DIY Solar Panels World

Sizing Your Solar Energy Panels – Part 3

This is the third and final part of the “Sizing Your Solar Energy Panels” series. Have you done some calculations for your future solar power system yet? If you have been doing those mini exercises, you’ll most likely find a suitable solar panel for your home by now.

The next step requires us to find an appropriate-sized battery bank, inverter and charge controller. Let’s look at each of these:

1. The Inverter

The inverter you choose has to be sized according to the demands of the alternating current (AC) side of the circuit. Therefore you will choose a specification according to the loads in your house (with a little buffer in case you increase your loads over time). Pretty straightforward.

2. The Charge Controller

You’ll at least need a basic charge controller to begin with. Until you get fussy about how advanced you want this component to be, more affordable models will do just fine. You’ll need to get a specification that fits the output current (Amps) of your solar panel arrays. If you intend to scale up your solar power generator, you’ll do better with a larger charge controller with room to accommodate more solar panels than with two smaller-sized ones.

3. The Battery Bank

The size of your battery bank depends on how you want to use your solar panels. You can size your battery banks such that it can get you through thick clouds that pass by, or you can size them so you can get through three solid days of solar eclipse and a power outage at the same time. It really depends on you. But take note that over-sizing isn’t always realistic. You have to take into consideration the space they occupy and the how much they’ll cost you.

If your home is grid-tied, provided there aren’t frequent power outages, the size of your battery bank isn’t critical. Just size it to take care of cloudy days will do. You can still maintain your lifestyle by drawing power from the grid.

When you design your battery bank, you’ll have less power loss (through wires) if the voltage is higher. If you are able to design a 48-volt system, you can conserve more power than when you use a 24-volt or 12-volt system.

DIY Solar Panels — Charge Controller Basics

If you’ve ever built DIY solar panels of a considerable size, you’ll probably come across this important component — the charge controller. The role of a charge controller is to regulate the charging voltage on the batteries.

When sunlight gets brighter, solar cells produce more voltage. Excessive voltage may cause over-charging which may damage your batteries. You’ll need this component if you want to store excess electricity from your solar energy panels.

Many modern charge controller units have a 3-stage cycle:

1. Bulk Phase – During this phase, the charging voltage gradually rises to approximately 14.4 to 14.6 volts (to charge a 12V battery). It is at this stage when charging current is maximum.

2. Absorption Phase – Voltage is maintained at the bulk level for a specified time. As the battery is charged up, current tapers off gradually.

3. Float Phase – After the absorption phase, voltage is lowered to about 13.4 to 13.7 volts (float voltage) and batteries draw a very small, maintenance current until it goes through the discharge cycle.

There are several different types of charge controller to choose from — some with fanciful LCD displays and others with battery temperature monitor. If you are building your first solar power generator, it may be more practical to buy basic ones to begin with. After you’re more acquainted with these components, you’ll have more knowledge to get the most out of more advanced charge controllers. Most multi-stage, Pulse Width Modulation (PWM) types of charge controllers will do great, really.