My Solar Mini 4 Hermes verdict is simple: it's a fast, free brain for Hermes Agent that handles basic agentic jobs well, but it is not frontier level and you shouldn't treat it like it is.

Solar Mini 4 is Upstage AI's new small model, and it's free for two weeks on Nous Portal, the model portal Hermes Agent connects to.

I set it up in Hermes Cloud, Hermes Desktop, the Hermes dashboard and my Agent OS, then tested it on a ping and a real research job.

This page goes through it feature by feature, gives each part a score, and ends with who should use it.

If you only want the bottom line, look at the scores table in the next section.

Solar Mini 4 Hermes Verdict At A Glance

These are my own ratings from setting it up and testing it, not a lab benchmark.

Feature My score One-line verdict
Price 5 out of 5 It's free for two weeks on Nous Portal, which is hard to beat.
Setup 4 out of 5 Four routes all work, but the paid-variant trap costs it a point.
Speed 4.5 out of 5 Both of my tests came back fast, which suits agent loops.
Research quality 3.5 out of 5 It returned a sourced, structured news brief, but you must still check the facts.
Hard reasoning and writing 2 out of 5 It's not frontier level, and it's nowhere near Claude Opus 5.5.
Reliability 3 out of 5 Free access can be rate limited, and one viewer said it ran badly.
Overall 3.5 out of 5 It's a great free daily helper and a poor choice for hard jobs.

What Solar Mini 4 Is

Solar Mini 4 is a compact model made by Upstage AI, a lab in South Korea.

It's a mixture-of-experts model with 35 billion parameters in total and 3 billion active on each step.

Its context window is roughly 500,000 tokens, which OpenRouter lists as 524,288.

Artificial Analysis gives it a score of 24 on its Intelligence Index.

Artificial Analysis also says that's one point higher than Nemotron 3 Ultra, which has 55 billion active parameters.

So it punches well above its size, which is the headline claim in my video.

Artificial Analysis calls it a proprietary model, which means you can't download the weights and run it on your own machine.

I've written a separate Solar Mini 4 breakdown if you want the model background and every way to access it.

Feature 1: Price And The Free Window

The biggest feature is the price, because it's free for two weeks on Nous Portal.

Nous Portal is Nous Research's portal, and Hermes Agent talks to it natively.

That makes Solar Mini 4 one of the easiest free brains you can drop into Hermes right now.

The catch is the word "two weeks", so don't build anything that breaks when the promo ends.

My score for price is 5 out of 5.

Feature 2: Setup Routes

I tested four ways to set it up, and every one of them worked.

Route How it works My take
Hermes Cloud You go to portal.nousresearch.com/cloud, create an agent, open the model section, click "Free" and pick Upstage Solar Mini 4. It's the easiest route because nothing runs on your computer.
Hermes Desktop You create a new profile named after the model, refresh the models list and pick Solar Mini 4 from the free models. It's my favourite because one profile per model makes testing safe.
Hermes dashboard You run hermes dashboard, open Models, click "Set main model", type "solar", choose Nous Portal and pick the free variant. It's quick, but this is where the paid-variant trap lives.
Agent OS You open the Hermes tab, pick the solar mini 4 profile and chat with Hermes directly. It's the best route if you compare models side by side.

The trap is real, so I'll spell it out.

When you type "solar" into "Set main model", you see a free Solar Mini 4 and a paid one.

Pick the paid one by mistake and your free agent starts costing money.

That one design detail is why setup gets 4 out of 5 instead of 5.

Feature 3: Speed

Speed is where Solar Mini 4 shines inside Hermes.

When I typed "test" into a fresh profile, it replied quickly and told me the session was live.

It also noted that memory was switched off, which is normal on a brand-new profile.

The research job came back fast too, which matters in an agent because every tool call waits on the model.

A slow brain makes a whole agent feel slow, and this one doesn't.

My score for speed is 4.5 out of 5.

Feature 4: Research Quality

My real test was a job I'd normally hand to an agent every week.

I asked for the latest AI automation news from the last seven days.

It returned a structured breakdown, a list of sources and a "what stands out" section.

It also surfaced an Oracle launch I hadn't seen, which is exactly what a research agent should do.

The output was useful, but it's a free small model, so I'd still click through every source before sharing it.

My score for research quality is 3.5 out of 5.

Feature 5: Hard Reasoning And Writing

This is where the honest part of the review comes in.

Solar Mini 4 is not frontier level.

It's not like Claude Opus 5.5, and it won't plan complex builds or write polished long-form content to that standard.

Small active-parameter models are built for speed and cost, and they trade away depth to get there.

If your job needs real thinking, put a stronger model in that Hermes profile instead.

My score for hard reasoning and writing is 2 out of 5.

If you want to see which models actually top the coding charts, my best AI models for coding ranking covers that.

Feature 6: Reliability And Rate Limits

Free models are shared by a lot of people, so they get rate limited.

When that happens, you'll see slow replies or errors partway through a task.

The fix is to refresh the model list first, because a missing model is usually just a stale list.

hermes model --refresh wipes the picker cache and re-fetches every provider's live model list.

If it's still limited, switch the profile to another free model and come back later.

