OFF GRID SOLAR SYSTEM

Choosing the very best off-grid Solar system is challenging as off grid solar systems are sometimes more complicated than common grid-connected solar systems. In this post, we highlight some of the many factors to consider which need to be taken into account and go over the various off-grid system types available. We also explain why a good quality 'inverter/charger' is vital to developing a trustworthy off-grid system. Finally, we will dive into the various brand names available and figure out which systems are best matched to different applications.

Many people believe off-grid Solar systems can be easily put together. This might hold true when it comes to a small caravan or cabin, however in reality, bigger off-grid systems used for houses and businesses need to be carefully developed by a knowledgeable solar installer or system designer.

Solar and battery storage systems need to be installed by a skilled licensed electrical expert. Modern big scale off-grid planetary systems are typically high voltage and can produce and keep substantial amounts of energy which can result in damage, fire or major injury if the installation does not satisfy all relevant regulations, standards and guidelines.

The 5 Main Components Of An Off Grid System

Battery Inverter/charger or Multi-mode Inverter

Solar inverter (AC) or Solar charge controllers (DC).

Battery bank.

Solar panels.

Generator (Optional).

Off grid Solar system types - Air Conditioner or DC coupled.

Off-grid systems are constructed utilizing either A/C or DC paired power sources. Air Conditioner combined generation sources include common solar inverters, wind turbines or backup generators (gen-sets), while DC coupled sources consist of MPPT solar charge controllers or micro-hydro systems.

Whether a system is A/C or DC paired is normally based on the size of the system. A lot of small-scale systems less than 5kW are DC combined and use solar charge controllers. Larger off-grid systems can be either AC or DC paired depending upon the type of inverter/charger (multi-mode inverter) utilized, and the compatibility with various solar inverters (A/C) or solar charge controllers (DC). Most modern multi-mode inverters can be both Air Conditioning and DC combined, which develops a very protected, flexible system with multiple charging choices.

Little Off Grid Solar Systems.

Most small-scale off-grid Solar systems used on caravans, boats, small houses and cabins use solar charge controllers, likewise called solar regulators, which are connected in between the solar panel/s and battery. The job of the charge controller is to ensure the battery is charged properly and more significantly, not overcharged. Many solar charge controllers likewise have load output terminals which are typically utilized for simple DC lighting circuits. In small systems, simple battery inverters are utilized to offer Air Conditioning power, and are readily available in various sizes, from tiny 150W inverters up to 3000W and even greater.

DC-coupled solar charge controllers have been around for decades and are offered in 2 main types, PWM and MPPT. Read more about solar charge controllers here, plus how to size little scale off-grid solar systems correctly. More powerful MPPT Solar charge controllers as much as 100A are used on bigger scale off-grid solar power systems. These are a really effective and reputable method of charging and managing high capability lithium or lead-acid battery systems.

Secret factors to consider when sizing off-grid solar systems.

Daily average energy usage (kWh) - Summer season and winter.

Peak load (kW) - Maximum power drawn from appliances.

Average constant load (kW).

Solar direct exposure - Location, climate, orientation & shading.

Backup power alternatives - During poor weather condition or shutdown.

With the above considerations in mind the key element of an off-grid power system is the primary battery inverter/charger typically referred to as a multi-mode inverter as they can normally operate in both off-grid or on-grid modes.

Battery Inverter/chargers.

In Air Conditioner paired off grid systems, the battery inverter/charger is the heart and brains of the system. Its main task is to provide 'pure sine wave' Air Conditioning power, and it should have the ability to meet the power requirements of the home appliances under all conditions. In addition, the inverter/charger controls the battery charging and monitors energy flow from all other sources such as solar, wind, hydro or backup generators. Below is more information about picking the very best inverter battery chargers.

The battery inverter/charger ought to be adequately sized and designed to power appliances such as water pumps, refrigerator compressors and air-conditioning systems which require extremely high surge (peak) power during startup. This is where lots of less expensive inverters can fail. If multiple appliances are performing at the very same time then the inverter must likewise be able to supply continuous power under all conditions including higher temperature levels, so should be sized correctly to represent temperature de-rating. Again this is where more affordable (transformerless) inverters can often journey, especially throughout high summer temperatures.

Technical Guide.

Suggested for solar Professionals - See our Technical guide to picking and sizing off-grid and energy storage systems.

Off Grid Battery Options.

Lead-Acid.

Till just recently, conventional lead-acid deep cycle battery systems were the most typical and trusted alternative for off-grid systems. Lead-acid batteries are a proven technology and can last as much as 15 or more years if they are not held at raised temperatures (above 40 degC), and are sporadically discharged too low. Lead-acid batteries require exact battery charging following a particular charge cycle plus temperature sensors to adjust voltage settings. Most well recognized off-grid inverter/chargers provide programmable charge voltage settings along with sensing units to exactly charge under all conditions. Lead-acid deep cycle batteries are still commonly utilized and use several advantages over lithium.

One of the most considerable benefits of lead-acid batteries differs from contemporary lithium batteries; the battery will not shut-down at a low voltage or low state of charge (SOC). This is important, specifically in emergency situations or when a backup generator stops working. Lead-acid batteries can be discharged down to 0% state of charge if required for backup, however it is not recommended as it can significantly minimize the life of the battery.

Benefits.

Compatibility with many inverters.

Proven and trusted technology.

Safe, extremely low danger (sealed Gel/AGM).

Battery will not cutout at low SOC or low voltage **.

Long life (if not over released).

Quickly recycled.

Disadvantages.

Lower performance - around 80%.

Low energy density - Very heavy.

Functional capacity minimal - Max 40% DoD on routine basis.

Not modular - Fixed size as soon as set up.

