Product advice small solar

DIY
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1

Good day,

I have an off grid cabin with 2 separate solar systems.

Small

2x 50wh solar panels connected to an Smartsolar 75/15 connected to 2 80ah batterys feeding the inverter.
Inverter is used once or twice a week for the larger tools. it almost never uses more than 25% of the battery. so they are toped up in a few days.
The rest of the time, the controller needs to waste the energy since it cannot store it.

Big (since it is a little bit bigger than Small :wink: )

2 250wh panels, connected to an brandless controller. (where the display is broken) connected to 2 100ah batteries, feeding all 12V systems.
this system does it job most of the time without issue’s. but i can’t monitor it anymore. and in the winter, while charging it with a Bluesmart charger, i need to disconnect it from the battery since the controller sees charging as “overcharging“ and start wasting the new energy.

so my first thought was, buy another Smartsolar and we are good to go.

But here is the problem. the model i want, doesn’t exist in 35A.

They only exist with 2 connections (Solar and Battery) and are missing the Load side.

Question 1
If i am correct i need:

  • A 35A Controller connecting my pannels to the battery
  • A Battery protector to disconnect my load when the battery is empty
  • A smart shunt if i want to monitor my load

That is a lot compared to its smaller brother. since they have all this build in.

the real question is there a better option?

for example, if i split the 2 250wp pannels, and add 2 smaller controllers?

is this a good option? and if yes, can i merge the load side? or will i be limited to 20A load (i don’t see the problem with this, 20A should be more than enough)

Downside of this is, my panels don’t have a lot of direct sunlight. and moving from Serie to parallel would stop the charging earlier on the day, missing some of the energy.

Question 2

Is it possible to use the excess energy from the small system to feed the big system.

Question 3

I currently use the app on my phone to connect with bluetooth.

I want to add a VE direct cable to a raspberry so i can monito it remote.

Since the devices can form a bluetooth network. do i need one cable, or one cable per device?

Hope you can make this more clear to me.

Many thanks

Mark

2

Any advice?

At least the question about ve.direct shouldn’t be a difficult one for an advanced victron user?

3

If you have more than 1 Victron SmartSolar then they can network but only to synchronise charging, or share battery voltage from say a SmartShunt. To use an Rpi or GX device you would need to connect all 3 by VE Direct cable.

You could share charge from the small to the big system by using a DC to DC charger, the Victron Orion series. The smallest is the isolated 12/12 18A but it should throttle itself to only export the excess to the big system.I

On the big system, what you should do is set the absorption and float voltages on the solar controller to be 0.1V higher than on the ac charger. That way, the solar takes priority over the ac.

in terms of future equipment it is hard to advise without knowledge of the panels specs and location. A single 150/35 and battery protect may be better.