Complete Solar Panel Installation Design Calculations with Solved Examples – Step by Step Procedure
Below is a DIY (do it yourself) complete note on Solar Panel design installation, calculation about No of solar panels, batteries rating / backup time, inverter/UPS rating, load and required power in Watts. with Circuit, wiring diagrams and solved examples. Anyone who follows the simple steps (DIY tutorial) below can install and connect solar panels in home for residential applications.
If you pick this article related to solar panel installation, You will be able to;
- To calculate the no of solar panel (with rating)
- To calculate the rating of Solar panel
- To calculate the rating of batteries for Solar panel system
- To calculate the back up time of batteries
- To calculate the required and charging current for batteries
- To calculate the charging time for batteries
- To calculate the rating of charge controller
- How much watt solar panel we need?
- Connect Solar Panel in Series or Parallel?
- How to select the proper solar panel for home
- UPS / Inverter Rating for load requirement and much more…
Solar Panel Installation: Step by Step Procedure with calculation and examples
Before we start, its recommended to read the article about proper selection different types of solar panels and photovoltaic panel for home commercial use as well. To the point, lets know how to wire and install a solar panel system according to the proper calculation and load requirements.
Suppose, we are going to install a solar power system in our home for a total load of 800W where the required backup time of battery is 3 hours (You may use it your own as it is just for sample calculation)
Load = 800 Watts
Required Backup time for batteries = 3 Hours
- Inverter / UPS Rating =?
- No of batteries for backup power =?
- Backup Hours of batteries =?
- Series or Parallel Connection of Batteries = ?
- Charging Current for Batteries = ?
- Charging Time for batteries = ?
- Required No of Solar Panel =?
- Series or Parallel Connection of Solar Panels = ?
- Rating of Charge Controller = ?
Inverter / UPS Rating:
Inverter / UPS rating should be greater than 25% of the total load (for the future load as well as taking losses in consideration)
800 x (25/100) = 200W
Our Load 25% Extra Power = 800200 = 1000 Watts
This is the rating of the UPS (Inverter) i.e. We need 1000W UPS / Inverter for solar panel installation according to our need (based on calculations)
Required No of Batteries
Now the required Back up Time of batteries in Hours = 3 Hours
Suppose we are going to install 100Ah, 12 V batteries,
Now for one Battery (i.e. the Backup time of one battery)
But our required Backup time is 3 Hours.
Therefore, 3/1.5 = 2 → i.e. we will have to connect two (2) batteries each of 100Ah, 12V.
Backup Hours of Batteries
If the number of batteries are given, and you want to know the Backup Time for these given batteries, then use this formula to calculate the backup hours of batteries.
1200 Wh x 2 Batteries = 2400 Wh
2400 Wh / 800 W = 3 hours.
In the first scenario, we will use 12V inverter system, therefore, we will have to connect two (2) batteries (each of 12V, 100 Ah) in Parallel. But a question raised below:
Why Batteries in Parallel, not in Series?
Because this is a 12V inverter System, so if we connect these batteries in series instead of parallel, then the rating of batteries become V1 V2 = 12V 12V = 24V while the current rating would be same i.e.100Ah.
Good to Know: In Series Circuits, Current is same in each wire or section while voltage is different i.e. Voltage are additive e.g. V1V2V3….Vn.
That’s why we will connect the batteries in parallel, because the Voltage of batteries (12 V) remains same, while its Ah (Ampere Hour) rating will be increased. i.e. the system would become = 12V and 100Ah 100Ah = 200Ah.
Good to Know: In parallel Connection, Voltage will be same in each wire or section, while current will be different i.e current is additive e.g. I1I2I3…In
We will now connect 2 batteries in parallel (each of 100Ah, 12V)
i.e. 2 12V, 100Ah batteries will be connected in Parallel
= 12V, 100Ah 100Ah = 12V, 200 Ah (Parallel)
Good to Know: Power in watts is additive in any configuration of resistive circuit: P Total= P1 P2 P3. Pn (Neglecting the 40% installation loss)
Charging Current for Batteries
Now the Required Charging Current for these two batteries.
(Charging current should be 1/10 of batteries Ah)
200Ah x (1/10) = 20A
Charging Time required for Battery
Here is the formula of Charging Time of a Lead acid battery. Charging Time of battery = Battery Ah / Charging Current T = Ah / A
For example, for a single 12V, 100Ah battery, The charging time would be:
T = Ah / A = 100Ah / 10A = 10 Hrs (Ideal Case)
due to some losses, (it has been noted that 40% of losses occurred during the battery charging), this way, we take 10-12 A charging current instead of 10 A, this way, the charging time required for a 12V, 100Ah battery would be:
100Ah x ( 40/100 ) = 40 (100Ah x 40% of losses)
the battery rating would be 100Ah 40 Ah = 140 Ah (100Ah losses)
Now the required charging current for the battery would be:
140Ah / 12A = 11.6 Hours.
Required No of Solar Panels (Series or Parallel) ?
Now the required No of Solar Panels we need for the above system as below.
