That is simply one component. From the batteries to the inverter and out to the pump is a lot of things that must work together to deliver the most available power. I am trying to be generous here but you seem to have made up your mind that the problem is your inverter. My test showed that a HF inverter of lesser rating than your SolArk could start a 1/2hp pump under pressure and operate it without problems.
Ok great. Then yes, an autotransformer will help. I personally wouldn't use a split-phase high frequency inverter. But if I did, it would have a transformer of some kind connected.
Is your inverter the 5k 120/240 or the 5k 120 (newer version)?
I have a 3500 watt Trace and a 3500 watt Outback that can do it. Of course they are a heavy, low frequency units.
Which it why running a test starting a 120vAC 1/2 hp pump on my 3kw HF inverter was of interest. The OP review of his SolArk lacks enough detail to know if it is a bad unit or there is an issue with how he has it setup. Since he seems bent on going another direction I am bowing out of this Thread.
What is that add-on component?
Split phase 240/120. It's the Sol-Ark (5K) before they started offering the EMP hardened units.
If it is split phase 240v than each 120v leg is likely only 2500w max. In practice this could be lower since an imbalanced leg issue can arise. I would guess this is the cause of your pump starting problems.
the pump is a shallow well pump...25ft... 1/2hp single phase. works fine with the generator. going out for a 240V jet pump today. I don't have a well and don't intend one. we're hauling water and using above ground storage tanks. if the 240v works, and I'm betting it does with confidence - I'm going the mount the old one on the water hauler with the generator and also have the water hauler for fire fighting purposes. I do have the manual for the Sol-ark. it's a 5K split phase 240/120.
Before you buy a new pump many pump motors can be wired dual voltage either 120 or 240. Check the name plate.
that is part of it. but I did isolate the draw to only the pump when I made every attempt to solve the problem. I even thought the pump was bad, but it worked fine when I tested it on the generator...but for the house with nothing else running, the inverter still wouldn't run it. other than the pump,, my loads are well balanced, but I typically don't have any load over 500w on either leg at any time. exception is when running one of the mini splits....in economy mode they level off around 500w, in full turbo 1600w... but they are single phase so I watch my load when using them.
The pump imbalanced the leg all by itself. A 5000w 240v split phase is not a 5000w 120v setup. You would need a 10,000w 240v split phase to equal that.
If his SolArk has the ability to be setup for full power on just one 120v output (Some of these can be wired that way) than he would not need a 240v pump. However if his home is wired as a 240v split phase setup he would have to jumper the two legs of his breaker panel together and do without any 240v appliances.
It would have been nice, but the pump wasn't switchable to 240v. I had ordered one from Lowe's (2wks ago) and picked it up today.
I did setup a generator input to "grid" input for the inverter. This works VERY well and is HIGHLY configurable. ... I mean awesome. The inverter will parallel to the generator and use both PV and Gen at the same time. only drawback to that is the inverter will follow the cycle speed of the generator....that's what my other post is about....trying to clean up that power. There's a solution someone suggested and I will try it sometime in the future. but I very rarely need the generator. so it's not on my hot list.
