Simplifying Solar

Felz Energy Consultants  ·  felzenergy.com  ·  Own Your Energy

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I live entirely off solar energy — in a van, on a farm in Costa Rica, and everywhere in between. This is the no-fluff breakdown I wish someone gave me on day one. Let me help you find your free.

How Solar Actually Works

Here's the simple version nobody tells you: the sun hits your panel, electrons start moving, and that movement is electricity. That's it. No fuel. No combustion. No monthly bill from a corporation that doesn't care about you.

A solar panel is made of photovoltaic (PV) cells — thin slices of specially treated silicon that release electrons when photons of light strike them. That flow of electrons is direct current, or DC. From there, your system routes that power through a charge controller (which manages battery charging and prevents overcharge), into a battery bank for storage, and then through an inverter that flips DC into AC — the kind of electricity that runs your fridge, your lights, your power tools, and whatever else you've got.

The beauty of solar is its simplicity once you understand the fundamentals. There are no moving parts in a panel. They're silent. They work in the jungle, in the desert, on a rooftop in Georgia, on a van rolling down the highway. The sun doesn't send you a bill. That's the whole deal.

The Core Components of Any Solar System

Every solar setup — whether it's a 100W panel on a camper van or a full 10kW off-grid homestead — is built from the same basic building blocks:

• Solar panels — Capture sunlight and convert it to DC electricity. Rated in watts (e.g., a 400W panel).
• Charge controller — Sits between your panels and battery bank. Regulates voltage and current to protect your batteries and maximize charging efficiency. MPPT controllers are the gold standard.
• Battery bank — Stores the energy your panels produce so you can use it when the sun isn't shining. Lithium (LiFePO4) batteries are the best option today for longevity, depth of discharge, and weight.
• Inverter — Converts DC from your batteries to AC for your appliances. Pure sine wave inverters are what you want — they're safe for sensitive electronics.
• Wiring, fuses, and disconnects — The circulatory system of your build. Undersized wire or missing fuses are how systems catch fire. Size everything properly.

The order of operations: sun → panels → charge controller → battery bank → inverter → your loads. Every component has to be matched to the others. That's what system design is all about.

The Only Formula You Need

People overthink solar. But electrically speaking, everything starts with one equation. Burn it into your brain:

Think of electricity like water moving through a hose. Volts are the water pressure — how hard it's being pushed. Amps are the volume of water actually flowing through. Watts are the total work getting done at the other end. Crank up the pressure (volts) or open the valve wider (amps) and you get more power.

This one formula will answer almost every question you have about your system. How much power does my panel produce? W = V × A. How much current will my wire carry? A = W ÷ V. What voltage do I need? V = W ÷ A. It's all the same equation rearranged.

Real Examples You'll Actually Use

Let's say you have a 300W panel rated at 30V. At peak production it puts out 10 amps (300W ÷ 30V = 10A). Simple.

Now say that same panel is part of a 12V system. You'd need a charge controller that steps the voltage down to 12V — and because power is conserved, the current goes up. Your 300 watts at 12V means 25 amps (300 ÷ 12 = 25A). That's why wire gauge matters so much in low-voltage systems — high amps need thick wire or things get hot.

Step One Before Anything: Do Your Load Calculation

Here's where most people go wrong — they start by shopping for panels and batteries before they even know how much power they actually need. That's backwards. You wouldn't build a house before drawing the blueprints. A load calculation is your blueprint.

A load calculation is simply an accounting of every electrical device you plan to run — what it draws in watts, how many you have, and how many hours per day you plan to use it. Add it all up and you know your total power demand. Everything else — your battery bank size, your panel wattage, your inverter rating — is sized from that number.

What a Load Calculation Tells You

A proper load calculation gives you more than just a wattage number. It tells you:

• Total load in watts — the peak demand your system needs to handle at any given moment. This sizes your inverter.
• Daily energy consumption in kWh — how much energy you burn through in a full day. This sizes your battery bank.
• Monthly energy consumption — useful for understanding your overall energy footprint and comparing against utility bills.
• Current draw in amps at 120V and 240V — critical for sizing your wiring, breakers, and charge controllers correctly.
• Recommended circuit breaker sizes — so you know exactly what protection your system needs.