Scenario 1: DC Load is Not Connected = Only Battery Charging
We know the famous power formula (DC)
P = VI ………… (Power = Voltage x Current)
Putting the values of batteries and charging current.
P = 240 Watts
these are the required wattage of solar panel (only for battery charging, and then battery will supply power to the load i.e. direct load is not connected to the solar panels)
240W/60W = 4 Nos of Solar panels
Therefore, we will connect 4 Solar Panels (each of 60W,12V,5A) in parallel.
The above calculations and system was only for battery charging (and then battery will supply power to the desired Load) to AC electrical appliances, which will get power through inverter and DC loads via Charge controller (via charged batteries)
Scenario 2: DC Load is Connected as well as Battery Charging
Now suppose there is a 10A directly connected load to the panels through inverter (or may be DC load via Charge Controller). During the sunshine, the solar panel provide 10A to the directly connected load 20A to the battery charging i.e. solar panels charge the battery as well as provide 10A to the the load as well.
In this case, the total required current (20 A for Batteries Charging and 10 A for directly connected load)
In this case above, total required current in Amperes,
20A 10 A = 30A
Now, I = 30 A, then required Power
P = V x I = 12V x 30A = 360 Watts
I.e. we need 360 W system for the above explained system (This is for both Direct Load and Batteries Charging)
Now, the number of solar panels we need
360/60W = 6 Nos of Solar Panels
Therefore, we will Connect 6 Nos of Solar panels in parallel (each of 60W, 12V,5A)
Rating of Charge Controller
As we have calculated above that the charging current for 200Ah battery is 20-22 Amperes (22A For Battery Charging10A for direct DC Load), therefore we can use a charge controller about 30-32 Amp.
Note: The above calculation is based on ideal case, so it is recommended to always choose a solar panel some bigger then we need, because, there are some losses occurs during battery charging via solar panel as well as the sunshine is not always in ideal mood.
How Much Watts Solar Panel We need ?
We have shown a very simple method in the previous post to find that How much Watts Solar Panel We need for our Home Electrical appliances? depends on the sunshine time and the load in watts we need to power up an electrical appliance.
Which One Solar Panel we Select ?
Among lots of brands and material of solar panels like c-Si, String Ribon, Thin Film Solar Cells (TFSC) or (TFPV), Amorphous silicon (a-Si or a-Si:H),Cadmium Telluride (CdTe) Solar Cells, Copper Indium Gallium Selenide (CIGS/ CIS) Solar Cells, BIPV: Building Integrated Photovoltaic Panels, Hybrid Solar Cells and PV Panels, We have discussed in a very details post “different types of solar panels with advantages/advantages, cost, and applications” This way, you will be able to find which is the best type of Solar Panel for Home Use?
kVA 10kw Solar PV System Household off Grid Solar System
Find Similar Items
Product Description
| Model | 1KW | 2KW | 3KW | 4KW | 5KW |
| 330W Solar Panels | 3 PCS | 6 PCS | 9 PCS | 12 PCS | 16 PCS |
| Inverter | 1 Set | 1 Set | 1 Set | 1 Set | 1 Set |
| MPPT controller | 1 Set | 1 Set | 1 Set | 1 Set | 1 Set |
| Battery | 2 PCS | 4 PCS | 4 PCS | 8 PCS | 8 PCS |
| PV/DC Cable | 100 Meters | 200 Meters | 300 Meters | 300 Meters | 400 Meters |
| PV Combiner Box | 1 Set | 1 Set | 1 Set | 1 Set | 1 Set |
| Connector | 5 PCS | 5 PCS | 10 PCS | 10 PCS | 10 PCS |
| Mounting Structure | Customized with roof or ground |
FactorySafe Package Solar Projects FAQ
Q: Why choose DAH s olar panel and solar system? 1. Complete set Configuration, with all parts, do not need extra materials. 2. Has engineer team 7x24hours online for pre-sale and after-sale service. 3. Easy for installation,user manual with pictures to teach installation from A to Z. 4. Professional proposal, uniform design, 100% tested before delivery, reliable quality. 5. Nice-designed package for safety transportation.
Q: What solar solutions can you provide? We can provide below solar system solution below: On grid Solar system: Feed electric appliance, extra power sell to grid Off grid Solar System: With battery bank storage power for night or rainy days Hybrid Solar System: Both off-grid and on-grid functions are available
Q: What is the lead time? Generally, it will take about 7-10 working days for production depending on the quantity and the product you needed is solar panel or complete set system.
Q: What is your monthly capacity? Solar Panel Monthly capacity is a round 11 0MW
Q: How long is the warranty of your products? 12 Years Limited PV Module(s) Warranty 25 years Limited Power Output Warranty
Q: Which payment term do you have? We support Credit card, Bank transfer, Western Union, LC and so on.
Company Introduction: Anhui Daheng Energy Technology Co., Ltd (DAH Solar for short) was established in 2009 with capacity 1.5GW per year.
We are a National High-Tech Enterprise, specialized in PV Modules development and manufacturing, PV power station R D, operation and maintenance.
