Fully specified solar PV 48v off-grid system with:

• 5kW solar array 20x Axitec Power AC-250P/156-60S 250W Polycrystalline solar panel
• SMA Sunny Boy 5000TL Inverter
• SMA Sunny Island 8.0H Off-Grid Inverter
• 1x 48v Battery Bank
• Additional switchgear

The centrepiece SMA Sunny Island off-grid inverter is a powerful, smart and functional device, designed to make operation easy. Ideal for locations where grid connection is unfeasible due to expense, location or logistical reasons, this system supplies uninterrupted AC power supply even in the most wild or isolated areas. Capable of delivering a continuous output of 6kW (or a peak output of 11kW); this system is well suited to powering a house or business with high power requirements. There is no generator included in this pricing.

This 'smart' system creates an AC mini-grid between the solar inverter, off-grid inverter, and the house. This means the house can use electricity from the array without it going through the off-grid inverter, theoretically allowing you to use the 6kW continuous output of the Sunny Island and 5kW from the panels if at maximum output.

Design
The difficulty with off-grid systems is that they can be complicated to design. In order to alleviate this challenge we've done all of the work for you. Not only have all the major components been specifically chosen for the compatibility with one another, but all of the more minor elements have been carefully selected according to their specifications.

Output
Before going any further, we urge you to read this section on planning your system and our full tutorial section in the top left.

Predicting solar array output depends on a few variables, please contact us with your location so that we can provide you with estimates.

Battery bank capacity depends on the amount of current you draw. The faster you discharge a battery bank, the lower the overall capacity for that cycle. If you use the SMA 8.0H inverter at its maximum continuous output (6000w), you will discharge the battery bank to 50% (not recommended to go lower) in 4 hours and receive 25.3kWh. Rapid discharge in this way is not recommended as it stresses lead-acid batteries. You should go easier on the bank. The total amount of power in this case would depend on your consumption profile. Below are some examples based on C (discharge) rates down to 50% Depth of Discharge (DoD).

If you draw 913 watts per hour, you will have 50 hours of power at this rate (C100) and your total power will be 45.7kWh.
If you draw 1595 watts per hour, you will have 25 hours of power at this rate (C50) and your total power will be 39.9kWh.
If you draw 3240 watts per hour, you will have 10 hours of power at this rate (C20) and your total power will be 32.4kWh.

Knowing how you will consume energy is an important calculation in sizing the system to your needs. It is unlikely that your consumption will be as straightforward as above. You will have surges and lows so it is never an exact science. Having an inverter with a 6000w continuous rating will allow you to run heavy appliances if necessary. The 11kW 3-second surge will allow you to start motors and tools.

Having discharged your battery bank completely, and if the sky is still overcast, a generator acts as a standby reserve of emergency power. The Sunny Island will start it automatically, and use it to recharge the battery bank to 100%. It is limited by the the amount of DC charge this unit can put out which is 115A. You will also have to perform an equalisation (maintenance) charge every few months to make sure you are fully recharging the cells and keeping them in line.

Lifetime
The most important part of an off-grid PV storage system is the battery bank. Treating it correctly will prevent you from needing to replace the most important component prematurely. Batteries have cycle ratings based on the typical depth of discharge. If you only consume 20% of the battery banks power before recharging it daily, your battery bank will last much longer than if you discharge it to 50% daily. You are most likely to go down to the 50% rating during overcast conditions (winter) so this is where you reduce the lifetime.

Rolls 5000 series batteries are amongst the best you can buy for this application, their 10 year warranty backs that up. At 20% DoD you will have 5000 cycles, at 50% you will have 3200 cycles.

Additional Components

This is a demonstration model only. Please call us on 0333 444 7655 for your bespoke system