I'm wondering if 6x100w solar panels will be too much for my Victron smartsolar 100/30 charge controller. The solar panels will be mounted flat on the roof of my RV, powering 2 Trojan T105's. The solar panels each put out a max of 17.3V and 5.78A. I'm also wondering if i should connect the panels in series or parallel?
You already have the PV panels?
17.3V is panel VOC?
If yes, you can make 2 strings of 3 panels each in series and then connect the two strings in paralel.
Each string will have 17.3x3=51.9V (well under the 100V maximum allowed for your 100/30 charger).
In good weather you won't use the entire power on that 12V system.
But in bad weather, the PV panels will generate much less than 600W.
To clarify, VOC is 21.6V, VPM is 17.3V. And no, I haven't purchased the panels as if yet.
Can you fit 60 cell PV panels? Those have better price per Watt.
How about those batteries: do you already have them?
If not, look into LiFePO4 batteries. Better suited for solar.
I'm purchasing a new travel trailer, so will have to measure the roof to see if they'll fit. The 100w panels i've been looking at on Amazon go for about $105CDN. Any chance you could shoot me a link to the panels you would recommend?
I've had the 2 T105's for a season now and have been happy with them. The LiFePO4's could be a good upgrade once the Trojans bite the dust.
Suggest you use the MPPT calculator on Victron site (Google “Victron MPPT Calculator”) and the Circuit Wizard on Blue Seas website. Both are pretty good for sizing panels, controller, wire gauge and fusing. Then you can make a more informed decision on your own.
600W of panel would definitely work nice for those cloudy days but 6 panels is a lot of wiring....bit of a spaghetti show on the roof!
I have a single 320W panel on my small RV trailer with 2 T105s, have not had a power issue yet when camping. The largest load we run in summer is TV on a small inverter however.
I like your idea of moving to lithium once the T105s are done, think I will do the same.
Nice setup! What kind of mounting bracket is that? I was planning on flat mount, but yours looks great.
Thank you. I designed and built the mounting arrangement.
When popped up it can be rotated 360 deg., but have found that it does just fine laying flat most often when camping in summer. The option of tilting is nice to maximize solar gain in spring and fall or when the only access to sun is through an opening in the trees for example.
In winter I leave it up always to shed snow and keep the batteries charged.
It just endured a big windstorm last week here in B.C., was very happy to see it still there in the morning!
But back to yur system, I really think that 600W might not be necessary especially once you have lithium batteries which will give you almost twice the useable capacity - all depends on your loads and usage of course.