Our products have been approved by international certification like TUV, IEC, CE, INMETRO, FIDE etc. And China domestic certification like CQC, Leader, ISO9001, ISO14001, OHSAS18001, etc.
DAH Solar has already rooted in domestic market, at the same time, we are actively exploring the international markets, and has established the sales network more than 100 countries from all over the world, such as Ukraine, Germany, Poland, Brazil, Mexico, etc.
DAH Solar continuously invests on the R D of the products and has already gained more than 60 patents at present. The Smart PV module and Cloud monitoring platform developed by DAH Solar goes at the forefront of solar industry. We are determined to be world-renowned Smart PV module and system provider.
We have the ability to provide customized design and support various solar systems, such as commercial and home off-grid solar systems, hybrid solar systems, grid-connected solar systems, solar lighting systems, etc. We have professional engineer team for system design, qualified sales team to offer you solution, thoughtful logistic department colleagues help you customers complete and received the orders safely.
DAH Solar provide solar system design services and technical consultation upon different requests. We have sales engineer always at your service 24/7. Looking forward to have chance working with you, trust you will love our quality and service.
kW DIY Solar Installation Kit w/SolarEdge Inverter
High-Capacity Option: 15kW DIY Kit with SolarEdge Inverter and Pv Optimizers
This kit is one of the highest-capacity options available for a solar power system. It produces 10,000 watts of DC (direct current) power and requires 575 square feet of space on roofs or grounds. With unobstructed south-facing views of the sun, you’ll have maximum energy outputs that exceed the average electric consumption in the United States.
Photovoltaic (PV) optimizers attach to the back of each panel and isolate individual outputs. If a panel is covered in shade, only that panel will be affected while the rest perform at their maximum levels.
What’s included
What’s Not Included
Wire, conduit, fittings, breakers, AC/DC Disconnects (if required), junction boxes and a sub panel (if required) can be purchased at any electrical supply shop, Home Depot or Lowes. Our technical support representative will provide a shopping list once your plans are complete.
Plans, interconnection and other services are available for an additional fee.
Will This Kit Work for Me?
If you’re looking to offset large loads with a cost-effective system that combines the benefits of microinverters and string inverters, then this option may be a fit for you.
To be certain if this is the right kit for you, contact us for a free estimate and custom recommendations, personalized for your home’s energy needs.
Why Choose GoGreenSolar DIY Kits?
If you’re comfortable with reading and working from plans, diagrams and instructions, our DIY kits can cut your installation costs by as much as 60%. And, yes, you will still receive tax credits.
Another option is hybrid DIY installation where you do some, but not all, of the installation. Purchase the kit and ask for professional help when and where needed. If you reside in one of our service areas, we will be happy to refer you to installers. We can also help you determine which DIY approach is best for you.
Choose DIY Solar Installation
Did you know? You can install a solar panel system with some help within a weekend or a few depending on your trade skills. Not up to DIY? Hire one of your trusted contractors to install for you.
GoGreenSolar solar panel kits include a complimentary roof layout, installation support and permit approval guarantees so you don’t have to figure it out all on your own.
If you’re handy with tools, love learning new skills, or enjoy managing and completing projects, DIY solar installation could be ideal for you. Many DIYers take satisfaction in the process and are proud of the results!
Save thousands of dollars
Going DIY can save you 10,000 or more, depending on system size. Tax credits still apply for equipment, hardware and any other installation services you utilize.
Have more control over your solar project
You get to make decisions on equipment selection, location of solar panels and timeline for your installation.
End-to-end support with a money-back guarantee
GoGreenSolar is with you every step of the way during your installation. We’re also the only DIY solar company with a money-back guarantee. If your permit isn’t approved even after following our instructions we’ll provide a full refund.
Some permit applications may require one or more plan revisions and resubmissions. Please supply us with all information necessary to make these revisions. Permit must be applied for with the city within 30 days of delivery of the permit package and any resubmissions must be resubmitted within 14 days of receiving the revised plans.
Our guarantee does not apply to installations on unsafe structures, unpermitted structures, ground mounts, structural engineering, structures not constructed to local building codes and other atypical building designs. This guarantee only applies to our standard solar system kits, it does not apply to custom orders or solar systems not designed by our engineers.
Interested in this solar panel kit for your home or business?
Contact us for a free estimate, and we’ll provide custom recommendations that are personalized for your energy needs.
- Solar made easy with complete solar kits
- Permitting and tech support designed for DIYers
- Step by step installation support
x.png?v=62085328141785377301674165465 alt=Go Green Solar logo width=200 height=77 /
Orange County, California
1630 South Sunkist Street Ste E Anaheim, California 92806 Copyright © 2006-2021 GigaWatt Inc, DBA GoGreenSolar.com
Blog
Reviews and information on the best Solar panels, inverters and batteries from SMA, Fronius, SunPower, SolaX, Q Cells, Trina, Jinko, Selectronic, Tesla Powerwall, ABB. Plus hybrid inverters, battery sizing, Lithium-ion and lead-acid batteries, off-grid and on-grid power systems.
