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Solar Mini 4 Hermes: The Quick Start, And Where It Fits In Your Agent OS
Solar Mini 4 Hermes is the quickest free brain upgrade you can give Hermes Agent right now, because Upstage's new Solar Mini 4 is free for two weeks on Nous Portal.
You can set it up in Hermes Cloud, Hermes Desktop, the Hermes dashboard or the Hermes tab of my Agent OS.
The question people ask me is whether a free model is worth adding to a serious agent setup.
My answer is yes for the fast, easy jobs, as long as you pick the free variant and keep the hard work on a stronger model.
What Solar Mini 4 Hermes is, in one minute
Solar Mini 4 is a compact model from Upstage AI, a lab in South Korea.
It is a mixture-of-experts model with 35 billion parameters in total and 3 billion active at a time.
Its context window is roughly 500,000 tokens, and OpenRouter lists it at 524,288.
Artificial Analysis scores it 24 on its Intelligence Index, which it says is one point above Nemotron 3 Ultra with 55 billion active parameters.
Artificial Analysis also describes it as a proprietary model, so there are no weights to download and run offline.
Right now it is free for two weeks on Nous Portal, the model portal from Nous Research that Hermes Agent plugs into.
Solar Mini 4 Hermes simply means making that model the brain of a Hermes profile.
I keep the model background short here, because my full Solar Mini 4 guide covers the specs and every access option.
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The Solar Mini 4 Hermes quick start: four routes
Every route ends in the same place, which is a Hermes profile running on the free Solar Mini 4.
| Route | Where you click | Best for |
|---|---|---|
| Hermes Cloud | portal.nousresearch.com/cloud → create agent → model section → scroll → Free → Upstage Solar Mini 4. | Running a free agent with nothing installed on your machine. |
| Hermes Desktop | New profile named after the model → refresh the models list → Nous Portal → Solar Mini 4 from the free models. | Testing a new brain without touching your main agent. |
| Hermes dashboard | hermes dashboard → Models → Set main model → type "solar" → Nous Portal → the free variant. | Setting the main model for a profile in under a minute. |
| Agent OS Hermes tab | Hermes tab → pick the solar mini 4 profile → chat. | Comparing brains side by side inside one dashboard. |
If you are brand new to Nous Portal, hermes portal logs you in and sets Nous up as your provider first.
If you like the terminal, hermes profile create solar-mini-4 makes the profile and hermes -p solar-mini-4 chats in it.
The one setting you must get right
Type "solar" into Set main model and you will see two Solar Mini 4 entries under Nous Portal.
One of them is free and one of them is paid.
Pick the paid one by accident and your "free" agent quietly starts billing you on every task.
So read the label, pick the free variant, and check it again before you hand the agent any real work.
That single click is the whole difference between a free setup and a surprise invoice.
How Solar Mini 4 fits into an Agent OS workflow
Most people treat a new model like a new chatbot, and that is the wrong way to think about it.
In my Agent OS, a model is a part that I slot into a profile, not a product I live inside.
I run one Hermes profile per model, so every brain gets its own settings and memory.
The Hermes tab in the Agent OS reads those same profiles, so switching brains is a two-click job.
That means a new free model like Solar Mini 4 can take over the easy jobs without touching the profile I rely on every day.
The lanes I use
This is how I decide which jobs go to the free brain and which go to a stronger one.
| Job in the Agent OS | Which brain I give it | Why |
|---|---|---|
| Weekly news and market briefs | Solar Mini 4 (free variant) | It is fast, it cites sources and the job is easy to check. |
| Summarising long files | Solar Mini 4 (free variant) | The roughly 500,000-token context window takes in a lot at once. |
| Sorting notes and tagging tasks | Solar Mini 4 or another free flash model | Small repeatable jobs suit small fast models. |
| Planning a build or a campaign | A frontier model such as Claude Opus 5.5 | Hard planning is where small models fall over. |
| Client-facing final copy | A frontier model plus my own review | Mistakes here cost trust and money. |
| Anything that pays, sends or deletes | A human approval step | No model should own an action you cannot undo. |
Solar Mini 4 sits in the fast, cheap lane, and that is exactly where a 3-billion-active model belongs.
How I tested it before trusting it
I never let a new brain near real work until it passes two quick tests.
The first test was the single word "test" in a fresh chat.
It replied fast, told me the session was live and noted that memory was switched off, which is normal on a new profile.
The second test was a real job, which was the latest AI automation news from the last seven days.
It came back quickly with a breakdown, a list of sources and a "what stands out" section.
It even flagged an Oracle launch I had not heard about, which is exactly what I want from a research agent.
That is a solid pass for a free model on a basic agentic task.
A test plan you can copy into your own Agent OS
- First, type "test" and check that the session comes back live.
- Second, ask for the latest news in your industry from the last seven days with sources.
- Third, ask it to read a folder and summarise the three newest files, so you see the tools working.
