30A Flush Mount PWM Solar Controller

wildebus said:
Ref the Dual battery charging thing. I am not convinced those are really any different to the controllers that have a "load" connection as well as the battery. With most reasonable ones you can configure the load to be active when the battery is at a certain level of when the PV input is present.
In fact, if you did use the "Load" as a secondary battery connection and set it to be in when the battery is above a certain level, then it could provide a trickle charge to the starter when on mains hookup with a charger? Think I might have to have a look at that?
Click to expand...
I had a quick look at the Victron MPPT Controller configuration (easy to do as in their app you can create Demo versions of all the products to play around with :)

I chose the SmartSolar 100/20 (that is the one I have for the testing) and as an example I can configure the load output to go on at say 13.3V and off at 12.8V (I chose those values as they would be same as a VSR on and off).
This means you could use the Load Output like that secondary battery output on the controllers that have that, but would would work on both Solar and EHU.
Pretty handy stuff actually and finally a use for the Load Output! :p Most non-Victron controllers don't have the same level of configurability but I think something similar should be possible?
As an aside, if that load/secondary battery output has a lower current limit then you would like, you could also use that output to switch a high-power relay on and off instead, so a way upgrade the power for under an extra fiver (y)

The only downside on the Victron side is that they don't have a LOAD output on any new Solar Controllers bigger than the 100/20. However they do have a 'virtual' load signal so could be used with a relay as mentioned above, but does start to get more complicated :(
 
trevskoda said:
Hope you get the we controller im using soon so i can see whats really going on,very good tests so far. (y)
PS i have also found this new one on the market for duel battery charging.View attachment 50706
Click to expand...
The little controller you talked about actually arrived in the post today so I have put in as the next controller to be tested once the battery drops some charge.
I did cable it up and switch it on .... 99.9% sure it is NOT an MPPT - but I do like the look and feel of it, mind. I am still requesting a refund however as it is not as described and I really don't need another PWM Controller (got about 7 at the moment!)

That one above looks quite nice. For £19 it would be steal if MPPT. I wonder how much it will end up being? I would think maybe upto £40 could be ok?
 
This unit here would appear to be well priced at £30 - https://www.ebay.co.uk/itm/10A-20A-...er-Battery-Regulator-12V-24V-UK/143320706555?
s-l1600.jpg

It has a settable LOAD OFF and LOAD ON - that could be used as a 2nd battery charging output
 
All vely interesting,bet some stuff is not as advertised.
No my we unit is even in poor overcast sky giving in morn/evening 13.7 and 14.4 min day into two 90ah batterys.
 
trevskoda said:
All vely interesting,bet some stuff is not as advertised.
No my we unit is even in poor overcast sky giving in morn/evening 13.7 and 14.4 min day into two 90ah batterys.
Click to expand...
Yup, the PWM Controllers obviously work :) but the key question is if there is any value in changing to an MPPT?
It might well be that someone gets enough charge from a PWM to not need to spend more money on a better controller.

PS. I did a search and that unit you linked to has standard "buy it now" price of £59. Not bad, but I think I would at that price spend a little more on getting the Victron to take advantage of the extra configurability as well as the known quantity and long warranty.
 
So probably when in full overhead sun, that 200W max will be coming into the controller at around 18V and 11A natively (if you disconnect the battery and measure the voltage of the PV you will get an indication).
I am going to guess that if you had a MPPT, you could be getting around 15.5A - 14A depending on the state of charge of the battery. With a PWM, you will max out at 11A tops.
There is a common quoted number of an MPPT being 30% more efficient but often accompanied by "if you have a big array" but I would say it would affect EVERY array (and if you had them in series, you would have wasted the 2nd panel entirely (but you knew to have in parallel :) )
I suspect if you just changed to an MPPT, you could potentially harvest up to 70W more power from your 200 array (full sun, low battery). Sadly, the PWM limitations are most apparent when you need as efficient a harvest as you can get (low battery). But no matter what the panek is doing, I am pretty sure you are still discarding 25% minimum of what the panels could give you (and 25% of a 200W array will have cost what? £40 minimum? That is not far off the cost of a genuine MPPT controller)

Your solar controller is on test at the moment. Started at 7:30 and will finish at noon to take reading.
 
You must log in or register to reply here.

Users who viewed this discussion (Total:0)

Back
Top