◆ PARALLAX

Shed full of tools in Tennessee, maybe 35 north, so winters are mild, lows usually above 50F. I got a 150W panel from a pawn shop for 40 dollars. Thinking 400Ah lead-acid, maybe a 2000W inverter, run some lights and a radio. No fridge, no heater, just basics. Where do I start?

Anon, you are in good shape actually. 35N is far better than 47N -- your December insolation is maybe 3.5 to 4 peak sun hours, not 2.5, so you can sustain more load.

Math: 150W times 3.75 hours is about 560Wh per day; after inverter loss call it 500Wh. If you run 300W of lights and radio in the evening, that is well under what you harvest, so on most days you are fine and the battery is just buffering cloudy stretches. With 400Ah of lead-acid you have a lot of buffer if you respect the 50% floor. In Tennessee you rarely get more than a week or two of grey sky, so you can ride it.

But the 150W panel is your real constraint. The panel is the ENGINE; everything else is just storage and switching. If you can swing 300W eventually, do it.

Anon, Dan is right, and I will add one thing: do not buy 400Ah right away. Buy 200Ah, run it three months, and learn your actual load curve. You may use far less than you think, or far more. Then size the bank to reality, not theory.

For 35N you do not need my winter discipline. Your bigger enemy is summer heat killing the batteries -- lead-acid hates heat more than cold. Keep them shaded and ventilated, a cool corner of the shed. And K7 is right about fusing: at 12V on a small system, 4AWG and a 60A fuse; at higher voltage and longer runs, heavier copper. Use a wire-gauge chart, do not guess. Start small, measure for three months, then scale.

Anon, one more practical thing: do not buy a 2000W inverter for a 150W panel. That inverter can draw 30W idle, which is a fifth of your whole panel output gone just to keep it powered. Get a smaller pure-sine, maybe 1000W, and keep it OFF except when you need it -- flip a breaker.

Better still, run 12V DC for the lights and the radio and use the inverter only for AC you cannot avoid, like a laptop or a power tool. A radio runs fine on 12V. Lights run fine on 12V. You would be surprised how little you actually need 120V for. Separating the two sides takes a couple of hours to plan and saves you money and power for years.

Good thread turning into gold. One meta note: Anon is asking the right questions now because Otto and Dan and Barb answered with NUMBERS, not "LiFePO4 is the future" or "lead-acid is bulletproof." Load, insolation, usable capacity, depth of discharge, efficiency. That is how you plan instead of guess.

Anon, take the homework seriously: measure your actual loads for two weeks before you buy a single battery. A cheap plug-in watt meter, plug the gear in, write down the numbers. Thirty minutes of work that saves you 500 dollars in wrong purchases. The method beats the gear every time.

Thanks everyone. This thread actually made sense instead of "just buy the biggest battery you can and pray." I bought a plug-in watt meter, going to measure everything in the shed for two weeks and then come back with real numbers. Also going to buy the smaller panel instead of gambling on a big system, start with 200Ah lead-acid, skip the 2000W inverter and run 12V DC for lights and radio, with a small inverter only for tools. Back in three weeks with the measurements. Thanks for the actual math instead of vibes.

Anon, that is EXACTLY the right approach. You just saved yourself a couple of thousand dollars in mistakes and you have not even bought the solar yet. Measure, think, then buy.

For anyone else reading: that is the real prep. Not the gear, not the brand. It is the discipline to measure, think, and size for your actual life instead of your fantasy. My winter is tight, so I ration hard. Anon is in mild Tennessee, so he is fine with modest gear. Neither of us is "better" -- we are just matched to our own reality. Winter will come and the sun will set early, but if you know your numbers you survive it. That is the whole point.