One viewer also left a comment saying it ran badly for them, so quality clearly varies.

My score for reliability is 3 out of 5.

Feature 7: The Free Alternatives Sitting Next To It

One underrated feature of the Nous Portal route is that Solar Mini 4 isn't alone.

When I recorded, the free list in Hermes Cloud showed these models.

Free model Maker Where it fits
Solar Mini 4 Upstage It's the fast, small all-rounder I tested in this review.
Step 3.7 Flash StepFun It's a flash model I'd use as the first backup.
Ling 3.1 Flash inclusionAI It's another flash model for a second opinion.
Nemotron NVIDIA It's a free option from a big lab.
Laguna XS 2.1 Poolside It's a small model with a coding focus.
LongCat 2.0 Meituan It's a much larger model that's worth testing while it's free.

Having backups one click away makes the rate limits much easier to live with.

🔥 Want my full Hermes model-testing setup? Inside the AI Profit Boardroom, I've got Hermes Agent training, the Agent OS with its Hermes tab, and courses on DeepSeek Harness, Claude Opus 5.5 and Jev AI. You'll be learning alongside 3,400+ members with four coaching calls a week. → Get access here

Solar Mini 4 Hermes Versus My Other Options

Here's how it stacks up against the choices most Hermes users are weighing.

Option Cost in Hermes Strength Weakness
Solar Mini 4 (free variant) It's free for two weeks on Nous Portal. It's fast and fine for basic agentic tasks. It's not frontier level and it can be rate limited.
Another free Nous Portal model It's free while it stays on the list. It's a quick swap when Solar Mini 4 is busy. Quality varies a lot from model to model.
Claude Opus 5.5 You pay for it. It's far stronger on hard reasoning and writing. It costs real money on every task.
A local model It's free to run on your own machine. Your data stays private and offline. It needs a strong computer and it's often slower.

If you're weighing harnesses as well as models, my DeepSeek Harness review is worth a read.

How To Set It Up Without Falling For The Trap

Here's the shortest safe path I can give you.

  1. Create a new Hermes profile named after the model, such as solar-mini-4, so your main agent stays untouched.
  2. Run hermes dashboard, open Models and click "Set main model".
  3. Type "solar", choose Nous Portal and pick the variant labelled free.
  4. Type "test" into a new chat and check that the session is live.
  5. Give it one real research job and check the sources.
  6. If it's slow or missing, refresh the model list or switch to another free model.

That's the whole setup, and it takes about five minutes.

Who Should Use Solar Mini 4 In Hermes

You should use it if you want a free, fast brain for research, summaries, sorting and first drafts.

You should use it if you like testing new models in their own profiles before you commit to anything.

You should skip it for client-facing final copy, complex builds and anything involving money or deletions.

You should also skip it if you need guaranteed uptime, because free access can be rate limited.

🔥 Want to know which brain to put in each Hermes profile? Join the AI Profit Boardroom and ask me on one of the four weekly coaching calls, with 3,400+ members already running Hermes. → Join the AI Profit Boardroom

Final Verdict

Solar Mini 4 earns 3.5 out of 5 from me as a Hermes brain.

It's free, it's fast and it handled a real research task well.

It's not frontier level, the free window is short, and the paid variant sits one wrong click away.

Use it for the easy jobs, keep a stronger model for the hard ones, and you'll get real value out of it.

Related Reading

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FAQ: Solar Mini 4 Hermes Review

Is Solar Mini 4 good in Hermes Agent?

It's good for fast, basic agentic tasks like research and summaries, and it's free for two weeks on Nous Portal.

It's not frontier level, so hard planning and polished writing belong on a stronger model.

What is the biggest mistake when setting up Solar Mini 4 in Hermes?

The biggest mistake is picking the paid variant.

"Set main model" shows both a free and a paid Solar Mini 4 under Nous Portal, and you must select the free one.

How does Solar Mini 4 compare with Claude Opus 5.5 in Hermes?

Claude Opus 5.5 is far stronger on difficult work.

Solar Mini 4 wins on price during the free window and on speed for simple tasks.

Can I run Solar Mini 4 locally with Hermes?

No, you can't.

Artificial Analysis describes it as a proprietary model, so you use it through Nous Portal or another hosted provider.

What are the best free alternatives to Solar Mini 4 in Hermes?

The free list I saw also had Step 3.7 Flash, Ling 3.1 Flash, Nemotron, Laguna XS 2.1 and LongCat 2.0.

The list changes, so check it inside Hermes before you pick.

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About Julian

I'm Julian Goldie, an SEO entrepreneur, author and founder of the AI Profit Boardroom, which has 3,400+ members.

I help business owners scale with AI agents, automation and SEO.

  • I've built a 7-figure agency, Goldie Agency, with a team of around 50 people.
  • I've grown a YouTube channel to 400,000+ subscribers.
  • I wrote the Amazon best-sellers "SEO Link Building Mastery" and "Agency Marketing Mastery".
  • My Udemy courses have taught over 50,000 students.

→ Get my best AI training inside the AI Profit Boardroom

Pick the free variant, test it on your own jobs, and you'll know within ten minutes whether Solar Mini 4 Hermes earns a place in your setup.