In most home PV panel installation systems, the 12V system for both solar panels and batteries is fairly prevalent. Depending on the exact system needs, 24, 36, 48, 72VDC (and so on) are employed in increasingly complicated and heavy load systems.
For a 48V inverter, how many solar panels do I need?
The solar panel working voltage must be at least 4V to 5V greater than the battery charging (absorption) voltage, not the nominal battery voltage, for an MPPT charge controller to work properly. The real-world panel operating voltage is typically roughly 3V lower than the ideal panel voltage (Vmp).
All solar panels have two voltage ratings, which are calculated using standard test conditions (STC) at a cell temperature of 25 degrees Celsius. The first is the maximum power voltage (Vmp), which decreases significantly in foggy situations and even more so when the temperature of the solar panel rises. The second is the open-circuit voltage (Voc), which drops as temperature rises. In order for the MPPT to work properly, the panel operating voltage (Vmp) must always be several volts higher than the battery charge voltage in all conditions, including high temperatures – read the section below for additional information on voltage drop and temperature.
Because most (12V) solar panels operate in the 18V to 22V range, which is substantially higher than the normal 12V battery charge (absorption) voltage of 14.4V, panel voltage decrease due to high temperature is not a major issue with 12V batteries. Also, conventional 60-cell (24V) solar panels are not a problem because they operate at significantly higher voltages of 30V to 40V.
When two or more solar panels are linked in series with 24V batteries, there is no difficulty, but when only one solar panel is attached, there is a problem. While the Vmp of most conventional (24V) 60-cell solar panels is 32V to 36V, which is greater than the battery charging voltage of roughly 28V, the difficulty arises when the panel temperature rises and the panel voltage drops by up to 6V on a hot day. Because of the significant voltage drop, the solar voltage may fall below the battery charge voltage, preventing the battery from fully charging. When only one panel is being used, a bigger, higher voltage 72-cell or 96-cell panel can be used to get around this.
When charging 48V batteries, the system will require at least 2 panels in series, but 3 or more panels in series will work significantly better, depending on the charge controller’s maximum voltage. Because most 48V solar charge controllers have a maximum voltage (Voc) of 150V, you can connect up to three panels in series. The higher voltage 250V charge controllers can handle strings of 5 or more panels, making them significantly more efficient on bigger solar arrays because the number of strings in parallel is reduced, lowering the current.
Note: Because panels connected in series can produce dangerous voltage levels, they must be installed by a competent electrical professional and adhere to all local norms and laws.
Is it possible to connect solar panels to the inverter directly?
Although it is theoretically possible to connect an inverter directly to a solar panel, in most circumstances, the inverter’s limited input tolerances will prevent this.
Any solar panel’s generated voltage is not always the same as the panel’s rated voltage output. As a result, the output voltage of a 12-Volt solar panel might vary from less than 12-Volts to 18 or even 22-Volts.
Is a 48V inverter superior to a 12V inverter?
When determining whether to employ a 12, 24, or 48 volt system, it’s crucial to think about your individual energy needs. In short, if your energy needs exceed 3,000 watts, a 48 volt system is the way to go. Choose a 24 volt system if your energy needs are between 1,000 and 5,000 watts. Choose a 12 volt system if you want to build a smaller, DIY system for your RV, van, or compact home. Don’t be tricked into thinking that 48 volt is the greatest option simply because it has a higher rating. You must evaluate your individual demands, existing components, and the system as a whole, just as you do with everything else in a solar installation.
To charge a 48V 100ah battery, how many solar panels do I need?
To demonstrate how it works, I’ll use 400Wh/day as an example. The following estimate indicates how many 100 watt solar panels I’d need to recharge each battery:
This battery may be charged in less than a day, roughly 5 hours, with a single 100 watt solar panel.
To recharge this battery in less than a day, I’d need two 100-watt solar panels.
About 800 Wh/day is generated by 2 x 100 watts.
Because solar circuits always have losses, I’d recommend increasing the size of your solar panels by 30 to 50 percent. Every passing cloud will lower the energy produced, in addition to the power lost owing to inherent circuit losses.
To charge a 48V 200Ah battery, how many solar panels do I need?
Before we can answer this query, we need a little more information on the battery. Will the battery be totally depleted despite its 200Ah capacity?
This would be a unique situation.
I don’t recall ever completely depleting a battery. Although some lithium-based batteries can be discharged to zero, allowable discharge levels vary by battery type and design.
