar?

Thanks

 

[Lenny HB]

I don't have a way of measuring my daily output but it looks like you are getting a very good output from 540 Watts.
Do you know what your max output was today?
I would expect at this time of year not to get much more than a third of the max output.

 

[Bobby-gg]

I'd say that is pretty good.

I've got 1kw of angled panels in a remote location, today on a so so day in Northumberland I got 1.62kwh, whereas two days ago with clear blue skies all day I got 2.5kwh

 

[Wissel]

I don't have a way of measuring my daily output but it looks like you are getting a very good output from 540 Watts.
Do you know what your max output was today?
I would expect at this time of year not to get much more than a third of the max output.

This is a screenshot from the app:

Would you say this is okay from my setup?

I'm leaving the van parked on the sunny side tonight to get an idea of a full day tomorrow. I won't start the van, so will hopefully see exactly what goes into the battery via the BMS.

This was today (screenshot just taken), but I've driven the van a little, so total charge wasn't just solar:

So total charge today was 2.38kw, consumed was 1.7kw (been testing everything in the van continually as leaving here in a few days).

 

[DBK]

You won't get more energy out of the panels than you use - disregarding losses. So your figures sound about right but if you upped your power usage would the panels respond? Only one way to find out - plug in an electric heater and run it for a while.

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[Lenny HB]

The peak output of 435 watts is 80% of the max. On flat mounted panels at this time of year I would say that is impossible. I would question the setup of the monitor.

 

[Wissel]

You won't get more energy out of the panels than you use - disregarding losses. So your figures sound about right but if you upped your power usage would the panels respond? Only one way to find out - plug in an electric heater and run it for a while.

I'd ran my battery as low as I dared over the last few days as I'd planned to test the solar today/tomorrow

I have my BMS set pretty conservatively with usable capacity at 4.8kw. At this moment it's at 1.76kw, so hopefully flat enough still for a full test tomorrow.

 

[Wissel]

The peak output of 435 watts is 80% of the max. On flat mounted panels at this time of year I would say that is impossible. I would question the setup of the monitor.

That's interesting.

I have two seperate monitors, the Victron and my BMS, and have flicked between them a few times today and they seemed about the same.

Tomorrow I'll fire one app on phone and the other on tablet and screenshot at exactly the same time. I'll do this a few times throughout the day and once dark and update this thread.

What would you expect the peak output to be out of interest?

 

[Lenny HB]

What would you expect the peak output to be out of interest?

About 30% to 40% of max.

 

[Wissel]

About 30% to 40% of max.

So a lot of difference then.

I've just double checked all the settings in Victron Connect and in my BMS. They are both correct and completely independent of each other, so hopefully any fault will show up in tomorrows figures

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[Wissel]

Wanted to try and record the whole days power usage and solar charge, so started just after sunrise:

No charge showing yet (obviously) in either app.

BMS is showing .39kw used so far today, this is with the following left on all night:
Fridge, inverter, router, 2 x phone charger, twin 18650 charger, MaxxFan (setting4), and PC with 27" monitor on for about 30 mins.

I'll try to remember to photograph the apps every couple of hours today.

 

[Wissel]

Just after 9am:

Victron saying it's currently charging at 9.4a, BMS (at the battery) saying 9.3a.

Total charge for day so far:
Victron say: 0.11kw
BMS says: 0.11kw

So fairly the same so far. See what it's like at 11am ish.

PS: My BMS measures charging and draw separately. It does this by having all chargers connected through one live and all draws connected to another. Both cables have coulomb counters on the measure current through each cable.

 

[Raul]

Wissel
Your set up works very well. To get 1,84kwh a day from 540wp is pretty good for end of march. That equates to 3,4 sun hrs. In the summer you can do 6-7 sun hrs, like 3-3,5kwh per day. Don’t get hung up to much on peak output, is dependable on usage and temperature. The hotter will get, the bigger the drop in performance. Spring and autumn is best for peak power, but overal harvest for total daily energy is the time with the longest day light, midd summer.

 

[funflair]

What battery capacity have you got? you seem to have put in 150amps yesterday but 9am today your BMS shows 24% ? or am I reading it wrong.

 

[Wissel]

Wissel
Your set up works very well. To get 1,84kwh a day from 540wp is pretty good for end of march. That equates to 3,4 sun hrs. In the summer you can do 6-7 sun hrs, like 3-3,5kwh per day. Don’t get hung up to much on peak output, is dependable on usage and temperature. The hotter will get, the bigger the drop in performance. Spring and autumn is best for peak power, but overal harvest for total daily energy is the time with the longest day light, midd summer.

Thanks

It was a pretty sunny day yesterday to be fair, but nice to know I'm likely to get more in the Summer.

What battery capacity have you got? you seem to have put in 150amps yesterday but 9am today your BMS shows 24% ? or am I reading it wrong.

My battery capacity is 400Ah. I'd run the batteries down to around 10% before yesterday (ready for this test) and although I put a lot in yesterday, I used a lot in the evening and this morning (again, trying to run them down a bit).

Okay, at 11am ish:

Victron saying it's currently charging at 18a, BMS (at the battery) saying 17.8a.

Total charge for day so far:
Victron say: 0.49kw
BMS says: 0.47kw

Maximum solar watts seen so far = 249w

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[funflair]

Thanks

It was a pretty sunny day yesterday to be fair, but nice to know I'm likely to get more in the Summer.


