Hi all, a newbie here as well
First of all, what an amazing forum, reading all the topics here have given me a better understanding on using solar power.
So i need some assistance here with a dilemma i have:

I  have already bought 2x200ah 12v batteries, and over the next couple of day i intend to buy 3x330w panels and an inverter.
My goal is to provide power to my washing machine and pool pump during the day, and then power some floodlights in the yard at night. 

My pool pump has a variable speed motor 400wph (3200w per day) 
and my washing machine consumes 200wph of power (400w per day)
flood lights in the yard at night power consumption 800w (80w x 10 hours) 80amps DC per night consumption at 12v (hope my math is correct here)

so advise please:
1-is the 3x330w solar panels enough to provide power to pool pump and washing machine during the day as well as charge the 2 batteries that will power the floodlights?
2- What type/make/model of inverter should i buy that will allow me to do this, but also have eskom power as a backup if needed?

Hope this makes sense..

looking forward to your responses
Iiceman

1 hour ago, Iiceman said:

Hi all, a newbie here as well

Welcome to the forum.

Quote

I  have already bought 2x200ah 12v batteries, and over the next couple of day i intend to buy 3x330w panels and an inverter.

I'll bet that will be a 145 V max Voc Axpert, since these are the cheapest. It's been established that three 330 W panels will be too much voltage for these inverters, but if you can find 300 W panels that are 60-cell (not 72-cell as all present 330 W panels are), then that would be fine.

Quote

My pool pump has a variable speed motor 400wph (3200w per day) 
and my washing machine consumes 200wph of power (400w per day)
flood lights in the yard at night power consumption 800w (80w x 10 hours) 80amps DC per night consumption at 12v (hope my math is correct here)

Yikes! Such mangling of units (not uncommon for newbies). But once you get the idea of multiplying power (in watts) by time (in hours), you get energy (in Watt.hours), it all becomes much easier to figure out.

So your pool pump is 400 W (or Wh/h if you like) x 8 hours = 3200 Wh (the 8 hours and the 3200 Wh are really per day).

Your washing machine averages 200 W (mine has peaks of 2000 W for heating the water; I take it yours does not?) x 2 hours/day = 400 Wh/day.

Your flood lights are presumably 80 W, so over the course of 10 hours per night that's 800 Wh/day.

At night, with the 80 W load, call it 100 W with losses, that's about 4 A from the battery (100 W / 25 V = 4 A).

So your energy load (ignoring losses) is 3200 + 400 + 800 = 4400 Wh/day.

Quote

so advise please:
1-is the 3x330w solar panels enough to provide power to pool pump and washing machine during the day as well as charge the 2 batteries that will power the floodlights?

Again, ignoring losses (and there are plenty): on the best days, you'll get the equivalent of 5 hours of peak sun, but you can only bank on 75% of nominal power. So that's

330 x 3 x 5 x 0.75 = 3700 Wh (per day). So you're well short before we consider efficiency, and that doesn't take into account shorter days in winter, shading, rain, imperfect orientation, and so on.

Let's see if the battery will last running the flood lights. It sounds like it's lead acid; let's say we can only use 50% of capacity before lifetime suffers acutely. Ignoring capacity fade etc, and taking the battery voltage to be a round 25 V, we have

25 V x 200 Ah x 50% = 2500 Wh. From above, you need 800 Wh over the 10 hours, so that's a comfortable load for the battery.

Quote

2- What type/make/model of inverter should i buy that will allow me to do this, but also have eskom power as a backup if needed?

Well, that depends on what you want to run during a blackout. Let's say it happens at night, from the above, you have a maximum of 2500 - 800 = 1700 Wh, call it 1500 Wh to include at least some losses. So if the blackout is 4 hours duration, that would allow 1500 Wh ⁄ 4 h = 375 W. So you could run a smallish, efficient fridge and freezer, and maybe a few very low power LEDs. You'll probably want a few more creature comforts than that, so I'd say you'll soon need more battery, and we've already established more panels are needed.

The Axpert inverters are popular because they're inexpensive, and they have a utility and solar battery charger built in (so they're really inverter-chargers). They also have some relays for switching loads from utility to battery.

