Is Your Off-Grid Solar System Dimensioned Proportionally to Maximize Your Investment?
An off-grid solar solution has three main components: Solar panels, solar charge controllers (SCCs), and batteries.
Not too complicated, right? However, you must dimension each one appropriately to maximize your investment. What does that look like? The production, inverter, and storage capacities should be proportional to each other to avoid excess capacity on one side of the equation but falling short on the other.
For example, a rancher asked us to replace his solar batteries. His ailing lead-acid battery bank had ~16 kWh nominal storage capacity (= ~8 kWh usable capacity), but he only has six solar panels, each with 200 to 300W maximum production capability, aimed in the wrong direction.
His storage capacity far exceeds his production capability, even if he doesn’t use much power. Additionally, he has two Outback inverters that are too big for his needs. They draw a substantial amount of power even in standby mode. A sizable portion of the production is used to keep these inverters on even if no other consumption is present.
The root cause of his frustration is poor dimensioning, and replacing the batteries won’t solve it. The batteries, no matter old or new, are simply “hungry” all the time because there isn’t enough solar production to top them off (which accelerates degradation, especially for lead-acid batteries).
In this case, an effective solar system improvement isn’t just about replacing batteries. To make the most of his investment, this client should add solar panels to boost production and dimension the battery bank so that the energy storage meets his needs, while not so large that the cells never have the opportunity to reach full charge.
We also recommend disconnecting one of the two Outback inverters. He doesn’t have large loads, and the house has a 24V system. Using just one inverter reduces unnecessary power draw when in standby mode.
What about the SCCs? Depending on the model, an SCC can effectively handle a specific amount of input from the solar panels. Based on the number of panels in a system, we can determine how many SCCs we need to optimize the solar power captured.
For clients with small- to mid-sized systems, we often recommend using two smaller SCCs (instead of one large one), wired in parallel for redundancy and resiliency. Even if one string of solar panels or SCC has issues, the system will retain half of its production capability.
If you suspect that your system isn’t dimensioned proportionally, don’t fret. In many cases, small and low-cost adjustments can make a substantial difference.
Is your off-grid system dimensioned to maximize your investment? Schedule an evaluation to find out.