My battery capacity is 400Ah. I'd run the batteries down to around 10% before yesterday (ready for this test) and although I put a lot in yesterday, I used a lot in the evening and this morning (again, trying to run them down a bit).

Okay, at 11am ish:

View attachment 478902

Victron saying it's currently charging at 18a, BMS (at the battery) saying 17.8a.

Total charge for day so far:
Victron say: 0.49kw
BMS says: 0.47kw

Maximum solar watts seen so far = 249w

Ah OK, I was thinking that you weren't going to last a cloudy day if you started at just over 20%, we have 520 watts a reasonably sunny day and making over 16 amps at mid day but the batteries will be getting towards full and the van is on a slope away from the sun so not ideal, if you are parked alongside a building are you getting reflected light?

 

[Wissel]

Ah OK, I was thinking that you weren't going to last a cloudy day if you started at just over 20%, we have 520 watts a reasonably sunny day and making over 16 amps at mid day but the batteries will be getting towards full and the van is on a slope away from the sun so not ideal, if you are parked alongside a building are you getting reflected light?

Possibly

1pm:

Victron saying it's currently charging at 20.9a, BMS (at the battery) saying 20.3a.

Total charge for day so far:
Victron say: 1.01kw
BMS says: 0.96kw

Maximum solar watts seen so far = 292w

 

[Wissel]

3pm:

Victron saying it's currently charging at 17.5a, BMS (at the battery) saying 17.3a.

Total charge for day so far:
Victron say: 1.51kw
BMS says: 1.44kw

Maximum solar watts seen so far = 299w
(much cloudier today here than yesterday though)

 

[Wissel]

5pm:

Victron saying it's currently charging at 10.9a, BMS (at the battery) saying 10.5a.

Total charge for day so far:
Victron say: 1.80kw
BMS says: 1.71kw

Maximum solar watts seen so far = 299w

PS: Ignore the state of charge reading on the BMS. Until the cells reach their balancing current (3.4v), the soc won't reset. It's because I haven't filled the cells for weeks - the coulomb counters aren't accurate over time and don't state full until balancing is achieved. It will jump to 100% soon and then be more accurate again for a few weeks.

I generally look at cell voltage to gauge soc. Cells are currently at 3.35v, which is around 85-90% full in real terms.

 

[Bobby-gg]

Looks good, I'm still getting 150w at 17:24 on my 1kw of angled panels, and I've hit my highest harvest this year so far of 2.58kwh, but that's going into batteries that aren't doing much work at the moment.

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[funflair]

I think you have done pretty well, time of year etc, your numbers are higher than mine but we were fully charged just after mid day, it has prompted me to go up and clean the panels and they were filthy

 

[Wissel]

Final reading. Almost 7pm and now some of the panels in shade:

Total charge for day:
Victron say: 1.90kw
BMS says: 1.80kw

Maximum solar watts seen = 299w

Nice and warm all day, but always cloudy. Pretty happy with the readings.

 

[Wissel]

After looking back on the above figures, I think Lenny HB had a good point yesterday. After checking all the settings on my BMS and the Victron app last night, I did notice my firmware was out of date and updated it.

looking at the app tonight:

It's clear that the Vmax is a lot lower today. It's much lower than when the van was parked in the shade, so was obviously wrong. Makes sense the Pmax was also wrong. So thanks Lenny

Anyway, it's been useful to me monitoring an entire days charge. Hopefully it will be useful to someone else at some point.

Myself, I knew to fit as much solar as I could, but didn't really know more than a guesstimate how much actual charge it would give me. Now I know what I'll get on a good day at the end of March

If I remember I'll do the same test at the end of April and post here again. Might help someone at some point in time. Thanks all.

 

[Lenny HB]

I quite as wondering how you managed those figures.

Had a play with mine today, I have 3 x 100 watt panelsp6p in parallel, Votronic MPPT regulator, 3 x 78ah Gel batteries. Also I Am on the south coast.
I ran the batteries down at bit and checked to solar output 11 am and 2 pm. My max was around 11 amps 150w, 50 % of max, better than I would expect at this time of year, sky's must be really clear.

 

[lekkerSA]

Please can anyone advise why my VictronConnect app does not show the battery min value that I see on all the photos here My system is functioning fine in all other respects

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[Raul]

Please can anyone advise why my VictronConnect app does not show the battery min value that I see on all the photos here My system is functioning fine in all other respects

First make sure you got firm aware 1,54 on the solar charger. To do that click settings, then 3 dots on the top right product info. Update settings. If that does not do it:
Go to phone settings, Bluetooth then forget device. Pair it again. I had a glitch with the battery monitor and re pairing sorted it out. Try that.

 

[lekkerSA]

tnx for quick response, Raul, will try that

 

[Hammie]

I’ve got a large flat solar panel linked to two batteries. How would I find out the wattage please as there is no documentation for the solar setup. The van is an 04 so it is not very techie.

 

[Hammie]

There is a meter of sorts displaying the input or so I’m told

 

[Lenny HB]

I’ve got a large flat solar panel linked to two batteries. How would I find out the wattage please as there is no documentation for the solar setup. The van is an 04 so it is not very techie.

Meaure the panel then look online sellers give the dimensions.
A polycrystalline panel will be slightly larger than a monocrystalline panel for the same output.

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