September 10, 2022 Jason Svarc
Choosing the best off-grid solar system is not easy as off-grid systems are many times more complicated than common grid-connected solar systems. In this article, we highlight some of the many considerations which must be taken into account and discuss the various off-grid system types available. We also explain why a good quality inverter-charger is vital to building a reliable off-grid system. Finally, we will dive into the different brands available and determine which systems are best suited to different applications.
Many people believe off-grid solar systems can be easily put together. This may be true in the case of a small caravan or cabin, but in reality, larger off-grid systems used for homes and businesses need to be carefully designed by an experienced solar installer or system designer.
The 5 main parts of an off-grid system
Off-grid system types. AC or DC-coupled
Off-grid systems are built using either AC or DC-coupled power sources. AC-coupled generation sources include common solar inverters, wind turbines or backup generators (gen-sets), while DC-coupled sources include MPPT solar charge controllers or micro-hydro systems.
Whether a system is AC or DC-coupled is generally based on the size of the system. Most small-scale systems are DC-coupled and use efficient MPPT solar charge controllers. Larger off-grid systems can be either AC or DC-coupled depending on the type of off-grid inverter-charger used, and compatibility with different solar inverters (AC) or solar charge controllers (DC). Most modern inverter-chargers can be both AC and DC-coupled, which creates a very secure, flexible power system with multiple charging options and can enable black-start operation if the main inverter shuts down, the backup generator fails or the batteries are depleted.
Small DIY off-grid solar systems
Small-scale off-grid solar systems and DIY systems used on caravans, boats, small homes and cabins use MPPT solar charge controllers, also known as solar regulators, which are connected between the solar panel/s and battery. The job of the charge controller is to ensure the battery is charged correctly and more importantly, not overcharged. Most small 12V/24V solar charge controllers also have load output terminals which are often used for simple DC lighting circuits. In small DIY systems, simple ‘plug-in’ style inverters are used to provide 240V or 120V AC power. These are available in many different sizes, from tiny 150W inverters up to 3000W or higher.
Note: Small-scale, low-voltage systems can still cause damage or serious injury if not installed correctly. we recommend all systems are installed by a trained, licensed solar or electrical professional.
DC-coupled solar charge controllers have been around for decades and are available in two main types, PWM and MPPT. Learn more about solar charge controllers here, plus how to size small-scale off-grid solar systems correctly. powerful MPPT Solar charge controllers up to 100A are used on larger scale off-grid solar power systems. These are a very efficient and reliable way of charging and managing high-capacity lithium or lead-acid battery systems.
Key considerations when sizing off-grid solar systems
- Daily average energy consumption (kWh). Summer and winter
- Peak load (kW). The maximum power drawn from loads
- Average continuous load (kW)
- Solar exposure. Location, climate, orientation shading
- Backup power options. During poor weather or shutdown
With the above considerations in mind, the key component of an off-grid power system is the main battery inverter-charger often referred to as a multi-mode inverter as they can usually operate in both off-grid or on-grid modes.
Technical Guide
Recommended for solar professionals. See our Technical guide to selecting and sizing off-grid and energy storage systems.
A solar professional should be able to put together what is known as a load table to help determine which type and size inverter is best suited to your individual needs. A detailed load table is also required to size the solar array, battery and backup generator.
High-performance off-grid solar system using a Victron Quattro inverter/charger, Lithium battery system, DC-coupled with two MPPT solar charge controllers
Lead-acid batteries
Until around 3 or 4 years ago, lead-acid deep cycle battery systems were the most common and reliable option for off-grid systems. Lead-acid batteries are a proven technology and can last 15 or more years if they are not held at elevated temperatures (above 40 degC), and are not regularly discharged too low. Lead-acid batteries require precise battery charging following a specific charge cycle plus temperature sensors to adjust voltage settings. Most well-known off-grid inverter-chargers offer programmable charge voltage settings along with sensors to precisely charge under all conditions. Lead-acid deep cycle batteries are still used and offer several advantages over lithium as outlined below.
One of the most significant benefits of lead-acid batteries is unlike modern lithium batteries; the battery will not shut-down at a low voltage or low state of charge (SOC). This is important, especially in emergencies or when a backup generator fails. Lead-acid batteries can be discharged down to 0% state of charge if needed for backup, but it is not recommended as it can severely reduce the life of the battery.
Advantages
- Compatibility with most inverters.
- Proven and trusted technology.
- Safe, very low risk (sealed Gel/AGM).
- The battery will not cutout at low SOC or low voltage
- Long life (if not over discharged)
- Easily recycled
Disadvantages
- Low round-trip efficiency. 75% to 80%
- Low energy density. Very heavy
- Usable capacity limited. Max 40% DoD on a regular basis
- Not modular. Fixed size once installed
- Cannot sustain a partial state of charge for long periods
- High temperatures can drastically reduce battery life
Cutout voltage SOC based on inverter settings and rate of discharge.
Lithium-Ion
Over the last few years lithium-ion battery systems have become extremely popular due to their high round trip efficiency (92% to 98%), compact size, lightweight and scalability. In contrast, lead-acid battery banks have a fixed size or capacity whereas lithium systems do not suffer this limitation. This flexible sizing allows for additional capacity to be added at a later stage, which is a real bonus for both installers and customers alike.
