MPPT vs PWM - The Solar Controller Test!

[SquirrellCook]

Other option would be stick down panels, flexible ones, which I have looked at but for good ones they cost quite a lot

If I'm guessing right, it's got a glass fibre boat attached to the top. You could bond some fasteners to the roof and string some rails along it.
If you make of adapt some set screws or machine bolts to have a large diameter head you could bond them to the surface of your roof with Glass fibre resin. Then to reinforce them and spread the load use squares cut from wide aramid tape and resin that over them with the stud protruding.

 

[RAW]

If I'm guessing right, it's got a glass fibre boat attached to the top.....

Really ? Would never have thought that, thought it would be sheet metal. It's a 1995 Transit and am struggling to find any information about them online, anything I look at seems to be post 2000 Transits. Do you have a link to verify what you are saying ? If it's GRP roof then will hopefully still be solid.

 

[SquirrellCook]

I can't confirm for sure, but that's a very deep pressing for steel if it is. The corroding fasteners above the windscreen also suggest it's grp.
Well worth asking.

 

[wildebus]

I can't confirm for sure, but that's a very deep pressing for steel if it is. The corroding fasteners above the windscreen also suggest it's grp.
Well worth asking.

I am pretty sure you are correct saying it is GRP.

Robert, if you look at lower roofed Transits they all tend to have seams on the roof as they are made up in steel panels, just like the sides are. The photo of my van does not show it very well, but on my LT, there is a front and a rear pressed panel, and there are two identical pressed steel panels in-between. And they (both VW and MB as same bodyshell) mix and match the panels to suit the vehicle size. I would be surprised if Ford did not do something similar for their normal roofs.

Quick test to check ... get a strong magnet and see if it sticks to the roof

I don't know it it is of any use or interest, but I used 3M VHB tape to attach a pair of semi-flexible solar panels to a VW T5 Poptop. the Panels were fibreglass backed and the roof was unpainted self-coloured GRP - As soon as the tape made contact it was bonded and could not budge a millimetre - and it takes 48 hours to bond fully so will be even more solid then!

 

[wildebus]

Ok, so back on subject.

The testing with the solar panels has not really made much impact due to the combination of bad time of year for testing plus lots of restrictions such as house and trees.
Harvesting has dropped down to well below 1W per panel now so that is it for the day. To eliminate Location and Panel difference, I have swapped over the cables and will leave running for a second day.
Total harvest from 200W of PV Panel today .... 73Wh - That works out to be just 6Ah of energy back into the battery.

Will wait until end of play tomorrow to evaluate the results and do the comparisons.

Conclusions after two days of testing using Solar Panels?
Don't bother doing solar controller comparisons with PV panels in Late October in Scotland!

I see that the performance of the MPPT controller looks to be better than the PWM (as to be expected), but in reality, it is hard to judge how much a different it makes as the solar performance is so poor, even a 30% improvement over sod-all will still be sod all.

As mentioned, Day 1 got 73Wh of energy in total with the two panels. Day 2 went down to 29Wh of Harvest.

I think I said earlier on this thread, or maybe elsewhere, that a drive to the shops will get you more power in? Well, I thought I would show a graph to show what I mean ... Below is a snapshot of the middle half of the day (6AM to 6PM)

That vertical line , labeled 09:15 - 09:24? well in that 9 minutes I put more Wh into my batteries then the 200W of Solar Panels contributed for the entire day on the controller test.
Unless you have a very clear and unobstructed line of sight to the sun, solar in the winter is extremely limited and it really doesn't matter how good your solar controller is, you will still get virtually nothing and idling your engine for 5 minutes will get you what a 100W panel may contribute in an entire day.

Now no doubt there are people who will say they harvest loads all year round, but this is my own conclusion from my testing in my location, with trees that obtruct the low sun, lots of cloud and a fairly short solar day - think it is called "real life in the north of the UK"

Out of curiosity, I have put the Victron MPPT back on a panel and will see that that does for the day. It looks a fairly similar overcast day.