Because lead-acid batteries are the most prevalent high-power battery in use currently, I’ll base my response on that.
In general, assuming 4 peak-sun-hours per day, a 200Ah lead-acid deep-cycle battery would require a 300 watt solar panel to fully recharge from 50% depth of discharge (DOD). With a clear sky, charging might be completed in one day.
To charge a 48V battery, how many amps do I need?
As in most other areas, 48 volt charger technology has kept up with the technological revolution, and current battery charging philosophy employs three stage (or two or four stage) microprocessor regulated charging patterns.
These are “smart chargers,” and good ones are hard to come by in retail outlets.
Bulk, absorption, and float mode are the three stages or steps in lead acid battery charging (or sometimes complete shut off in some cases). Qualification, or equalization, is often seen as a separate stage, generally for commercial reasons. To maintain battery capacity and service life, follow the battery manufacturer’s recommendations for charging processes and voltages, or use a high-quality microprocessor-controlled charger.
A fixed charging voltage, high enough to “push” energy (amps) into the battery pack, would be found on an earlier 48 volt charger.
The easier this forcing process is, the lower the initial battery pack voltage (state of discharge), therefore you may see the amp meter (if provided) run up to the charger’s maximum output amperage and stay there for some time.
The tougher it is for the 48 volt charger to force the amps in when the battery pack voltage rises, as it happens as the state of charge climbs, therefore the amp rate lowers. The charger eventually reaches a point where its output voltage can no longer force any more current into the battery pack, and current almost stops. However, depending on where this voltage point is, it may be high enough to overcharge the batteries over time, or keep them in the gassing stage, drying out flooded batteries. For this reason, this sort of charger should be closely watched and disconnected when the amp meter reaches the lowest setting. Some older technology units contain timers, which, depending on the setting and battery charge status at the start of the charge cycle, might result in overcharging if set too long or undercharging if set too short. Both conditions can harm batteries, with overcharging inflicting more damage. Undercharging causes sulphation to build up on the plates and eventually harden, reducing battery capacity. The most common sign of sulphation is reduced run time on batteries that aren’t extremely old, such as in a golf cart that sits unmaintained for several months a year.
The “smart chargers” are designed with today’s charging philosophy in mind, and they also use data from the battery pack to deliver maximum charge benefit with minimal monitoring.
The microprocessor allows for a complete charge cycle without the use of a timer, and it does not undercharge or overcharge, instead completing in a long-term maintenance mode (float mode) or shutting down and monitoring the pack.
If utilized consistently, this enables for optimum battery management and maximum battery life.
True Gel batteries require a specific charge profile, which necessitates the use of a gelspecific, gel selected, or gel appropriate charger.
Gel batteries have a peak charging voltage of 2.3 to 2.36 volts per cell, which comes out to 55.2 to 56.6 volts for a 48 volt charger, which is less than a wet or AGM battery requires for a full charge.
In a real Gel battery, exceeding this voltage can generate bubbles in the electrolyte gel, which can cause lasting damage because the bubbles in the gel do not disperse when the over voltage condition is removed.
Three Stage Battery Charging
In a 48-volt charger, the BULK stage accounts for around 80% of the recharge, during which the charge current is held constant (in a constant current charger) while the voltage rises. A properly sized charger will provide the battery with as much power as it can handle up to chargercapacity (25 percent of battery capacity in amp hours), while not raising a wet battery beyond 125 degrees Fahrenheit or an AGM or GEL (valve regulated) battery above 100 degrees Fahrenheit. For AGM or some flooded batteries, the target voltage for a 48 volt charger is 2.4 to 2.45 volts per cell, or 57.6 to 58.8 volts.
The AGM/flooded 48 volt charger’s ABSORPTION stage (about the final 20%) involves the charger holding at the absorption voltage (between 57.6 VDC and 58.8 VDC, depending on charger set points) and gradually decreasing the current until the batterypack is fully charged.
The battery pack may have some permanent sulphation if it won’t keep a charge or the current doesn’t diminish beyond the specified recharge period.
The charge voltage is dropped to roughly 2.25 volts per cell (around 54.0 VDC) and held constant in the FLOAT stage, while the current is reduced to less than 1% of battery capacity.
This mode can be used indefinitely to keep a fully charged battery pack. Instead of maintaining a float voltage, some chargers turn off and monitor the batteries, commencing a charge cycle if necessary.