Lithium batteries have a much higher energy density compared to lead-acid and are therefore lighter and more compact. A huge advantage of lithium is the ability to sustain a low state of charge (partial state of charge) for a prolonged amount of time without any negative effects such as sulfation which is a common problem with lead-acid batteries. Also, extremely high charge rates can be achieved using lithium with charging times up to 70% faster than lead-acid.
Also, see our complete solar battery review. A detailed comparison of the latest lithium batteries from the leading manufacturers.
Advantages
- Very high round trip efficiency. 92% to 98%
- Very high energy density. Compact and Lightweight
- High charge and discharge rates allowed
- No degradation issues with partial state of charge
- Modular and scalable systems (upgradable)
- Safe and low risk (if charged correctly), in particular LFP cells.
- Most lithium batteries come with a 10 year warranty
Disadvantages
- Can shutdown at high temperatures (45 degC)
- Can shutdown at low temperatures (below 5 degC)
- Can ‘trip off’ under continuous high surge loads.
- difficult to recycle at end of life.
- May not function without a compatible inverter (CANbus)
Off-grid Lithium Batteries
Managed lithium
The Pylontech US series and BYD LVL Premium series are popular managed lithium batteries used for grid-connected or off-grid systems as they are compatible with a wide range of hybrid and off-grid inverters including SMA and Selectronic, and Victron. See the full list of managed lithium battery options here.
Self-managed lithium
There are several self-managed lithium battery options available that also contain a BMS but do not require a communication connection (such as CANbus) with the inverter in order to operate. Most self-managed batteries are modular and able to be scaled to create very large capacity battery banks (up to 500kWh). Popular brands include Simpliphi, GenZ, Discover AES and Powerplus Energy. Much like managed batteries, the internal BMS is used to monitor the state of charge, temperature and cell voltages. Another advantage of this type of battery system is it can be easily retrofitted and used to replace existing lead-acid battery banks since they do not require any special communications or connections. In the event of a system shut down or system black due to a low state of charge or low voltage, most self-managed batteries will restart automatically and do not require manual activation or reset to restart operation.
best Lithium off-grid batteries
In my direct experience and based on feedback from many professional off-grid installers, self-managed lithium batteries are generally the most reliable choice for off-grid systems. Managed lithium batteries are also a very good reliable option but can be problematic as they rely on communications which can become unstable, especially at a low state of charge and low temperatures. Most self-managed lithium battery systems are compatible with almost all off-grid inverters; they are also very modular, do not require communication cables and can be expanded to create larger capacity energy storage systems that are better suited to off-grid systems. Additional capacity can also be added at a later stage if required. Self-managed lithium batteries can also be used as a ‘drop-in’ replacement for older lead-acid batteries and are compatible with most inverter-chargers and MPPT solar charge controllers.
The recommended self-managed lithium (Lithium Ferro Phosphate) batteries from the leading battery manufacturers include Simpliphi, GenZ, Discover AES, PowerPlus Energy and Zenaji Aeon.
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-proven and reliable technology that is compatible with virtually all off-grid inverters and solar charge controllers. Lead-acid battery banks can also be more reliable in some situations as the battery will not automatically shut down in extreme temperatures or when a low state of charge is reached. In addition, they can be easily recycled using existing infrastructure.
battery Inverter-chargers
Modern off-grid solar systems use battery inverters-chargers to manage batteries, solar, and backup power sources such as a generator. The inverter-charger is the heart and brain of an off-grid system. Its primary job is to supply pure sine wave AC power, and it must be able to meet the power requirements of the appliances under all conditions. Inverter-chargers sometimes referred to as multi-mode inverters, are the central energy management system and can be either AC-coupled with solar inverter/s or DC-coupled with solar charge controller/s.
When designing an off-grid power system, the battery inverter-charger must be adequately sized and selected according to the appliances it will be running. Some equipment such as water pumps, fridge compressors and air-conditioning units require very high surge (peak) power during startup, and this is where many cheaper inverters can fail. If multiple appliances are running at the same time, the inverter must also be able to supply continuous power under all conditions including higher temperatures. If high temperatures and high loads are common, the inverter must be sized correctly to account for temperature de-rating. Again this is where cheaper (transformerless) inverters can often trip, especially during high summer temperatures. Learn more in our technical guide to selecting an off-grid inverter.
Best off-grid inverter-chargers
Here is our list of the leading off-grid inverters on the market based on reliability, service, continuous and peak (surge) power rating, energy management software, AC source control, flexibility and remote monitoring.
These inverter-chargers are all available in a range of different power output ratings (kW) to suit different applications depending on the continuous and peak power requirements. In addition, the top 5 inverters can be AC or DC-coupled using compatible solar inverters or solar charge controllers.
Off-grid Inverter power comparison
Inverter-chargers are available in a wide range of sizes from 2.4kW up to 20kW and can be connected in parallel or three-phase configurations for even greater power requirements. Naturally, these powerful inverters are much more expensive than common grid-connected solar inverters or compact all-in-one hybrid inverters and can cost anywhere from 1400 to 7000 depending on the rated power output (48V inverters up to 10kW).
