I have a small solar panel system. I can charge all of my USB devices easily, can run some LED light bulbs, use my laptop for many hours, and if need be use my desktop computer for about two hours. Constructing a small solar system is fun, makes you think, and can yield some satisfaction from being able to collect some "free" energy from the sun. The video above has information for an off-grid solar system. Below are some notes and suggestions for a bigger off-grid solar system.
- 1 Solar panel.
- 1 Charge control unit.
- 1 Battery.
- 1 Inverter.
- 1 Grounding kit.
-- 8 gauge for inverter to ground.
-- 4 or similar gauge for battery to inverter.
-- 10 to 12 gauge for control unit to battery.
-- 10 to 12 gauge for solar panel to control unit.
- Optional, but recommended:
-- Clips for cables connecting to battery.
- Tools to clip cables, tighten screws.
- It is important to note that there are always risks when dealing with electricity. One should respect it, but we should not fear it. If you don't have a background in electronics then this project may not be for you as there are risks of fire and electrocution if equipment is not handled correctly. The latter is harder if the solar kit is using minimal parts, which is the goal of this post.
- When connecting cables do NOT complete a circuit (aka touching with your skin the positive and negative terminals at the same time).
- Your footwear should be non-conductive (rubber soles, and thicker is better).
- Do NOT have inverter switch turned on when installing cables.
- Connecting solar panels to controller unit while in peak sunlight can cause sparks, connect when little to no sunlight.
- Connecting anything to the battery can cause sparks, so keep flammable materials or anything that can catch fire (paper, etc) away from the battery. br /> - This setup is NOT for connecting your solar equipment to the house's electrical system. It is meant to be independent.
- We will be doing a 12V-based system. So, 12V solar panels, 12V charge control unit, 12V battery, and 12V input inverter. In doing this we have all components being compatible with each other.
- The setup I have in mind is a single panel. Having a single panel enables us to eliminate a great chunk of information (such as describing series and parallel circuits, etc).
- What we need to be concerned with this panel is the size and how much we can get out of it. At some point it is best to mount the panel in a location where the sun shines. A simple panel gives flexibility, whereas an array of panels restricts us.
- The higher the wattage the faster our battery can be charged. The 100 Watts one should be good for summer time, but if you are looking into putting heavier use then the higher wattage ones may be more useful.
- Note that weekly cleanup can help reduce dust on the surface and therefore improve the energy harvested.
- Suggestions for panel:
-- Good: Renogy 100 Watts 12 Volts Monocrystalline Solar Panel.
-- Better: Newpowa 150 Watt 12V Solar Panel High Efficiency Module.
- Sometimes this is referred as a "regulator" which is very appropriate. This device is the brain of the whole operation. The purpose of the control unit is to route the electricity from the solar panel and place an appropriate amount on the battery. If the battery is charged then the control unit stops charging the battery--therefore preventing hazards to the battery.
- There are so many control units available. I would recommend having one that has USB ports as this allows you to charge USB devices without the need for the inverter.
- Besides matching the voltage from the solar panel and battery it is important to keep the current of the control unit be greater than what the panels can deliver. For example, if the control unit states 20A as the current capacity then you better ensure that your solar panel delivers less than 20A. The two solar panels I suggested above, individually, deliver less than 20A. For the panels above you would have to connect multiple panels in order to go over the current limit, and if that was the case then you would need a much higher current capacity controller. Luckily we don't have to worry about this if we have a single panel.
- The load on the charge control unit is unused in my system.
- Suggestions for charge controller:
-- Mohoo 20A Charge Controller with USB Ports, 12V - 24V.
- One aspect that is important to batteries is the capacity. The higher the "Ah" the better. There are many types of batteries available on the market, but the deep cycle ones seem to be reasonable.
- Most batteries do NOT do well when they are at full capacity. They also do NOT do well when drained from power. Therefore we need that charge control unit to be set up such that it prevents over charging it. Also, the inverter should shut down when it reaches some lower voltage. When charge/discharge is done correctly the lifespan of the battery can be prolongued.
- Suggestions for battery:
-- Universal UB121000 12V 100 Ah Deep Cycle AGM Battery.
-- Universal UB-4D, 12V, 200 Ah, Deep Cycle.
