Power Supplies

Transformerless PV Inverter Claims Efficiency and Cost Records

The Sol-Ark 8K PV inverter from Portable Solar LLC (Sol-Ark) has claimed records for 48V battery-based inverter efficiency using innovative design that is easy to install and even easier to use.

"We discarded traditional design methodologies of dc-coupled and ac-coupled battery systems. We reduced the cost 25%+ by combining all of the electronics into a single dc transformerless system. Transformers are needed for power conversion and 120/240V split phase in/out, but they are massive, expensive, and create lots of wasted energy," stated Bhawna Oberoi, Business manager at Sol-Ark.

"Eliminating transformers allowed us to achieve 97% efficiency. That is unbelievably high while using affordable 48V external batteries. Several expensive 380V battery solutions claim high efficiency but fail to include the 380V conversion losses to an internal 50V battery.

"Our engineers have been invited to present their new design methodology at Intersolar 2018 and Solar Power International 2018. Below you can see a side by side specification comparison of Sol-Ark 8K, Tesla, Outback, Magnum, Pika, Solar Edge, and Darfon.

Performance comparison. (click on table to enlarge)

"High Peak Power for Off-Grid: Grid Tied battery backup designs have good continuous power selling back to the Grid but sacrifice peak power for starting big motors Off Grid. Peak Power is why traditional DC Coupled inverters continue to dominate Off Grid applications. Even though the Sol-Ark 8K has good continuous Grid Tie power, we doubled component values for 20KW peak Off Grid power. The 20KW power was expensive, but it improves long term reliability and cooling of the system.

"Off-Grid Features Reduce Battery Size: Since we have such a large customer base that lives Off Grid, we incorporated programmable smart loads for running A/C and hot water on solar power instead of batteries (adding years to their lifespan and reducing size). One of the single biggest problems Off Grid is knowing how much battery capacity you have left. Will you have enough power if it rains tomorrow? Not to worry. We incorporated a proprietary % battery learning algorithm that even accounts for aging batteries.

"Great Ease of Use: Sol-Ark 8K was designed to be the easiest battery solar install ever. We also used a color touchscreen GUI so consumers could understand at a glance.

"Built to Survive Nuclear War: Because of our background [top secret defense contractors], we hardened Sol-Ark 8K against EMP, Solar Flare, and cyber-attack. Independent government labs hit Sol-Ark 8K about 140 times at twice the military levels (100KV/m) without damage to the inverter, appliances, or solar panels," concluded Oberoi.

Portable Solar LLC
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