Most of these inverters can supply double or more of the continuous rating for a short amount of time to handle surge power spikes from motors, compressors, pumps etc. The surge rating is critical for off-grid systems to operate under all the various load conditions expected without tripping out or shutting down unexpectedly. This output power rating can also be reduced under higher ambient temperatures.
For more detailed information about selecting off-grid and hybrid inverters see our ‘Technical guide to sizing a hybrid inverters and off-grid power systems’.
Selectronic SP PRO
Best off-grid inverter. 5kW power ratings
The SP PRO inverter-chargers from Selectronic, based in Australia, feature the highest 30-minute power rating and highest peak/surge power rating along with a wide range of control methods including relays and digital inputs and outputs which can be configured for load management or generator control. However, it’s not just hardware that’s impressive, the SP PRO also features possibly the most advanced energy management software in the industry.
Premium quality comes at a premium price, and the SP PRO inverters are one of the most expensive options available; however, considering the high cost of off-grid systems, paying a little more is well worth it for the power and features needed for a reliable off-grid system. The impressive features and high performance, together with a leading 10-year warranty place the SP PRO at the top of our list.
See the full Selectronic SP PRO review here
SP PRO basic specifications
- Type: Multi-mode Inverter-charger (AC or DC coupled)
- Use: Solar storage, back-up (UPS), off-grid
- Sizes available (power output): 3.0kW, 4.5kW, 5.0kW, 7.5kW, 15kW, 20kW
- Pass through power: 15kW built-in (28kW external contactor)
- Compatible Battery types: Lead-acid, lithium-ion, flow, sodium-ion
- Battery System Voltages: 24V, 48V, 120V
- 63A pass-through power rating (15kW AC) or 125A (30kW)
- Very high surge power output (2.5 x rated continuous power)
- Battery temperature monitoring for longer battery life (lead-acid)
- Battery sense monitoring and a mid-string sensor for precise battery charging (lead-acid Gel and AGM)
- Managed AC-coupling with FIMER, Fronius, and Select-Sun solar inverters
- Very powerful software package with remote access and monitoring.
- Unique pre-charge feature for safer startup
- Compatible with many popular lithium battery systems
- Generator auto start, control and monitoring
- AC / DC coupling capability
- Parallel and 3-phase capability
- A separate solar inverter or solar charge controller is required
- Full off-grid capability when used with Selectronic certified (Scert) Fronius or FIMER solar inverters
- Additional generator contactor required if used with dual AC sources.
- Additional Select.live unit required for remote monitoring and setup.
Price bracket – From AU4500 (4.5kW)
See detailed specification datasheet. Selectronic SP PRO series
Victron MultiPlus
Best off-grid Inverter. 2kW to 5kW power rating
Victron Energy based in the Netherlands is a well known, international, high quality manufacture with a wide product range including battery chargers, sinewave inverters, inverters-chargers, DC/DC converters, transfer switches, battery monitors, charge controllers and more. Victron offer the most cost effective range of multi-mode inverters with a huge range of sizes including the new MultiPlus II inverters/chargers. For many applications the Victron is a great quality, lower cost option, especially for DC coupled systems. The Victron remote system options are extremely advanced and offer full remote access and control, as well as some powerful monitoring features. Victron products are also simple to setup and offer a huge range of different add-ons and configuration options.
See the full Victron Energy Review here
Basic specifications: (8 sizes available) plus other variations
- Type: Inverter-charger (DC or AC-coupled)
- Use: Solar storage, back-up (UPS), off-grid
- Solar Array Size (Solar input): N/A
- Sizes available (power output): 0.7kW, 1.3kW, 1.6kW, 2.4kW, 4.0kW, Update June 2021. New larger 8kVA and 10kVA now available.
- Pass through power: 3.6kW. 11.5kW. Also a 23kW (100A) model is available.
- Compatible Battery types: Lead-acid, lithium-ion, Redox Flow battery
- Battery System Voltage: 12V, 24V, 48V
- Economical Inverter-charger option
- Med-High surge power output
- High pass-through power capability
- Battery temperature monitoring for longer battery life
- Generator auto-start and monitoring available
- AC coupling with Fronius, SMA, SolarEdge, and some Delta solar inverters
- Dual AC outputs for non-essential loads (high-power units only)
- Programmable software with remote access and Wi-Fi App
- 3-phase capability parallel for higher power output
- A separate solar inverter or solar charge controller is required
- Victron size the inverters in kVA, not kW (ref datasheet)
- Full capability only when used with Victron regulators and colour control panel (CCGX) and Venus GX
- Larger capacity Quattro inverters are also available (up to 15kVA)
Price bracket – from AUD1600 (2.4kW)
See detailed specification datasheet. Victron Multiplus inverter specs
SMA Sunny Island
Best off-grid inverter for extreme environments
SMA Solar Technology is a leading German solar energy equipment supplier founded in 1981 and is one of the world’s largest manufacturers of solar inverters. The well regarded Suny island inverters are a proven performer in harsh outdoor environments in particular sub-zero temperatures.
