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Configuration, Set-up & Installation of Home Solar Energy Storage System

2024-06-06

What is a Home Solar Battery Energy Storage System (BESS)?

BESS home solar energy storage system installation and set-up

The Home Solar energy storage system, also known as a household solar energy storage system, is an important component of distributed energy resources (DER). Distributed energy supply can achieve cost savings in transmission and distribution, improve energy quality, and enhance energy efficiency. For households, it can reduce electricity costs by increasing self-consumption ratio, participating in ancillary services, and serving as an emergency backup power source in the event of major disasters or other factors causing power outages, thereby improving the reliability of household power supply. For the grid, the rapid increase in the proportion of variable renewable energy (VRE) will further widen the gap between the generation curve and the consumption curve. Energy storage can shift electricity in time to assist the grid in balancing generation capacity and demand.

The home solar energy storage system is similar to a mini energy storage station, and its operation is not affected by urban power supply pressure. During off-peak electricity consumption times, the battery in the household energy storage system can be charged for use during peak electricity demand or power outages. In addition to serving as an emergency power source, the household energy storage system can also balance the electricity load, thereby saving household electricity expenses. Household energy storage systems are becoming increasingly popular among residential users, and depending on whether the user is connected to the grid, household energy storage systems can be categorized as on-grid, off-grid, or hybrid. Here, we will briefly introduce the off-grid household energy storage system.

Components of a Home Solar Battery Energy Storage System

The household energy storage system mainly consists of Solar Panels, batteries, battery management systems, charge controllers, inverters, and energy management systems. The battery is the core of the energy storage system, capable of storing and releasing energy. The battery management system monitors the status and operation of the battery. The charge controller converts AC power to DC power for battery charging. The inverter converts DC power to AC power for household use. The energy management system manages and controls the entire system.

Solar panels
Battery pack
Battery Management System (BMS)

Solar Inverter

plan and configure a household solar energy storage system

Types of household Solar Systems

Off-grid solar power system

The household energy storage system mainly consists of solar panels, batteries, battery management systems, charge controllers, inverters, and energy management systems. The battery is the core of the energy storage system, capable of storing and releasing energy. The battery management system monitors the status and operation of the battery. The charge controller converts AC power to DC power for battery charging. The inverter converts DC power to AC power for household use. The energy management system manages and controls the entire system.

Note:

Both off-grid and on-grid photovoltaic systems can allow the city grid to supply power to the household, but only on-grid systems allow the household’s solar power to be input to the city grid (for profit). Therefore, on-grid systems require intelligent bidirectional metering.

On-Grid solar power system

Strictly speaking, an on-grid solar system is not a type of household energy storage system. This is because the electricity generated by the photovoltaic power generation system on the roof or in the courtyard is supplied synchronously to the city grid, and the household does not need battery storage. With a battery-less on-grid system, almost all of the household’s electricity consumption relies on the city grid. Of course, the household’s daytime electricity consumption can consume a portion of the solar power generation, which is then subtracted from the consumption and supplied to the city grid. However, the household’s peak electricity consumption period is often at night, while solar power generation mainly occurs during the day. Therefore, households with on-grid power generation systems primarily consider selling the generated electricity to the city grid for profit, which is a part of the household income and can be considered as compensation for paying electricity bills when consuming electricity at home.

Off-grid and on-grid energy storage system

By adding a battery module to a battery-less on-grid system, it becomes an off-grid and on-grid energy system. This type of photovoltaic system has very intelligent and flexible modes to adapt to different situations. For example, if a household has a very large area of photovoltaic panels, the solar power generated daily can not only cover all household electricity consumption but also have surplus electricity to sell to the city grid. When the household is away on vacation and electricity consumption is almost stopped, the household’s solar power will not be wasted and can continue to supply the city grid.

These are the three types of household solar energy systems. After understanding these concepts, are you considering planning and configuring a solar energy system for your home? If so, the following factors are what you should consider.

How to plan and configure a household solar energy storage system

Understand the household’s electricity consumption

If you have a household electricity bill, you can directly use the higher monthly electricity consumption as a reference.

Alternatively, you can manually calculate the load power and high-frequency activity time of household lighting and appliances, record the daily operating time of each, and summarize the daily electricity consumption of the household in kWh.

For example

The following is a specific electricity consumption record for a household. Your situation may be different, but you can use this template:

Home Appliance	Max Operating Power	Daily Operating Hours	Daily Power Consumption
Hair dryer	1.5kw	0.5h	0.75kwh
Washing machine	2kw	0.5h	1kwh
Refrigerator	0.1kw	8h( work with intervals)	0.8kwh
Air conditioner	1kw	4h(work with intervals)	4kwh
Micro oven	1kw	0.3h	0.3kwh
TV	0.2kw	4h	0.8kwh
Computer	0.1kw	5h	0.5kwh
Lights	0.1kw	12h	1.2kwh

The daily electricity consumption for this household is 9.35 kWh,

and the total power when all appliances are working simultaneously is 4 kW.

