How to grow solar system

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akoppela asked Jun 2, '22

How to grow solar system

Hello. My name is Andrey.

I’m designing system for my small camper. I’m going to put camper on the land and build house from solar energy. There is no grid on the land, so it will be off-grid system with support of generator.

My plan is to start small and then grow the system to power the whole house. I calculated my daily load to be around 75ah at max at the moment. Can be reduced to 20-30ah for cloudy days. I have purchased 2kW inverter generator.

This is the list of products I’m thinking to get:

- Solar panel 360W-24V Mono

- SmartSolar MPPT 100/30

- MultiPlus 12/1200/50-16

- VE.Bus Smart dongle

- Interface MK3-USB (VE.Bus to USB)

- Cerbo GX

- Lynx Power In

- SmartShunt 500A/50mV

- Battery switch on/off 275A

- Lithium SuperPack 12,8V/100Ah High current (M8)

- Cables, fuse holders, fuses, circuit breakers, etc..

The total power of the system will be 3kW with power assist from Multi.

Does that look like a good working system? It seems that I can upgrade it with just extra batteries and more solar panels (maybe a bigger MPPT controller needed in front, like 100/50). What would be a nice way to grow the system otherwise? E.g. if I want to switch to 24/48v system for house. Or what I can modify in my design to be able to expand it in the future?

Thank you.

solar

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Answer 1 · 2022-06-02T16:46:47Z

kevgermany answered · Jun 02, 2022 at 04:46 PM

Ok for starting, but if you want to upgrade to a 24 or 48V system, it will be very expensive. I would think about starting with a 48V system. Extra cost is three batteries and a 48/12V DC:DC converter.

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Answer 2 · 2022-06-02T16:51:39Z

seb71 answered · Jun 02, 2022 at 04:51 PM

You should look at Wh, not Ah.

Make a 48V (48V battery) system from the start. More efficient. And same MPPT gives you more power at higher battery voltage (if you have the panels, too).

That 100/30 is small for a house system and it is complicating any upgrades. Get an 150/xx SmartSolar MPPT. I would say 60A at least (so SmartSolar 150/60Tr). And preferably a big PV array to match (about 3500W), from the start. It will be be difficult to find the same panels a few years later.

You can skip the VE.Bus Smart Dongle.

Lynx Power In is nice and compact, but it is expensive. You can DIY an alternative from copper bars and fuse holders.

That inverter generator was not the best choice.

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akoppela commented · Jun 05, 2022 at 02:06 PM

Thanks for the tip to work with Wh. Makes more sense and easier to understand.

Yes for house it's going to be 48v system. I realized I'd make two system. One small for my trailer and bigger for a house. That would make a good test for solar system before I'm going to build a big one.

If you do want an inverter based generator (eg for noise reasons under lower loading), get one that is at least 30% larger than required than an equivalent AVR based model to help prevent nuisance overloads.

Regarding inverter generator it should be fine, I can always adjust current limit. E.g. for 1200 Wh battery I'd just need 3a at 220v to charge the battery in 2 hours. Is that correct? Did you refer to some other info about inverter generator?

So the VE.Bus Smart Dongle can be avoided because Cerbo GX would provide all the info? Is so maybe I can go for non smart versions for other components as well.

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