Divide the amp hours to be replaced by 90 percent of the charger’s rated output to get an estimate of how long it will take to recharge.
A 100 amp hour battery pack with a 10% discharge, for example, would require 10 amps to be replaced.
We got 10 amphours/(.9×5) amps = 2.22 hour recharge time estimate using a 5 amp 48 volt charger. A battery pack that has been deeply depleted deviates from this formula, taking more time to replace per amp.
Experts differ in their suggestions for how often you should recharge.
It appears that the depth of drain has a greater impact on battery life than the frequency with which it is recharged.
Lead acid batteries, even sealed varieties (AGM and Gel), prefer to be maintained fully charged as much as feasible.
Recharging when the equipment is not going to be utilized for a while (for example, during a mealbreak or whatever) can keep the average depth of discharge over 50% for a serviceday.
This primarily applies to battery applications in which the average depth of discharge each day is less than 50% and the battery may be fully recharged once per 24 hours, such as in an industrial application. This is referred to as “opportunity charging.”
Equalization is essentially a charge that may be managed. Although some charger manufacturers refer to the peak voltage reached by the charger at the end of BULK mode (absorptionvoltage) as an equalization voltage, it is not strictly correct. This approach can benefit higher capacity wet(flooded) batteries, especially those that are physically tall. If a wet battery is not cycled on a regular basis, the electrolyte might stratify over time. Equalization involves raising the voltage over the average peak charging voltage, far into the gassing stage, and holding it there for a set (but limited) time. This stirs up the chemistry throughout the battery, “equalizing” the electrolyte’s strength and removing any free sulphation on the plates.
The design of sealed batteries (AGM and Gel) virtually eliminates stratification, and almost all makers of these batteries advise against it (advising against it). Although certain manufacturers (particularly Concorde) provide a technique, it is vital to follow the voltage and time parameters to avoid battery damage.
Volt Charger Sizes
A 48 volt charger can be made from a low milliamp output (300, 500 milliamps) that plugs into a 115 volt power outlet and can deliver up to 20 amps. Some of the smaller components, like antique chargers, are unregulated and merely have a fixed voltage output. These take a long time to charge and should be avoided if at all feasible. Smaller amp capacities are suitable for smaller batteries, such as those used in electrical and security applications or for kid scooters with 1.3 to 12 amp hours. They can also be used to maintain larger batteries. A medium amp output 48 volt charger would be in the 10 amp range, and could be used for a variety of applications requiring 100 amp hours of battery or more, as well as applications requiring a consistent amp load (power supply application). To prevent the charger from returning to the boost or bulk stage in a power supply condition, the steady draw should be a small percentage of the charger’s maximum amp capacity. The larger components of the 48 volt charger versions have an output of roughly 18 to 20 amps (except commercial, 220 VAC input types, or 3 phase). These are utilized in battery banks with a lot of amp hours or in applications that need to recharge quickly. When a generator is employed as the AC power source, the larger units are sometimes used, and generator run time is a major factor.
The charger should be roughly 25% of the battery capacity (ah = amp hour capacity), according to most battery manufacturers.
A 100 ah 48 volt battery pack, for example, would require a 25 amp 48 volt charger (or less).
Larger chargers can shorten charging times, but they can also shorten battery life.
Smaller chargers are fine for long-term floating, such as a 2 or 4 amp “smart charger,” but they would be inefficient or burn up if used to bulk charge large capacity, deeply drained batteries.
Is it possible to utilize a solar panel and an inverter without a battery?
A hybrid solar inverter does not require batteries to operate. This system is connected to solar panels as well as the electrical grid, which provides power from both sources.
Solar panels create energy that is directed to the house for consumption, and they do not need to produce enough electricity to power a full family because power grid deficiencies may be made up.
The following are some of the benefits of installing solar electricity without a battery backup:
- Electricity bill savings
- Installing it is less expensive.
- Better for the environment
- There are fewer parts to maintain.
The fact that it will not give power during a blackout or power loss is a huge negative. Batteries are used in a battery backup arrangement because they allow electricity to be stored for later consumption.
The size of the battery banks varies, and both the solar panels and the power grid are used to charge them. The benefit is that the lights remain on even if there is a power loss.
It is, however, more expensive to install and maintain because there are more components.
If you reside in an area with a consistent and stable power supply, a solar power installation system without battery backup will save you money.
Choose Solar is your number one choice in Melbourne for purpose-built mounting equipment for the solar power industry, as well as high-quality solar batteries and inverters.