Can not sustain partial state of charge for extended periods.

Heats can considerably lower battery life.

** Cutout voltage & SOC based on inverter settings and rate of discharge.

Lithium-Ion.

More just recently lithium-ion battery systems have become exceptionally popular due to the high effectiveness (92% to 98%), compact size, light-weight and scalability. In contrast, lead-acid battery banks have a fixed size or capability whereas lithium systems do not suffer this restriction. This versatile sizing permits additional capacity to be included at a later phase, which is a genuine perk for both installers and clients alike.

Lithium batteries have a much greater energy density compared to lead-acid and are for that reason lighter and more compact. A huge benefit of lithium is the capability to sustain a low state of charge (partial state of charge) for an extended amount of time with no negative impacts such as sulfation which is a typical issue with lead-acid batteries. Likewise, very high charge rates can be attained using lithium with charging times as much as 70% faster than lead-acid.

Also see our total solar battery evaluation - In-depth contrast of the leading lithium and lead-acid batteries from the leading makers.

Advantages.

Extremely high performance - Approx 97%.

Extremely high energy density - Light weight and compact.

High charge and discharge rates allowed.

No degradation with partial state of charge.

Modular and scalable systems.

Safe and low risk (if charged correctly).

10 year warranty.

Downsides.

Can shutdown at heats (45+ degC).

Can shutdown at low temperature levels (listed below 5 degC).

Can 'journey off' under continuous high rise loads.

Can be tough to recycle at end of life.

Might not function without a compatible inverter.

Finest Battery For Off-Grid Systems.

Handled lithium.

Many lithium battery systems consist of a BMS which needs a devoted communication link to the inverter in order to run. If the inverter isn't compatible with the battery then they can not operate together and will not work. Among the biggest issues with this kind of system is that if communication is lost or suffers disturbance then frequently the inverter or battery will shutdown to make sure the battery is not over charged or discharged. For instance, the BYD B-Box Pro battery has been reported to shutdown when exposed to low temperatures below 5 degC.

The BYD B-Box Pro battery is a popular handled lithium battery utilized for grid-connected systems as they are compatible with a large variety of hybrid and off-grid inverters including SMA and Selectronic, and Victron. Nevertheless, some efficiency and functional issues have actually been noted with the BYD batteries, particularly in low temperature level areas. LG chem RESU 48V batteries are popular, however only for 'little' off-grid systems due to the restricted constant discharge rate of 5kW. For larger off-grid systems the LG chem rack mount battery system is a better bigger capability option.

Finest Battery For Off-Grid Solar.

In my direct experience and based upon feedback from numerous expert off-grid installers, self-managed lithium batteries are the best and most reputable option for off-grid systems. Managed lithium batteries can be troublesome as they rely on communications which can journey off or end up being unsteady, especially at low state of charge and low temperatures. The majority of self-managed lithium battery systems are usually high quality and do not struggle with communication concerns. They are likewise modular, versatile and can be broadened to create larger capacity energy storage systems which are much better matched for off-grid systems. Additional capability can likewise be included at a later phase if needed.

Lead-acid Batteries.

In specific applications high performance lead-acid batteries are still an excellent choice for off-grid systems. Lead-acid is a well shown and dependable technology which is compatible with essentially all off-grid inverters and solar charge controllers. Lead-acid systems can likewise be more dependable in some scenarios as the battery will not immediately shutdown in severe temperature levels. In addition, they can be quickly recycled using existing recycling facilities.

The Heart Of An Off Grid System - The Battery Inverter/Charger.

Modern off-grid planetary systems use multi-mode inverters/chargers to handle batteries, solar, and back-up power sources such as a generator. The inverter/charger is the main energy management system and can be either AC paired with solar inverter/s, or DC combined with solar charge controller/s, or both. Learn more about Air Conditioner and DC paired systems here.

Early off-grid systems used basic battery inverters and were extremely basic in contrast as the battery charger was a separate unit. These basic inverters generally had low power ranking listed below 2kW and thus were only efficient in powering low energy home appliances like lights, fans and little pumps.

Lots of modern-day multi-mode inverter/chargers are very powerful (as much as 20kW) and are created to run high intake appliances like air-conditioners, big pumps, electric ovens and warm water systems, which require high constant power or high startup 'surge' present. Naturally these effective inverter/chargers are much more expensive than common grid-connected solar or little capability hybrid energy storage systems and can cost anywhere from $1500 to $6000 * depending on the ranked power output. (* 48V inverter/chargers approximately 8kW).

Finest off grid inverters - Multi-mode Inverters.

Here is our list of the leading off-grid inverters on the market based upon dependability, service, constant and peak (surge) power score, energy management software application, AC source control, versatility and monitoring.

Selectronic - SP PRO series (Australia).

Victron Energy - Multiplus or Quattro (Netherlands).

SMA - Sunny Island series (Germany).

Wilderness Power - Radian or FXR series (USA).

Schneider Electric - Conext SW or XW+ (Italy).

These inverters are all offered in a variety of various power output rankings (kW) to suit various applications depending upon the continuous and peak power requirements. In addition these leading 5 inverter/chargers can be both Air Conditioner or DC coupled using suitable solar inverters or solar charge controllers.

See futher information in the off-grid/hybrid multi-mode inverter review.

Off grid Inverter power comparison.

There are numerous inverters readily available with different output scores from as low as 2.4 kW approximately large 20kW continuous output. The majority of these inverters can provide double or more of the constant rating for a short amount of time to deal with rise power spikes from motors, compressors, pumps and so on. This rise rating is vital for off-grid systems to operate under all the different load conditions anticipated without tripping out or closing down all of a sudden. This output power score can likewise be reduced under greater ambient temperatures.