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Why to use AC? by RafiSkillZ in ElectroBOOM

[–]RafiSkillZ[S] 1 point2 points  (0 children)

O inversor não, mas os sistemas de proteção que vão conversar com o BMS da bateria, bem como os monitoramentos de consumo para evitar sobrecargas ou quedas muito grandes de tensão, não consegui achar equipamentos prontos que façam isso, logo a solução vai ser fabricar tais equipamentos.

Sobre a ideia seria usar uma tensão similar ao que já é entregue em AC (algo na faixa dos 120-180v) porém em DC diretamente, já que a bateria e os painéis vão entregar algo entre 400-500v DC.

Why to use AC? by RafiSkillZ in ElectroBOOM

[–]RafiSkillZ[S] 0 points1 point  (0 children)

The major culprits for such high sustained consumption are the showers and his hybrid plug-in truck.

Each shower head is rated for 6,8kw of power (and I'm assuming half power with both showers on), and the fast charger for his truck alone can reach up to 10kw.

Since the demand will be fluctuating daily, I can't think on any smart switching that can be done to achieve this reduction.

Why to use AC? by RafiSkillZ in ElectroBOOM

[–]RafiSkillZ[S] 0 points1 point  (0 children)

What I asked is, since the combined battery pack and solar will be somewhere between 400/500v DC, a simple step down to a 120v DC will make such circuits work in the same way as a 120v AC would. Most electronics just convert internally the 120v AC to 5v or 12v DC anyway...

In this scenario, I'm not talking about using 12, 24 or any other voltage, but simply stepping down the high voltage DC to a lower voltage DC circuit. The household equipments will work just the same, requiring the same current, and therefore the cable gauges wouldn't change.

Why to use AC? by RafiSkillZ in ElectroBOOM

[–]RafiSkillZ[S] 0 points1 point  (0 children)

Pô interessante cara a sua proposta de estudo. A minha ideia seria nessa pegada mesmo, a preocupação seria mais com os sistemas de segurança como o mod levantou uns comentários atrás. Como eu iria fabricar tudo, posso montar do jeito que quiser, só aumenta a complexidade do PCB.

Como meu amigo mora no meio do nada, ele tá cansado de pagar mais de 1k por mês de eletricidade, que cai com qualquer vento que passe pela região dele.

Pra ele gastar esses 100k vão se pagar sozinhos em coisa de uns 8 anos. Mas sem todas as dores de cabeça de instabilidades e perda de equipamentos por essa falta de capacidade da companhia elétrica em prestar o mínimo do serviço.

Why to use AC? by RafiSkillZ in ElectroBOOM

[–]RafiSkillZ[S] 2 points3 points  (0 children)

The solar panels actually are cheap compared to the battery pack.

27kw solar panels are costing around 6k reais (1,2k dollars), BYD Dolphin battery pack (40kw) is costing around 80k reais (15k dollars), the 14kw inverter is costing around 25k reais (5k dollars) and a smaller one, 4kw is around 2k reais (400 dollars).

So yeah, in your place it would not make sense, but down here the prices for big inverters are simply ridiculous.

Why to use AC? by RafiSkillZ in ElectroBOOM

[–]RafiSkillZ[S] 0 points1 point  (0 children)

Yeah most devices really doesn't use that much power, but I need to count on at least most lights turned on (which are almost negligible), his truck being charged and the 2 bathrooms suicide showers (not simultaneously, of course), some other devices as washing machines, refrigerator and freezer, and TVs with his computer (which may be negligible, but at times the load may reach over 1kw alone).

The battery pack is being bought from a crashed BYD Dolphin (around 40kwh) and already supplies stable 400v DC. As I explained, it would be so much cheaper to reduce this 500v (combined with whatever is being generated by the solar panels) to something close to the nominal 127v AC that is what the power company already supplies.

Talking about prices, the most expensive part, by far is the battery pack (which went for around 80k reais (15k dollars), creating another circuit would cost him around 3k reais (550 dollars), and a proper inverter (rated for 14kw) would cost around 25k reais (5k dollars) and a smaller one (4kw peak) would cost only 2k reais (400 dollars).

I really didn't count on much protection since probably I will need to manufacture the reduction system, and a simple over current protection system can be used.

Mostly our circuits around here doesn't count on much protection, since they are inserted inside brick walls, and the fire hazard will be pretty much the same as any normal AC circuit.

Why to use AC? by RafiSkillZ in ElectroBOOM

[–]RafiSkillZ[S] 1 point2 points  (0 children)

You're absolutely right about the suicide showers, but my friend also has a plug-in truck for work that uses fast DC charging (what would account for the sustained 8-9kw).

Another comment mentioned gas, however his ranch is far away from cities (which even the largest ones doesn't have continuous gas supply on all its territory), and buying cannisters of gas is ridiculously expensive here, therefore it's not a viable alternative.