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Sizing Your Solar Power System (Water Analogy)

When thinking about how to size your solar power system, it can be helpful to look at it in a way that’s easier to understand.  A good way to do this is to imagine your solar power installation is a water system.

The Water Tank – This would be your battery bank, and the water is the electricity.  Your tank should be big enough to store water for a timeframe that you decide.  Will it be a small tank for short term emergencies, or a large tank for long term operation?

The Level of your Water Tank – This is your battery bank voltage.  The resting voltage of your battery bank (under a slight load) will tell you where your storage level is.
-    A 48 volt DC system will vary from 44 volts (tank empty) to 52 volts (tank full)
-    A 24 volt DC system will vary from 21.5 volts (tank empty) to 26 volts (tank full)

Water Supply – Your water tank is filled by your solar panels, or your water supply.  The more solar panels you have, the quicker you can refill your water tank.

Water Pressure – The pressure of your water system is your operating voltage.  Wiring solar panels in series will increase your system pressure going into the tank.  Likewise, your choice of power inverter will determine your system pressure on the outlet side (generally 120 VAC or 240 VAC)

Water Flow – The amount of water flowing through your system is your electrical current.  Wiring solar panels in parallel will increase your flow going into your tank.

Power – Power is the combination of pressure x flow (or voltage x current), whether in water terms or electrical terms.  Increasing either flow or pressure (or both) will increase your power delivery.  The key to any electrical system is efficient power delivery, and so higher voltages are desired to help keep the electrical currents low, within the limits of practicality.

Water Distribution – When laying out your distribution network, all your pipes have to be big enough and strong enough to carry the pressure and flow.  The faucets and nozzles are your electrical receptacles.  The pipes are your electrical wires.

Booster Pump – Think of your power inverter like a booster pump.  It is taking your water in at a lower pressure, and delivering at a higher pressure.  It is also converting DC energy to AC.

The trick to a successful off grid energy installation is balancing the different parts of your systems, and making sure you always have electricity for your use.  We highly recommend people install modular design so that you can fine tune your power generation once you get the hang of things.  Your initial installation should be big enough to get you going, and then add an extra bank of batteries, solar panels, or inverter down the road if you think necessary.

MicroGrid Living

- MicroGrid Power Systems
- Benefits of the MicroGrid
- Running on DC Electricity
- Things to Think About
- Sizing Your Microgrid Power System
- Energy Conservation Strategies
- Hybrid Power Systems

MicroGrid Solar Power

- Solar Power Applications
- Photovoltaic Solar Panels
- Increasing Solar Panel Performance
- Mounting PV Solar Panels
- Solar Power Tracking Systems
- One Axis Solar Panel Tracking (Passive)
- Solar Power Cost & Payback
- Sizing your Solar Power System

MicroGrid Power Devices

- Wind Turbines
- Wood Burner Systems
- Thermal Power Systems
- DC Thermal Generators
- Hydro Turbines

MicroGrid History

- Nikola Tesla Source of Human Energy
- Nikola Tesla Energy from the Medium
- James Watt & the Steam Engine
- Marcellus Jacob Wind Turbine

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