Batteries are your energy reservoir, and the size and type of battery used is critical. The use of batteries in off-grid or grid-interactive (grid connected with a battery backup) systems requires careful design and consideration.
A truly off grid solar system must incorporate batteries to achieve true energy independence. Batteries function as the ‘bank’ where excess renewable is deposited and then later withdrawn when needed. SAGE Energy is proud to be dealers of Canada’s own (and Nova Scotia’s own) Surrette batteries.
Batteries are the energy reservoir in solar power systems, and it is important to choose the size and type of battery carefully. Surrette, based in Springhill NS, has the well-earned reputation for building one mean battery. Their red solar batteries are the preferred storage solution for solar systems in both Canada and the US. It’s a reputation based on capacity, cycling performance and long life.
What makes a Surrette battery better?
- The Surrette solar batteries are designed for cycling performance – repeated discharges over and over.
- Extra thick plates offer more capacity and longer life
- The unique “resistox” plate design offers more resistance to corrosion and maximizes the life of the battery.
- Backed by industry leading warranties.
Off-grid battery services
Battery failures are rarely the fault of the batteries themselves. Properly sized battery banks that are well-maintained will last 5-15 years, depending on the model and usage.
– Battery bank sizing
– Battery upgrades
– System diagnosis and repairs
– System tutorials and maintenance
An off-grid solar power system is not plug-and-play. The biggest part of the work is maintaining the battery bank.
Can I get enough batteries to run my grid-tied house?
Short answer: No. Although it can occasionally be possible, we hardly ever recommend “unplugging” a conventional home. Generally speaking, even an energy-efficient home uses too much power to be feasible in an off-grid situation.
How many days of load should I size my battery bank?
A battery bank should be sized (as a minimum) to a capacity of 5 days of load. Energy use in most home power systems increases over time, so consider sizing larger than that.
Can I use multiple parallel strings?
The ideal battery bank is the simplest, consisting of a single series of cells that are sized for the job. Under no circumstances is it advisable to install more than three parallel battery strings. The resulting bank will tend to lose its equalization, resulting in accelerated failure of any weak cells. Weak cells will be difficult to detect because they will “steal” from the surrounding cells, and the system will suffer as a whole and will cost you more in the long run.
What is DOD (Depth of Discharge)?
A battery is fully discharged when it can no longer give a useful current (flow of electrons) for your application. As you use it, the voltage drops too. The depth of discharge (DOD) is how much has been discharged. For example, a 20% DOD means 20% of its capacity has been discharged. The State of Charge (SOC) is just the opposite of the DOD. If the DOD is 20% then the SOC is 80%: 20% discharged is the same as saying 80% remaining charge – the glass is either 20% empty or 80% full.
How do I know when my batteries need to be replaced?
A battery has reached the end of it’s lifetime when you the battery can’t hold as much of a charge anymore; it’ll do less and less between recharges.
The general rule-of-thumb is do not discharge more than 50%. Basically, the deeper you discharge it on a regular basis, the shorter the useful lifetime of the battery.