Tiny House – 110V Grid

Tiny House – 110V Grid

Many people like solar but don’t want to cramp their style by switching to 12 Volt only. In this set up we made it a bit bigger with regular 110Vac grid output too. As mentioned before, due to the high DC currents on bigger power consumption we like to raise the DC voltage to keep it a bit under control.

Charge controller and 48Vdc cabinet
Charge controller and 48Vdc cabinet

This setup uses 48 Volt DC power with a maximum charging current of 30 amps. These two values determine a lot of other variables. Batteries require an average load current between 1/12 and 1/8 of the capacity. So this would bring us on batteries between 240Ah and 360Ah. Since we don’t use the full 30 amps we choose 220Ah golf cart batteries that each handle 6 Volts, so we need 8 pieces. These batteries are also available in 340Ah which would work as well but is a bit more expensive.

So 48V x 220Ah stores over 10kWh (10.56kWh) of power to use. We are a strong believer of discharging only 20% (Our reason) out of the batteries for longer battery life, so that brings 2kWh a day. That is more than enough to run lights, a refrigerator, a freezer, radio, tv, computer and a lot more.

Taking out 2kW a day means we have to put in approx. 3kW. To use the co-called 12V PV-panels we now need 4 pieces in series to reach the 48V. Look at a standard solar panel output: 150Wp (18.9V/7.9A) in series of 4 equals 600Wp.
Then use 3 of those series in parallel (1800Wp 75.6V / 23.7A together) then the system  should recharge in about 2 hours of sun.

Of course 1800Wp could easily be formed out of 9x 200Wp, 8x 250Wp or even 6x 300Wp panels but that is up to you.

Nice DC-AC inverter
Nice DC-AC inverter

To have some extra power an inverter of 3kW is used and a distribution box with 6 circuit breakers of 15A. To provide some extra safety a 25A GFCI breaker is used as main breaker, that can only function is the is a ground rod connected to provide decent grounding.

Distribution box
Distribution box

Funny accessory: kWh-meter

Something there is absolutilly no need for but is funny to have is a kWh meter. Since you don’t have to pay anyone fees for electricity it seems useless. On the other hand calculations are good, measuring and checking is better, this way you can check your usage, if you can use 2kWh a day it should be 14 or less after a week. Less is no problem, but more is a nice pointer you need more solar panels and bigger or extra batteries.

GFCI, kWh-meter and 6 regular MCB’s
GFCI, kWh-meter and regular AC MCB’s