Inverter/charger with Generator

This system is similar to the previous one with a 24V 200Ah battery, but now we add solar panels and a generator.

We also have an inverter/charger instead of a separate inverter and battery charger.

Curious why i like the Victron Multiplus 2? Watch my video review about it here.

Parts used

Only use the fuse i recommend. Do not trust other brands. Check my video why.

Description

This system uses 4x 325W solar panels in a 2S2P configuration. A lithium battery at 24V and 200Ah for a total storage capacity of 5,120Wh. You can expand the battery capacity by adding more batteries in parallel. The good thing about this battery is that it already has a DC breaker, so you don’t need to add a fuse.

A 2000VA inverter/charger with a 50A charging current for the generator in one device.

2000VA is not the same as 2000W. Generally the power factor is 0.8, so we multiply VA (volt-ampéres) by 0.8 to become: 2000VA*0.8=1,600W

Charge controller

Let’s see what charge controller we need. If the mentioned solar panels are not available, you can repeat these calculations for your panels. (check my video on how to calculate a charge controller)

365W ×4 solar panels =1,460W

1,460W/28.8V =51A charging current

The solar panel specs are:

  • Power: 365W
  • Open Circuit Voltage (VOC): 48 V
  • Short Circuit Current (ISC): 9.83 A
  • Maximum Power Voltage (VMP): 39.10 V
  • Maximum Power Current (IMP): 9.33 A

The voltage is quite high, so i think we should use a charge controller with a 150V PV input limit.

Since we have 4 panels, it’s best to wire in 2S2P, that is two panels in series and then in two parallel sets.

The maximum input voltage is:

48Voc ×2 panels in series ×1.25= 120V

Let’s say the distance to the charge controller is 70 feet or 20 meters.

We need 8 AWG PV cables to keep the voltage below 3%. (check my video about voltage drop)

Since the max current will be 51A and we have a combined voltage of 120V, we can use the victron 150V/60A charge controller.

System sizing

The maximum current the system will draw is:

(2000VA/25.6V)*1.25 =98A

The total capacity of the battery is:

25.6V×200Ah=5,120Wh

To recharge the battery in one day, we need a total of:

5,120Wh/(365W ×4 panels)= 3.5 sunhours

This makes the system correctly sized. You need to be able to recharge the battery in one day, which equals 3 or 4 sunhours (1000W/m²).

Generator

If there is no sun, the generator will recharge the battery. The honda generator has a power output of 3,000W. I recommend using 50-70% of the generators power output to save on fuel and reduce noise (3000W*0.7=2,100W maximum).

The Victron multiplus 2 has a maximum charging current of 50A, at 25.6V, this is a power of: 50A*25.6V=1,280W.

The battery has a capacity of 5,120Wh, if we divide that by the charging power, we get: 5,120Wh/1,280W= 4 hours to recharge the battery. You can add another battery charger to the generator to charge it quicker. But i recommend a maximum of 40A. You can use this one.

Estimate runtime

Let’s repeat the same calculations to estimate the runtime of a fridge.

300W* 8 hours = 2,400Wh daily power consumption

inverter idle power consumption is 15W for 24h = 360Wh

2,400Wh + 360Wh = 2,760Wh of power consumption per day

battery capacity is 5,120Wh/2,760Wh = 1.8 days of runtime.

You can repeat this calculation for other devices as well. If you run DC appliances, you don’t have to include the inverter idle consumption.

 

Questions? Send me an email here.