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What is the best off-grid solar system

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4 hours ago, Fred said:

What is the best off-grid solar system? Any one know?

If your roof space is adequate 
My easy rule of thumb is 

Get an inverter equal to the maximum allowable in your state 

And install solar panels about 20 % greater in kw over the inverter size 

The current best size panels are 330w each 

If you have slight shading issues an inverter is more cost effective 


If you have shade issues then it’s best to look at a mini inverter system 

Then if feasible - consider battery storage 



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1 minute ago, Fred said:

I am taking about off-grid solar, I don't think any inverter limitations exist.

Then the same rules apply minus the max inverter size 

So you need to work backwards 

Roof space and how many panels it can accommodate 

Or Free standing if you don’t want to use the roof ( rural area ) 

Inverter 20% less than what the panels can produce ( that’s for a little headroom and better efficiency) 

A battery storage system for night use 

I would also factor in - a solar hot water system to minimise heavy power draw 



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@Fred - if you don't want to answer the questions or offer more than just one line replies, no one here (or anywhere for that matter) can give you genuine advice.

It's like me asking, "What's the best car?". But I live down a 60km dirt road, so an Aston Martin is not the right answer.

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@Fred it really depends on needs and what you want to spend. 

You need to give yourself an uptime requirement, e.g. 'I want to meet my power requirements xx % of the time'. 

For what it's worth a 99% system means that nearly 4 days are offline. 

If you were doing it properly IMHO you'd have:

  • Solar PV to whatever your demand is
  • Good thermal storage because its cheaper
  • Battery to suit
  • (Optionally) smart UPS for critical loads (internet, security, etc - enough for the house to tell itself what's happening under all conditions)
  • Diesel SGP for backup
  • Optional automatic or manual changeover switching

You would also need switchboard that still meets AS3000 and is compliant with requirements for multiple supply sources. That it is offgrid does not exempt a home from regulatory compliance. 

Done cheaply for a 5kW solar system, marginal batteries and inverter, limited thermal storage and an entry-level SGP this is a $20k job.

I have a customer with a (well) over $100k install across ~15kW of LG panels, four LG Chem batteries, two SolarEdge inverters, a 12kVA Cummins/Stamford genset, multiple thermal storage, critical loads independently backed up, an industrial-grade switchboard hookup, good DR on his HVAC and semiautomatic changeover switching. It wasn't cheap. It's rock solid.

You will not get out of a capable installation done right for under $35k without gas; you might be able to get something decent down to $25k with gas. You can go less, I wouldn't.

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14 hours ago, Fred said:

I am taking about off-grid solar, I don't think any inverter limitations exist.

Just picked up on this and careful here. 

For a purely off-grid system (no grid at all) it's possible to go your own way though I'd stick to standards. Not least for safety, and more for what you plug in will have power quality expectations that are consistent with mains norms.

There are people running non-standards-grade inverters on pure offgrid that do make power, but I wouldn't. Especially for a whole house. This, and DC system faults aren't to be trifled with. There are no small mistakes.

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2 hours ago, Fred said:

I have choices

Selectonic, Ingeteam, Victron, Schneider., which one?


I have no familiarity with Ingeteam though the other three are all well-regarded, Selectronic probably the best of them - they're local (Victorian), they're built like the proverbial brick house, on the solar side they integrate particularly well with Fronius. 

Probably SMA is the only real step up in that their control solutions for proper microgrid/offgrid is better - they have a full turnkey solution - but many Australian offgrid people have sites working happily with Selectronic.

Theres a few solutions locally that will do control for them and other assets.

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