How to Use the Felz Energy Load Calculator

I built the Load Calculator at Felz Energy specifically so you don't have to do this math by hand or pay someone to do it for you. Here's how to use it:

1. Head to felzenergy.com/electric-load-calculator — it's free, no login required.
2. Click "Add Appliance" for each electrical device you plan to run. Enter the appliance name, its wattage, and the quantity you have.
3. Repeat for every load in your system: refrigerator, lights, fans, phone chargers, laptops, power tools — everything.
4. Click "Calculate Load." The tool instantly shows your total watts and kW, daily and monthly kWh, current draw at 120V and 240V, and recommended breaker sizes.
5. Use those numbers as the foundation for your system design. Your daily kWh number is what you'll feed into FelzCalc next.

Run your load calculation now → It takes about five minutes and will save you from buying the wrong equipment.

Series, Parallel, or Both? Wiring Your Panels the Right Way

Once you know your load and you've chosen your equipment, you need to wire your panels together correctly. This is where most DIYers freeze up — and where most solar salespeople charge you for knowledge that should be free. So let's break it down.

When you connect multiple panels together, you're choosing whether to add their voltages or their currents. Your charge controller or inverter has specific input voltage requirements — those specs tell you which way to wire. The diagrams below use real numbers so you can see exactly what happens to volts, amps, and watts in each configuration.

Series Wiring — Voltage Stacks Up

Connect the positive terminal of one panel to the negative terminal of the next. Keep going down the line. Each panel adds its voltage to the string, while the current stays the same as a single panel.

Figure 1: Three 20V / 8A / 160W panels wired in series. Voltage triples to 60V; current stays at 8A; total power = 480W.

Three identical 20V / 8A panels are connected end-to-end: the positive of Panel 1 connects to the negative of Panel 2, and so on. The result is a 60V string that still carries only 8 amps — but delivers the full 480W of combined power. Notice that the total wattage (3 × 160W = 480W) is the same whether you wire in series or parallel. What changes is the shape of the electricity — higher voltage, same current.

One important shading note: in a series string, if one panel gets shaded or underperforms, it drags down the output of the entire string. Keep your series strings free of shade throughout the day.

Parallel Wiring — Current Stacks Up

Connect all positive terminals together and all negative terminals together. The current from each panel adds up, while voltage stays constant at a single panel's voltage.

Figure 2: Three 20V / 8A / 160W panels wired in parallel. Current triples to 24A; voltage stays at 20V; total power = 480W.

All three panels share a common positive bus (red) and a common negative bus (blue). Each panel contributes its 8 amps to the shared bus, giving you 24 amps total at the original 20 volts. Same 480W of power — just shaped differently: more current, lower voltage. Parallel wiring is also more shade-tolerant, because a shaded panel only reduces its own contribution, not the output of the other panels.

Series-Parallel — The Best of Both Worlds

Wire panels into series strings first (to build the right voltage), then connect those strings in parallel (to multiply the current and total wattage). This is the standard for larger systems that need both a specific voltage AND high power output.

Figure 3: Four 20V / 8A / 160W panels in a 2S2P configuration (2 series strings of 2 panels, wired in parallel). Result: 40V, 16A, 640W.

Panel 1 and Panel 2 form String 1 — wired in series for 40V at 8A. Panel 3 and Panel 4 form String 2 — also 40V at 8A. The two strings then connect in parallel, keeping voltage at 40V while doubling the current to 16A. Total output: 40V × 16A = 640W from four panels. This "2S2P" configuration is one of the most common arrangements in off-grid home systems.

The core principle: no matter how you wire them, the total power in watts is always the same — it's just the voltage and current combination that changes. Series-parallel lets you dial in both to match your equipment's requirements precisely.

Configure Your System with FelzCalc — It's Free

Once you've done your load calculation, you have the numbers you need to design your system. FelzCalc at Felz Energy takes those numbers and figures out exactly how to wire your panels, how many you need, and what your system specs will look like.