- This is what converts the direct current electricity from the 12V battery into ~120V alternative current. The inverter allows us to connect small fans, light bulbs, and home electronics.
- Some inverters emulate a sine wave, but they end up creating a buzzing noise when you connect electronics. So, I recommend a pure sine wave inverter for a much better experience.
-- MicroSolar 12V 1000W (Peak 2000W) Pure Sine Wave Inverter, with Battery Cable & Remote Wire controller.
- Grounding is a way to allow, if in the case of equipment malfunction, the flow of electrons to go somewhere -- that somewhere preferably is a large pool/surface such as earth. The goal with a grounding route is to enable a path for electricity to go through to that ground pool such that people or equipment are at a reduced risk. In an ungrounded situation the flow of electrons may take unexpected paths which can include humans.
- One spot for grounding is on the inverter. Connect a cable from the inverter to a grounding rod. Preferably the rod should be made of highly conductive material, such as copper.
- Grounding a solar panel is also a good idea. This can be done by connecting a cable to the metal frame of the solar panel, and routing to a grounding rod.
- Note that the grounding rod should be placed as deep as possible on the ground.
-- Skywalker Signature Series Ground Rod.
Image source: bazaronweb.com
- The gauge of the cable is important here. The thicker the cable the more current can flow through. Usually a lower AWG means thicker, whereas a higher AWG means thinner. The recommendation of inverters is also to limit the distance of the cables to as little as possible -- generally they state that it helps the battery perform better, reduces signal noise caused by the current flow, and is also safer. The order in which you connect your equipment can be important in order to reduce sparks.
- Wiring is probably the most time consuming portion. You are going to be cutting, attaching, routing all of these cables. Also, when doing this you solidify where your equipment is going to stay. I think about wiring as playing with legos, we need the right fit in order to achieve the desired result. Connect positive terminal to positive terminal, and negative terminal to negative terminal.
- Cable for inverter to ground. Inverters generally do not provide a cable for this, so you will have to spend some money. Suggestion: 8 gauge flexible ground wire.
- Cables for inverter to battery. Many inverters, including the MicroSolar, come with cables included -- which are less than 6 feet long and are of appropriate gauge. If one is to go longer than 6 feet then one needs to increase the thickness of the cable (lower gauge). Suggestion: TEMCo 4 gauge cables. Do NOT have the inverter ON, ensure it is OFF before connecting cables.
- Cables for charge controller to battery. These cables don't have to be that thick either, and they would be similar to those of solar panel to controller unit. Suggestion: 12 gauge cable is sufficient.
- Cables for solar panel to controller unit. To connect the solar panel to the charge controller unit you are going to need MC4 cables. It is important to figure out the length that you want before ordering. Also, the thickness of the cable does not have to be that big as the current achieved by a single solar panel is not that great. Suggestion: Renogy cables. Note that you are likely going to have to trim the cables at one end.
- Clamps allow you to connect and disconnect easily and safely to equipment. I would have clamps for the wires connecting the inverter to the battery. The higher clamp current capacity the better. The concern is that the inverter and battery interact, and there will be large amounts of current flowing through the clamps so the higher the better, and also if in the future you intend on upgrading the solar kit is wise to "future proof". I went all the way to 500A clamps, but it is likely unecessary.
-- Suggestion: Forney 54722 Clamps.
- Fuses are things that burn out in order to prevent too much electricity from reaching equipment. If you want to safeguard the equipment then having several fuses is a good idea. However, for a simple setup it is quite unlikely that there are major equipment risks.
- Place your equipment in a dust free environment. Over time dust can diminish function of your equipment, so it's best to avoid it.
- Place your equipment in a cool, dry, and ventilated environment. Some equipment will heat up so it's best to provide both coolness and ventilation. A moist place is not good for electronics for many reasons, so keep things dry.
- A single panel is unlikely to provide sufficient power for large usages--but things like tablets, phones, and laptops should be ok. Also, solar power is dependent on environment conditions, such as clouds, snow, dust, etc. -- so use it as a complement with your house's electric system. At the moment solar power seems to be increasing in popularity and is also becoming cost-efficient. I think that solar can help reduce the massive shipping and burning of other materials in order to create energy. If the trend with "greener" forms of energy continues then I think we can create better environments for ourselves and many species in our one wonderful planet.