General musings and rambling thoughts on my system

[hagensieker]

I have 400 watts of panels pointed 5 degrees south of south I hit max output about 2 PM. On a cloudless day I'm tossing in just over 400 watts into 2 Battleborn 100ah and soon to be 3 as soon as the FedEx guy shows up with it in a couple days.

I top off almost every day before noon when I'm generally at half PV input capacity. That's all good as far as I'm concerned. However I don't do much with the power until the evening. I notice that when the system does pull from the battery such as when my 12v fan is on or the Alpicool C20 fridge compressor kicks on that the Solar charger feeds me whatever I'm consuming. If the fridge is pulling 35w the solar charger gives me 37 or so watts.

This is kind of making me feel like "I'm doing it wrong". I should be charging every device in the house, or running the vacuum off of the solar.........you get the idea. I have a 2000 watt inverter. I think I'll start using my Jackery power stations a heck of a lot more in the other rooms and charging them during the day off the solar board.

I even wonder if I can get one of those new, super efficient split unit AC's and run off of it during the day for the upcoming summer months. Or a small efficient window unit. Time to break out the calculator. Some of those new AC's sip power.

At any rate I think I'm letting a lot of sun power go to waste even though my current needs are being met. I never really take advantage of those peak sunlight hours.

 

[svetz]

...This is kind of making me feel like "I'm doing it wrong"....

We love a challenge! Okie dokie, let's see whatcha got...

... I notice that when the system does pull from the battery such as when my 12v fan is on or the Alpicool C20 fridge compressor kicks on that the Solar charger feeds me whatever I'm consuming....

That's a bit hard to follow. So, generic answer. Power flows from high voltage to low. Since the SCC is "charging" the battery it must output a higher voltage than the battery. When you turn a device on (e.g., a DC fan), since the voltage is higher from the SCC it should flow from the SCC to the fan (or inverter). Any excess solar power should still go into the batteries assuming they need charging. BUT, if you're pulling more watts (e.g., running a 25 amp 120V hot water heater) than the solar can provide, then it's voltage lags and the battery stabilizes the voltage - in effect both the solar and the battery are now providing the power.

... If the fridge is pulling 35w the solar charger gives me 37 or so watts.

Strikes me this is a combination of two things. First, there are also conversion losses. For example 35W / .95 eff = 37W.
Probably the bigger one is that at 35 watts and 12V the fridge is using (35/12)= 2.9A. V/I=R where the R of your fridge is a constant. Since the SCC voltage is higher (let's say 0.5V), then amps must be higher too. 2.9/12 x 12.5 = 3. amps. Watts = volts x amps, so if both are higher, the wattage should be higher - in this case 12.5 x 3. = 37.7 Watts.

... I should be charging every device in the house, or running the vacuum off of the solar.........you get the idea. ....

From the bit above it sounds like you are running them off solar, so no I don't get what you're saying.

...I even wonder if I can get one of those new, super efficient split unit AC's and run off of it during the day for the upcoming summer months.

Watts is watts. As long as the inverter, panels, and battery can supply the watts, it'll power whatever you want whether that's christmas lights that can be seen from space or a minisplit.

...At any rate I think I'm letting a lot of sun power go to waste even though my current needs are being met. I never really take advantage of those peak sunlight hours.

That's typically the case. Once the batteries are charged if you're not using it your losing it. BUT, usually that's a plus as not all days are full sunshine and that means you might be able to get by with reduced solar input. You might be able to play some tricks like put your hot water heater on a timer so it only draws watts at solar noon. You could also freeze a block of water during the day and then put it in the refrigerator at night to thaw.

Anyway, hope that helps!

 

[Supervstech]

Yeah, if your battery is full before noon, I’d say you should add some loads that you use on grid to the solar setup...

if you end up getting an ac setup on there, post your results so we can all learn too.

I would think if your nightly usage is replenished before noon, you certainly have capacity you could use during the day...