A DC System: The Reset

[DuncanCT]

Ok so the other thread has got carried away a little.

I find this a very interesting subject but DISCLAIMER: I am NOT an expert in any electrical matters.

I think to set out a basic goal for the concept:

During load shedding it would be good to have a couple of thing running. Now I don't want to vacuum the house or boil water. The vacuum can wait till the powers back and the best solution for water heating would be a gas system. But if I was able to watch TV, use a laptop (it could be charged when you had power and last the load shedding) have the wireless router work with it and have basic lighting.

Having a look at the AC/DC Adapters:
Wireless Router (Netgear): 12VDC 1A
Explora: 12VDC 3.75A

Are any of the newer TV's suppled but 12VDC adapter?

Know I understand that there is a problem moving high current DC over longer distances but surly the current mentioned in the above electronics isn't that high? (again read the disclaimer) Also assuming that that is the maximum current draw specified and not the constant.

This could be powered by a 12V battery system and a charger that could run off the mains when available or a basic solar kit?

Please can this thread try to be kept positive and what is possible instead of whats not. And anyone else add what low current 12/24 VDC devices that could be added.

 

[itareanlnotani]

Yes, viable, but you can't run too long a length from the DC side, as voltage drop will be an issue.
One or two panels 250W panels would be fine with say 2 x 260Ah batteries.

Don't discharge > 40% (30% is better). 2 x 260Ah@12v = 6240W. So about 2KW usable.

P=V*A (Power = Volts * Amps)
If your draw is 12v @ 1A thats 12W/hr.
12v * 3.75 = 45W/hr

Tv, Laptop guessing probably 300-500w /hr

So 2KW (2000W) would give you about 5-6 hrs of usable battery @ 357W usage (300W tv/laptop + 12w + 45w per hr).

You'll need an inverter for the non 12v stuff., so will lose more through that +- 85% efficiency for a cheap inverter.
Still, its quite doable.


Panels should be in the R2-3000 range, a cheap 12v controller a few hundred (they're less than 40RMB for the average ones I see used here, so should be less than R200), and batteries - from R2000-4000 depending what you buy.

Depth of discharge is the important thing. Don't believe the hype about lifetime. Read the specs. Carefully, and balance your discharge vs cost. 30-40% DoD (depth of discharge) is typically the sweet spot if you want 7-8year lifetimes, if you go higher, its more like 3-5years.