Solar Charge Controller

[jon.h]

Hi folks, 

 

I am fitting two 330w panels to my boat and would appreciate the advice of any experts in the field. The model of the panels are SRP-330-BMB, specs are here: 

 

https://www.seraphim-energy.com/wp-content/uploads/download/SRP-(320-335)-BMB-DG_Frame_158.75_EN_2019V2.0.pdf

 

What MPPT charge controller would you recommend for this? I'd really like to keep the cost down.

 

I seem to work out that Max V = 91v and Max A = 54a. The specs are tested at 25 degrees C so their max is not necessarily accurate when cold. When I've calculated it based on a lowest possible temperature of -5 degrees C it increases to potentially 54a. I want to be sure the charge controller is not overloaded.

 

Am I looking too much into it?

 

Can someone point out where I'm going wrong plz, if I am. All the Victron MPPTs aside from being pricey seem to have such low amperage.

[Onewheeler]

Looks about right for a reasonable temperature spread (if you're series connecting on a 12 V system). You'll only get that current under exceptional circumstances, and all (most?) MPPT controllers will current limit before they destroy themselves. A 100 V / 50 A controller will be more than adequate. In reality unless you're tracking the sun accurately and you're somewhere sunny you won't lose much with a lower current output controller. It's easier with a 24 V system!

Edited July 10, 2020 by Onewheeler
Speelchucker

[Detling]

You will never reach 50A in the UK I have 600W mounted flat through a 40 Amp controller and the highes recorded is 33.4 amps. You are better off connecting the panels in parallel because of partial shading, which will limit the current significantly through the shaded panel, and if in series all panels. The Controllers to look at the reasonable end of the market, are MakeSkyBlue, good reliable and tracks well it is lower priced but beware of fakes it has been copied a lot, as are all good things. Victron do nice ones not that expensive and some have bluetooth conectivity so you can see what is happening and set up using your phone near the box they also support Lithium batteries. EPEver/Tracer are not bad but older technolgy and do not track the power as well as the other two, this can add up to over 10% power missed on a day with lots of small clouds. Outback is all singing and dancing but you pay for that. There are undoubtedly others but I do not know of them.  As said a 50A will be more than enough and a 40A will limit the current to 40 amps in the unlikely event the input exceeds that, possibly for a few minutes at midday, when your batteries should be full on a sunny day.

[dor]

You will only have a chance of seeing that maximum current at a few minutes past one on 21st June if you have accurately tracked the sun.

I would have though a 40A controller would be more than adequate, and will just cap the current on the rare possibility that the panels could produce more.

[Onewheeler]

I have had 80% of maximum theoretical power out of our panels once, and they were flat on the wheelhouse roof. That was halfway down France though.

[RufusR]

If Vmax is 91V then you need to look at something bigger than 100v controller as on a cold sunny days which we can get in UK the Vmax can do above the Vmax and excess volts can kill your controller , 8 v is not really enough headroom IMO . look at 150v , Victron are good , I have a Midnite solar classic 150 which in my biased opinion is the best solar controller on the market its awesome but it is a 90amp plus controller so maybe a bit overkill here unless you want all the extra neat features such as smart load diversion , internet connectivity , end amps Absorption termination , skip days , HyperVOC for those cold sunny days i referenced above , the list goes on I love it . PeterBoat has this too I believe 

 

EPEver do OK budget ones which work OK ( bit slow and buggy , I had  one before the midnite ,) they are cheap and cheerful but quite reliable . they certainly do the current and are current limited but not sure if they have 150v one 

 

 

[dmr]

Ive just fitted the Victron Smart Solar (earlier this week) and am quite impressed. It does not have any display which is a bit sad, but does work very well with my iphone and Bluetooth. Its possible and easy to adjust the various voltage settings (absorption, float and equalise etc) which is very useful.

 

The advantage of big solar panels is getting some charge on cloudy days and in the winter, so I would not worry about wasting a bit of potential output if we ever get a sunny day again.

 

.................Dave

[Jen-in-Wellies]

1 hour ago, RufusR said:

If Vmax is 91V then you need to look at something bigger than 100v controller as on a cold sunny days which we can get in UK the Vmax can do above the Vmax and excess volts can kill your controller , 8 v is not really enough headroom IMO . look at 150v , Victron are good , I have a Midnite solar classic 150 which in my biased opinion is the best solar controller on the market its awesome but it is a 90amp plus controller so maybe a bit overkill here unless you want all the extra neat features such as smart load diversion , internet connectivity , end amps Absorption termination , skip days , HyperVOC for those cold sunny days i referenced above , the list goes on I love it . PeterBoat has this too I believe 

 

EPEver do OK budget ones which work OK ( bit slow and buggy , I had  one before the midnite ,) they are cheap and cheerful but quite reliable . they certainly do the current and are current limited but not sure if they have 150v one 

 

 

According to the linked data sheet on the OP's panels, each panel has an open circuit voltage of 41.2V and a voltage when maximum power is being extracted of 34.8V under standard test conditions, which are only realistic for a sunny day with no clouds at the equator, not the UK, even on the sunniest day. I'm not sure where he gets 91V from. Two times 41.2 is 82.4V, which is well within the capabilities of a 100V controller. The voltage is controlled by the semiconductor physics of the device and is limited. A 100V controller will be fine.

Jen

[Onewheeler]

1 hour ago, Jen-in-Wellies said:

According to the linked data sheet on the OP's panels, each panel has an open circuit voltage of 41.2V and a voltage when maximum power is being extracted of 34.8V under standard test conditions, which are only realistic for a sunny day with no clouds at the equator, not the UK, even on the sunniest day. I'm not sure where he gets 91V from. Two times 41.2 is 82.4V, which is well within the capabilities of a 100V controller. The voltage is controlled by the semiconductor physics of the device and is limited. A 100V controller will be fine.

Jen

91 V (I make it 92 and a bit volts) is the open circuit voltage at -5 C (OP's estimate) or -20 C (mine). It is just about credible if the batteries were disconnected / refusing to take charge but the panels were still connected (which shouldn't happen, but might). 8 V margin is in any case plenty for something like this.

[RufusR]

3 hours ago, Jen-in-Wellies said:

According to the linked data sheet on the OP's panels, each panel has an open circuit voltage of 41.2V and a voltage when maximum power is being extracted of 34.8V under standard test conditions, which are only realistic for a sunny day with no clouds at the equator, not the UK, even on the sunniest day. I'm not sure where he gets 91V from. Two times 41.2 is 82.4V, which is well within the capabilities of a 100V controller. The voltage is controlled by the semiconductor physics of the device and is limited. A 100V controller will be fine.

Jen

 

1 hour ago, Onewheeler said:

91 V (I make it 92 and a bit volts) is the open circuit voltage at -5 C (OP's estimate) or -20 C (mine). It is just about credible if the batteries were disconnected / refusing to take charge but the panels were still connected (which shouldn't happen, but might). 8 V margin is in any case plenty for something like this.

In that case you are correct I didnt see the spec sheet ( or didnt read it lol .  Victrons 50 /100 Smart solar is a good MPPT at a reasonable price for this ( alot cheaper than the 150volt ones  . You may get EPever a bit cheaper but having owned one the OP will be happier with the Victron unless on very tight budget . 

 

Its a shame Midnite dont do a controller between their 30A kid and 96A Classic as really they are Les Ballon de Chein when it comes to solar controllers 

 

Edited July 10, 2020 by RufusR