See the full SMA inverter Review.
Basic specifications: (3 sizes available)
- Type: Inverter-charger (AC-coupled)
- Use: Solar storage, back-up (UPS), off-grid
- Solar Array Size (Solar input): n/a
- Sizes available (power output): 3.3kW, 4.6kW, 6.0kW
- Pass through power: 11.5kW
- Compatible Battery types: Lead-acid, lithium-ion (refer to manufacturer)
- Battery System Voltage: 48V
- High pass through power capability
- High surge power output
- Battery temperature monitoring for longer battery life
- Powerful software package with remote monitoring
- Generator auto start and monitoring (optional)
- Dual AC inputs (grid and generator)
- Very good IP54 weather rating
- AC / DC coupling capability
- 3-phase capability parallel for higher output
- Separate solar inverter or solar DC regulator required
- Full capability when used with SMA or compatible solar inverters
- External automatic transfer switch required to enable battery backup
- When configured as a hybrid inverter, grid isolation (backup mode) is not instantaneous. 2-3 sec delay.
Price bracket – From 3800
See detailed specification datasheet. SMA Sunny Island specs
Outback Power FXR VFXR
Best small capacity off-grid inverter. Split phase, North America
Founded back in 2001 by three power systems design engineers, Outback Power has grown to become one of the leading manufacturers of off-grid power systems in North America. The company produces an advanced range of inverter/chargers designed for off-grid residential and commercial installations, along with the highly regarded Flexmax range of MPPT solar charge controllers. In addition to the popular FXR vented VFXR series designed for off-grid use, the Radian series of bi-directional inverter/chargers were developed for advanced hybrid (grid-connected) energy storage systems.
Basic specifications: (5 sizes available) plus other variations
- Type: Inverter-charger (DC-coupled)
- Use: Solar storage, back-up (UPS), off-grid
- Solar Array Size (Solar input): N/A
- FXR sizes available (power output): 2.0kVA, 2.5kVA, 3.0kVA
- VFXR sizes available (power output): 2.8kVA, 3.5kVA, 3.6kVA (Modular configuration. parallel for greater power requirements).
- Compatible Battery types: Lead-acid or lithium-ion
- Battery System Voltage: 12V, 24V, 48V
- Available in six models for 120VAC or 230VAC
- Med-High surge power output
- Pass through power capability
- Battery temperature monitoring for longer battery life
- Generator auto-start and monitoring available
- Programmable software with remote access.
- 3-phase capability parallel for higher power output
- Separate solar DC regulator required
- Inverters sized in kVA, not kW (ref datasheet)
- Full capability only when used with Mate3 control
- Larger capacity is available with parallel configuration, up to 10 inverters.
- AC coupling is only available with Radian series inverters.
Price bracket – from US1800 (2.0kW)
See detailed specification datasheet. Outback FXR VFXR inverter specs
Sol-Ark 12K 15K
Best All-in-one Off-grid Inverter. Split phase, North America
Sol-Ark is a relatively new US-based company that distributes an all-in-one hybrid/off-grid inverter manufactured by Deye inverter Technology Co. The inverter is available in two varieties, a 12K and 15K model and has been customised to suit the US market with many features, including dual MPPT’s, ground-fault, arc-fault and lightning protection built-in, integrated load centre with DC and AC isolators, and remote access, including monitoring. While feature-packed, it does have some compromises; the Sol-Ark inverter is transformerless, meaning it has a limited surge power rating and will struggle to power large inductive loads such as pumps and compressors. Note the real-world loads (a combination of inductive and basic resistive or heating loads) are about 20% lower than the specifications listed. Additionally, each 120V leg is limited to 4.8kW (12K model), so the loads must be managed accordingly.
Basic specifications:
- Type: Hybrid Inverter-charger. All-in-one unit
- Use: Solar storage, backup (UPS), Off-grid
- Max Solar Array Size (Solar input): 13kW (12K), 19kW (15K)
- Power rating 12K (continuous output): 7.5kW real-world loads
- Power rating 15K (continuous output): 9.5kW real-world loads (Modular configuration. parallel for greater power requirements).
- Compatible Battery types: Lead-acid or lithium-ion
- Battery System Voltage: 48V
- Split phase. 120VAC or 240VAC
- 200A pass-through power rating (15k)
- Parallel capability for higher power requirements.
- Inbuilt Ground-fault and Arc fault detection (GFD)
- Inbuilt lightning protection (PV)
- Integrated battery DC isolator and AC source/load isolator
- Generator auto-start and monitoring built-in
- Programmable software with remote access.
- Colour touch-screen display
- Transformerless Inverter with limited surge power rating
- The real-world loads are approx 20% lower than the specifications listed.
- Higher power output available with parallel configuration
Price bracket – 12K from US6800, 15K from 8200
See detailed datasheets. Sol-Ark 12K specs, Sol-Ark 15K specs
Disclaimer: Solar and battery storage systems must be installed by an experienced licensed electrical professional. Modern large scale off-grid solar systems are typically high voltage and can generate and store huge amounts of energy which can result in damage, fire or serious injury if the installation does not meet all relevant regulations, standards and guidelines.
