Add a battery to your solar energy system

Solar batteries are gaining more popularity as they provide solar panel owners with lots of benefits. Why should you consider adding an energy storage to your solar power system? Read the post and you will get the answers to this and other questions, such as installation costs, ways to retrofit a solar system, etc.

Retrofitting a Solar System with Energy Storage

Energy storage systems for residential use, such as Powerwall by Tesla, are becoming more popular and less expensive. A lot of companies and households consider the option of retrofitting their photovoltaic arrays with storage batteries.

A residential energy storage system provides quite a few advantages and is particular attractive for those who have a PV system installed. A battery allows both consuming more energy on-site and saving it for backing-up in case of an outage. The ones whose power rates depend on time of use or who have to pay a demand charge are enabled to save funds by consuming electricity stored in a battery during high-rate hours.

Solar array owners who think about adding batteries to their PV installations have a few widespread questions, which we have answered below.

Is it difficult to retrofit solar power systems with back-up batteries?

It depends on how your power generating system is designed – if the possibility to add a battery was intended or not.

The so-called storage-ready systems are equipped with inverters which allow easy integration of batteries with PV systems. In this case, it is easy to add a battery with almost no auxiliary equipment.

In the event the solar system’s design does not imply a battery addition, it is somewhat more difficult to install storage. Owners of such systems can choose one of the following: either apply an AC-coupling or replace the existing inverter.


AC-coupling presupposes integrating an additional inverter into the solar panel system. In this case, one does not have to remove an existing inverter, thus saving on upfront costs. Besides, AC-coupling allows more flexibility in terms of a battery capacity in relation to the solar array. The drawback of this option is some drop of efficiency with the course of time.

AC-coupling battery

Alternating current is used in the majority of houses, while PV panels generate DC power. When converting direct current into alternating current, some energy gets lost. Installation of the AC-coupled back-up storage presupposes one more conversion step, which reduces the efficiency of AC-coupled solutions.

There are storage systems, such as Powerwall 2 by Tesla, that have inbuilt inverters, which can be mounted next to the existing inverters. Such batteries are categorized as AC-coupled systems as well.


Another option is replacing the existing inverter by a new one compatible with a battery. No string inverter can work much longer than a decade. That is why, if your solar array has already worked for 5 years or more, we recommend you considering a universal solution, such as Pika Islanding Inverter.

DC-coupling Battery

The key advantage of a DC-coupling is higher efficiency due to lower loss of the electricity generated by PV modules when converted. But such solutions cost higher upfront because the replacement of existing inverters lead to additional expenses on re-designing and re-wiring of a solar system.

Which batteries can be integrated into the existing solar panel systems?

The majority of solar batteries can be combined with a small scale residential or commercial solar system. What type of batteries to select depends on why you plan to install an ESS.

There are very few battery types that can make you completely independent from utility grids. The capacity of most storage systems like Powerwall by Tesla is insufficient for powering the building during several days in case of continuous clouds, raining or snowing.

In case you primarily plan to use a battery as a back-up source of energy during blackouts, we would recommend such high-capacity options as Harbor™ Smart Battery by Pika Energy or sonnenBatterie eco. But if you pay a demand charge or your electricity tariff rate is time-of-use, and you’d like to consume less power in peak hours, you may content yourself with batteries of smaller size, for example storage solutions by Enphase.

All energy storage projects differ from each other. When you plan to add a back-up battery to the solar system, you have to inform the installation specialists of the system’s parameters, your power consumption, as well as what you are installing a battery for. This information will help to define what type of a battery will be optimal for your business or household.

How expensive is it to install a battery?

It is not difficult to install back-up batteries. While installing a solar array, installers have to work on the rooftop. As for a solar battery, it is placed on the earth – commonly in some garage-like structures. So, the process doesn’t require as many people and they do not need to ascend a roof, which simplifies the logistics. That is why it is cheaper to install batteries than solar modules.

In case the existing power generating system works well and does not need to be considerably upgraded, the cost of installation will hardly exceed $1,000. However, the price is dependent on how much electricians charge for their labour where you live. Keep it in mind that replacement of the existing inverter will last longer and be more expensive.

Who can help you in case your solar installation company does not install batteries?

Though solar batteries are becoming more popular, they are not as widespread as solar panels so far. Some solar installation firms install storage systems as well. In the event your installation specialists cannot add a battery to your solar system, you can do one of the following:

  1. Request your solar installation company to recommend a battery installer. Probably, some other clients have already wondered about adding a battery. So, first of all, refer to your solar installer to learn if there are any battery installation specialists nearby.
  2. Ask your friends, relatives or people in the neighborhood. This is how most shoppers get in touch with solar installers. Contact those who already have solar batteries (or at least PV panels) at home, and they are likely to recommend you the company. Somebody’s installer specializes in battery addition, that’s for sure.
  3. Look for installers via the network of ESS manufacturers. Those who have already chosen the type of battery to install may ask the battery maker to assist in finding an installation company. Many producers of batteries for small-scale solar systems cooperate with installation specialists trained for working with this particular equipment.