Best installed cheapest and accurate way to measure Wattage

[olignyf]

Hi,

What would be the best permanent equipment to measure Wattage in a sub-2000W solar system.
How is the current loss by those meters?
If it is cheap enough I would measure the Wattage at two place, from the panels and before (or after?) the inverter.

This is what I found so far

Amazon.ca

My setup will be :

• solar: one or two solar panels of 100W
• controller: a Victron 75/15
• battery: one or two 12V80AH/20HR SOLARPLEX GEL
• inverter: Victron

Thanks!
Francois

 

[chrisski]

The one you listed has a 100 amp shunt, and if you are using a sub 2000 watt inverter, I suspect you will pulll up to 200 amps, especially if battery voltage sags, which will be more than your 100 amp shunt is rated for.

The VIctron is a 500 amp shunt. It has a negligible current draw. I’ve had that hooked to the battery in storage for a month with the solar panels shut off and SOC still reads 100%, so the draw is negligible.

If by 2000 watt system you mean inverter, I’d want to put a shunt of at least 300 amps on it. I don’t think I’ve seen that, but 500 amps is available.

Also, if you do mean 2000 watts of inverter, the batteries you mentioned are way underpowered for that. Last GELs I looked at were rated for 30% of the 20 Hour rate. That would mean a very small inverter, like 500 watts or less.

EDIT: Not sure about the 75/15, but my Victron 100/30 and 100/50 measure wattage and amps from the panels, so if the 75/15 does that also, you would not need a shunt there.

 

[olignyf]

EDIT: Not sure about the 75/15, but my Victron 100/30 and 100/50 measure wattage and amps from the panels, so if the 75/15 does that also, you would not need a shunt there.

I guess it is via the Bluetooth + mobile app that you can see the measurement on the Victron charge controller? I bought the model without Bluetooth (BlueSolar MPPT) ?

Thanks, I was wondering if 500 watts made sense for the inverter. Yes I was considering up to 2000W.

 

[chrisski]

Just check your battery spec sheet to see the max discharge rates. If it is 30%, each battery can handle up to 250 watts of inverter, so it could take you two batteries to make the 500 watt inverter. (80 ah *.3=24 a; 24a*12volts=288 watts)

 

[chrisski]

Alright, I was confused. The 30% I remembered was a charge rate, so no more than 24 amps of charging per battery.

I’m not sure what discharge rate of gels are, but 160 ah of batteries seems pretty small for a 2000 watt inverter.