Solar Panel re-work advice

[Cactus Sailing]

I'm looking to upgrade my Solar producing power on our boat and after finally deciding on where i can physically fit aforementioned panels without too much interference i have come up with a reasonable solution to fit another 120w in the form of two 60w panels.

but currently i have just the one 40w panel on a PWM controller which will mean a miss matched system.

push comes to shove i could get rid of the 40w panel, and replace that with a 60w as the whole thing will just about fit with 3x60w panels, but im on a budget.

so i guess thats the question really, if im upgrading do i just take the 40w panel off, discount it and use for other purposes / ebay it along with the PWM controller etc. and just start again, or has anyone a sensible solution to add 2x 60w panels onto the system in parallel

the only sensible thing i can think of is keep the newer 2x60w panels on a separate circuit and feed in via a new MPPT, and eventually swap out the existing panel in the future, either that or save up a bit more and just do it properly? (i did see a video by Will Prowse where he connected a MPPT & PWM unit to the same battery and they didn't counteract each-other, so in theory a circuit of 40w + 2x60w could work?)

 

[Pete7]

Easy to spend someone's money but how about keep the 40w and add two new 60w panels through a new MPPT controller.

20A 12v/24v MPPT charge Controller - EPever XTRA 2210N - 100VOC PV - LCD Meter

 

[alan]

Could you explain why you have a "mis-matched" system?
What is wrong with fitting all three panels in parallel and keeping your PWM controller (as long as the controller will handle the total current)??
I have a permanent 50W panel and two 100W panels which I only fit for summer cruising; all going through a 20 amp PWM controller; been working fine for ten years or more.

Alan.

 

[LONG_KEELER]

Yup. I was thinking the same thing.

I have two panels at 20w and one at 15w which is all I can wiggle in for my small boat,
connected in parallel to a 20A PWM.

 

[simonfraser]

are they connected with quick release plugs ?
in which case you can just disconnect one or more if you are generating too much power for the existing controller during the summer

 

[LONG_KEELER]

Doesn't the PWM take care of that ?

 

[Tim Good]

In terms of panel price and quality i have 3 x 120 panels. One is very expensive and two are cheap ebay types. The cheap ones have works perfectly fine for 4 years now and output equally as well. I have rig them in series so it is important they are the same wattage. Rigging in series means you do need a new MPPT controller but it does mean your existing wiring might not need to be upgraded since the voltage is increased and not the current. There are advantages also to have them in series in terms of efficiency since the controller calculates the maximum power point (MPPT).

If you stick a 60w alongside you 40w then you'll have to go parallel and upgrade you wiring to suit the new higher current.

I might add.... if you do splash out on a Victron MPPT then also spalash on the bluetooth connector. Its very satisfying and useful to be able to monitor what you are getting from the panels.

 

[Pete7]

One other nice feature of the Victron is the bluetooth battery temp and voltage widget, which supplies data to the MPPT. Since the water temeprature is cold at the moment and therefore the batteries in the bilges, the MPPT adjusts voltage up to take this into account.

There are two models and the blue one is the latter with a greater wifi range compared to the black one.

Smart Battery Sense - Victron Energy

Pete

 

[differentroads]

I'm looking to upgrade my Solar producing power on our boat and after finally deciding on where i can physically fit aforementioned panels without too much interference i have come up with a reasonable solution to fit another 120w in the form of two 60w panels.

but currently i have just the one 40w panel on a PWM controller which will mean a miss matched system.

push comes to shove i could get rid of the 40w panel, and replace that with a 60w as the whole thing will just about fit with 3x60w panels, but im on a budget.

so i guess thats the question really, if im upgrading do i just take the 40w panel off, discount it and use for other purposes / ebay it along with the PWM controller etc. and just start again, or has anyone a sensible solution to add 2x 60w panels onto the system in parallel

the only sensible thing i can think of is keep the newer 2x60w panels on a separate circuit and feed in via a new MPPT, and eventually swap out the existing panel in the future, either that or save up a bit more and just do it properly? (i did see a video by Will Prowse where he connected a MPPT & PWM unit to the same battery and they didn't counteract each-other, so in theory a circuit of 40w + 2x60w could work?)

I have two 80W panels wired in series to an mppt regulator plus a 50W panel wired seperately to the Solara pwm regulator that came with the boat. This all works together fine despite being, as I feared too, 'mismatched'. I've checked the 50W panel's contribution under a variety of conditions including the 80W panels cranking out maximum current and very little, battery around 60% up to around 80% charged and it adds 1 to 2 Amps depending on conditions and its orientation to the sun (usually suboptimal as I tend to orientate it differently to the other panels to extend the hours that I get charge e.g. towards the setting sun.

 

[Rappey]

I read that it's more important to have identical panels with a mppt controler so the computer can work out clever charging. Mix panel size and outputs and it really screws with the controler.
Can mix and max with a pwm as it stops anything over 12v, hence less efficient than mppt but lots cheaper and still does a great job.
I run 2 x 25 into a pwm which has 2 battery outputs so one feeds starter battery at 5%,other 95% going to domestic, and a 160 into a mppt to feed domestic bank.

 

[Tim Good]

I have two 80W panels wired in series to an mppt regulator plus a 50W panel wired seperately to the Solara pwm regulator that came with the boat. This all works together fine despite being, as I feared too, 'mismatched'.
[/QUOTE

Yep me too... I have 360w in series into a MPPT and then a 60W into a Solara regulator and they both seem to work fine together. They don't seem to force one or the other into float.