Proof of Concept

A project log for Mini Solar System

A small off grid solar system that can provide long term emergency power for household appliances

Drew PilcherDrew Pilcher 08/17/2022 at 08:320 Comments

I started with the following components (prices include shipping):

2x L02M100N-1 monocrystalline solar panels from ECO-WORTHY. $90 each. Mine have slightly different specs due to being purchased a year apart.

1x PG-12V55-FR Powersonic 12V 55Ah Sealed Lead Acid Battery. $120 Old but unused from ebay.

1x Tracer1206AN Epever MPPT Solar Charge Controller. $49 from ebay.

1x PS-1200JCR Giandel 1200W Sine Wave Inverter. $200 from amazon.

Basic math:
The chest freezer draws an average of 40W continuously (tested with a kill-a-watt).

Dividing by the 90% max efficiency of the inverter gives 45W

For approx 16 hours a day the system will run on the lead acid batteries. Estimating the efficiency of the batteries is difficult. I believe it varies a lot depending on the range of the battery charge you're using. Lets assume 80%.

(16h * 45W / 0.8) + (8h * 45W) =  1260Wh per day required from the solar panels

Assuming and average battery voltage of 13V. 16h * 45W / .80 / 13V = 69 Ah per day from the batteries.

Each solar panel produces 100W nominally for approximately 4 hours per day (depends on geographic location and climate). That's 400Wh per panel per day.

The charge controller claims "up to 98% efficiency" which is probably not realistic. Lets call it 90%

Each panel therefore produces 360Wh per day. So I would need 4 panels.

Getting started:

My proof of concept was to simply hook everything up and see if it works. Meaning it can charge the battery and power the freezer at least briefly.

I decided to located the electronics in the basement instead of near the panels to make the system easier to tinker with.

I used an extension cord to carry the DC from the solar panels inside. Including an extremely jankey connection under the panels which I need to replace asap.

Conclusions after testing: