Recently I published a build video for a 576 watt hour solar generator. The community has nicknamed it the STN576. People have also asked about the cost. I didn’t want to publish the costs without an explanation and breakdown comparison, between the Goal Zero Yeti 400 lithium, and Yeti 400 lead acid as some standard examples.
The point of this post is to help the community understand the true cost of a solar generator, and how cheaper at the cash register is not always cheapest to own over the products lifetime.
Okay, let’s turn it over to John to explain this spreadsheet.
John Schultz N0JDS:
This comparion is based on the the result of the following calculation:
- (Total System Cost / Total Delivered WH of system for it’s expected lifetime) * 100 Watt Hours
- The Total Delivered WH over the expected lifetime is calculated by (useable WH rating of the pack * the expected number of cycles)
This gives us an objective metric to compare the actual cost for every delivered 100 watt hours of energy for any given solar generator system or battery pack.
There is no cost factored in for solar panels or any other means of recharging the pack. This formula seeks to isolate the actual cost of delivered WH of a pack regardless of the source of charging energy.
As we see in the spreadsheet, the STN576 costs ~650$ to build with all best components, compared to 600$ for the Yeti Lithium and 450$ for the Yeti Lead Acid. What should be clear is:
- How many charge cycles before battery or system replacement.
- Total watt hours of the system.
- The useable storage capacity of the system.
So the best way to understand how much your solar generator costs is by understanding the cost per 100 watt hours, and it’s expected lifetime (charge cycles). Certainly the Goal Zero Yeti is cheaper to buy at the cash register, but the Goal Zero Yeti will also need to be replaced several times before the STN576 reaches end of life. Moreover the STN576 end of life upgrade, is as simple as replacing the user serviceable and upgradable cells.
The presumably “cheaper price” at the cash register Goal Zero offers you, is offset by the fact that you’ll need to buy many more of them over the same amount of time, had you built it yourself. The addition of the full sine wave inverter is also not an adequate reason to choose the Goal Zero, since a full sine wave inverter can be purchased for 50 bucks, and integrated into the STN576 as well. In the end, it’s all “marketing”.
It’s easy to be misled by the price we pay at the cash register!
Food for thought.