Here is a chart showing the kind of difference in Solar Energy between yesterday and a day in Mid-August

Less then 10% of the Solar Radiation is being received!

Another Conclusion? Don't rely on Solar Panels in Scotland in the Wintertime. (I already knew this one )

I'll probably do another controller test, but if at home will have to wait until Spring next year due to my test environment as the low solar radiation means no useful data is really getting obtained and any results are pretty irrelevant.

 

[SquirrellCook]

Don't bother doing solar controller comparisons with PV panels in Late October in Scotland!

I got 160Wh in Doncaster yesterday with 400watt array, though it is shadowed by the house until the afternoon. As soon as I'm mobile again I'll fit two more panels.

 

[wildebus]

I got 160w in Doncaster yesterday with 400watt array, though it is shadowed by the house until the afternoon. As soon as I'm mobile again I'll fit two more panels.

OK, you got a peak of 160W but how many Wh did you get for the entire day? As the saying goes, 1 swallow does not a summer make.

 

[RAW]

Another Conclusion? Don't rely on Solar Panels in Scotland in the Wintertime. (I already knew this one )

I was speaking to a Boat Owner the Other day who has the following set-up:
1KW Solar panels
Unknown amount of Traction batteries (Lead Acid ones from Forklifts he said)
Controllers and Inverters etc Supplied by Outback Power (expensive and similar standard to Victron I think)
He reckons on his canal boat that gives him around 85% of all power needed for electrical kit including fridge and washer for the year

Here's my output from the single 285W Panel on Sylvia yesterday in Hebden Bridge

My feeling from Reading @wildebus and others is that for Full-Time Van I would like to have a minimum of two of these panels and ideally 3 e.g approaching potential 1KW and at least 600 AH of Batteries for FT - any comments on that would be interesting from any folk that are FT already ?

 

[Lord Lucan]

If I had a 120v panel and a 20amp Victron with 125ah battery for just occasional water pump, led lights and a coolbox, would this be adequate for 2nighter with no hook-up.

 

[wildebus]

If I had a 120v panel and a 20amp Victron with 125ah battery for just occasional water pump, led lights and a coolbox, would this be adequate for 2nighter with no hook-up.

It depends on the coolbox (and time of year!)

if it is a compressor coolbox (such as a Dometic Coolfreeze) then I would say you would be just about ok throughout the year and in the summer time your solar panel will put back in what you use so you could go much more than 2 nights.
If you are talking a 'traditional' coolbox (like the ones with the fan on top), they will suck your battery dry! well, maybe a bit extreme, but with those you generally need to turn them off overnight and even with summer solar you would be hard pressed to keep up with the use to survive a weekend.

 

[RAW]

If I had a 120v panel and a 20amp Victron with 125ah battery for just occasional water pump, led lights and a coolbox, would this be adequate for 2nighter with no hook-up.

Do you mean 120W Panel ? I don't think 120W panel with 125AH battery would be sufficient for use in the UK apart from 3 months a year in the situation you are proposing. Even with a 285W Panel and around 230AH of Battery and a Victron 100/30 MPPT I am not getting past Bulk State of charge yesterday with the only operational bit of Kit in the Van being a Raspberry Pi, albeit powered by a Decent 12V -> 5V Car Adaptor thingy so some Power draw there as well.
I don't have detailed information on what the draw is but will sort that when I wire something else in that I got from Banggood as below:

[£6.08 27% OFF] 12V To 5V DC DC Converter Module With USB Output Power Adapter 15W Electronic Accessories & Supplies from Electronic Components & Supplies on banggood.com

12V To 5V DC DC Converter Module With USB Output Power Adapter 15W

www.banggood.com

They were a bargain IMO, I bought Two....