- Fourth, ask a follow-up that depends on the previous answer, so you know it keeps context.
- Fifth, click through every source it gives you before you share anything.
Rate limits and switching to other free models
Free models are shared by a lot of people, so they get rate limited.
When Solar Mini 4 is busy, you will see slow replies or errors in the middle of a job.
My first move is to refresh the model list, because a missing model is usually a stale cache.
hermes model --refresh wipes the model picker cache and re-fetches every provider's live list.
My second move is to switch to another free profile and carry on working.
When I recorded, the Hermes Cloud free list looked like this.
| Free model on Nous Portal | Maker | Role in my Agent OS |
|---|---|---|
| Solar Mini 4 | Upstage | My fast default for research and summary jobs while it is free. |
| Step 3.7 Flash | StepFun | The first backup when Solar Mini 4 is rate limited. |
| Ling 3.1 Flash | inclusionAI | A second flash model for cross-checking answers. |
| Nemotron | NVIDIA | A free fallback from a big lab. |
| Laguna XS 2.1 | Poolside | A small model I test on light coding chores. |
| LongCat 2.0 | Meituan | A much larger model worth trying while it stays on the free list. |
The list changes over time, so check it inside Hermes before you build around any one model.
Because the free window is two weeks, I keep the model as one setting in the profile, so the end of the promo is a one-click change.
Honest notes on quality
Solar Mini 4 is not frontier level.
It is not Claude Opus 5.5, and it will not plan complex builds or write polished long-form content to that standard.
One viewer told me it ran badly for them, so results clearly vary by task and setup.
What it does well is speed, and while the promo lasts it costs nothing.
For research, summaries, sorting and quick drafts, it earns its place in the fast lane.
If you want a fully free stack that also runs offline, my Hermes free forever guide covers the local route.
Five Solar Mini 4 Hermes mistakes I see people make
The first mistake is changing the model on your main profile instead of making a new one.
Your daily agent should keep working while you test a new brain on the side.
The second mistake is picking the paid variant because it appears near the top of the list.
Always look for the free label before you click.
The third mistake is assuming the model has vanished when it does not show up.
Refresh the model list first, because that fixes it most of the time.
The fourth mistake is forgetting that the free window lasts two weeks.
Decide now which free or paid model takes over that profile when the promo ends.
The fifth mistake is giving a small model a frontier-sized job and then blaming the model.
Keep it in the fast lane and it will do exactly what you need.
Using the dashboard from inside the Agent OS
You do not have to open a terminal to reach the Hermes dashboard.
In my Agent OS, the manage section opens the same dashboard where you set the main model.
That means the whole loop of creating a profile, setting the free Solar Mini 4 and chatting with it happens in one place.
It is a small thing, but it is the reason I can test a new model in five minutes instead of an afternoon.
What to do next
Create a solar-mini-4 profile today and set the free variant as its main model.
Run the five-step test plan, then give it your most boring weekly job.
If it passes, leave it in the fast lane and keep your stronger brain for the hard work.
If you want the whole Agent OS with the Hermes tab, the profiles and the training already set up, it lives inside the AI Profit Boardroom, with 3,400+ members and four coaching calls a week.
Also On Our Network
FAQ
Is Solar Mini 4 free in Hermes Agent?
Yes, for now. Solar Mini 4 is free for two weeks on Nous Portal, which Hermes Agent connects to. You must pick the free variant, because a paid variant sits in the same model list.
How do I set Solar Mini 4 as the main model in Hermes?
Run hermes dashboard, open Models, click Set main model, type solar, choose Nous Portal as the provider and select the free Solar Mini 4 variant.
Can I use Solar Mini 4 in the Agent OS?
Yes. Create a solar mini 4 profile in Hermes, then open the Hermes tab in the Agent OS, pick that profile and chat with Hermes directly.
What should I do when Solar Mini 4 is rate limited?
Refresh the model list first, then switch to another free Nous Portal model such as Step 3.7 Flash, Ling 3.1 Flash or Nemotron, and switch back later.
Is Solar Mini 4 good enough to replace a frontier model in Hermes?
No. It is fast and free and handles basic agentic tasks, but it is not frontier level. Keep planning, hard reasoning and client-facing copy on a stronger model such as Claude Opus 5.5.
Final word on Solar Mini 4 Hermes
Make a separate profile, pick the free variant and give it the fast, easy lane in your Agent OS.
That is how you get real value out of Solar Mini 4 Hermes while the free window is open.
About Julian
I'm Julian Goldie, an AI entrepreneur, SEO expert and the founder of the AI Profit Boardroom, which has 3,400+ members.
I help business owners scale with AI agents, automation and SEO.
My YouTube channel has 400,000+ subscribers, and I run Goldie Agency, a seven-figure SEO agency.
Related guides on agentos.guide
→ Solar Mini 4: What It Is And How To Use It
→ Hermes On Your Claude Subscription
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