You've settled on a 24 V system, because you have only 2 12 V batteries. But it's more efficient to run a 48 V system, if you want the bigger loads (3 kW or 5 kW are typical Axpert sizes). I note that lead acid batteries don't appreciate heavy discharge current. If you limit the largest loads to C/2 (for a 200 Ah battery this would be 100 A), then at 25 V that's 2500 W, not enough (again, ignoring losses for simplicity) to max out a 3 kW inverter. So perhaps for your starter system, consider a 2 kW inverter.

I'll leave it for others to suggest other brands.

Edited May 7, 20197 yr by Coulomb
White space.

1 hour ago, Coulomb said:

Welcome to the forum.

I'll bet that will be a 145 V max Voc Axpert, since these are the cheapest. It's been established that three 330 W panels will be too much voltage for these inverters, but if you can find 300 W panels that are 60-cell (not 72-cell as all present 330 W panels are), then that would be fine.

Yikes! Such mangling of units (not uncommon for newbies). But once you get the idea of multiplying power (in watts) by time (in hours), you get energy (in Watt.hours), it all becomes much easier to figure out.

So your pool pump is 400 W (or Wh/h if you like) x 8 hours = 3200 Wh (the 8 hours and the 3200 Wh are really per day).

Your washing machine averages 200 W (mine has peaks of 2000 W for heating the water; I take it yours does not?) x 2 hours/day = 400 Wh/day.

Your flood lights are presumably 80 W, so over the course of 10 hours per night that's 800 Wh/day.

At night, with the 80 W load, call it 100 W with losses, that's about 4 A from the battery (100 W / 25 V = 4 A).

So your energy load (ignoring losses) is 3200 + 400 + 800 = 4400 Wh/day.

Again, ignoring losses (and there are plenty): on the best days, you'll get the equivalent of 5 hours of peak sun, but you can only bank on 75% of nominal power. So that's

330 x 3 x 5 x 0.75 = 3700 Wh (per day). So you're well short before we consider efficiency, and that doesn't take into account shorter days in winter, shading, rain, imperfect orientation, and so on.

Let's see if the battery will last running the flood lights. It sounds like it's lead acid; let's say we can only use 50% of capacity before lifetime suffers acutely. Ignoring capacity fade etc, and taking the battery voltage to be a round 25 V, we have

25 V x 200 Ah x 50% = 2500 Wh. From above, you need 800 Wh over the 10 hours, so that's a comfortable load for the battery.

Well, that depends on what you want to run during a blackout. Let's say it happens at night, from the above, you have a maximum of 2500 - 800 = 1700 Wh, call it 1500 Wh to include at least some losses. So if the blackout is 4 hours duration, that would allow 1500 Wh ⁄ 4 h = 375 W. So you could run a smallish, efficient fridge and freezer, and maybe a few very low power LEDs. You'll probably want a few more creature comforts than that, so I'd say you'll soon need more battery, and we've already established more panels are needed.

The Axpert inverters are popular because they're inexpensive, and they have a utility and solar battery charger built in (so they're really inverter-chargers). They also have some relays for switching loads from utility to battery.

You've settled on a 24 V system, because you have only 2 12 V batteries. But it's more efficient to run a 48 V system, if you want the bigger loads (3 kW or 5 kW are typical Axpert sizes). I note that lead acid batteries don't appreciate heavy discharge current. If you limit the largest loads to C/2 (for a 200 Ah battery this would be 100 A), then at 25 V that's 2500 W, not enough (again, ignoring losses for simplicity) to max out a 3 kW inverter. So perhaps for your starter system, consider a 2 kW inverter.

I'll leave it for others to suggest other brands.

Hi Coulomb

thanks for the assistance, makes a lot more sense now, really appreciate you taking the time to help out a newbie...

Hi @liceman 

For what it's worth, here is what the graphs look like for my (brand new) 3x330W JA panels.

The absolute best day netted me 5.03kWh - but that is currently an outlier.

Average is sitting somewhere between 3 and 4kWh per day - assuming I can keep the loads stable enough to get the panels producing at max.

That translates roughly to (at peak - 12 noon) something like 750W coming down (i.e. 250 per panel).

The (sometimes more useful) graph attached. In case you are wondering: yes, I need more panels.

 

Edited June 28, 20197 yr by demaniak
Adding that I indeed do need more panels.