What about charging tool batteries directly from a solar panel without an inverter? I have charged up 36 volt tool batteries with a 12v panel and a MPPT boost controller alone. Don't know if this was a good idea, but it worked. I had to wire a broken battery charger to hold the battery. It just seems like a waste of electricity using an inverter going from DC to AC then from AC to DC to charge these batteries. We are a Makita outdoor power equipment dealer, and they have a charger that uses a cigarette lighter to charge. We also carry Stihl and Echo, but they don't have that option. It would be nice to build a system that could do this from solar without an inverter. The problem with the Makita charger using a auto cigarrette lighter plug is that they take a long time to charge. Makita 2 - 18v 5Ah batteries would take 3 hrs 20 minutes. These same 2 batteries last about 30 minutes bring used in a line trimmer. The Makita AC chargers can charge these 2 batteries in about 45 minutes. For a landscaper using outdoor power equipment all day long, they would need about 360 watts/hr charging batteries. California is making these lanscapers convert to battery power by 2024. The pictures posted show what I've tried so far, 36v Stihl seemed to work, the 2- 18v Makita batteries in series didn't (no way to balance charge for that set up). The specs of the panel I used. Seems like the equipment manufactureres would come up with a viable way to charge batteries out in the field. The solar generators with pure sine wave inverters seem like the only option at this point.