 

[wildebus]

Do you mean 120W Panel ? I don't think 120W panel with 125AH battery would be sufficient for use in the UK apart from 3 months a year in the situation you are proposing. Even with a 285W Panel and around 230AH of Battery and a Victron 100/30 MPPT I am not getting past Bulk State of charge yesterday with the only operational bit of Kit in the Van being a Raspberry Pi, albeit powered by a Decent 12V -> 5V Car Adaptor thingy so some Power draw there as well.
I don't have detailed information on what the draw is but will sort that when I wire something else in that I got from Banggood as below:

[£6.08 27% OFF] 12V To 5V DC DC Converter Module With USB Output Power Adapter 15W Electronic Accessories & Supplies from Electronic Components & Supplies on banggood.com

12V To 5V DC DC Converter Module With USB Output Power Adapter 15W

www.banggood.com

They were a bargain IMO, I bought Two....

well, keeping the battery from discharge, yes you make a good point.
However.... if the scenario was to start with a full (100%) battery, be able to then to run for 2 nights and avoiding having the battery run below a critical level (50% SOC typically) and THEN be able to recharge the battery from split-charge and mains hookup, he could be ok depending on Coolbox type.

This is a typical pattern for me where I am parked and get little solar due to low sun and shading

From a full battery bank I am only down to 60% SOC even after 10 days of poor solar (so typical of wintertime), with the Fridge is on full time, plus the usual monitoring stuff (Victron Venus, Router, MiFi, etc). If I can do that with 645Ah of Batteries, then I think 1/5th of the time and a battery bank 1/5 as large should be doable without going down below 50%

In contrast, the same time period, but in the summer shows you can be self sufficient even when using much more power ...
Yes I have a larger Solar Array but a lot of the time you can end up with more potential then you can use (batteries nearly full so the charge in is current limited which can mean a 400W array cannot harvest more than a 100W array)

 

[SquirrellCook]

OK, you got a peak of 160W but how many Wh did you get for the entire day? As the saying goes, 1 swallow does not a summer make.

Sadly that was Wh, about to edit.

 

[RAW]

@wildebus thanks for latest graphs, where is your consumption bar data gained from ? Do you have Venus OS plugged into a BMV-712 or similar ?

 

[wildebus]

@wildebus thanks for latest graphs, where is your consumption bar data gained from ? Do you have Venus OS plugged into a BMV-712 or similar ?

that data is obtainable when you have both a BMV and a Solar Controller into the Venus OS Unit. It adds another dimension to the data. I recommend you get another VE.Direct - USB Dongle and then you will see what is happening much clearer. With just one cable, use the BMW connection as you can always download history from the MPPT via Victron Connect and meld that with the VRM downloaded data

 

[wildebus]

I got 160Wh in Doncaster yesterday with 400watt array, though it is shadowed by the house until the afternoon. As soon as I'm mobile again I'll fit two more panels.

This is why Solar is brilliant in the summer but in winter does not in all honesty do anything useful. The sun is just too low for solar to be any use unless you have a unencumbered view of the southern sky and near vertical panels - that 160Wh would take an alternator well under 30 minutes to put in.
FWIW, yesterday I also got 160Wh as it happens

I am parked north of a tall house and have tall trees to the side so that low sun is a killer for me.

 

[Lord Lucan]

Coolbox has a quiet running fan.

The badge states 4-5amps at 12v

 

[wildebus]

Coolbox has a quiet running fan.

The badge states 4-5amps at 12v

Hmmm. that will probably be a constant 4-5 Amps. that will take your full 125Ah Battery down to the likely recommended minimum charge of 50% in around 15 hours or so
They really are only picnic boxes and not that great for camping sad to say. lots of frozen water to fill it up initially and turn it off overnight and you might be ok in the summer (and in the winter, outside could be cooler than inside a coolbox!)

 

[SquirrellCook]

Sun tomorrow, so should get some Wh’s

 

[trevskoda]

My small table top fridge burns 3ah and i have ran it into 2 days on 2 linked 90ah batteries before requiring a charge .this was a bench test in spring/summer.