How to build a small off-grid system and select the right components? This is a very common question we get from our customers.
Do you have a small cottage or weekend caravan? Are you somewhere without a connection to the grid?
To have electricity nowadays is an indispensable need – a small fridge, laptop, LED light, phone charger, etc...

A small off-grid system is built from the battery, solar panel, MPPT regulator and DC/AC inverter.

BATTERY

The main component is the battery. The standard voltage for the small off-grid system is 12 V. The capacity of the battery depends on the daily consumption of connected equipment. 

Fridge                         – 0.46kW / 24h
LED light                     – 0.10kW / 24h
NTB + phone charger   – 0.15kW / 24h
Summary                   – 0.71kW / 24h

If your daily consumption is 710W, we should add 20% of capacity for reserve and to secure the longest possible live cycle and stability of the battery (by a lower DoD). It is, in this situation, 0.84kW.
The battery with the nearest higher capacity that we offer is a 12V 90Ah battery with the real capacity of 1.08 kW.
https://www.ev-power.eu/LiFeYPO4-batteries-12V-1-1/Lithium-Battery-12V-90Ah-WB-LP12V90AH.html
With this battery, you will have some reserve for your consumption.


SOLAR PANEL

In this model situation, we do not assume it will be working all year long. Usually, the cottage or caravan is used from March to September.

Our goal is to have a solar panel which can produce your daily consumption. During this months the 300Wp solar panel can produce at least 900 W for a day. 

https://www.ev-power.eu/Solar-Systems/Solar-panels-PV-module/Solar-panel-GWL-Sunny-Mono-300Wp-60-cells-MPPT-32V-Full-black.html
If you will use two smaller panels, for example, 2 x 165 Wp, you can connect the panels serial or parallel. You decide according to your conditions and parameters of MPPT regulator.

MPPT regulator

Choose the MPPT regulator according to the parameters: by the maximal input from solar panels and what power it can handle.

We choose MPPT 12/24V, 20A, Input 100V with max PV array power 390 W.
https://www.ev-power.eu/mppt-pwm/MPPT-Solar-Charger-12-24-V-20A-Input-100V-LCD-UI-XTRA2210N.html#tab3


DC/AC inverter

Choosing the right inverter depends on the consumption and power of your electrical devices.
On the market, there are many different inverters. Not all of them can work with their nominal power. According to this fact, it is better to choose a little bit more expensive inverter on which you can certainly rely on. For the right choice, you will also have to know which devices will be switched ON all the time and which we can switch OFF. Or if all the devices will be switched ON at the same time. One of the most used inverters is 12/230V 800VA.

https://www.ev-power.eu/Victron-Energy/Inverters-DC-AC/Victron-Invertor-DC-AC-12V-230V-800W.html

This is the basic off-grid system dimensioned for a low price. If you need a system suitable for long-lasting severe weather, or somewhere where the battery could not be charged, we recommend to double up this system to 12V 200Ah and 2x 300Wp solar panel. 

If you want to get help with choosing the right component, contact us on email: tech@gwl.eu
You can find more information on our blog: https://www.ev-power.eu/blog/