DIY Solar Installation – Part 1 – Required Items

Solar

I wanted to try a small solar power setup to find how much that will help me in saving my electricity bills. But after starting to setup the system I found there are many small but crucial factors. This series will document what I found and
learnt while setting up the system. This first part is about the components or parts needed for a solar power setup. For a basic solar setup, the following things are needed

  1. A solar panel – there are many types and many manufacturers. The types commonly available are Poly-crystalline and Mono-crystalline. Normally all low power panels (2 – 40 watts) are poly-crystalline. For higher wattage panels (50+ ) normally both options are available. Mono-crystalline panels performs (little) better than poly-crystalline panels. So if you really don’t mind the extra cost then you can go for mono-crystalline panels. Else poly-crystalline panels are perfectly good also. And in cloudy weather that little extra of mono panels will not matter much. One important thing is the built of the panel. The built and the frame should be strong enough to withstand bad weather for many years. All low to medium wattage panels are 12 volts. High wattage panels (300+ watts) are normally 24 volts. So while purchasing make sure you are buying what you need.
    My 12v, 60 watts Luminous panel in cloudy weather gives .71 Amps to as low as .17 Amps.
  2. A solar charge controller (or solar inverters) – This is an important thing. This thing is different from normal Lead Acid battery charger. Though the panel(s) can be connected directly to load and battery but that will damage both. A 12 volts panel’s power
    production at it’s peak can reach to 18 volts. The solar charge controller

      1. Reduces the voltage to proper charging voltages. It starts with cyclic charge voltage and when the battery is full it switches to float.
      2. Advanced charge controllers have charge profile settings – that is there are options to select the type of battery being used. It will charge the battery in an optimum way, thus increasing the life of battery.
      3. Charges the battery and also supplies power to the load at the same time.
      4. It prevents reverse current flow – battery to solar – at night.
      5. Most of them have some overload or short circuit protection.

    There are two types of chargers. MPPT and PWM. PWM controllers are quite cheap. Most low amp controllers (6A, 5A, 10A) are PWM. If possible go for MPPT controllers – they do buck-boost conversion inside and hence is more efficient.
    Most controllers support both 12v / 24 volt panels. Having the 24 volt option is good – in case in future more higher wattage panels are installed. Also preferred is the controller having option to select battery type
    (SLA/GEL/Flood).

    Solar Inverters – Inverters are good when the power needs to be distributed over many rooms or floors. 12 or 24 volt dc will drop a lot when carried long distances. Once way to compensate is to use a higher gauge wire. But that will cost much more than using an inverter.
    Please note Solar inverters are different from normal inverters and have the functionality of both solar charge controller and an inverter.
    Inverters are of two types – PWM and Pure Sine wave. PWM inverters are cheaper but is not good for running any inductive load like motors or any device that has a transformer in it.

  3. A Suitable Battery – Both Lithium-ion and Lead Acid batteries can be used. Lead acid batteries are lot cheaper in comparison to lithium ion and also the charge
    controller for lead acid batteries are cheaper. Lead acid batteries are of mainly three types – sealed lead acid/, AGM, flood. Flood batteries should be preferred for long years of service and low operation cost.
    Most battery manufacturers don’t provide any warranty to SLA/Gel batteries if used in solar setup or inverters. The flood batteries can be serviced at a low cost locally. The battery type needs to be set in the controller – else the
    battery life will also get reduced. To know more on batteries you can visit these articles

     

  4. Load – 12v fans and lights can be directly used. Alternately An inverter can be used to convert the 12v dc to 220v ac and run 220 v devices. But here is a catch – most low cost inverters doesn’t produce pure sine-wave. Not supplying pure sine-wave to motors, transformers, and filament lamps can damage or shorten the life of those devices. Also there will be humming sound and unwanted vibrations. Pure sine-wave inverters are costly. Non sine wave inverters – commonly called as PWM or Modified Sinewave inverters – can be used for SMPS based devices – like Led lamps, phone chargers, led tvs, internet routers.
    .
  5. Wires – Though the common concept is to use “DC Wires” but in reality there is nothing special in wires used for carrying DC currents. What is needed is high quality, pure copper wire with good shielding. Normal AC wires that we use (the two coloured twisted wire) is not pure copper, isn’t suitable for high currents and the shield or cover is not good enough for outside use.
    It is good if the shield of the wire that will be used to connect panel and charge controller has UV protection. That part of the wire will be exposed to sunlight, heat, cold and rain, without good coating/cover the wire will not last long. Good quality copper wire is costly hence a few more rupees to ensure longevity is desirable.
    Another important factor is wire gauge. It should be suitable for the current to be carried. The longer the wires the higher the gauge needed. If you need to distribute power in different rooms and floors then using an inverter would be cheaper.

The above is for self and home use. Bigger setups that can generate more power which can be send back to grids will need “net meters”.

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