About the Author. Jason Svarc is a CEC accredited off-grid stand-alone power system specialist who has been designing and installing off-grid solar power systems for 10 years. During this time he also taught the CEC accreditation off-grid design and installation course at Swinburne University (Tafe). Having designed, installed, commissioned and monitored hundreds of off-grid systems for households and businesses over the years, he has gained vast experience and knowledge of what is required to build a quality, reliable, high-performance off-grid solar power system.
Solar questions?
Visit our community discussion about off-grid systems in our solar info forum.
UNDERSTANDING ON-GRID, OFF-GRID AND HYBRID GRID TIED UPS
On-grid or grid-tie solar UPS are by far the most common and widely used by for homes and commercial purpose. These UPS do not require batteries and use solar inverters and are connected to the electricity grid. Whatever excess solar power is generated is exported to the electricity grid and owner get paid a feed-in-tariff (FiT) or credits for the energy you export.
But there is a challenge, On-grid solar UPS or Grid Tied UPS are unable to work or generate electricity during a blackout due to safety reasons. Since blackouts usually occur when the power grid malfunctions; If the solar UPS was still feeding electricity into a damaged grid it would risk the safety of the people repairing the fault/s in the network. It also stops working during voltage fluctuation. In both the cases there will be wastage of Solar Energy.
Off-grid UPS
Off-grid UPS are not connected to the power grid that is why they require batteries for power storage. Off-grid solar systems must be designed such a way that they generate enough power throughout the year and have enough battery capacity to meet the home’s requirements, even in winters and monsoon when there is less sunlight.
High cost of batteries and off-grid UPS means off-grid systems are much more expensive compared to on-grid systems and so are usually only needed in places which are in remote areas and are far from power grid like vacation homes, resorts, farm houses etc.
What is Hybrid Grid-Tie Solar System?
A hybrid solar system has best of both On grid and off grid. It combine solar and battery storage in one and are now available in many different sizes and configurations.
Due to the decreasing cost of battery storage, systems that are already connected to the power grid can start taking advantage of battery storage as well. This means storing solar energy which is generated during the day and it at night.
When the stored energy is less, the grid is there as a back-up, allowing consumers to have the best of both worlds. Hybrid Solar System allow full control over your power, while keeping you
grid-connected in case of emergency. Hybrid Solar System generate power similar to a normal grid-tie solar system but use special hybrid inverters and batteries to store power for later use.
This quality to store energy enables most hybrid systems to also operate as a backup power supply during a power outage like UPS.
If there is a power failure or the grid becomes unstable the unit will automatically switch over to battery supply immediately and continue to operate independently from the electricity grid.
Why to store solar energy in a battery?
Many governments and network operators have reduced the solar feed-in tariff or FiT. This means traditional grid tied systems have become less attractive as most people are working during the day and not at home to use the solar energy as it is generated, thus the energy is fed into the grid for very little return.
A solar hybrid system stores your excess solar energy and can also provide back-up power during a power outage. This is perfect for domestic use, farm houses, resorts, vacation homes etc. Hybrid GTI systems enable you to store solar energy and use it when you face an electricity cut. The ability to store and use your solar energy when desired is referred to as self-use or selfconsumption. It works in the same way as an off-grid power system but the battery capacity required is far less, usually just enough to cover peak consumption (8 hours or less) as opposed to 3-5 days with a typical off-grid system.
Flexibility
A common misbelief about solar is that if you install a Grid Tied UPS, you’ll always have power during outages. In most cases, this is not true. Traditional GTI systems automatically shut off during power failure for safety purposes, cutting off power generation from your solar panel system. If you want to keep your home or commercial establishment running on backup solar power during a grid failure, hybrid GTI UPS paired with batteries are perfect solution. Some hybrid UPS have both on-grid and off-grid capabilities, allowing you to continue running on solar power even if the grid fail.
Easier installation process
One of the biggest benefits of a hybrid inverter is that it combines the functionality of two separate pieces of equipment into one. This mean an easier installation process for your solar installer. Depending on the of the individual components and the labor cost, you may save money by installing a hybrid UPS from the get-go as opposed to paying for both a solar UPS and a battery-specific UPS separately.
Easy Monitoring
With a hybrid UPS, all of your solar electricity–whether being sent to the grid, self-consumed on your property, or being stored in your battery–is converted through one component. This allows for “centralized monitoring,” which means you can monitor both your solar panel system and battery performance through one platform.
Latest Technology
While Off Grid is an obsolete technology, Hybrid Grid Tie is latest, cost effective and more useful.
Future-ready
(Add- on is possible)
A hybrid system is possibly the most expandable, future-ready home solar setup. With some customisable hybrid systems, you can expand capacity by buying more panels or batteries. Hybrid systems may also be compatible with newer solar technologies — for example, an electric vehicle (EV) might function as one of the ‘batteries’ in a hybrid setup.