Using this household as an example, to configure its photovoltaic system, we need to make some calculations:

This household needs an inverter with output power larger than 4 kW at any time, as appliances require additional power at starting stage. So, please consider to select an inverter 1.5 times larger. If the household plans to add more appliances in the future, an even larger power inverter should be considered. Alternatively, if the homeowner chooses a 4 kW inverter or a smaller one, the household must have grid power as a supplement for electricity consumption.

Considerations for configuring a home solar energy storage system

To allocate a solar energy system for this case, we need to consider the following aspects:

Estimate how much of the household electricity consumption the photovoltaic energy can cover
Estimate how long the energy storage battery can support on cloudy days
Whether to allow grid power to charge the energy storage battery
Estimate the area of roof and/or courtyard available for solar panels
Understand the local sunshine duration
Whether the household wants to sell the PV energy to city grid, and this policy is there

BESS home solar energy storage system calculation plan and installation

Calculation method for home solar system configuration

Assuming the current market situation:

a 500W solar panel occupies approximately 2 square meters;

the daily sunshine duration for a specific project is 5 hours (please look up for your regional sunshine hours);

and for this case of household’s daily electricity consumption is 4 kW.

Area of solar panels, output power, and inverter configuration

Configuration Plan	Solar Panel Mode and Quantity	Covered Area	Total PV Output	1 sunny day PV Yielding (default 5 hours)	Inverter Input Power (Stretch method)
1	500W X 4 nos	8 m2	2 kW	10 kW	3 kW
2	500W X 8 nos	16 m2	4 kW	20 kW	5 kW
3	500W X 10 nos	20 m2	5 kW	25 kW	6 kW
4	500W X 12 nos	24 m2	6 kW	30 kW	8 kW
5	500W X 16 nos	36 m2	9 kW	45 kW	kW

PV Energy, Household Electricity Consumption, and Battery Storage Capacity Calculation

Configuration Plan	1	2	3	4	5
Every Sunny Day PV total Output	2 kW	4 kW	5 kW	6 kW	9 kW
Household Daily Power Consumption	4 kW	4 kW	4 kW	4 kW	4 kW
Daily PV Balance Power	-2 kW	0 kW	1 kW	2 kW	5 kW
Battery Storage Baseline* [1 day PV feed]	2kW (39.22A /51V)	4kW (78.43A /51V)	5kW (98.05A /51V)	6kW (117.65A /51V)	9kW (176.47A /51V)
Lithium Battery [2 days’ feed]	no balance, no increase	no balance, no increase	Balance 1kw plus daily PV 5kw	Balance 2kw plus daily PV 6kw	Balance 4kw plus daily PV 9kw
Lithium Battery [ N days’ feed] (shall deduce solo PV backup days)	no balance, no increase	no balance, no increase	Balance 1kw plus daily PV 5kw x (N-1)	Balance 2kw plus daily PV 6kw x (N-1)	Balance 4kw plus daily PV 9kw x (N-1)

Issues that need pay attention to

Please note the DOD issue

The lithium battery DOD rate (Depth of Discharge) means the usable proportion of its capacity. Usually the LiFePo4 Battery DOD is 80%, so the battery capacity indicated on Line “Battery Storage Baseline” is required usable capacity, divided by 0.8 for converting to physical battery capacity. Exg. 39.22A /51V 49A; 78.43A 98A;

Please note the inverter input power, output power and charge power

Solar inverters have different parameters for input power, output power and charge power. The output power usually is the same as input power or slightly smaller; The charge power is usually smaller than the previous two.

Please note the cloudy day issue

If your energy storage batteries are only charged by PV power, and your household depends on your energy storage, you need consider how many cloudy days / nights your energy storage can cover. Increase the PV array and battery capacity, as to achieve one sunny day charge can sustain your household power consumption for successive cloudy days / nights. It’s critical for houses without city grid electricity, or blackout kicks in some times.

Please note the on-grid option

If your area allows you to sell your PV electricity, and you plan to sell balance PV power simultaneously, you need on-grid inverter and extra 2-way smart power meter. In this case, you can:

use no-battery plan, for you only sell PV power for money (hedge against your electricity bill)
use schemed battery storage, for consideration such as EV car consumption, mobile usage, back-up for blackout for anticipated days.