DIY Solar Panels hook Up
Photovoltaic solar panels convert sunlight directly to dc voltage. This is useful to power devices directly as it were or convert to alternating current voltage through an inverter. This article focus on different methods in use to hook up solar panels to batteries; appliances; electric motor; and mains power outlet.
Hooking up Solar Panels to Batteries
The cable which connect to solar panels through solar cable entry box is two and similarly power inlet to any battery and dc appliance is two. So you may connect your solar panels directly to any rechargeable batteries. You can connect to your appliances without damage. In doing this, however you have to follow basic instruction to do it right.
- The voltage from the solar panels must match the voltage of the battery for instance, you need a 12V panels to charge 12 Volts batteries.
- The size of the solar must measure up with battery size. A big size panels will supply excess power to tiny battery in bright sunlight.
Solar Panels Voltage Output
Voltage output of a solar panel is dependent on the sunlight. Open circuit voltage output of panels in full sun is almost twice the voltage of the battery to charge. Solar panels produce power at their maximum power point, which is usually about 60% of the open-circuit voltage. For example, if you have a 12V solar panel, open-circuit voltage in full sun is about 24V. You need to consider the capacity and voltage of your panels as well as the size of the batteries. You need panels that will put 5% (at least) of the ampere hours capacity of the battery in as current. For example, if you have a 100 amp-hour battery, you’ll need enough panels to put 20 amps in at the voltage of the battery.
You can connect many batteries with the same voltage in parallel to get more amps and more watts. You can also connect batteries in series to get the voltage your inverter needs. But most cheap inverters have 12 volts input, and work from 10.5 volts to about 14.5 volts. However for your battery to last long the system needs well designed. In situation when you have deficit of sunlight for a long period, a user tends to continuing using the batteries at great risk therefore it is necessary to include a low voltage battery disconnect devices in the design.
Solar Panels Battery System
The battery might be a wet Lead Acid, Gel type or deep cycle all the same in this regards. A fully charged like new car battery or other about that size will supply about 1000 watts briefly, so you should not expect to run appliances rated more than 1000 watts except with a very large battery.
The battery voltage needs to match the appliance’s voltage for appliances using low voltage direct current from battery. But most equipment require 110V/220V which means you need an inverter. Th inverter should voltage of your battery as input and the voltage of your appliance as output. A 1000 watt inverter rated about 2000 watts surge is probably best, but other inverters will probably work. Typically they have full protection from user errors, and turn themselves off if conditions are not right. If you have the voltage correct the appliance will draw the current and watts the appliance needs. That is f the inverter and battery can supply that much current and watts.
Connecting solar panel directly to a battery?
When connecting solar directly to battery without a charge controller, it is OK to put a diode in the line. A diode is an electrical check valve, allowing current to flow in one direction only. This will allow the panel to charge the battery, but not let the battery discharge into the panel at night. Most panels today come with diodes already installed in the junction box.
The panel voltage, or “Open Circuit Voltage,” should be higher than the battery full charge voltage. If the 12V battery full charge is 13.5V, panels’ wiring are for 18 volts. Then they can charge a 12 volt battery. The panel voltage will simply sag to match the battery’s charging curve voltage during the daytime.
Second, if the panels max amps, or, “Short Circuit Current,” rating is below 2% of the battery’s amp hour capacity, then the panel will never overcharge the battery. For example, if the battery is 75AHr and the panel short-circuit current is just 1.5A, then the panel can never able to overcharge the battery which means you may connect the battery directly to the panels or vice versa. A panel in direct sun without anything hooked to it should put out about 17 or 18 volts, unless the wiring is for some other nominal voltage other than 12. For example, if you have a 50W panels with maximum amperage of 6 amps, to charge a battery which wired for an amp hour capacity of 440 AH, you are well within the 2% window, you may not use a charge controller.
Ensure that you keep the batteries watered at least once a month with distilled water, they will go through some electrolyte this way.
How to connect a solar panel to a motor?
A solar panel cannot operate a motor by itself. A typical system operates like this: The solar panel is connected to a charge controller. The charge controller is connected to a battery which is connected to a motor controller. The motor controller is connected to the motor. All these components must be compatible with each other. So, in other words, you can’t run “just any old motor” with a solar panel. Typical use is a system like an solar powered electric gate opener
How Connect Power Outlet to Solar Panel?
- Determine Your Power Requirement
The use of energy-saving lights like solar tubes or sun tunnels or LEDs gives you the same light output for 100W as incandescent lights of 500W is most efficient; this means you can have much light for less number of solar panels. Then you need a solar panel that can produce 100 watts for as long as you want (at a 100 watt lighting system) or 200 watts for 1/2 the time you want, etc. Allow a good 10% or so for inverter inefficiencies, and 10% or so for reserve, so 120 watts per 100 watts.
After you have this, you will want
- A Charge controller,
- A Battery, or Battery Bank with enough amp-hours to support your system, plus a good 10% or so reserve, plus another 10% or so for inverter inefficiencies (remember the over sized solar panel above, this is why),
- then of course you also need a 12-volt DC to 120-volt AC, 60 Hz system (or 240 volt AC 50 Hz system, depending on your AC system) inverter. The battery should be deep-cycle series between 2, and parallel between banks of 2 for the 12-volt portion of the system.
Voltage Controller Vs Charge Controller
Charge controller is for charging batteries with a high current array while Voltage controller sends solar power directly to a device like a water pump. In this case, you don’t connect a solar panel directly to your device it must pass through a voltage controller when you don’t involve battery in the system. The most efficient charge controllers use what’s called Maximum Power Point Technology (MPPT) which lets the panels operate at their most efficient point throughout the battery’s charging cycle. The charge controller should have the same or higher wattage as the panels it controls – if you’re not sure of wattage, assume that they are the same as similar area panels you find for sale
- In summary,
You can connect solar panel directly to battery through a diode if the panel short-circuit current is about 2% of the amp hour ratings of your battery.
- If the array Short Circuit Current is higher than 2% of the AHr of the battery bank, then you will need a charge controller between the battery and the solar panel.
- The open-circuit voltage of a 12v panel is about 18v which is sufficient to fully charge a 12 v battery to its maximum at 13.5v to 14.5v.
You can add solar panels in series for high voltage; you can add solar panels in parallel for high current output depending on your application. To connect panel(s) to a device or appliance, you will need a voltage controller between the panel and the device.
You can minimize number of panels for your output by using energy efficiency appliances especially for lighting.
Charge Controller; Voltage Controller; Deep Cycle Batteries; Diodes
Midwest Renewable Energy Association MREA.ORG
Solar Energy International, solarenergy.org