I spent months designing solar systems for people one-on-one before I built the tool — because I got tired of watching people pay for information they could get for free. Enter your panel specs, your target voltage, and your power requirements, and it generates a wiring configuration on the spot.

1. Run your load calculation at felzenergy.com/electric-load-calculator. Get your daily kWh and total watts.
2. Decide on your system voltage: 12V, 24V, or 48V depending on your build size.
3. Choose your panels. Note the panel voltage (Voc and Vmp) and current (Isc and Imp) from the spec sheet.
4. Open FelzCalc at felzenergy.com/configuration-page and enter your numbers. It tells you how many panels to wire in series, how many strings to run in parallel, and what your total system output looks like.
5. Use that configuration to purchase wire, fuses, and a charge controller or inverter rated for your specs.

Start your system design with FelzCalc →

Sizing Your Battery Bank and Panel Array

Your load calculation gives you your daily energy consumption in kWh. Now let's use that number to size the two biggest parts of your system.

Sizing Your Battery Bank

Your battery bank needs to store enough energy to cover your daily consumption plus a buffer for cloudy days. Design for 1 to 3 days of autonomy — meaning your batteries can power your loads for that many days without any solar input.

Formula: Battery Capacity (Wh) = Daily Consumption (Wh) × Days of Autonomy ÷ Depth of Discharge

Depth of Discharge (DoD) refers to how deeply you can drain your battery. For lithium (LiFePO4) batteries, DoD is typically 80–90%. For lead-acid, stick to 50% to preserve battery life.

Example: You need 2 kWh per day, 2 days of autonomy, lithium at 85% DoD: 2,000 × 2 ÷ 0.85 = ~4,700 Wh (4.7 kWh) of battery capacity.

Sizing Your Solar Array

Your panels need to produce enough energy each day to refill your batteries. The key variable is your "peak sun hours" — the average number of hours per day that sunlight is strong enough to produce full-rated panel output.

Formula: Panel Wattage Needed = Daily Consumption (Wh) ÷ Peak Sun Hours

Example: You need 2,000 Wh per day and get 5 peak sun hours. 2,000 ÷ 5 = 400W of panels. Add 20–25% for real-world losses (heat, wiring, inverter inefficiency) — so aim for ~480–500W of panels.

The Most Common DIY Solar Mistakes

I've seen a lot of solar builds — good ones, bad ones, and some that were genuinely dangerous. Here are the mistakes I see most often:

• Skipping the load calculation. If you don't know what you're powering, you can't design a system. Do this first, every time.
• Undersizing the wire. High current through undersized wire generates heat. Heat in wiring causes fires. Calculate your amps, look up the correct wire gauge, and size up from there.
• Forgetting fuses and disconnects. Every circuit needs overcurrent protection. This isn't optional — it's what stands between a fault and a disaster.
• Mixing battery types or ages. Never mix lithium and lead-acid in the same bank. Don't add new batteries to an old bank. They charge differently and will cause problems.
• Buying cheap inverters. A modified sine wave inverter will damage sensitive electronics. Get a pure sine wave inverter — not optional if you're running a refrigerator, medical equipment, or anything with a motor.
• Not accounting for startup surge. Motors draw 3–7× their running wattage on startup. Your inverter needs to handle this surge, not just the running load.
• Shading a series string. Even partial shade on one panel in a series string can tank the whole string's output. Plan your panel placement carefully.

You've Got Everything You Need to Start

Solar isn't complicated once you understand the fundamentals. The sun produces energy. Panels capture it. Batteries store it. Inverters make it usable. W = V × A governs all of it. The rest is just choosing the right sizes and wiring it correctly.

Start with your load calculation. Know what you need to power before you buy a single piece of equipment. Then use FelzCalc to turn those numbers into a real system design. And if you get stuck — Felz Energy offers solar design consultations and we sell the gear you need to get it done right.

The grid is not your only option. The sun is free. The knowledge is free. The tools to design your system are free. All it takes is the decision to own your energy.